textured Tetragonal BiFeO3 Film and Its Photoelectrochemical

Subscriber access provided by UNIVERSITY OF ADELAIDE LIBRARIES

Article

Highly (001)-textured Tetragonal BiFeO3 Film and Its Photoelectrochemical Behaviors Tuned by Magnetic Field Haomin Xu, Yuanhua Lin, Takashi Harumoto, Ji Shi, and Ce-Wen Nan ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.7b07644 • Publication Date (Web): 17 Aug 2017 Downloaded from http://pubs.acs.org on August 18, 2017

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.

ACS Applied Materials & Interfaces 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 20

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

ACS Applied Materials & Interfaces

Highly (001)-textured Tetragonal BiFeO3 Film and Its Photoelectrochemical Behaviors Tuned by Magnetic Field Haomin Xu 1, Yuanhua Lin 1,*, Takashi Harumoto 2, Ji Shi 2,*, Cewen Nan 1 1 State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, People’s Republic of China. 2 Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8552, Japan. KEYWORDS tetragonal BiFeO3, polycrystalline substrate, magnetic controlled, photo induced electron, lifetime

ABSTRACT

Highly (001)-textured BiFeO3 film in tetragonal phase (T-BFO) with a giant c/a ratio was firstly obtained on quartz/polycrystalline ITO substrate. Our results indicate that the polycrystalline ITO layer with small surface roughness is a critical point to control the growth of T-BFO structure. It should be ascribed to the fact that a Bi-rich phase interlayer (~5 nm) could be formed on ITO, which acted as a crystal seed layer and thus induced the growth of (001)-textured

ACS Paragon Plus Environment 1


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 20

T-BFO structure. The observed weak room temperature ferromagnetism should be attributed to Fe valance change. Open circuit potential measurements under 360 µW/cm2 full spectra irradiation show that the open circuit potential and the lifetime of photo induced carriers increased under applied magnetic field, which reveals that the applied magnetic field can manipulate the photo electrochemical behaviors of BFO film. Our findings offer a simple way to fabricate highly (001)-textured T-BFO film, which make it desirable to obtain extensive applications for these oriented BFO films. Introduction Bismuth ferrite (BiFeO3, BFO) has been widely studied as a room temperature single phase multiferroic material (Tc~1103 K，theoretical polarization is around 100 μC/cm2 in room temperature (RT)，TN~647 K, G-type antiferromagnetic structure, display week ferromagnetism in RT due to 62 nm spin).1-3 In the past decades, the ferroelectric and ferromagnetic properties of BFO have been widely studied.4-6 Meanwhile, BFO is also a chemically stable semiconductor with small band gap (2.1-2.7 eV), and has been proved to have intriguing photoferroelectric, photocatalytic and photo electrochemical (PEC) properties.7-11 All the findings imply the promising potential applications of BFO films in the fields of energy conversion, environment protection and multifunction electric device manufacture, and it is of great significance to further study the interaction between multiferroic and photo-induced properties of BFO. It has been found that the properties including ferroelectric, antiferromagnetic and photoelectric properties of BFO films are highly sensitive to the film texture as well as the phase composition. For example, up to now, it has been proved that (001)-oriented tetragonal BFO (T-BFO) performs better electronic properties; R-BFO and T-BFO has different band gaps; crystal and domain


Page 3 of 20

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


orientation of BFO can cause spatial selective of the photochemical activity.12-16 All of these results show that it makes great sense to further study the textured BFO as well as its properties. Generally, in conventional ways only on textured bottom layer can textured BFO layer grows, which require high cost single crystal substrates or complex fabrication process.1, 4, 18 Chemical solution deposition is one of the most commonly used chemical methods, still needing single crystal substrates or a seeding layer.19, 20 It is of great importance to find a way to obtain textured BFO films much more easily and lower costly. Among all the phases existing in the epitaxial BFO thin films, the tetragonal phase with giant c/a ratio is of particular interest as it was predicted to exhibit giant polarization of around 150 µC cm-2 due to first principle calculation (FPC). It is predicated that this kind of BFO phase is a stable state and could be formed on polycrystalline substrates with the presence of a properly controlled buffer layer, and it is worth to figure out a way to implement this predicition.21-23 In this paper, we used the metal oxide Sn-doped In2O3 (ITO) as the conductive bottom layer, low cost high-temperature quartz as the substrates, and successfully fabricated BFO films with (001)-preferred orientation in tetragonal phase with a giant c/a ratio around 1.22. People have studied PEC properties and external electric field controlled PEC properties (i.e. the polarization effect on PEC properties) of T-BFO before, 24

but few studies about magnetic controlled PEC behaviours have been reported due to the

equipment limit especially the introduction of magnetic field (MF). In this work, we found a way to apply parallel or perpendicular MF to film samples and investigated the MF effect on PEC behaviour of as prepared (001) T-BFO. Experimental section Fabrication and characterization methods of T-BFO films. All the films were fabricated by magnetron sputtering method. The BFO and ITO targets used in the sample fabrication were



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 20

bought from High Purity Materials KOJYUNDO Chemical Laboratory Co. LTD., Japan. The detailed parameters are as follows. BFO, composition: Bi1.1FeOx, purity: 99.9%, size: 2 inch diameter, 3 mm thickness with Cu-backing plate. ITO, composition: In2O3:SnO2＝95:5 wt%, purity: 99.99%, size: 2 inch diameter, 5 mm thickness. ITO layer was first deposited on the substrates, followed by BFO layer. By changing sputtering power, gas compositions, pressure in chamber, depositing temperature and time, the film quality can be modulated. The crystal structures and phase compositions were characterized by D8 Bruker AXS and MRD Philips (PANalytical). Atomic force microscope (AFM) was applied to observe the roughness of surface. Microstructures were studied by transmission electron microscope (TEM). Energy dispersive x-ray (TEM-EDX) was used to determine the element compositions in films. Measurements of magnetic controlled PEC properties. The time dependence open circuit potential (OCP) was carried out in a three-electrode system (SUNCUT, China) by an electrochemistr workstation (CHI 660D, CHENHUA, Shanghai, China)). The details are as reported before.25 Parallel and perpendicular MF of 1850 Oe, 3900 Oe, 6900 Oe was imposed to the film sequentially. Result and discussion

Morphology and crystal structure of T-BFO films. Thin ITO bottom layer was pre-prepared in pure Ar atmosphere, and the surface roughness is controlled below 1 nm. Under high temperature and low O2 partial pressure, only the (00l)pc peaks were detected in normal θ-2θ XRD scans, and no impure or second phase was observed (Figure 1(c)). The positions of the peaks fitted well with the simulation results (Figure 1(d)), and the value of out-of-plane lattice parameter cpc of T-BFO could be confirmed as 4.63 Å. The simulated position of each atom in a


Page 5 of 20

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


cell refers to the theoretical calculation results.26 Same results can also be obtained on silicon substrates. The 2D XRD pore figures further confirmed the strong (001)-textured T-BFO (Figure 2 (a, c)). The Phi scanning method is always used to figure out whether the film is in plane textured or not. Under certain Chi value, bright spots are supposed to appear if the film has texture in that direction, reversely a bright circle will appear (Figure S1). According to Figure 2 (b, d and e), the (001) T-BFO is out-of-plane in order but in-plane random, and Figure S1 (b) gives a brief illustration of this kind of crystal structure. The value of a is calculated as around 3.79 Å according to the spot positions of facets (011) and (111). Generally, the BFO crystal structure could be stabilized in several different crystal systems, and it has been proved that undoped BFO films with a pseudotetragonal phase is in Pm space group,27 thus it is believed that the as-prepared BFO film is in Mc-type tetragonal phase (β=90º, a/b=1, Pm space group). The experiment results revealed that the T-BFO on ITO could remain stable at RT and atmospheric pressure, and it transferred to other phases as annealing it at high temperature under high oxygen pressure atmosphere. Moreover, the ITO layer could be confirmed as a polycrystalline layer due to the bright arc of ITO facet (222) (Figure 2 (a)). To understand the T-BFO growth mechanism, we conducted a series of contrast experiments. Increasing the thickness and roughness of ITO layer while other conditions remained the same would introduce impure phase as well as R-BFO (Figure 1(b)), which indicated that the roughness of ITO layer should be controlled under at least 1 nm in order to get pure textured T-BFO. ITO/BFO film was also deposited on (001)-MgO single crystal substrate under the same conditions. We found that unlike the polycrystalline ITO film on quartz, ITO layer was in (222)-preferred orientation and no textured BFO layer could be obtained, mainly R-BFO being grown instead (Figure 1 (a)). Moreover, our experiments showed no crystalized BFO appeared if



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 20

depositing BFO on quartz substrate directly. These results indicate that polycrystalline ITO layer with small surface roughness is necessary for (001)-textured T-BFO film. For the BFO layer, we found that under the condition of neither low depositing temperature (under 650 ℃) nor high O2 partial pressure can textured pure BFO films grow, which means high depositing temperature and low O2 partial pressure are necessary when preparing BFO layer. According to the TEM images, the thickness of ITO is around 34 nm, and BFO is 80 nm. The interface of ITO and BFO is quite smooth (Figure 3(a)). The selected area electron diffraction pattern shows the strong texture in BFO film (Figure 3(b)). TEM-EDX shows the exact element compositions on the cross section of BFO layer, Bi:Fe=1.68:1.71 (Table S1), close to 1:1, indicating the film should be BiFeO3. Line scanning TEM-EDX displays evident Bi-rich phase on the interface between ITO and BFO (Figure 4), indicating that an interlayer exists. Same Bi-rich layer also appears in another part (Figure S2). According to Liu et.al, T-BFO with a large c/a ratio could grow on β-Bi2O3 layer because of a large lattice mismatch betweenβ-Bi2O3 and BFO, and they also predicted that this kind of T-BFO phase could be formed on polycrystalline substrates with the presence of a properly controlled buffer layer β-Bi2O3.21 We confirmed this prediction and we believe that the 5 nm Bi-rich interlayer contributed to the highly textured T-BFO being able to grow on ITO layer. The high resolution TEM image of the interface layer is shown in Figure. S3. The interlayer is poorly crystallized which can hardly be seen clearly from high resolution TEM, and it is difficult to obtain accurate information on the phase composition of Bi-rich phase. Further work is needed to get the accurate information on the phase composition and the orientation of Bi-rich interlayer. Even though Bi-rich interlayer could be also formed on other two kinds of substrates, the Bi-rich buffer layer is determined by ITO layer, depending on whether the ITO layer is in highly textured or whether it is smooth enough. It was


Page 7 of 20

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


reported that growth kinetics can also influence the formation of T-BFO. During the growth process, the material system would reach equilibrium and fulfil a specific phase after a complex competition of strain, interface energy, etc.28, 29 In this work, it is also likely that the interface energy of T-BFO (001) facet is the lowest when growing on ITO and thus contributes to the final growth of (001)-textured T-BFO film according to the Wulff theory.30 This hypothesis is devoid of valid experimental or theoretical evidence and further study is needed. Magnetic properties of T-BFO film. A ferromagnetic hysteresis loop was obtained and a saturation magnetization was 6 emu/cm3 for a maximum magnetic field of 5000 Oe at RT (Figure S4). There is no magnetic anisotropy according to the M-H curves. The weak room temperature ferromagnetism should be attributed to the Fe valance change as agreed in previous study. The optical property and open circuit potential decay measurements of T-BFO film. The band gap of T-BFO was calculated from UV-vis absorption spectra as 2.7 eV (Figure S5) using the method mentioned before.9 The time dependence of open circuit potential decay (OCPD) was measured with the light illumination on and off. When the light was on, there was an obvious and subtle response with 0.21 V OCP. The illumination lasted 50s and then stopped. The OCP decayed after the illumination, and the decay rate reflected the recombination rate of the photoelectrons and holes (Figure 5 (a)). The magnetic field controlled open circuit potential decay of T-BFO film. A 6900 Oe MF parallel (MFP) and perpendicular (MFPP) to the film surface was applied separately to study the effect of external magnetic field on the PEC behaviours of as prepared T-BFO film, and the OCP was 0.273 V and 0.265 V respectively (Figure 5 (a)). Once the light was off, the accumulated electrons were slowly discharged. The electron density in the conduction band would decay due to the charge recombination, with the OCPD rate directly determined by the recombination rate.



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 20

We observed that the sample applied with a magnetic field had a significantly slower OCPD rate than the sample without MF, suggesting slower recombination kinetics when applying MF. To evaluate the recombination rate of the photogenerated electrons and holes more precisely, we used the electrons lifetime as an indication of electron-hole separation rate at the interface. The longer electrons lifetime can be used as an indication of higher electron-hole separation rate at the interface. 31 The decay lifetime () of the accumulated electrons can be calculated using the following equation, 32, 33 = −

(1)

Where is the potential dependent lifetime, the Boltzmann constant, the time, T the absolute temperature, the charge of an electron and the open circuit potential. The calculated decay life time is plotted by fitting the time dependent potential curves after switching off the light (Figure 5 (d)). It is evident that the lifetime is longer when a magnetic field applied to the T-BFO film. MF with other intensity (1850 Oe and 3900 Oe) was imposed to the film as well, and the stronger the MF was the longer would be. Nevertheless, would not increase obviously with the increase of MF when the MF was perpendicular. The mechanism of magnetic-field-controlled photoresponse could be explained as follows. When the film is illuminated by light, photo-induced carriers will be generated, while the carriers will move in certain directions (Figure 6 (a)). The carriers with the velocities parallel to magnetic field move along the original direction and are not affected by the MF, and the carriers with the velocities unparalleled to the MF would be confined to circular paths or move in a spiral pattern and then be trapped (Figure 6 (b, c)).34 The lifetime will increase with MF applied because the carriers are trapped and cannot move freely. Since T-BFO film shows weak ferromagnetism and the anisotropy is not obvious, the magnetic property of T-BFO should affect little on the


Page 9 of 20

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


photoresponse when an external magnetic field was applied. The fact that the intensity of MFPP affected less the lifetime could be explained as follows. When the light is off and the electrons begin to combine, the electrons dominantly move along the out-of-plane direction. Those electrons are not affected by MFPP but strongly affected by MFP. We noticed that MFPP has significant influence on the OCP, but little influence difference between 1850 Oe, 3900 Oe, 6900 Oe. We further tested time dependence of open circuit potential of our sample with applied magnetic field in the range of 0 Oe, 500 Oe, 1000 Oe, 1500 Oe, 3000 Oe and 4500 Oe perpendicular to the film surface and obtained that the critical perpendicular field which significantly influence the OCP should be around 1500 Oe (Figure S6). Photogenerated electrons accumulate at the surface of electrode and meanwhile undergo combination with photoinduced holes. The OCP remains stable when the generation and combination reaches a balance. The MF helps restrict the combination process and thus increase OCP. As discussed before, MFPP can only affect the motions of photogenerated electrons that not moving along the out-of-plane direction when they go combination, which occupy small part of the photogenerated electrons. MFPP below 1500 Oe cannot restrict the carriers combination prominently, while MFPP above 1500 Oe increases the accumulated electrons under light illumination and reaches a maximum, thus there is a rising spurt of OCP at 1500 Oe MFPP and afterwards changes little when further increasing the MFPP. Conclusion In summary, we provided a low cost way to prepare (001) T-BFO films and first introduced the external MF in modulating PEC properties of films. T-BFO film with highly (001)-preferred orientation was obtained on polycrystalline ITO layer with small surface roughness, which was pre-deposited on low cost quartz substrate. The results have never been reported before. The



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 20

growth mechanism is explained as the Bi-rich interlayer between ITO and BFO induced the growth of (001) T-BFO. We found that MF can be effective to suppress the recombination of photoinduced carriers and further separate them according to the increase of the lifetime of photoinduced electrons. The lifetime increases obviously with the increase of MFP but changes slightly with the MFPP. Our results indicate that the magnetic field is valid in controlling the process of solar energy conversion in the films, and multifunctional sensor or device based on T-BFO will be desirable in the spintronics filed. In the future, the mechanism of magnetic-field-controlled photoresponse should be further studied. ASSOCIATED CONTENT Supporting Information. This material is available free of charge via the Internet at http://pubs.acs.org. More details about equation 1; a brief illustration of the crystal structure of as prepared T-BFO film; element analysis on BFO sample; the TEM image of interface; the M-H loops; the UV-vis absorption spectra; the critical field perpendicular to film that significantly influence the OCP. AUTHOR INFORMATION Corresponding Author *E-mail: [email protected] (Y.H.L). *E-mail: [email protected] (J. S.). ORCID Haomin Xu: 0000-0002-6282-0747 Author Contributions


Page 11 of 20

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 manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. Notes The authors declare no competing financial interest. ACKNOWLEDGMENT This work was financially supported by the National Key Research Programme of China, under grant No. 2016YFA0201003, and also supported by National Natural Science Foundation of China (No. 51532003, and 51672155) REFERENCES (1) Wang, J.; J. B. N., R. Ramesh; N. A. Spaldin. Epitaxial BiFeO3 Multiferroic Thin Film Heterostructures. Science 2003, 299, 1719-1722. (2) Neaton, J.; Ederer, C.; Waghmare, U.; Spaldin, N.; Rabe, K., First-principles Study of Spontaneous Polarization in Multiferroic BiFeO3. Phys. Rev. B 2005, 71, 014113. (3) Fischer, P.; Polomska, M.; Sosnowska, I.; Szymanski, M., Temperature Dependence of the Crystal and Magnetic Structures of BiFeO3. J. Phys. C Solid State 1980, 13, 1931-1940. (4) Rao, S. S.; Prater, J. T.; Wu, F.; Shelton, C. T.; Maria, J. P.; Narayan, J., Interface Magnetism in Epitaxial BiFeO3-La0.7Sr0.3MnO3 Heterostructures Integrated on Si (100). Nanoletters 2013, 13, 5814-5821. (5) Sando, D.; Agbelele, A.; Daumont, C.; Rahmedov, D.; Ren, W.; Infante, I. C.; Lisenkov, S.; Prosandeev, S.; Fusil, S.; Jacquet, E.; Carretero, C.; Petit, S.; Cazayous, M.; Juraszek, J.; Le



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 20

Breton, J. M.; Bellaiche, L.; Dkhil, B.; Barthelemy, A.; Bibes, M., Control of Ferroelectricity and Magnetism in Multi-ferroic BiFeO3 by Epitaxial Strain. Phil. Trans. R. Soc. A 2014, 372, 20120438. (6) Ray, J.; Biswal, A. K.; Babu, P. D.; Siruguri, V.; Vishwakarma, P. N., Magnetic Origin of Dielectric Transition in BiFeO3. AIP Conf. Proc. 2014, 1591, 1595-1597. (7) Lin, Y.; Yuan, G.; Liu, R.; Zhou, S.; Sheehan, S. W.; Wang, D., Semiconductor Nanostructure-based Photoelectrochemical Water Splitting: A Brief Review. Chem. Phys. Lett. 2011, 507, 209-215. (8) Li, S.; Lin, Y. H.; Zhang, B. P.; Wang, Y.; Nan, C. W., Controlled Fabrication of BiFeO3 Uniform Microcrystals and Their Magnetic and Photocatalytic Behaviors. J. Phys. Chem. C 2010, 114, 2903-2908. (9) Xu, H. M.; Wang, H. C.; Shen, Y.; Lin, Y. H.; Nan, C. W., Photocatalytic and Magnetic Behaviors of BiFeO3 Thin Films Deposited on Different Substrates. J. Appl. Phys. 2014, 116, 174307. (10) Fan, Z.; Yao, K.; Wang, J., Photovoltaic Effect in an Indium-tin-oxide/ZnO/BiFeO3/Pt Heterostructure. Appl. Phys. Lett. 2014, 105, 162903. (11) Xu, H. M.; Wang, H. C.; Shen, Y.; Lin, Y. H.; Nan, C. W., Low-dimensional Nanostructured Photocatalysts. J. Adv. Ceram. 2015, 4, 159-182. (12) Zhang, Y.; Schultz, A. M.; Salvador, P. A.; Rohrer, G. S., Spatially Selective Visible Light Photocatalytic Activity of TiO2/BiFeO3 Heterostructures. J. Mater. Chem. 2011, 21, 4168-4174.


Page 13 of 20

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


(13) Xu J. P.; R. J. Z.; Chen Z. H.; Wang Z. Y.; Zhang F.; Yu X.; Jiang A. Q.; Zheng Y. X.; Wang S. Y.; Chen L. Y. Optical Properties of Epitaxial BiFeO3 Thin Film Grown on SrRuO3-buffered SrTiO3 Substrate. Nanoscale Res. Lett. 2014, 9, 188. (14) Schultz, A. M.; Zhang, Y.; Salvador, P. A.; Rohrer, G. S., Effect of Crystal and Domain Orientation on the Visible-Light Photochemical Reduction of Ag on BiFeO3. ACS Appl. Mater.& Inter. 2011, 3, 1562-1567. (15) Daumont, C.; Ren, W.; Infante, I. C.; Lisenkov, S.; Allibe, J.; Carretero, C.; Fusil, S.; Jacquet, E.; Bouvet, T.; Bouamrane, F.; Prosandeev, S.; Geneste, G.; Dkhil, B.; Bellaiche, L.; Barthelemy, A.; Bibes, M., Strain Dependence of Polarization and Piezoelectric Response in Epitaxial BiFeO3 Thin Films. J. Phys. Condens. Matter. 2012, 24, 162202. (16) Chang, H. W.; Yuan, F. T.; Yu, Y. C.; Tu, S. Y.; Lin, P. C.; Wang, C. R.; Yang, A. B.; Tu, C. S.; Jen, S. U., Formation of BiFeO3 (110) Films on Ferromagnetic CoPt (111) Electrode Layer on Glass Substrates at Reduced Temperatures. J. Appl. Phys. 2015, 117, 17C721. (18) Yan, F.; Xing, G. Z.; Li, L., Low Temperature Dependent Ferroelectric Resistive Switching in Epitaxial BiFeO3 Films. Appl. Phys. Lett. 2014, 104, 132904. (19) Zhang, Q.; Valanoor, N.; Standard, O., Epitaxial (001) BiFeO3 Thin-films with Excellent Ferroelectric Properties by Chemical Solution Deposition-the Role of Gelation. J. Mater. Chem. C 2014, 3, 582-595. (20) Sun, W.; Zhou, Z.; Li, J. F., Sol-gel-processed (001)-textured BiFeO3 Thin Films on Pt (111)/Ti/SiO2/Si Substrates with PbO Seeding Nanocrystals. RSC Adv. 2016, 6, 489-494.



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 14 of 20

(21) Liu, H.; Yang, P.; Yao, K.; Ong, K. P.; Wu, P.; Wang, J., Origin of a Tetragonal BiFeO3 Phase with a Giant c/a Ratio on SrTiO3 Substrates. Adv. Funct. Mater. 2012, 22, 937-942. (22) Hatt, A. J.; Spaldin, N. A.; Ederer, C., Strain-induced Isosymmetric Phase Transition in BiFeO3. Phys. Rev. B 2010, 81, 054109. (23) Ricinschi, D.; Yun, K. Y.; Okuyama, M., A Mechanism for the 150 µC cm−2 Polarization of BiFeO3 Films Based on First-principles Calculations and New Structural Data. J. Phys. Condens. Matter. 2006, 18, L97-L105. (24) Song, J.; Kim, T. L.; Lee, J.; Cho, S. Y.; Cha, J.; Jeong, S. Y.; An, H.; Kim, W. S.; Jung, Y.-S.; Park, J.; Jung, G. Y.; Kim, D. Y.; Jo, J. Y.; Bu, S. D.; Jang, H. W.; Lee, S., Domain-Engineered BiFeO3 Thin-film Photoanodes for Highly Enhanced Ferroelectric Solar Water Splitting. Nano Research 2017, 1-14. (25) Xu, H. M.; Wang, H.; Shi, J.; Lin, Y.; Nan, C., Photoelectrochemical Performance Observed in Mn-Doped BiFeO3 Heterostructured Thin Films. Nanomaterials 2016, 6, 215. (26) Tütüncü, H. M.; Srivastava, G. P., Electronic Structure and Lattice Dynamical Properties of Different Tetragonal Phases of BiFeO3. Phys. Rev. B 2008, 78, 235209. (27) Christen, H. M.; Nam, J. H.; Kim, H. S.; Hatt, A. J.; Spaldin, N. A., Stress-induced R−MA−MC−Tsymmetry Changes in BiFeO3 Films. Phys. Rev. B 2011, 83, 144107. (28) Zhang, J.; Ke, X.; Gou, G.; Seidel, J.; Xiang, B.; Yu, P.; Liang, W. I.; Minor, A. M.; Chu, Y. H.; Van Tendeloo, G.; Ren, X.; Ramesh, R., A Nanoscale Shape Memory Oxide. Nature communications 2013, 4, 2768.


Page 15 of 20

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


(29) Li, Q.; Cao, Y.; Yu, P.; Vasudevan, R. K.; Laanait, N.; Tselev, A.; Xue, F.; Chen, L. Q.; Maksymovych, P.; Kalinin, S. V.; Balke, N., Giant Elastic Tunability in Strained BiFeO3 near an Electrically Induced Phase Transition. Nature communications 2015, 6, 8985. (30) Wang, L.; Zhou, F.; Meng, Y. S.; Ceder, G., First-Principles Study of Surface Properties of LiFePO4: Surface Energy, Structure, Wulff Shape, and Surface Redox Potential. Phys. Rev. B 2007, 76, 165435. (31) Avasare, V.; Zhang, Z.; Avasare, D.; Khan, I.; Qurashi, A., Room-temperature Synthesis of TiO2 Nanospheres and Their Solar Driven Photoelectrochemical Hydrogen Production. Int. J. Energ. Res. 2015, 39, 1714-1719. (32) Kang, Q.; Cao, J.; Zhang, Y.; Liu, L.; Xu, H.; Ye, J., Reduced TiO2 Nanotube Arrays for Photoelectrochemical Water Splitting. J. Mater. Chem. A 2013, 1, 5766-5774. (33) Antony, R. P.; Bassi, P. S.; Abdi, F. F.; Chiam, S. Y.; Ren, Y.; Barber, J.; Loo, J. S. C.; Wong, L. H., Electrospun Mo-BiVO4 for Efficient Photoelectrochemical Water Oxidation: Direct Evidence of Improved Hole Diffusion Length and Charge separation. Electrochim. Acta. 2016, 211, 173-182. (34) Zhao, W.; Liu, Z.; Wei, P.; Zhang, Q.; Zhu, W.; Su, X.; Tang, X.; Yang, J.; Liu, Y.; Shi, J.; Chao, Y.; Lin, S.; Pei, Y., Magnetoelectric Interaction and Transport Behaviours in Magnetic Nanocomposite Thermoelectric Materials. Nature nanotechnology 2017, 12, 55-60.



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 20

Figure 1. XRD spectra of (a) (001)-MgO/ITO (~34 nm)/BFO (80 nm), (b) quartz/ITO (~60 nm)/BFO (80 nm), (c) quartz/ITO (~34nm) /BFO (80 nm), (d) simulation powder peaks of T-BFO using the parameters of a~3.79 Å, c~4.63 Å.


Page 17 of 20

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


Figure 2. (a) 2D XRD pole figure of T-BFO in the out-of-plane direction; (b) 2D XRD pole figure when Chi~51º; (c) Phi scanning at 2θ~19º in the out-of-plane direction, and the bright spot indicates a highly textured structure along [001] direction; the in plane Phi scanning at (d) (011), 2θ~ 30.4º, Chi~51 º and (e) (111), 2θ~ 38.6º, Chi~61 º, the bright circles indicate the random orientation along Chi~51 º and Chi~61 º .



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 20

Figure 3. (a) TEM image of silicon/ITO/T-BFO; (b) the selected area electron diffraction pattern from the white pane area marked in (a).

Figure 4. (a) Elemental profiles determined by EDX scanning (along the yellow line in (b)), which demonstrates the presence of Bi-rich interlayer. (b) TEM image of cross section of BFO, and the yellow line extends from BFO to ITO layer presents the direction of line scanning.


Page 19 of 20

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


Figure 5. (a-c) Time dependence of open circuit potential of T-BFO film under 360μW/cm full spectrum light irradiation, (a) with 6900 Oe parallel and perpendicular MF; (b) with 1850 Oe, 3900 Oe, and 6900 Oe MFP (parallel 1, 2, 3 respectively); (c) with 1850 Oe, 3900 Oe, and 6900 Oe MFPP (perpendicular 1, 2, 3 respectively). (d-f) Electron lifetime measurements determined from the decay of open circuit potential after illumination, and d, e, f is corresponding to a, b and c respectively.



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 20

Figure 6. The schematic illustration on magnetic-field-controlled photoresponse. (a) An illustration on the mobility of the photo-induced carriers in T-BFO film. (b) The motions of carriers parallel to the magnetic field, in which the moving directions of carriers will not be affected by the magnetic field. (c) The motions of carriers perpendicular to the magnetic field, in which the carries would be confined to circular paths or move in a spiral pattern and then be trapped.

Table of Contents graphic


textured Tetragonal BiFeO3 Film and Its Photoelectrochemical

Recommend Documents