doped strontium aluminate - ACS Publications

Subscriber access provided by University of South Dakota

Applied Chemistry

Facile development of photoluminescent textile fabric via spray-coating of Eu (II)-doped strontium aluminate Tawfik Khattab, Mohamed Fawzy Rehan, Yousry Hamdy, and Tharwat Ibrahim Shaheen Ind. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/acs.iecr.8b01594 • Publication Date (Web): 30 Jul 2018 Downloaded from http://pubs.acs.org on August 6, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Industrial & Engineering Chemistry Research

Facile development of photoluminescent textile fabric via spray-coating of Eu (II)-doped strontium aluminate Tawfik A. Khattab, a* Mohamed Rehan, a* Yousry Hamdy, b Tharwat I. Shaheena a

b

Textile Industries Research Division, National Research Centre, 33 El-Behouth Street, Dokki, Giza 12622, Egypt. Spectroscopy Department, National Research Centre, 33 El-Behouth Street, Dokki, Giza 12622, Egypt.

(*) corresponding author: Dr / Mohamed Rehan ([email protected]) and Dr / Tawfik Khattab ([email protected]).

Abstract The present paper focuses on the development of novel smart fabrics having warning photoluminescent properties that keep light emitting for a period of time in absence of the illumination source. Phosphorescence commonly brings added value for safety enhancement. Herein, we introduce a textile material coated with a photoluminescent layer. Dysprosium and europium doped strontium aluminate phosphor were admixed with a mixture of an adhesive binder and distilled water to afford the pigment-binder formula which then applied directly onto wool fabric using spray-coating technique. Results declared that the optimal excitation wavelength of the coated fabric occurred at 365 nm and emission peak was also observed at 517 nm. A homogenous phosphorescent layer was assembled on the surface of the wool fabric relying on the pigment concentration existed on the pigment-binder formula. This coated layer represents a substantial development of greenish-yellow, bright white, turquoise, and off-white colors as described by CIE Lab color space data under ultraviolet irradiation. The decay curves and life-time of phosphorescence was investigated. The fluorescent optical microscope, energy dispersive X-ray analysis, photoluminescence spectroscopic data, scanning electron microscopy and elemental mapping are described. The comfort properties of treated wool fabrics were evaluated by studying their stiffness and air permeability. Page 1 of 31

ACS Paragon Plus Environment

Industrial & Engineering Chemistry Research 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 31

Keywords: SrAl2O4:Eu2+, Dy3+; Spray-coating; Phosphorescence; Warning garment; wool fabric.

1. Introduction Smart clothes have the ability to sense and respond to an external stimulus, such as light, pressure, magnetic and electric fields, heat, pH, solvent polarity, and chemical agents

1-4

. For

example, smart fabrics can liberate medicine or moisturizer onto skin, monitor and adjust the muscular vibrations during the wearer's physical activity, and even liberate substances capable to regulate body temperature. Smart textiles are able also to alter their color, light up in a certain pattern or even function as displays presenting pictures and video. In general, there are three key parts that must exist in smart textiles comprising sensing, actuation, and control units. Merging textile finishing and miniaturized electronic devices are able also to create smart clothing that allow digital units to be implanted in such garments to impart the capability of communication, transformation, and energy conductivity 5-7. Photoluminescent materials have been used in a variety of applications. The most promising application is for safety directional means such as exit and directional signs in case of blackout circumstances due to power failure or fire. Photoluminescent safety marks can be formulated in paints and plastic strips or signs to assist evacuation by guiding and directing public to safe sites 8-10

. Phosphorescent pigments are characterized by luminescent properties due to their excitation

upon exposure to an illumination light source and their capability to store light energy. Photoluminescent materials are either made of organic compounds such as porphyrins and perylenes or inorganic materials such as SrAl2O4:Eu2+, Dy3+ which is known as photoluminescent pigments, enclosed in flexible or rigid solid systems, or liquids such as paints Page 2 of 31


Page 3 of 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


or printing liquid pastes

11-14

. However, photoluminescent organic colorants results in a number

of problems such as poor photo- and thermal stability, colorant gradual degradation, higher stiffness and low colorfastness properties such as poor washing and light colorfastness. Some of these weaknesses were defeated by handling dyes as pigments employing the microencapsulation processing; although such approach improves the stability of the photoluminescent materials, it commonly imparts a certain roughness and hardness to the fabric, reducing the fabric comfortability 15, 16. On the other hand, the inorganic pigment phosphors, such as SrAl2O4:Eu2+, Dy3+, are long persistence phosphorescent materials. Because of their highly photo- and thermal stability, resistance to fatigue, high quantum efficiency and long life, strontium aluminate phosphors replace sulfide phosphors in a variety of application. Such long afterglow inorganic phosphors are presently utilized in many goods such as switches, decorative articles, luminous indicators, guidance markings and table clothing. Up till now, several long-persistent photoluminescent pigment phosphors have been produced as primary emitters of different colors, such as SrMgSi2O6:Eu2+/Dy3+ or CaAl2O4:Eu2+/Nd3+ for blue MgAl2O4:Mn2+ for green

4, 19

17, 18

, SrAl2O4:Eu2+/Dy3+ or

, and CaS:Eu2+/Tm3+/Ce3+ or Y2O2S:Eu3+,Mg2+/Ti4+

20, 21

for red.

Compared to other long-lasting photoluminescent phosphors, SrAl2O4:Eu2+,Dy3+ has been proved to be an exceptional long-lasting phosphor as a result of its photo, thermal, chemical and physical stability, as well as its excellent brightness and extended persistence time (more than ~10 hours) 22, 23. In addition, such inorganic doped pigment phosphor is nontoxic, recyclable and non-radioactive

24, 25

and photonic traps

. A photoluminescent pigment consists of crystals of aggregated elements

26, 27

. The crystals can be distinguished as being luminescent as a result of

their excitation when charged by a light source, while the photonic traps are distinguished by their capacity to store light energetic photons, and therefore becoming phosphorescent. Thus,

Page 3 of 31



Page 4 of 31

upon turning the light source off, the crystals stay excited and keep discharging light which is usually supported by photonic traps such as Eu2+ and Dy3+ that can create photonic energy traps toward an extended phosphorescence time. As time proceeds, the stored light photons in the crystals will continue releasing till its entire exhaustion 28. Currently, reflexive and photoluminescent ribbons, which are clearly positioned on fluorescent clothing, such as warning garment, are comparatively harsh, rigid and less breathable

29, 30

. The

comfortability of warning textiles is a significant quality criterion that affects efficacy and competence. Hence, fabric permeability for moisture and air, in addition to photo- and thermal properties should be adapted. The aqueous pigment-binder spray-coating technique is a facile method that can be managed to produce coated garments hosting luminescent pigments. To the best of our knowledge, the development of luminescent textiles employing spray-coating of only an aqueous binder and SrAl2O4:Eu2+, Dy3+ has not been reported yet. The present paper reports the development of breathable, flexible and comfortable phosphorescent garments by applying dysprosium and europium doped strontium aluminates phosphor, that prepared by the high temperature solid state synthesis technique, in a luminescent layer on wool. Such phosphorescent garments are to offer safety and protective fabrics which have the additional benefit of being readily visible and locatable in the dark. Morphologies, surface composition and structure, colorfastness properties, and photoluminescence properties of the coated wool were investigated based on a variety of measurements.

2. Experimental details 2.1 Materials and Chemicals The wool fabrics (100 %) were kindly supplied by El-Mahalla El-Kobra Company, El-Mahalla, Egypt. The wool fabrics were scoured according to literature procedure

31

. A Printofix Binder

Page 4 of 31


Page 5 of 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


MTB was supplied by Clariant. Strontium carbonate (SrCO3), Aluminium oxide (Al2O3), Europium (III) oxide (Eu2O3), Dysprosium (III) oxide (Dy2O3) and Boric acid (H3BO3) were supplied by Sinopharm Chemical Reagent Co. Ltd, China. The SrAl2O4:Eu2+, Dy3+ was prepared according to literature procedure 4, 32, 33. 2.2 Fabrication of luminescent wool substrates by spray-coating The pigment-binder stock formula was prepared according to pervious work 4, by direct dispersion of ammonium hydroxide (0.1 wt %), diammonium phosphate (0.1 wt %) and binder additive (15 wt %) in distilled water (84.8 wt %). To prevent aggregation, the formula was then stirred using a magnetic stirrer for 10 minutes to allow full dispersion. Different formulations were prepared by adding different concentrations of the pigment phosphor SrAl2O4:Eu2+, Dy3+ (conc. 0.1, 1, 2, 3, 4 and 5 wt %) was added to the mixture with continuous stirring using the magnetic stirrer for 15 minutes. All formulations were then applied to 100 % wool samples using the spray-coating method. The treated samples were left for 30 minutes to air-dry at atmospheric conditions followed by thermofixation at 160˚C for 4 minutes in an automatic thermostatic oven (Werner Mathis Co., Switzerland). The coated samples were rinsed at 50°C, followed by rinsing with cold water and finally air-dried. 2.3 Characterization and Measurements All measurements were carried out under standard atmospheric conditions. Phosphorescence emission and excitation measurements of the coated wool fabrics were measured on a Spectrofluorometer JASCO FP-6500, Japan; equipped with phosphorescence accessory for phosphorescence lifetime measurements. All phosphorescence measurements were carried out at the same geometrical conditions. The light source is Xenon Arc Lamp 150 Watt with slit bandwidth 5 nm for both of excitation and emission monochromators. The samples were

Page 5 of 31



Page 6 of 31

irradiated with UV radiation source at 365 nm using the instrument source. The instrument offered corrected excitation spectrum; while the emission spectrum was corrected for the features of the emission monochromator and for the detection photomultiplier response. The phosphorescence emission spectrum was measured by excitation at the absorption maximum wavelength, and the excitation spectrum was measured at the phosphorescence emission maximum wavelength. An ultraviolet lamp of λ= 365 nm at a power of 6 was utilized as an irradiation source. Before and after ultraviolet irradiation, the color characteristics of the coated wool samples were recorded by colorimetry on a Texflash ACS Datacolor with a Spectraflash 600 spectrophotometer. The color changes are expressed using the colorimetric parameters (L*, a*, b*, K/S, and absorption spectra) which were recorded on an UltraScan PRO spectrophotometer (Hunter Lab, USA) with a D65 illuminant and a 10° standard observer. Fourier-transform infrared spectroscopy were recorded employing an FTIR spectrophotometer (Nexus 670, Nicolet, USA) in the spectrum range 4000-400 cm-1 with spectral resolution of 4.0 cm-1. The thermoluminescence spectra were carried out employing a FJ27A-I TL Dosimeter with a heating rate equal to 1˚C s-1. Bending length of the untreated (pristine) and treated wool samples were measured on Shirley Stiffness Tester along both warp and weft directions according to ASTM D1388 standard procedure. Air permeability testing of both treated and untreated wool fabrics was measured according to the ASTM D737 standard procedure using TEXTTEST FX 3300 air permeability tester at a pressure gradient of 100 Pa. All the bending length and air permeability values were the average of five readings for each sample. The surface free energy of the coated wool was measured using KRÜSS Drop Shape Analyzer DSA30S Tensiometer. Scanning electron microscopy (SEM) on a Quanta FEG 250 (Czech Republic) was employed to study the morphological properties, connected with Energy Dispersive X-ray

Page 6 of 31


Page 7 of 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Spectroscope (TEAM-EDX Model). The EDX diagrams were reported at 20 kV accelerating voltage and 21 mm working distance. Fluorescent optical microscope images were obtained from LEICA DM2500 microscope (EBQ 100-04). 2.4 Colorimetric and colorfastness properties The colorimetric data of wool fabrics before and after UV irradiation was measured using the CIE LAB color space data

4, 34

. The treated wool samples were exposed to UV irradiation for 5

minutes using a UV lamp (λ= 365 nm and 6 W) located 4 cm above. The UV lamp was turned off and the colorimetric properties were recorded directly. The colorfastness properties of the coated wool fibers was tested according to ISO standard methods 35, 36. 2.5 Reversibility of coated wool fabrics Luminescent features and technical behavior of the coated samples were described. The coated fabrics were exposed to ultraviolet irradiation for 5 minutes and then kept in the dark for 60 minutes to release the stored light and fade-back to their unexposed states. The irradiation-fading performance was repeated over 15 cycles. The phosphorescence emission spectra were recorded after each cycle. In order to acquire the reversibility of phosphorescence emission spectrum, the ultraviolet lamp (λ= 365 nm and 6 W) was positioned 4 cm above the sample. 2.6. Assessment of UV protection UPF (Ultraviolet Protection Factor) was performed to evaluate the UV shielding behavior and sun shield for the coated wool fabrics using the AS/NZS 4399:1996 standard procedure and by employing the UPF measuring system of a UV/Vis spectrophotometer (AATCC Test Method 183:2010-UVA Transmittance).

Page 7 of 31



Page 8 of 31

2.7. Assessment of antimicrobial activity The antimicrobial properties of the coated wool were examined against Escherichia coli as gram-negative bacteria, Staphylococcus aureus as gram-positive bacteria and Candida albican as fungus. The antimicrobial testing was carried out quantitatively employing the standard testing procedure according to the AATCC testing method 100-1999 for microbial counting.

3. Results and Discussion 3.1 Characterization and morphological properties The surface morphology and the elemental compositions of the SrAl2O4:Eu2+, Dy3+ on wool fibers were carried out as represented in Figure 1. As is evident from the SEM images, the wool surface was successfully coated with clusters of irregular shapes of micro-sized structures of strontium aluminate through deposition of the latter by the making use of spray-coating technique. The size distribution of the formed micro-sized pigment lied in the range of 10-40 µm, whereas, the main size average of micro-sized pigment was approximately around 15-30 µm. Although, this nano/micro-sized pigment tends to aggregate, and consequently, disperses little heterogeneously onto the wool surface. This could be attributed to the nature of chemical interaction of the pigment molecules, in question, with wool surface.

Page 8 of 31


Page 9 of 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Page 9 of 31



Page 10 of 31

Figure 1: Elemental mapping (A and B), EDX diagram (C), and SEM image (D) of the spraycoated wool fabric (3 wt% of spray formula)

Table 1: The elemental composition at three different positions of the spray-coated wool fabric (3 wt% of spray formula) Samples

C

O

Al

Wt. %

At. %

Wt. %

At. %

Region 1

47.8

57.32

29.99

Region 2

47.28

57.75

Region 3

47.95

57.96

Sr

Eu

At. % 2.24

Wt. %

At. %

27.00

Wt. % 4.19

4.24

29.92

27.44

5.30

2.88

30.17

27.69

5.24

2.65

Dy At. % 0.07

Wt. %

At. %

0.7

Wt. % 0.76

0.75

0.07

6.09

1.02

0.57

0.06

0.52

0.05

5.79

0.92

0.83

0.11

0.79

0.09

Besides, the elemental compositions of the coated wool were also studied by EDX spectroscopy. In addition, the compositions formula in atomic % and weight % at three different regions of the coated wool fabric were summarized in Table 1. Results depicted from Table 1 demonstrate that, the elemental compositions picked from different scanned areas were closely similar. This proves that the distribution of SrAl2O4:Eu2+, Dy3+ on wool surface is somewhat has uniformity which could be recognizable at a very low magnification. Moreover, the main chemical decompositions of nano/micro-sized pigment obtained from EDX spectra obeys the molar ratio used in pigment preparation. In order to examine the presence of the organic constituent and its attachment mechanism, FT-IR spectral analysis is the most significant analytical technique. The IR spectrum of the coated wool sample of 3.0 wt % was displayed in Figure 2. As known, wool is a natural protein-based fiber comprising free carboxyl and amine functional substituents at the terminal of the polymer chain which is composed of repeated amide units. This has been proved by the IR spectral bands at 3272 cm-1 (free -NH2), 3445 cm-1 (free -COOH), and 1629 cm-1 (NHCO). Upon the thermal fixation of the said binder-containing pigment phosphor on wool took place, a strong bonding may be created. Certainly, this could be affirmed by the overall good

Page 10 of 31


Page 11 of 31

behavior of sample under colorfastness as discussed below. Moreover, the prominent peak lied at 1629 cm-1 (for –NHCO) was shifted to higher wavelength at 1641 cm-1, while a new peak appeared at 1731 cm-1 was assigned to the free carboxylic carbonyl of the polyacrylic binder. This could be attributed to the hydrogen bonding arose between carbonyl amide of wool and carboxylic hydroxyl of binder and the electrostatic bond creation between carboxylic anion (COO-) or protonated amine (-NH3+) substituents of wool fibers and carboxylic anion (-COO-) of binder.

100 90

Transmittance %

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


80 70 60 50 40 30 20 10 0 4000

uncoated wool coated wool 3500

3000

2500

2000

1500

1000

500

Wavenumber (cm-1) Figure 2: FT-IR spectra of coated (3 wt % of spray formula) and uncoated wool fabrics with pigment phosphor

Page 11 of 31



Page 12 of 31

3.2 Colorimetric measurements With regarding to changes in the reflection spectra, color strength (K/S) and CIE (L*, a*, b*) color coordinates were measured in order to investigate the light sensing properties and to investigate color changes and technical performance prolonging with the photostability and fatigue resistance of the phosphorescent fabrics. The values of the three dimensional color system L*, a*, b*, and K/S were displayed in Tables 2 and 3, where L* represents the lightness, a* is assigned for the green/red color coordinates, while b* describes the blue/yellow color coordinates. Whereas, Table 3 displayed the coloration measurements of spray-coated wool fabric (3 wt% of spray formula) at different conditions; before (a) and under (b) UV (λ= 365 nm) irradiation for 5 minutes at atmospheric conditions; and few seconds (c) to 30 minutes (d) after the removal of the UV irradiation source. Thorough coated fabrics possess off-white shade similar to the pristine untreated wool fabric before applying spray-coating process. However, in the absence of ultraviolet irradiation, there is no significant change was observed in the K/S value upon raising the pigment concentration of the coated wool up to 5 wt. This confirms the transparency of the phosphorescent layer as a result of the low pigment concentration. On the other hand, after exposure to UV irradiation for a while, a remarkable increase in the K/S value was observed indicating a transformation from the lower faded color strength to higher values depends on the increasing of pigment concentrations. However, a negligible variation was observed in K/S value in case of the pigment concentration was higher than 3 wt%. It was also observed that the K/S values of the UV irradiated samples were lower than the corresponding unirradiated samples reflecting that, the phosphorescent pigment concentration increased that covered the original wool off-white color. These results demonstrated that, the best coloration

Page 12 of 31


Page 13 of 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


data were obtained at 3 wt% pigment phosphor concentration where no significant change was monitored in the K/S value at concentrations higher than 3 wt %. The exposure to ultraviolet led to a little increase in λmax value from the uncoated wool to the coated film matrix from 355 nm (before exposure to UV irradiation reflecting off-white color) to 365 nm (few seconds after the removal of the UV irradiation source reflecting a bright white color). However, higher wavelength maxima were monitored under UV irradiation at 460 nm affording greenish-yellow color, 495 nm with turquoise color after 30 minutes from the removal of the UV irradiation source. In absence of UV irradiation, all coated wool samples, in question, exhibited nominal differences in the values of L*, a* and b* upon increasing the pigment concentrations with comparing to the blank off-white uncoated wool fabric. Under the influence of UV irradiation, the negative a* value increased with decreasing in the positive b* value, which causes a variation in the shade from off-white to greenish-yellow. After 30 minutes from the removal of the UV irradiation source, a higher increase in the negative a* value accompanied with higher decrease in the positive b* value was detected revealing a change in the hue from bright white to turquoise was occurred. Table 2: Color strength and color space values of the coated wool fabrics at different pigment concentrations before and directly after ultraviolet irradiation for 5 minutes Pigment L* wt % Before After 0.1 72.59 69.42 1.0 72.24 68.03 2.0 71.21 68.38 3.0 71.04 69.86 4.0 70.93 67.65 5.0 70.88 68.51

a* Before After - 1.76 - 1.31 - 1.70 - 1.29 - 1.81 - 1.21 - 1.85 - 1.32 - 1.74 - 1.37 - 1.83 - 1.28

b* K/S λmax (nm) Before After Before After Before After 18.12 19.75 4.47 2.48 355 360 17.83 18.89 4.58 2.86 355 365 18.09 19.78 4.46 3.25 355 360 18.03 19.06 4.40 3.82 355 365 17.97 18.70 4.38 3.78 355 360 18.16 19.88 4.67 3.84 355 360

Page 13 of 31



Page 14 of 31

Table 3: Coloration measurements of spray-coated wool fabric (3 wt% of spray formula) at different conditions; before (a) and under (b) UV (λ= 365 nm) irradiation for 5 minutes at atmospheric conditions; and few seconds (c) to 30 minutes (d) after the removal of the UV irradiation source Sample

L*

a*

b*

K/S

a b c d Uncoated wool

71.04 69.45 69.86 68.28 72.18

- 1.85 - 2.41 - 1.32 - 3.67 - 1.82

18.03 14.94 19.06 9.79 18.53

4.40 5.04 3.82 4.98 4.27

λmax (nm) 355 460 365 495 355

color off-white greenish-yellow bright white turquoise off-white

3.3 Evaluation of photoluminescence properties Wool garments are highly comfortable natural fibers which are characterized by their ability to absorb up to third of its mass in moisture that is instantly starts to evaporate into the air. Although the reality that it is full of moisture, wool does not feel wet or clammy. Therefore, wool is considered a natural fiber and air conditioner in one. Wool is also a remarkable insulator, which is why it used in countless goods despite the weather

37

. The SrAl2O4:Eu2+, Dy3+ were

loaded on the surface of wool substrate by the spray-coating. Figure 3 displays photographs of the spray-coated wool fabric (3 wt% of the spray formula) before (a) and after (b) UV (λ= 365 nm) irradiated for 5 minutes at atmospheric conditions; and few seconds (c) to 30 minutes (d) after turning off the UV irradiation source. The spray-coating stock formula was prepared using two major components including the SrAl2O4:Eu2+, Dy3+ at different concentrations (0.1, 1, 2, 3, 4, and 5 wt %) and the binder additive. Such polyacrylic binder function as an organic layer holds and traps the pigment phosphor on wool surface through coordination combination 4 .

Page 14 of 31


Page 15 of 31

Figure 3: Photographs of the spray-coated wool fabric (3 wt % of the spray formula) before (a) and after (b) UV (λ= 365 nm) irradiation for 5 minutes at atmospheric conditions; and few seconds (c) to 30 minutes (d) after the removal of the UV irradiation source

Absorbance (Excitation Intensity)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


80 70 60 50 40 30 20 250

275

300

325

350

375

400

425

450

475

500

Wavelength (nm) Figure 4: UV-Vis excitation spectrum of the spray-coated wool fabric (3 wt %; emission wavelength 517 nm) after being irradiated by ultraviolet (λ= 365 nm) for 5 minutes Page 15 of 31



Page 16 of 31

Furth, figure 4 represented the UV-Vis excitation spectrum of the spray-coated wool fabric (3 wt%; exposed to 150°C for 60 minutes) after being irradiated by ultraviolet (λ= 365 nm) for 5 minutes. All coated wool fabrics exhibited reversible phosphorescent properties under UV light. However, the coated wool substrate with pigment concentration higher than 2 wt % was achieved phosphorescence with slow reversibility. After irradiation with ultraviolet (λ= 365 nm) for 5 min. at atmospheric conditions, the ultraviolet source was turned off, and the phosphorescent emission was recorded at the wavelength of maximum emission (λ= 517 nm) as a function of time. The phosphorescent effects were confirmed by the making use of UV-Vis excitation and phosphorescence emission spectra which displayed a broad and strong excitation with emission peaks in both of ultraviolet and visible regions, as signified from Figures 4 and 5 that the emission intensity slowly decreased with the time after removal of the light source. The coated wool fibers displayed greenish-yellow phosphorescence as also monitored by florescence microscopy (Figure 6) under ultraviolet irradiation.

Page 16 of 31


Page 17 of 31

0.5 min 1 min 2 min 3 min 4 min 5 min 6 min 7 min 8 min 10 min 15 min 30 min

60

Phosphorescence Intensity

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


50 40 30 20 10 0 400

440

480

520

560

600

640

Wavelength (nm) Figure 5: Phosphorescence emission spectra of the coated wool fabric 3 wt % after being irradiated with UV (λ= 365 nm) for 5 minutes followed by the removal of the UV irradiation light source at different time periods

Page 17 of 31



Figure 6: Fluorescent optical microscope images of the coated wool (sample 3 wt %)

(a) 500

Intensity (arb. Units)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 18 of 31

400

300

200

100

0 0

2000

4000

6000

8000

10000

Time (ms)

Page 18 of 31


Page 19 of 31

250

Intensity (arb. Units)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(b)

200

150

100

50

0 0

500

1000

1500

2000

2500

3000

3500

Time (seconds) Figure 7: Phosphorescence properties of the coated wool sample 3 wt % (excitation at 365 nm and emission at 517 nm); (a) lifetime and (b) decay time Both of lifetime and decay time are demonstrated in Figure 7a and 7b respectively. The range of calculation was between 0-9000 msec, reflecting a lifetime at 6705.07 msec (Standard error 0.00388487). It can be concluded from the curves (Figure 7) that the film showed long persistent phosphorescence. The afterglow profile of the colored luminescent layer on wool fibers displayed features similar to that of the luminescent solid pigment SrAl2O4:Eu2+,Dy3+

33

. The

emission band of the coated wool was around 517 nm, which is slightly lower than that of the luminescent SrAl2O4:Eu2+, Dy3+ obtained by the common solid state reaction approach. The emission spectral profiles of the six phosphor concentrations were similar in the spectrum range 400-650 nm. The beginning of the afterglow intensity curve of the coated wool was high. Lifetime curve of sample 3 wt% showed nonlinear relationship with time, therefore, the curve fitting method was performed to calculate lifetime components. The lifetime of the

Page 19 of 31



Page 20 of 31

phosphorescent layer on wool can be determined by the curve fitting method of lifetime curve fitted by the total of three exponential components with different decay times. Figure 7 showed that the afterglow decay curves were consisted of two regions, initial fast followed by subsequent slow decaying progression (Table 4). Dy3+ and Eu2+ are significant lanthanide ions in the production of phosphors with long persistent phosphorescence known as afterglow. The dopants Dy3+ and Eu2+ are well-known trap generating ions, which can highly lengthen the photons exhaustion. Hence, the afterglow curve intensity of the long lasting SrAl2O4:Eu2+,Dy3+ relies on the densities of the traps photons, while the length of afterglow relies on the depth of the trapped photons 32, 33. Table 4: Afterglow decay time of phosphor-coated wool sample 3%. Pigment phosphor on wool

τ1 (s)

τ2 (s)

τ3 (s)

SrAl2O4:Eu2+, Dy3+

6.85

314.39

3289.08

Figures 4 and 5 display the excitation and emission spectral curves of the fabric sample 3 wt% with excitation band at 365 nm and emission band at 517 nm. The emission and excitation spectra of SrAl2O4:Eu2+, Dy3+ arise from the 4f65D1↔4f7 transitions of Eu2+ ions 38. The sample showed no any characteristic emission of Eu3+ or Dy3+ ions refers to the full conversion of Eu3+ to Eu2+ ions occured and the absorbed energy by Dy3+ ions is transferred to Eu2+ ions. The excitation band shown in Figue 4 is a very broad band extending from 300 to 450 nm with a mximum wavelength at 365 nm. The bandwidth of the observed band is considered large which enables the excitaion of the sample with a wide range of light including the visible light. This property can be very useful in the application of the sample. The role of Dy3+ ions was to induce the formation of hole traps which could be thermally released after the light source was removed. The released holes was transferred to Eu2+ ions and return to the ground state of Eu2+ ions

Page 20 of 31


Page 21 of 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


producing prolonged light emission or afterglow

28, 39, 40

. In the present work, the concentration

of the Dy3+ ions was chosen to give the optimum afterglow properties. The lifetime decay curve shown above in Figure 7a is a well fitted with the following triple exponential function 41:

I (t) = I0 + A e -t/τ1 + B e -t/τ2 + C e -t/τ3

eq. 1

Where t is the time, Io and I are the photoluminescence intensity at initial time, while t, A, B, C are constants. The values τ1, τ2, τ3 are the decay times for the exponential components representing the fast, intermediate, and slow decaying processes. The fast decaying process can be attributed to the short time of electrons in the excited state of Eu2+ ions, while the intermediate and slow decaying processes were attributed to the shallow and deep trap energy centers of Dy3+ ions

42

. In this case, Eu2+ and Dy3+ ions represent the luminescence centers and the traps,

respectively 43. Heating luminescent substrates can usually discharge electrons from traps and release light. The thermoluminescence technique (temperature-dependent luminescence) is generally employed to investigate the trap distribution of luminescent agents. Thus, the thermoluminescence spectrum can be explored to understand the trap level distribution of the coated photoluminescent wool fabric (3 wt %) as shown in Figure 8. The temperature of thermoluminescence spectrum band was in the range of 340-510 K (~ 67-237˚C), while the temperature at the maximum wavelength of the relative intensity band was at 398 K (~ 125˚C). The thermoluminescence behavior can be attributed to the trap level present in a forbidden band of the seized electrons and holes. Upon increasing the temperature of the treated wool, the discharge of electrons and holes increases leading to stronger luminescence. At a certain temperature, the luminescence intensity started to weaken because both electrons and holes in traps decrease gradually generating a peak in the pattern of the thermoluminescence spectrum 32, 42, 43.

Page 21 of 31



240 220

Relative Intensity (a.u.)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 22 of 31

200 180 160 140 120 100 80 60 40 20 340

360

380

400

420

440

460

480

500

520

Temperature (K) Figure 8: Thermoluminescence spectra of the coated wool fabric (3 wt %) 3.4 Durability and photostability The main purpose of using spray-coating process was to introduce a smooth phosphorescent film with lower surface roughness, while maintaining the fabric’s flexibility and breathability maintained. One of the technical approaches for the evaluation of fabric flexibility is Shirley Stiffness Tester which determines the bending length in both warp and weft direction of the fabric. The results of bending properties and air permeability tests are shown in Table 5. In general, the coating process had almost no effect on air permeability, but slightly increased the fabric rigidity in both warp and weft direction upon increasing the pigment concentration. The spray-coated layer has a surface free energy of ~36 mN/m which was measured using a KRÜSS DSA30S tensiometer. This value verifies that the surface supports the wettability of the wool fabric to many solvents. The spray-coated fabric substrate has good thermal resistance and can with stand processing temperatures of 150 °C for up to 60 minutes in a conventional thermal Page 22 of 31


Page 23 of 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


oven without degradation or fatigue. The spray-coated wool substrates displayed softness to touch. No differences were monitored for the coated wool samples after washing. In absence of ultraviolet, generally, the depth of color shade and colorfastness of the coated substrates were very good to excellent as displayed in Table 6. On the other hand, the durability of the coated phosphorescent fabrics against washing, light, perspiration, rubbing and sublimation was evaluated by recording the variations in UV-Vis excitation and emission intensities after exposure to ultraviolet. In general, the results of durability and photostability were reasonable. A very good fastness against sublimation (thermal stability) was monitored, and there was no considerable difference of the hot pressing at neither nether 180°C nor 210°C. Table 5: Effect of coating on fabric stiffness and air permeability Pigment wt% Blank 0.1 1.0 2.0 3.0 4.0 5.0

Bending length (cm) Weft Wrap 3.48 3.96 3.97 4.35 4.16 4.42 4.30 4.56 4.52 4.61 4.68 4.69 5.13 4.82

Air permeability (cm3 cm-2 s-1) 32.84 29.71 28.36 28.07 27.90 26.55 26.43

Table 6: Fastness properties of the wool fabric Wash Pigment wt %

Shade

0.1 1.0 2.0 3.0

Off-white Off-white Off-white Off-white

4-5 4 4-5 4-5

4.0 5.0

Off-white Off-white

4 4-5

Alt.∗

Perspiration

St.∗

Acidic

Rubbing

Basic

Sublimation

Dry

Wet

180˚ C

210˚ C

Light**

4-5 4 4-5 4-5

Alt.∗ 4-5 4 4-5 4-5

St.∗ 4-5 4-5 4 4-5

Alt.∗ 4-5 4 4-5 4-5

St.∗ 4-5 4 4-5 4-5

3-4 3-4 3 3-4

3 3-4 3 3

4-5 4-5 4 4-5

4-5 4-5 4-5 4

6 6-7 6 6-7

4 4

4-5 4-5

4-5 4-5

4 4

4 4

4 3-4

3 3

4-5 4

4 4-5

6 6

Page 23 of 31



∗

Page 24 of 31

Alt. = alteration in color; St. = staining on cotton. The light fastness was evaluated using the blue scale (1 and 2-very poor, 3-poor, 4-fair, 5-good, 6 and 7-very good and 8-excellent)

∗∗

3.5 Fatigue resistance and emission reversibility The fatigue resistance was assessed by recording the UV/Vis absorbance after running the standard procedures of light, washing, rubbing, sublimation, perspiration fastness. The fatigue resistance feature of the treated wool was assessed under UV irradiation/darkening mutual steps (Figure 9; excitation at 365 nm; emission at 517 nm). The coated fabrics exhibited excellent fatigue resistance under repeated phosphorescent cycles. The phosphorescent properties and the technical behavior of the coated wool were evaluated by colorimetry. The treated wool was subjected to UV irradiation for 5 minutes and then kept in the dark for 60 minutes to discharge light and fade-back to its unexposed status. Each cycle of irradiation and fading was repeated over 15 cycles. The emission value was recorded after each cycle of irradiation and fading, and then compared to the value reported after the original ultraviolet exposure to indicate excellent reversibility without fatigue. Overall, the spray-coated photoluminescent wool fabric showed good fastness properties and reversible phosphorescence without fatigue during UV excitation.

Page 24 of 31


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Phosphorescence Intensity at 517 nm

Page 25 of 31

60

50

40

30

20

10

0 0

1

2

3

4

5

6

7

8

9 10 11 12 13 14 15 16

Number of Cycle Figure 9: Changes in the ratio of the emission value at 517 (pigment conc. 3 wt %) before and after ultraviolet exposure (λ= 365 nm) at atmospheric conditions. 3.6 UV-protection and antimicrobial properties The UV-shielding activity of wool fabrics can be directly evaluated by UPF. The UPF of the wool fabrics was measured and displayed in Table 7. It was observed that, the UPF value of the coated wool fabrics was increased as the pigment concentration increase. The enhancement of UV protection of the coated wool fabrics could be ascribed to the mechanism of the high UV absorption property of the pigment.

Page 25 of 31



Page 26 of 31

Table 7: UV-protection of both blank and treated fabrics Pigment wt % 0 0.1 1.0

UPF 45 76 100

2.0 3.0 4.0 5.0

117 124 133 142

The antimicrobial activities of the wool fabrics against pathogenic microorganisms were evaluated by using the plate agar count method as shown in Table 8. From this table, it was noted that, the blank wool fabrics had no inhibition effect on the reduction of all microorganisms. Furthermore, the coated wool fabrics showed different antimicrobial activity effect according to the pigment concentration. Table 8: Antimicrobial properties of both blank and coated fabrics Pigment wt % 0 0.1 1.0 2.0 3.0 4.0 5.0

Anti-bacterial (Bacterial Reduction %) Escherichia coli Staphylococcus (Gram –ve) aureus (Gram +ve) 0.00 0.00 52±1.3 51±1.4 60±1.4 58±1.2 73±1.2 71±1.2 85±1.3 83±1.3 94±1.1 92±1.2 97±1.3 95±1.3

Anti-fungal (Fungal Reduction %) Candida albican 0.00 9±1.2 23±1.4 35±1.1 41±1.2 51±1.1 59±1.2

Page 26 of 31


Page 27 of 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Conclusion Lanthanide-doped strontium aluminate phosphor was beneficial to afford long persistent phosphorescent functionality to wool fabrics while maintaining their pristine comfort properties such as appearance, air permeability, softness and colorfastness. We developed a simple spraycoating approach toward smart warning textiles with tunable photoluminescent properties and high durability. The spray-coating process was performed using an aqueous binder and inorganic phosphor. There were no significant changes detected in either stiffness or air permeability of the coated wool fabrics which proves maintaining the fabric’s flexibility and breathability. The and excellent reversibility, and photo- and thermal stability of the coated wool substrates make them promising for generic purposes in particular fields such as warning textiles. Therefore, this can be considered as an innovative, simple and significant technique, opening new horizons toward the

production

of

functional

warning

smart

textiles

particularly

for

safety

and

aesthetic/decorative purposes which could be easily turned into industrial production on a variety of textile materials.

Acknowledgements We would like to thank the technical support from Textile Research Division, National Research Centre, Cairo, Egypt.

Page 27 of 31



Page 28 of 31

References 1. Gashti, M. P.; Pakdel, E.; Alimohammadi, F., Nanotechnology-based coating techniques for smart textiles. In Active Coatings for Smart Textiles, Elsevier: 2016; pp 243-268. 2. Gashti, M. P.; Eslami, S., A robust method for producing electromagnetic shielding cellulose via iron oxide pillared clay coating under ultraviolet irradiation. Functional Mater. Lett. 2015, 8, (06), 1550073. 3. Gashti, M. P.; Ebrahimi, I.; Pousti, M., New insights into corona discharge surface ionization of polyethylene terephthalate via a combined computational and experimental assessment. Curr. Appl. Phys. 2015, 15, (9), 1075-1083. 4. Khattab, T. A.; Rehan, M.; Hamouda, T., Smart textile framework: Photochromic and fluorescent cellulosic fabric printed by strontium aluminate pigment. Carbohydr. Polym. 2018, 195, 143-152. 5. Gashti, M. P.; Gashti, M. P., Effect of colloidal dispersion of clay on some properties of wool fiber. J. Dispersion Sci. Technol. 2013, 34, (6), 853-858. 6. Nooralian, Z.; Gashti, M. P.; Ebrahimi, I., Fabrication of a multifunctional graphene/polyvinylphosphonic acid/cotton nanocomposite via facile spray layer-by-layer assembly. RSC Adv. 2016, 6, (28), 23288-23299. 7. Ojuroye, O.; Torah, R.; Beeby, S.; Wilde, A., Smart textiles for smart home control and enriching future wireless sensor network data. In Sensors for Everyday Life, Springer: 2017; pp 159-183. 8. Salter, S. C.; Gardner, C. L.; Surman, J. J., Photoluminescent logo for vehicle trim and fabric. In Google Patents: 2017. 9. Reddy, C. M.; Raju, B. D. P.; Sushma, N. J.; Dhoble, N.; Dhoble, S., A review on optical and photoluminescence studies of RE3+ (RE= Sm, Dy, Eu, Tb and Nd) ions doped LCZSFB glasses. Renew. Sust. Energ. Rev. 2015, 51, 566-584. 10. Pinto, T. n. V.; Costa, P.; Sousa, C. u. M.; Sousa, C. A.; Pereira, C.; Silva, C. J.; Pereira, M. F. R.; Coelho, P. J.; Freire, C., Screen-Printed Photochromic Textiles through New Inks Based on SiO2@ naphthopyran Nanoparticles. ACS Appl Mater Interfaces. 2016, 8, (42), 2893528945. 11. Wang, C.; Wang, J.; Wu, N.; Xu, M.; Yang, X.; Lu, Y.; Zang, L., Donor–acceptor single cocrystal of coronene and perylene diimide: molecular self-assembly and charge-transfer photoluminescence. RSC Adv. 2017, 7, (4), 2382-2387. 12. Zhang, X.; Xie, Z.; Wu, F.; Zhou, L.; Wong, O.; Lee, C.; Kwong, H.; Lee, S.; Wu, S., Red electroluminescence and photoluminescence properties of new porphyrin compounds. Chem. Phys. Lett. 2003, 382, (5-6), 561-566. 13. Guanming, Q.; Yongjie, C.; Jingqiang, C.; Xiujuan, G.; Hui, W.; Bo, S., Synthesis of long afterglow phosphors doped B SrAl2O4:Eu2+, Dy3+ and its luminescent properties. J. Rare Earth. 2007, 25, 86-89. 14. Jing, L.; Yan, Z.; Mingqiao, G.; Sida, F.; Tong, L., Superhydrophobic and luminescent cotton fabrics prepared by dip-coating of APTMS modified SrAl2O4: Eu2+, Dy3+ particles in the presence of SU8 and fluorinated alkyl silane. J. Rare Earth. 2016, 34, (7), 653-660. 15. Iacono, S. T.; Budy, S. M.; Moody, J. D.; Smith, R. C.; Smith Jr, D. W., Modular approach to chromophore encapsulation in fluorinated arylene vinylene ether polymers possessing tunable photoluminescence. Macromolecules 2008, 41, (20), 7490-7496.

Page 28 of 31


Page 29 of 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


16. Lee, J.; Park, J.; Kim, J.; Yi, W., Efficient visible photoluminescence from encapsulation of fluorescent materials inside single-walled carbon nanotubes. Colloids Surf A Physicochem Eng Asp. 2008, 313, 296-299. 17. Yamamoto, H.; Matsuzawa, T., Mechanism of long phosphorescence of SrAl2O4: Eu2+, Dy3+ and CaAl2O4: Eu2+, Nd3+. J. Lumin. 1997, 72, 287-289. 18. Lin, Y.; Tang, Z.; Zhang, Z.; Wang, X.; Zhang, J., Preparation of a new long afterglow blue-emitting Sr2MgSi2O7-based photoluminescent phosphor. J. Mater. Sci. Lett. 2001, 20, (16), 1505-1506. 19. Wang, X.-J.; Jia, D.; Yen, W. M., Mn2+ activated green, yellow, and red long persistent phosphors. J. Lumin. 2003, 102, 34-37. 20. Wang, X.; Zhang, Z.; Tang, Z.; Lin, Y., Characterization and properties of a red and orange Y2O2S-based long afterglow phosphor. Mater. Chem. Phys. 2003, 80, (1), 1-5. 21. Smet, P. F.; Moreels, I.; Hens, Z.; Poelman, D., Luminescence in sulfides: A rich history and a bright future. Materials 2010, 3, (4), 2834-2883. 22. Qin, J.; Zhang, H.; Lei, B.; Hu, C.; Li, J.; Liu, Y.; Meng, J.; Wang, J.; Zheng, M.; Xiao, Y., Thermoluminescence and Temperature‐Dependent Afterglow Properties in BaSi2O2N2: Eu2+. J. Am. Ceram. Soc. 2013, 96, (10), 3149-3154. 23. Kumar, A.; Kedawat, G.; Kumar, P.; Dwivedi, J.; Gupta, B. K., Sunlight-activated Eu 2+ /Dy3+ doped SrAl2O4 water resistant phosphorescent layer for optical displays and defence applications. New J. Chem. 2015, 39, (5), 3380-3387. 24. Liu, Y.; Xu, C.-N., Influence of calcining temperature on photoluminescence and triboluminescence of europium-doped strontium aluminate particles prepared by sol− gel process. J. Phys. Chem. B 2003, 107, (17), 3991-3995. 25. Ma, S.; Yuan, D.; Wang, X.-S.; Zhou, H.-C., Microporous lanthanide metal-organic frameworks containing coordinatively linked interpenetration: syntheses, gas adsorption studies, thermal stability analysis, and photoluminescence investigation. Inorg. Chem. 2009, 48, (5), 2072-2077. 26. Ren, X.; Zhang, D.; Tong, L.; Chen, X.; Ding, H.; Yang, H., The effects of Gd3+ doping on the ferromagnetic and photoluminescence properties of Co (Fe, Gd) 2O4@SiO2@(Y, Gd) 2O3: Eu3+ composites. Dyes Pigm. 2014, 111, 91-98. 27. Wang, Y.; Wu, W.; Fu, X.; Liu, M.; Cao, J.; Shao, C.; Chen, S., Metastable scheelite CdWO4: Eu3+ nanophosphors: Solvothermal synthesis, phase transitions and their polymorphdependent luminescence properties. Dyes Pigm. 2017, 147, 283-290. 28. Van den Eeckhout, K.; Smet, P. F.; Poelman, D., Persistent luminescence in Eu2+-doped compounds: a review. Materials 2010, 3, (4), 2536-2566. 29. Salter, S. C.; Surman, J. J., Photoluminescent blind spot warning indicator. In Google Patents: 2016. 30. George, M., Luminescent warning device. In Google Patents: 1944. 31. Rahman, M.; Nur, M. G., Feasible application of modern eco-friendly treatment of wool fabric before coloration. International Journal of Scientific and Research Publications 2014, 228. 32. Guo, X.; Ge, M., The afterglow characteristics and trap level distribution of chromatic rare-earth luminous fiber. Text. Res. J. 2013, 83, (12), 1263-1272. 33. Tang, Z.; Zhang, F.; Zhang, Z.; Huang, C.; Lin, Y., Luminescent properties of SrAl2O4: Eu, Dy material prepared by the gel method. J. Am. Ceram. Soc. 2000, 20, (12), 2129-2132.

Page 29 of 31



Page 30 of 31

34. Khattab, T. A.; Rehan, M.; Aly, S. A.; Hamouda, T.; Haggag, K. M.; Klapötke, T. M., Fabrication of PAN-TCF-hydrazone nanofibers by solution blowing spinning technique: Nakedeye colorimetric sensor. J Environ Chem Eng. 2017, 5, (3), 2515-2523. 35. Han, S.; Yang, Y., Antimicrobial activity of wool fabric treated with curcumin. Dyes Pigm. 2005, 64, (2), 157-161. 36. Khattab, T. A.; Haggag, K. M.; Elnagdi, M. H.; Abdelrahman, A. A.; Abdelmoez Aly, S., Microwave‐Assisted Synthesis of Arylazoaminopyrazoles as Disperse Dyes for Textile Printing. Z Anorg Allg Chem. 2016, 642, (13), 766-772. 37. Patnaik, A.; Mvubu, M.; Muniyasamy, S.; Botha, A.; Anandjiwala, R. D., Thermal and sound insulation materials from waste wool and recycled polyester fibers and their biodegradation studies. Energ. Buildings. 2015, 92, 161-169. 38. Chen, R.; Wang, Y.; Hu, Y.; Hu, Z.; Liu, C., Modification on luminescent properties of SrAl2O4: Eu2+, Dy3+ phosphor by Yb3+ ions doping. J. Lumin. 2008, 128, (7), 1180-1184. 39. Sun, H.; Pan, L.; Piao, X.; Sun, Z., Long afterglow SrAl2O4: Eu, Dy phosphors for CdS quantum dot-sensitized solar cells with enhanced photovoltaic performance. J. Mater. Chem. A 2013, 1, (21), 6388-6392. 40. Peng, T.; Huajun, L.; Yang, H.; Yan, C., Synthesis of SrAl2O4:Eu, Dy phosphor nanometer powders by sol–gel processes and its optical properties. Mater. Chem. Phys. 2004, 85, (1), 68-72. 41. Katsumata, T.; Nabae, T.; Sasajima, K.; Komuro, S.; Morikawa, T., Effects of Composition on the Long Phosphorescent SrAl2O4:Eu2+, Dy3+ Phosphor Crystals. J. Electrochem. Soc. 1997, 144, (9), L243-L245. 42. Qiu, Z.; Zhou, Y.; Lü, M.; Zhang, A.; Ma, Q., Combustion synthesis of long-persistent luminescent MAl2O4:Eu2+, R3+ (M= Sr, Ba, Ca, R= Dy, Nd and La) nanoparticles and luminescence mechanism research. Acta Mater. 2007, 55, (8), 2615-2620. 43. Chen, X. Y.; Li, Z.; Bao, S. P.; Ji, P. T., Porous MAl2O4: Eu2+ (Eu3+), Dy3+ (M= Sr, Ca, Ba) phosphors prepared by Pechini-type sol–gel method: The effect of solvents. Optical Mater. 2011, 34, (1), 48-55.

Page 30 of 31


Page 31 of 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Table of Contents (TOC) Graphic

Page 31 of 31


doped strontium aluminate - ACS Publications

Recommend Documents