Dual-Phase Nanostructural Glass Ceramics with Eu - ACS Publications

Subscriber access provided by CORNELL UNIVERSITY LIBRARY

Article

EuF3/Ga2O3 Dual-Phase Nano-Structural Glass Ceramics with Eu2+/Cr3+ Dual-Activator Luminescence for Self-Calibrated Optical Thermometry Daqin Chen, Shen Liu, Zhongyi Wan, and Zhenguo Ji J. Phys. Chem. C, Just Accepted Manuscript • DOI: 10.1021/acs.jpcc.6b08271 • Publication Date (Web): 06 Sep 2016 Downloaded from http://pubs.acs.org on September 9, 2016

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 free 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 accessible to all readers and 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.

The Journal of Physical Chemistry C 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 26

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

The Journal of Physical Chemistry

EuF3/Ga2O3 Dual-Phase Nano-Structural Glass Ceramics with Eu2+/Cr3+ Dual-Activator Luminescence for Self-Calibrated Optical Thermometry Daqin Chen*, Shen Liu, Zhongyi Wan, Zhenguo Ji College of Materials & Environmental Engineering, Hangzhou Dianzi University, Hangzhou, 310018, P. R. China

ABSTRACT To circumvent the requirement of small energy gap between thermally coupled levels of lanthanide probes in optical thermometry, a strategy using dual-activator fluorescence intensity ratio as temperature signal in dual-phase nano-structural glass ceramics was reported. Specifically, oxyfluoride glass with specially designed composition of SiO2-Al2O3-LiF-EuF3-Ga2O3-Cr2O3 was fabricated and subsequently glass crystallization was used to induce homogenous precipitation of hexagonal EuF3 and cubic Ga2O3 nanocrystals among glass matrix. Impressively, Eu2+ activators were produced after glass crystallization in air atmosphere, and Cr3+ emitting center was evidenced to incorporate into Ga2O3 crystalline lattice. As a result, temperature determination with high sensitivity of 0.8% K-1, large energy gap of 8500 cm-1 as well as superior thermal stability was realized by taking advantage of fluorescence intensity ratio between Eu2+ and Cr3+ as detecting parameter, which exhibited linear dependence on temperature. We believe that this preliminary investigation will provide a practical approach for developing high-performance self-calibrated optical thermometer. Keywords: optical materials, glass ceramics, nanocrystals; sensors; dual-emitting

1

ACS Paragon Plus Environment


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 26

INTRODUCTION Recently, noncontact optical thermometry has attracted great attentions since it can circumvent the drawbacks of inaccuracy and long response time of traditional contact temperature sensor, enabling its application in electromagnetically/thermally harsh surroundings.1-5 Temperature-sensitive optical parameters, such as lanthanide (Ln3+) based fluorescence intensity ratio (FIR) and transition metal (TM) based fluorescence lifetime, have been extensively used for temperature detecting by virtue of independence of sizes and shapes of measuring objects, fluctuations in the excitation density, spectral losses and external disturbance.6-14 Currently, lots of FIR-based

self-calibrated

optical

temperature

sensors

take

advantage

of

temperature-induced inverse electron population in thermally coupled levels (TCLs) of Ln3+ to realize accurate temperature detection.2 For instance, Er3+:2H11/2,4S3/2, Ho3+:5F4,5S2, Nd3+:4F5/2,4F3/2, Dy3+:4I5/2,4F9/2 and Eu3+:5D0,5D1 TCLs have been systematically investigated for potential applications as temperature probes.15-25 However, one of obvious shortcomings of this strategy is that the energy gap between TCLs of Ln3+ will be stringently required to be as small as possible to satisfy efficient electron population from lower emitting state to higher one via thermal activation.26 As a consequence, the obtained FIR values usually deviate from actual ones owing to overlapping emissions from TCLs, which will result in significant inaccuracies for temperature determination. To avoid the aforementioned intrinsic restriction of Ln3+ TCLs-based thermal probes, dual-activator based optical thermometers, which highly relied on different 2


Page 3 of 26

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


thermal-sensitive emitting behaviors of the two activators, have been reported recently.26-31 For example, Eu3+/Tb3+ activated metal-organic-framework

31,32

and

Pr3+/Tb3+ co-doped NaGd(MoO4)2 inorganic material 26 have been demonstrated to be applicable as optical thermometric media. Notably, detrimental energy transfers (ETs) between two activators usually occur ascribing to their abundant energy states and subsequently energy matching, which leads to the luminescent quenching for one of activators or even both of them. More recently, we have fabricated Ln3+/Cr3+ doped GdF3/Ga2O3 dual-phase glass ceramics (GCs) to explore their possible application in dual-activator based optical thermometry.33 One of advantages of such dual-phase GC is the effectively suppression of adverse ETs among the spatially confined distributions of Ln3+ in GdF3 and Cr3+ in Ga2O3. Unfortunately, the usage of Ln3+ as emitting centers has an inevitable shortcoming of small absorption cross-sections owing to their forbidden 4f→4f transitions. Herein, oxyfluoride glass with specially designed glass composition of SiO2-Al2O3-LiF-EuF3-Ga2O3-Cr2O3 was successfully fabricated by a melt-quenching route. Compared to the case reported previously,33 the present glass has higher Si4+/Eu3+ contents and lower Al3+ content, being beneficial for the formation of Eu2+ activator in the glass synthesizing in the air atmosphere, and importantly, the usage of Eu2+ as emitting centers, showing large absorption cross-section due to the allowed 5d→4f transition, can avoid the drawback of Ln3+. Notably, strong Eu2+ blue emission and Cr3+ deep-red luminescence (assigned to 2E→4A2 transition) were observed only after the formation of EuF3 and Ga2O3 dual-phase embedded GC via glass 3



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 4 of 26

crystallization. It is worthy of notice that such dual-phase GC can be achieved via the facile procedure of glass preparation, showing the merits of high transparency, a wide range of accessible chemical compositions, scale-up production as well as formation of complex shapes.34-40 To explore their possible application in optical thermometry, comprehensive temperature-dependent optical behaviors of the present Eu2+/Cr3+ dual-activator in nano-structural GC will be investigated.

EXPERIMENTAL SECTION Table 1 chemical composition of glass, crystallization condition, crystallization phase and transparency. Samples

Glass composition (mol%)

Crystallization condition

GC700

72SiO2-7Al2O3-7LiF-7EuF3-6.9Ga2O3-0.1Cr2O3

700 oC /2h

amorphous

transparent

GC750


750 oC /2h

EuF3 + Ga2O3

transparent

GC800


800 oC /2h

EuF3 + Ga2O3

translucent

o

Crystallization phase

Transparency

GC12Li


750 C /2h

EuF3 + Ga2O3

transparent

GC17Li


750 oC /2h

EuF3 + Ga2O3

opaque

EuF3 + Ga2O3

opaque

GC22Li


o

750 C /2h o

GC27Li


750 C /2h

EuF3 + Ga2O3

opaque

GC-Eu

72SiO2-7Al2O3-7LiF-7EuF3-7Ga2O3

750 oC /2h

EuF3 + Ga2O3

transparent

GC-Cr

72SiO2-7Al2O3-7LiF-7GdF3-6.9Ga2O3-0.1Cr2O3

750 oC /2h

GdF3 + Ga2O3

transparent

The compositions of precursor glasses (PGs), the crystallization conditions, the corresponding crystallization phases and transparency of GCs are tabulated in Table 1. Typically, about 20 g raw materials for each batch were completely mixed, melted in a covered alumina crucible at 1590 oC for 2h in the ambient atmosphere and then poured into a 300 oC preheated copper mold to naturally cool down to room temperature (RT). The as-quenched PGs were then cut into 4 mm2 square plates and were heat-treated at 700~800 oC and hold for 2h to obtain dual-phase GCs through glass crystallization. 4


Page 5 of 26

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


Differential scanning calorimety (DSC, STA449C NETASCH) measurement was performed on PG with a heating rate of 5 K/min to follow its thermal behavior. X-ray diffraction (XRD) analyses were carried out to identify the crystallization phases in the GC samples with a powder diffractometer (DMAX2500 RIGAKU) using CuKα radiation (λ=1.54 Å). Transmission electron microscope (TEM, JEM-2010) observations equipped with the selected area electron diffraction (SAED) were performed to investigate the distribution and size of the precipitated particles in the dual-phase GCs. TEM specimens were prepared by directly drying a drop of a dilute ethanol dispersion solution of GC pieces on the surface of carbon coated copper grids. High resolution TEM (HRTEM) images were used to identify the crystallinity of particles in glass matrix. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) observations were carried out to discern different types of crystallized phases in GCs on an FEI aberration-corrected Titan Cubed S-Twin transmission electron microscope (Tecnai F20) operated at 200 kV. X-ray photoelectron spectroscopy (XPS) was recorded to study the actual valences of chemical components in GC sample by a VG Scientific ESCA Lab Mark II spectrometer with two ultra-high vacuum 6 (UHV) chambers. The binding energies were calibrated to C1s peak (284.8 eV) of surface adventitious carbon. The photoluminescence (PL), PL excitation (PLE) spectra and Cr3+ decay curves of the PG and GC samples were recorded on an Edinburgh Instruments FS5 spectrofluoremeter equipped with both continuous (150 W) and pulsed xenon lamps. The Eu2+ decay curves of the GC samples were measured on an Edinburgh Instruments FLS920 5



spectrofluoremeter under the excitation of a 375nm picosecond pulsed diode laser (EI-EPL-375). The lifetime values were determined via the expression of

τ = ∫ I (t ) dt / I p , where Ip is the luminescent peak intensity and I(t) the time-dependent emission intensity. Temperature dependent PL spectra upon the heating/cooling cycle processes in the temperature ranging from 303 K to 563 K with a scanning step of 5 K were recorded on FS5 spectrofluorometer equipped with a homemade temperature controlling stage.

RESULTS AND DISCUSSION (a)

(b)

♦ hexagonal EuF3

♦

• cubic Ga2O3

♦♦

JPCDS No.20-0426 Ga2O3

GC800

GC22Li GC17Li GC12Li

Intensity (a.u.)

GC27Li 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 6 of 26

GC750

•

♦

♦♦

•

♦♦

•

•

• ♦

♦

GC750

GC700

PG

JPCDS No.32-0373 EuF3

10

20

30

40

50

2θ (degree)

60

70

80

10

20

30

40

50

2θ (degree)

60

70

80

Figure 1 (a) XRD patterns of GC samples with the addition of different concentrations of LiF (7, 12, 17, 22 and 27 mol%). (b) XRD patterns of PG and GCs (7 mol% LiF sample) after crystallization at various temperatures (700, 750 and 800 o C). Inset is the photographs of PG and GC750 sample. The standard crystalline diffraction data for hexagonal EuF3 (JPCDS No. 32-0373) and cubic Ga2O3 (JPCDS No. 20-0426) are also provided in (a). The design of appropriate PG composition is an essential prerequisite for achieving dual-phase GCs. The formation of homogenous glass was difficult without or with the addition of LiF content lower than 7 mol% for the present glass compositions. DSC curve of the precursor glass (Figure S1) shows two exothermic peaks centered at 685 oC and 745 oC, indicating the existence of dual-phase crystallization for the investigated sample. To simultaneously induce the formation of 6


Page 7 of 26

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


the two phases in glass matrix, the crystallization was performed in the temperature range of 700~800 oC. XRD patterns of GCs with the introducing of different LiF concentrations (7, 12, 17, 22 and 27 mol%) obtained by crystallization at 750 oC are shown in Figure 1a. All the GC samples show the precipitation of both hexagonal EuF3 phase (JPCDS No. 32-0373) and cubic Ga2O3 one (JPCDS No. 20-0426) among glass matrix. With increase of LiF content, the diffraction peaks become sharpened, i.e., the grain sizes of the crystallized particles increase. Unfortunately, this will make the fabricated GCs opaque (Table 1). Therefore, PG and GCs with the addition of 7 mol% LiF will be systematically studied in the following section to explore their possible application as optical thermometric media. Figure 1b shows the XRD patterns of the corresponding samples heat-treated at diverse temperatures (700, 750 and 800 oC) for 2h. Typical amorphous structure is found for the PG sample, and no crystallization phase is detected after crystallization at 700 oC. Further elevating crystallization temperature to 750 and 800 oC will result in the precipitation of EuF3 and Ga2O3 dual-phase simultaneously. As shown in the inset of Figure 1b, the color of glass changes from light green to gray after glass crystallization owing to the alteration of Cr3+ ligand-fields and the transparency of GC is retained. The microstructures of the GC samples were studied by electron microscopy. TEM image of GC750 (Figure 2a) shows two types of crystalline particles homogeneously distributing among glass matrix, which is consistent with XRD result. Combined with XRD peak widths, the large nanocrystals (NCs) with the sizes of 15~40 nm and the small ones with the sizes of 4~8 nm can be assigned to EuF3 and 7



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 8 of 26

Ga2O3, respectively. The corresponding SAED pattern (Figure 2b) exhibits discrete polycrystalline diffraction rings, confirming the formation of crystalline particles after glass crystallization. As verified by HRTEM images (Figure 2c, 2d), clear-cut crystalline lattice structures are found in both two types of particles. The lattice fringes are well resolved and typical interplanar distances of 3.10 Å and 2.50 Å are observed, corresponding to (111) plane of hexagonal EuF3 (Figure 2c) and (311) one of cubic Ga2O3 (Figure 2d). (a)

(b) EuF3 Ga2O3

EuF3

(c)

(d)

d(311)=2.50 Å d(111)=3.10 Å

10 nm

5 nm

8


Page 9 of 26

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


(e)

(f)

Si (g)

Al

(h)

Eu (i)

Ga

Figure 2 (a) TEM image of GC750 and (b) the corresponding SEAD pattern. HRTEM micrographs of (c) EuF3 and (d) Ga2O3 NCs. (e) HAADF-STEM image of GC750 with associated (f) Si (green), (g) Al (orange), (h) Eu (red) and (i) Ga (cyan) elemental mappings. As a supplement, STEM operated in HAADF mode was used to study microstructure of GC. Different to the case of TEM bright field image, the contrast of HAADF-STEM micrograph proportionally scales to ～Z2, where Z is the atomic number (Z) of sample.41 As a consequence, two types of nanoparticles are clearly observed with a brighter contrast than the aluminosilicate glass matrix (Figure 2e) because of the much larger atomic number of Eu (Z=63) concentrated in the EuF3 particles and Ga (Z=31) in Ga2O3 ones than those of Si/Al (Z=14/13) homogenously distributed in glass matrix. The Si, Al, Eu and Ga STEM elemental mappings for the GC750 sample (Figure 2f-2i) further confirm the precipitation of EuF3 and Ga2O3 dual-phase NCs after glass crystallization and the equal presence of Si and Al in glass matrix.

9



GC-Eu τ=513ns 2000 4000

0

Time (ns)

GC-Eu λex=369 nm 5

Eu : F0→ LJ Eu3+: 7F →5D 0 2

GC-Eu λex=393 nm 5

5

Eu : F0→ D1

5

7

D0→ F4

5

5

PG -E u

7

D0→ F2 7

3+ 7

D0→ F3

3+ 7

λ

3+ 4

4

Cr : T2 → A2

Eu : 4f→5d

7

4

λem=441nm 2+

D0→ F1

4

3+ 4

Cr : A2 → Τ2( F)

λex=369nm

nm

Cr : E → A2

4

GC-Eu λem=441 nm

4

=6 11

4

3+ 2

2+

Eu : 5d→4f

em

3+ 4

Cr : A2 → Τ1( F)

(b)

PL λex=400nm

GC-Cr PLE λ =720nm em PG-Cr

PL/PLE intensity (a.u.)

(a)

PL/PLE 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 10 of 26

PG-Eu λex=393 nm 300

400

500

600

Wavelength (nm)

700

300

400

500

600

700

Wavelength (nm)

Figure 3 PL and PLE spectra of (a) GC-Cr and (b) GC-Eu samples. Inset of (b) shows decay curve of Eu2+ emission in GC-Eu sample. Room temperature (RT) PL and PLE spectra of Cr3+ and Eu3+ single-activated GC samples (denoted as GC-Cr and GC-Eu respectively, Table 1) were provided in

Figure 3a, 3b. For Cr3+ single-doped PG, Cr3+ luminescence cannot be detected. However, for GC-Cr sample, strong crystalline-like Cr3+ luminescence, consisting of sharp emission peak at 720 nm assigned to the spin-forbidden Cr3+: 2E→4A2 transition and the phonon sideband background attributed to the 4T2→4A2 transition, and typical Cr3+ PL excitation bands centered at 400 nm (4A2→4T1(4F)) and 570 nm (4A2→4T2(4F)), are detected (Figure 3a). These results indicate the alteration of Cr3+ ligand-field environment from amorphous glass into crystalline lattice after glass crystallization. In fact, Cr3+ activators are expected to incorporate into Ga2O3 host by substituting octahedral Ga3+ site owing to the strong stabilization energy of Cr3+ in 6-fold ligand-field and the same ionic radii between Cr3+ (r=0.62 Å, CN=6) and Ga3+ (r=0.62 Å, CN=6).42 Decay curve of Cr3+ emission in the GC-Cr sample was presented in Figure S2. The lifetime in millisecond order is one of the characteristics of 2E→4A2 spin-forbidden transition of Cr3+ in crystalline environment. As revealed in

Figure 3b, Eu3+ characteristic 4f↔4f excitation/emission bands are observed for Eu3+ 10


Page 11 of 26

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


single-activated PG sample. Impressively, after glass crystallization (GC-Eu sample), intense broadband blue luminescence centered at 441 nm is observed, and the corresponding broad excitation band at 369 nm is recorded. Notably, the weak absorption peak (~465 nm) in Eu2+ emission band is originated from the 7F0→5D2 absorption transition of Eu3+. Such broadband excitation/emission is believed to be originated from the Eu2+ 4f↔5d allowed transition. The PL lifetime for Eu2+ in GC-Eu was determined to be 513 ns (inset of Figure 3b), which is one of the features of the allowed 5d→4f electric-dipole transition of Eu2+.43 Notably, owing to far larger absorption cross-section of Eu2+ than that of Eu3+, the PL spectrum of GC-Eu shows dominant Eu2+ blue luminescence even under 393 nm UV light excitation corresponding to Eu3+: 7F0→5L6 absorption transition (Figure 3b). Consequently, it can be concluded that the crystallization of EuF3 particles from glass matrix is beneficial for the emergence of Eu2+ emitting centers in air atmosphere. Regarding for the presence of Eu2+ ions, previous reports have shown their characteristic “blue” luminescence in oxyfluoride GCs.44,45 According to these studies, a strong blue luminescence showing a broad excitation spectrum has been assigned to the divalent europium ions in the glass matrix. As the excitation spectrum of the 441 nm luminescence does not show an obvious splitting for the 5d states in a crystal field it is more likely that 441 nm luminescence observed in the dual-phase GC is caused by the Eu2+ ions in the glass matrix. Generally, Eu2+ cannot be obtained in the glasses synthesized in the ambient condition. A reducing atmosphere is usually required to promote the reduction.46 In 11



the present glass ceramic, the formation of Eu2+ ions after glass crystallization in the air atmospheric condition may be explained via the optical basicity model.47-49 It has been predicted that the glass with an optical basicity below a certain critical value will be beneficial to reduce Eu3+ to Eu2+.49, 50 Unfortunately, the exact glass composition after glass crystallization is uncertain since the actual fraction of the precipitated EuF3 and Ga2O3 particles cannot be exactly determined. Therefore, the real optical basicity value cannot be evaluated for the present GC so far. 3+

95

100

+

Al 2p

4+

Si 2p

105

110

65

70

Binding energy (eV)

Li 1s

75

Binding energy (eV)

3+

80

85

50

52

54

56

58

60

62

Binding energy (eV) 3+

3+

Ga 3d

Cr 2p

Eu 3d32

2+

Eu 3d5/2

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 12 of 26

2+

3+

Eu 3d5/2 15

20

25

30

1110

570

580

590

Binding energy (eV)

O 1s

-

685

1200

2-

F 1s

Binding energy (eV)

1170

Binding energy (eV)

Binding energy (eV)

680

1140

Eu 3d32

690

525

530

535

540

Binding energy (eV)

Figure 4 XPS spectra for Si, Al, Li, Ga, Eu, Cr, F and O elements in GC750 sample In a further experiment, X-ray photoelectron spectroscopy (XPS) measurements were performed to determine the chemical valences of elements in GC750 sample. As expected, Si4+ 2p, Al3+ 2p, Li+ 1s, Ga3+ 3d, Cr3+ 2p, F- 1s and O2- 1s signals are observed (Figure 4). More importantly, both Eu2+ and Eu3+ peaks originated from Eu2+: 3d5/2,3/2 and Eu3+: 3d5/2, 3/2 are easily detected,51 confirming the presence of Eu2+

12


Page 13 of 26

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


in the dual-phase GC prepared under the ambient atmosphere. 3+

2

4

Cr : E→ Α2 2+

Eu : 5d→4f λex=411nm λex=393nm λex=388nm λex=360nm

Figure 5 2D excitation-emission topographical mapping of dual-phase GC750 sample. Insets are PL spectra of GC750 under light excitation with different wavelengths. To find out the suitable input light wavelength to simultaneously excite Eu2+ and Cr3+ dual-activator, excitation-wavelength-dependent two-dimensional (2D) PL mapping of the dual-phase GC750 sample was recorded with excitation wavelengths ranging from 250 to 500 nm, as shown in Figure 5. As expected, in the UV-violet light excitation region, strong Eu2+ blue emission is detected, while in the violet-blue light excitation region, intense Cr3+ deep-red luminescence is observed. Importantly, both blue and deep-red emissions originated from Eu2+: 5d→4f and Cr3+: 2E→4A2 transitions, respectively, can be simultaneously achieved when the excitation light wavelength is set in the range from 385 to 400 nm corresponding to both Eu2+: 4f→5d and Cr3+: 4A2→4T1(4F) absorption transitions (insets of Figure 5).

13


2+

Eu : 5d→4f 3+ 2 4 Cr : E → A2

5.5

2+

Eu : 5d→4f 3+ 2 4 Cr : E → A2

1.0 0.8

(d)

Page 14 of 26

FIR(IEu2+/ICr3+)=0.635+0.008×T

5.0 0.6 0.4 300

350

400

450

500

Temperature (K)

550

FIR(IEu2+/ICr3+)

(c)

PL 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

Relative intensity (a.u.)


Equ Weight Res

4.5

Pea Adj

E E

4.0 3.5

300

350

400

450

500

Temperature (K)

550

3.0 300

Experimental data Fitted line 350

400

450

500

Temperature (K)

550

(e)

Figure 6 (a) Temperature-dependent PL spectra and (b) normalized PL spectra of GC750 sample recorded from 313 K to 563 K. (c) Temperature-dependent Eu2+ PL intensity and Cr3+ one. Inset shows the variation of relative PL intensities of Eu2+ and Cr3+ activators on temperature. (d) Dependence of FIR (IEu2+/ICr3+) on temperature for GC750 sample. The fitted line for the experimental data is also provided. (e) Configurational coordinate diagrams of Eu2+ and Cr3+ emitting centers in dual-phase GC sample, showing thermal-activation induced energy-level crossover relaxation (ELCR) quenching mechanism for Eu2+ and Cr3+ activators. To explore the possible application of the as-fabricated dual-phase GC samples in optical thermometer, temperature-dependent PL spectra of GC750 under the excitation of 388 nm UV light measured in the range of 313 K to 563 K were presented in Figure 6a, and histogram of integrated intensities of the Eu2+: 5d→4f (441 nm) and Cr3+: 2E→4A2 (720 nm) transitions was shown in Figure 6c. Evidently, 14


Page 15 of 26

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


with increase of temperature, both Eu2+ and Cr3+ emissions gradually weaken. To better exhibit the variation of temperature-sensitive PL, all the emission spectra were normalized to Eu2+: 5d→4f emission band (Figure 6b), showing that the quenching of Cr3+ luminescence with increase of temperature is faster than that of Eu2+ one (inset of

Figure 6c). As a consequence, highly sensitive temperature determination can be expected if FIR between Eu2+ and Cr3+ is adopted as the detecting parameter of temperature. Importantly, the FIR (IEu2+/ICr3+) value of the present dual-phase GC monotonously increases when temperature is gradually elevated, as evidenced in

Figure 6d. In fact, such temperature-sensitive FIR can be linearly fitted according to the following equation:

FIR ( I Eu 2+ / I Cr3+ ) = 0.635 + 0.008T

(1)

The fitting gives the sensitivity of 0.8% K-1 for temperature measurement, which is comparable to the values previously derived from TCLs of Ln3+ single-activator thermometric materials.2 More importantly, the energy difference between Eu2+ (441 nm) emission band and Cr3+ (720 nm) one is about 8500 cm-1, which is far larger than those of conventional TCLs of Ln3+ activators (for instance, about 600~800 cm-1 for the 2H11/2 and 4S3/2 TCLs of Er3+ temperature probe)2, 6, 15 and is beneficial for signal discriminability.26 Herein, we provided a possible mechanism to elucidate the realization of highly sensitive temperature measurement by using the present dual-phase GC sample as optical thermometric medium. As illustrated in the configurational coordinate diagram (Figure 6e), the electrons in the excited state of Eu2+: 5d can be depopulated to 4f 15



ground state through radiative relaxation and/or nonradiative relaxation. The former will result in broadband blue luminescence while the latter will induce emission quenching via energy-level crossover relaxation (ELCR) between 5d excited state and 4f ground state.52 The activation energy (△E1) of Eu2+ thermal-quenching is actually correlated to the degree of electron-phonon coupling. As for Cr3+ activator, the ELCR process does not directly occur between 2E emitting state and 4A2 ground state but 4

needs the assistance of intermediate state of thermal-populated from 2E emitting state,

14

4

T2, where the

T2 one is

as depicted in Figure 6e. Therefore, the

thermal-quenching probability of Cr3+ activator is much higher than that of Eu2+ one as the thermal activation energy of Cr3+ (△E2 or △E3) is lower than that of Eu2+ in the present dual-phase GC. In fact, the decrease of Cr3+ PL intensity is indeed faster than that of Eu2+ one with elevation of temperature from RT to 563 K (Figure 6a-6c), which definitely supports the proposed mechanism. 5.5

(a)

(b)

563K

5.0

cooling IEu2+/ICr3+

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 16 of 26

heating

4.5 4.0 3.5 3.0 313K 1

2

3

4

5

6

7

8

9

10

Cycling number

Figure 7 (a) Temperature-dependent emission mapping upon the cycling process of heating and cooling over the temperature range from 313 K to 563 K (excitation wavelength: 388 nm). (b) Temperature-induced switching of FIR between Eu2+ and Cr3+ (alternating between 313 K and 563K). Finally, the thermal stability of the dual-phase GC for temperature detection was investigated. Temperature-dependent 2D PL mapping of GC750 sample upon cycling process of heating and cooling in the temperature range from RT to 563 K and then to 16


Page 17 of 26

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


RT was measured, as provided in Figure 7a. Impressively, PL intensities of both Eu2+ and Cr3+ activators in GC750 can almost restore to their original state when cooling the sample to RT. As confirmed in Figure 7b, such temperature-sensitive FIR (IEu2+/ICr3+) is repeatable and reversible after several cycling processes. Such excellent thermal stability for the present dual-phase GC product is believed to be ascribed to efficient protection of Eu2+ and Cr3+: Ga2O3 NCs by inorganic aluminosilicate glass matrix.

CONCLUSION In summary, hexagonal EuF3 and cubic Ga2O3 nanoparticles embedded transparent GCs have been successfully prepared by melt-quenching and subsequent glass crystallization. Interestingly, it was evidenced that the crystallization of EuF3 particles from glass matrix was beneficial for the formation of Eu2+ emitting centers in air atmosphere. TEM observations, PL/PLE spectra as well as XPS analyses for the dual-phase GC confirmed the spatially confined separation of Eu2+ in glass matrix and Cr3+ in Ga2O3 crystals, respectively. Importantly, different thermal-quenching PL behaviors of Eu2+ 5d→4f transition and Cr3+: 2E→4A2 one in the present GC was observed, which produced linearly temperature-dependent Eu2+/Cr3+ fluorescence intensity ratio. It is expected that the as-fabricated dual-activator GC with high detection sensitivity, excellent signal discriminability and thermal stability will enable its practical application as optical thermometric medium.

17



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 26

ASSOCIATED CONTENT Supporting Information The Supporting Information is available free of charge on the ACS Publications website. Figure S1-S2 showing DSC curve and decay curve of Cr3+ emission.

AUTHOR INFORMATION Corresponding Author *Tel.: +86-571- 87713542. E-Mail: [email protected] (Daqin Chen) Notes The authors declare no competing financial interest.

ACKNOWLEDGEMENTS We acknowledge the Natural Science Foundation of Zhejiang Province for Distinguished Young Scholars (LR15E020001), the National Natural Science Foundation of China (21271170, 61372025, 51402077 and 51572065) and the 151 talent’s projects in the second level of Zhejiang Province for supporting this work.

18


Page 19 of 26

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


REFERENCES [1] Fischer, L. H.; Harms, G. S.; Wolfbeis, O. S. Upconverting Nanoparticles for Nanoscale Thermometry. Angew. Chem. Int. Ed. 2011, 50, 4546-4551. [2] Wang, X. F.; Liu, Q.; Bu, Y. Y.; Liu, C. S.; Liu, T.; Yan, X. H. Optical Temperature Sensing of Rare-Earth Ion Doped Phosphors. RSC Adv. 2015, 5, 86219-86236. [3] Brübach, J.; Pflitsch, C.; Dreizler, A.; Atakan, B. On Surface Temperature Measurements with Thermographic Phosphors: A Review. Prog. Energ. Combust.

2013, 39, 37-60. [4] Wang, X. D.; Wolfbeis, O. S.; Meier, R. J. Luminescent Probes and Sensors for Temperature. Chem. Soc. Rev. 2013, 42, 7834-7869. [5] Wade, S. A.; Collins, S. F.; Baxter, G. W. Fluorescence Intensity Ratio Technique for Optical Fiber Point Temperature Sensing. J. Appl. Phys. 2003, 94, 4743-4756. [6] Dong, B.; Cao, B. S.; He, Y. Y.; Liu, Z.; Li, Z. P.; Feng, Z. Q. Temperature Sensing and in Vivo Imaging by Molybdenum Sensitized Visible Upconversion Luminescence of Rare-Earth Oxides. Adv. Mater. 2012, 24, 1987-1993. [7] Zheng, S. H.; Chen, W. B.; Tan, D. Z.; Zhou, J. J.; Guo, Q. B.; Jiang, W.; Xu, C.; Liu, X. F.; Qiu, J. R. Lanthanide-Doped NaGdF4 Core–Shell Nanoparticles for Non-Contact Self-Referencing Temperature Sensors. Nanoscale 2014, 6, 5675-5679. [8] Suo, H.; Guo, C. F.; Yang, Z.; Zhou, S. S.; Duan, C. K.; Yin, M. Thermometric and Optical Heating Bi-Functional Properties of Upconversion Phosphor Ba5Gd8Zn4O21: Er3+/Yb3+. J. Mater. Chem. C, 2015, 3, 7379-7385. [9] Seat, H. C.; Sharp, J. H. Dedicated Temperature Sensing with C-Axis Oriented 19



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 20 of 26

Single-Crystal Ruby (Cr3+ :Al2O3) Fibers: Temperature and Strain Dependences of R-Line Fluorescence. IEEE. T. Instrum. Meas. 2004, 53,140-54. [10] Hu, Y. L.; Zhang, Z. Y.; Grattan, K. T. V.; Palmer, A. W.; Meggitt, B. T. Ruby-Based Decay-Time Thermometry: Effect of Probe Size on Extended Measurement Range (77–800 K). Sens. Actuators A 1997, 63, 85-90. [11] Li, X.; Jiang, G.; Zhou, S.; Wei, X.; Chen, Y.; Duan, C. K. Luminescent Properties of Chromium(III)-Doped Lithium Aluminate for Temperature Sensing.

Sens. Actuators B 2014, 202, 1065-1069. [12] Suo, H.; Guo, C. F.; Li, T. Broad-Scope Thermometry Based on Dual-Color Modulation Upconversion Phosphor Ba5Gd8Zn4O21: Er3+/Yb3+. J. Phys. Chem. C

2016, 120, 2914-2924. [13] Uchiyama, H.; Aizawa, H.; Katsumata, T.; Komuro, S.; Morikawa, T.; Toba, E. Fiber-Optic Thermometer Using Cr-Doped YAlO3 Sensor Head. Rev. Sci. Instrum.

2003, 74, 3883-3885. [14] Chen, D. Q.; Wan, Z. Y.; Zhou, Y. Optical Spectroscopy of Cr3+-Doped Transparent Nano-Glass Ceramics for Lifetime-Based Temperature Sensing. Opt. Lett.

2015, 40, 3607-3610. [15] Pandey, A.; Rai, V. K.; Kumar, V.; Kumar, V.; Swart, H. C. Upconversion Based Temperature Sensing Ability of Er3+–Yb3+ Codoped SrWO4: An Optical Heating Phosphor. Sens. Actuators B 2015, 209, 352-358. [16] Wawrzynczyk, D.; Bednarkiewicz, A.; Nyk, M.; Strek, W.; Samoc, M. Neodymium(iii) Doped Fluoride Nanoparticles as Non-Contact Optical Temperature 20


Page 21 of 26

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


Sensors. Nanoscale 2012, 4, 6959-6961. [17] Zheng, K. Z.; Liu, Z. Y.; Lv, C. Q.; Qin, W. P. Temperature Sensor Based on the UV Upconversion Luminescence of Gd3+ in Yb3+-Tm3+-Gd3+ Codoped NaLuF4 Microcrystals. J. Mater. Chem. C 2013, 1, 5502-5507. [18] Zhou, S. S.; Jiang, S.; Wei, X. T.; Chen, Y. H.; Duan, C. K.; Yin, M. Optical Thermometry Based on Upconversion Luminescence in Yb3+/Ho3+ Co-Doped NaLuF4.

J. Alloys Compd. 2014, 588, 654-657. [19] Singh, A. K. Ho3+:TeO2 Glass, a Probe for Temperature Measurements. Sens.

Actuators A 2007, 136, 173–177. [20] Singh, A. K.; Rai, S. B. Upconversion and Optical Thermometry in Ho:TeO Glass, Effect of Addition of PbO and BaCO3. Appl. Phys. B 2007, 86, 661–666. [21] Du, P.; Luo, L. H.; Yu, J. S. Low-Temperature Thermometry Based on Upconversion Emission of Ho/Yb-Codoped Ba0.77Ca0.23TiO3 Ceramics J. Alloys

Compd. 2015, 632, 73–77. [22] Cao, Z. M.; Zhou, S. S.; Jiang, G. C.; Chen, Y. H.; Duan, C. K.; Yin, M. Temperature Dependent Luminescence of Dy3+ Doped BaYF5 Nanoparticles for Optical Thermometry. Curr. Appl. Phys. 2014, 14, 1067–1071. [23] Boruc, Z.; Kaczkan, M.; Fetlinski, B.; Turczynski, S.; Malinowski, M. Blue Emissions in Dy3+ Doped Y4Al2O9 Crystals for Temperature Sensing. Opt. Lett. 2012,

37, 5214–5216. [24] Meert, K. W.; Morozov, V. A.; Abakumov, A. M.; Hadermann, J.; Poelman, D.; Smet, P. F. Energy Transfer in Eu3+ Doped Scheelites: Use as Thermographic 21



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 26

Phosphor. Opt. Express 2014, 22, 961–972. [25] Tian, Y.; Tian, B. N.; Cui, C.; Huang, P.; Wang, L.; Chen, B. J. Excellent Optical Thermometry Based on Single-Color Fluorescence in Spherical NaEuF4 Phosphor.

Opt. Lett. 2014, 39, 4164–4167. [26] Gao, Y.; Huang, F.; Lin, H.; Zhou, J. C.; Xu, J.; Wang, Y. S. A Novel Optical Thermometry Strategy Based on Diverse Thermal Response from Two Intervalence Charge Transfer States. Adv. Funct. Mater. 2016, 26, 3139-3145. [27] Brites, C. D. S.; Lima, P. P.; Silva, N. J. O.; Millán, A.; Amaral, V. S.; Palacio, F.; Carlos, L. D. A Luminescent Molecular Thermometer for Long-Term Absolute Temperature Measurements at the Nanoscale. Adv. Mater. 2010, 22, 4499-4504. [28] Wang, Z. P.; Ananias, D.; Carné-Sánchez, A.; Brites, C. D. S.; Imaz, I.; Maspoch, D.; Rocha, J.; Carlos, L. D. Lanthanide-Organic Framework Nanothermometers Prepared by Spray-Drying. Adv. Funct. Mater. 2015, 25, 2824-2830. [29] McLaurin, E. J.; Bradshaw, L. R.; Gamelin, D. R. Dual-Emitting Nanoscale Temperature Sensors. Chem. Mater. 2013, 25, 1283-1292. [30] Sun, T. Y.; Zhang, D. Q.; Yu, X. F.; Xiang, Y.; Luo, M.; Wang, J. H.; Tan, G. L.; Wang, Q. Q.; Chu, P. K. Dual-Emitting Nanocomposites Derived from Rare-Earth Compound Nanotubes for Ratiometric Fluorescence Sensing Applications. Nanoscale,

2013, 5, 1629-1637. [31] Rao, X. T.; Song, T.; Gao, J. K.; Cui, Y. J.; Yang, Y.; Wu, C. D.; Chen, B. L.; Qian, G. D. A Highly Sensitive Mixed Lanthanide Metal–Organic Framework Self-Calibrated Luminescent Thermometer. J. Am. Chem. Soc. 2013, 135, 22


Page 23 of 26

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


15559-15564. [32] Cui, Y. J.; Song, R. J.; Yu, J. C.; Liu, M.; Wang, Z. Q.; Wu, C. D.; Yang, Y.; Wang, Z. Y.; Chen, B. L.; Qian, G. D. Dual-Emitting MOF Dye Composite for Ratiometric Temperature Sensing. Adv. Mater. 2015, 27, 1420-1425. [33] Chen, D. Q.; Wan, Z. Y.; Liu, S. A Highly Sensitive Dual-Phase Nano-Glass Ceramics Self-Calibrated Optical Thermometer. Anal. Chem. 2016, 88, 4099-4106. [34] Chenu, S.; Véron, E.; Genevois, C.; Matzen, G.; Cardinal, T.; Etienne, A.; Massiot, D.; Allix, M. Glass Ceramics: Tuneable Nanostructuring of Highly Transparent Zinc Gallogermanate Glasses and Glass-Ceramics. Adv. Opt. Mater. 2014,

2, 364-372. [35] Zhang, X.; Huang, L.; Pan, F.; Wu, M.; Wang, J.; Chen, Y.; Su. Q. Highly Thermally

Stable

Single-Component

White-Emitting

Silicate

Glass

for

Organic-Resin-Free White-Light-Emitting Diodes. ACS Appl. Mater. Interfaces 2014,

6, 2709-2717. [36] Herrmann, A.; Tylkowski, M.; Bocker, C.; Rüssel, C. Cubic and Hexagonal NaGdF4 Crystals Precipitated from an Aluminosilicate Glass: Preparation and Luminescence Properties. Chem. Mater. 2013, 25, 2878-2884. [37] Zhao, S. L.; Wang, X.; Sun, X.; Jia, G. H.; Huang, L. H.; Deng, D. G.; Xin, F. X.; Xu, S. Q. Structural Evolution and Enhancement of Luminescence in the Eu-Doped Oxyfluoride Glass Ceramics Containing NaGdF4 Nanocrystals. CrystEngComm 2013,

15, 7346-7353. [38] Chen, D. Q.; Xiang, W. D.; Liang, X. J.; Zhong, J. S.; Yu, H.; Ding, M. Y.; Lu, H. 23



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 24 of 26

W.; Ji, Z. G. Advances in Transparent Glass–Ceramic Phosphors for White Light-Emitting Diodes—A Review. J. Euro. Ceram. Soc. 2015, 35, 859-869. [39] Lin, C. G.; Bocker, C.; Rüssel, C. Nanocrystallization in Oxyfluoride Glasses Controlled by Amorphous Phase Separation. Nano Lett. 2015, 15, 6764-6769. [40] Zhou, S. F.; Jiang, N.; Miura, K.; Tanabe, S.; Shimizu, M.; Sakakura, M.; Shimotsuma, Y.; Nishi, M.; Qiu, J. R.; Hirao, K. Simultaneous Tailoring of the Phase Evolution and Dopant Distribution in Glassy Phase for Controllable Luminescence J.

Am. Chem. Soc. 2010, 132, 17945-17952. [41] Abel, K. A.; Boyer, J. C.; Andrei, C. M.; van Veggel, F. C. J. M. Analysis of the Shell Thickness Distribution on NaYF4/NaGdF4 Core/Shell Nanocrystals by EELS and EDS. J. Phys. Chem. Lett. 2011, 2, 185-189. [42] Chen, D. Q.; Wan, Z. Y.; Zhou, Y.; Ji, Z. G. Cr3+-Doped Gallium-Based Transparent Bulk Glass Ceramics for Optical Temperature Sensing. J. Euro. Ceram.

Soc. 2015, 35, 4211-4216. [43] Chen, D. Q.; Wan, Z. Y.; Zhou, Y.; Xiang, W. D.; Zhong, J. S.; Ding, M. Y.; Yu, H.;

Ji,

Z.

G.

Tuning

into

Blue

and

Red:

Europium

Single-Doped

Nano-Glass-Ceramics for Potential Application in Photosynthesis. J. Mater. Chem. C

2015, 3, 3141-3149. [44] Fu, J.; Parker, J. M.; Flower, P. S.; Brown, R. M. Eu2+ Ions and CaF2-Containing Transparent Glass-Ceramics. Mater. Res. Bull. 2002, 37, 1843-1849. [45] Secu, M.; Secu, C. E.; Polosan, S.; Aldica, G.; Ghica, C. Crystallization and Spectroscopic Properties of Eu-Doped CaF2 Nanocrystals in Transparent Oxyfluoride 24


Page 25 of 26

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


Glass-Ceramics. J. Non-Cryst. Solids 2009, 355, 1869-1872. [46] Zhang, X.; Wang, J.; Huang, L.; Pan, F.; Chen, Y.; Lei, B.; Peng, M.; Wu, M. Tunable Luminescence Properties and Concentration-Dependent, Site-Preferable Distribution of Eu2+ Ions in Silicate Glasses for White LEDs Applications. ACS Appl.

Mater. Interfaces 2015, 7, 10044-10054. [47] Duffy, J. A. Polarisability and Polarizing Power of Rare Earth Ions in Glass: An Optical Basicity Assessment. Phys. Chem. Glasses 2005, 46, 1-6. [48] Duffy, J. A. Optical Basicity of Fluorides and Mixed Oxide-Fluoride Glasses and Melts. Phys. Chem. Glasses 2011, 52, 107-114. [49] Bagga, R.; Achanta, V. G.; Goel, A.; Ferreira, J. M. F.; Singh, N. P.; Singh, D. P.; Contini, V.; Falconieri, M.; Sharma, G. Luminescence Study of Mixed Valence Eu-Doped Nanocrystalline Glass-Ceramics. Opt. Mater. 2013, 36, 198-206. [50] Wang, C.; Peng, M.; Jiang, N.; Jiang, X.; Zhao, C.; Qiu, J. Tuning the Eu Luminescence in Glass Materials Synthesized in Air by Adjusting Glass Compositions. Mater. Lett. 2007, 61, 3608-3611. [51] Vercaemst, R.; Poelman, D.; Fiermans, L.; Van Meirhaeghe, R. L.; Laflère, W. H.; Cardon, F. A Detailed XPS Study of the Rare Earth Compounds EuS and EuF3. J.

Electron Spectrosc. Relat. Phenom. 1995, 74, 45-56. [52] Blasse, G.; Grabmaier, B. C. in Luminescence Materials, Springer-Verlag, Berlin, Germany, 1994.

25



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 26 of 26

ToC figure

26


Dual-Phase Nanostructural Glass Ceramics with Eu - ACS Publications

Recommend Documents