Effects of excess Bi on structure and electrical properties of BiFeO3 thin films deposited on indium tin oxide substrate using sol–gel method

Xie, Xiaobin; Yang, Shiju; Zhang, Fengqing; Fan, Suhua; Che, Quande; Wang, Cuijuan; Guo, Xiaodong; Zhang, Liping

doi:10.1007/s10854-015-3693-9

Cited by 12 publications

(12 citation statements)

References 30 publications

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“…So, work is needed to understand the nature of defects giving rise to high conductivity in GFO, i.e., cations or anions vacancies or valence fluctuations of Fe ions. Similar issues were also faced in well‐studied material bismuth ferrite which is susceptible to having vacancies on Bi site due to Bi volatilization, fluctuations in Fe valence as well as oxygen vacancies . Though site engineering or atomic substitution can reveal some clues about the defect chemistry, often the information is indirect and is also plagued by lack of clear information on the site exchange especially in case of ions with higher atomic size mismatch such as Mg doping of GFO.…”

Section: Introductionmentioning

confidence: 90%

Effect of annealing atmosphere on leakage and dielectric characteristics of multiferroic gallium ferrite

et al. 2017

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Mutliferroic and magnetoelectric gallium ferrite (GaFeO 3 ) is plagued by substantial electrical leakage in polycrystalline form. Here, we report on understanding the conduction mechanism in gallium ferrite ceramic samples vis-a-vis processing conditions. The results show that oxygen annealed samples exhibit minimum electrical leakage as compared to air or nitrogen annealed samples suggesting the role of oxy3gen vacancies on electrical conduction. Detailed time and temperaturedependent impedance spectroscopy analysis of the samples showed higher activation energy of conduction in oxygen annealed samples than in air or nitrogen annealed samples. The lower activation energies of 0.3-0.4 eV in nitrogen/air annealed samples were attributed to higher oxygen vacancy concentration while oxygen annealed samples with low oxygen vacancy concentration exhibited higher activation energy of~0.50 eV (high frequency, i.e., grain) and 0.98 eV (low frequency, i.e., grain boundary), latter due to superior level of oxygenation at the grain boundaries. Further, X-ray photoelectron spectroscopy revealed that the oxygen vacancies are compensated by the valence fluctuation between Fe 2+ / Fe 3+ ions whose extent is higher in air/nitrogen annealed samples than in oxygen annealed samples. The conduction mechanisms that could be active are most likely to be double ionization of oxygen vacancies and hopping from Fe 2+ to Fe 3+ states, latter especially in oxygen deficient samples.

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Section: Introductionmentioning

confidence: 90%

Effect of annealing atmosphere on leakage and dielectric characteristics of multiferroic gallium ferrite

et al. 2017

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“…10,16 The Bi-excess (Bi 1.04 Fe 0.98 O 3.00 , ∇[Bi] = 0%) heterostructures (purple data, Figure 5f) also show nearly ideal dielectric permittivity, consistent with prior work on Bi-excess (up to 10% excess) ceramics wherein bulk-like dielectric permittivity was observed. 34 Upon moving to Bi-deficiency and/or in the presence of ∇[Bi], however, the dielectric permittivity falls dramatically and the variants show a trend inverse to that from the leakage response ( Figure 4d). The reduced dielectric permittivity may be explained by the fact that these heterostructures exhibit the most extensive interfacial interdiffusion and we propose that this interdiffusion creates a region of lower capacitance which dominates the dielectric response of the films.…”

Section: Chemistry Of Materialsmentioning

confidence: 96%

Nonstoichiometry, Structure, and Properties of BiFeO₃ Films

et al. 2016

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We explore the effect of growth conditions on the cation and anion chemistry, electrical leakage, conduction mechanisms, and ferroelectric and dielectric behavior of BiFeO 3. Although it is possible to produce single-phase, coherently strained films in all cases, small variations in the pulsed-laser deposition growth process, specifically the laser repetition rate and target composition, result in films with chemistries ranging from 10% Bi-deficiency to 4% Bi-excess and films possessing Bi gradients as large a 6% across the film thickness. Corresponding variations and gradients in the O chemistry are also observed. As a result of the varying film chemistry, marked differences in surface and domain morphology are observed wherein Bi-deficiency stabilizes atomically smooth surfaces and ordered stripe domains. Subsequent investigation of the current−voltage response reveals large differences in leakage current density arising from changes in both the overall stoichiometry and gradients. In turn, the film stoichiometry drives variations in the dominant conduction mechanism including examples of Schottky, Poole−Frenkel, and modified Poole−Frenkel emission depending on the film chemistry. Finally, slightly Bi-excess films are found to exhibit the best low-frequency ferroelectric and dielectric response while increasing Bi-deficiency worsens the low-frequency ferroelectric performance and reduces the dielectric permittivity.

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“…The presence of the (014) and (110) peaks at 2 ≈ 31.5° and 32° reveal a perovskite BFO phase belonging to rhombohedral R3c space group 52,97 , which is present in both samples treated under the same thermal conditions. In addition, a small amount of a secondary phase in the film was detected along with the pure BFO peaks is assigned to Bi2O3, which is in agreement with previous reported study 91,95 . Many literatures have studied the crystal structure of BFO thin films deposited on different substrates.…”

Section: 3supporting

confidence: 92%

“…The film morphology is consistent with previously reported studies of BiFeO3 thin films 71,75 . The formation of voids within bismuth ferrite thin films could be attributed to the volatile of Bi during thermal treatment, which lead to the formation of secondary phases 95,96 , this can be further confirmed by XRD data. The volatilization of Bi is a well-known phenomenon that affects the stoichiometry via the appearance of bismuth and oxygen vacancies 95 .…”

Section: 3supporting

confidence: 52%

“…The formation of voids within bismuth ferrite thin films could be attributed to the volatile of Bi during thermal treatment, which lead to the formation of secondary phases 95,96 , this can be further confirmed by XRD data. The volatilization of Bi is a well-known phenomenon that affects the stoichiometry via the appearance of bismuth and oxygen vacancies 95 . This is confirmed in terms of Kroger-Vink notation according to the following reaction:…”

Section: 3supporting

confidence: 52%

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Synthesis of Bismuth Ferrite for Photoelectrochemical Water Splitting

Albagle¹

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Synthesis of Bismuth Ferrite for Photoelectrochemical Water Splitting by Fagr Albagle Converting solar energy to chemical fuels is one of the alternative solutions to address the sustainable energy challenges in the world. This can be achieved through photocatalytic conversion of solar energy to chemical energy stored in hydrogen (H2) via photoelectrochemical water splitting. It still remains a significant challenge in developing semiconductors as photoelectrodes for photoelectrochemical water oxidation. The objective of this project is to develop and synthesize a semiconductor-based material for photoelectrochemical water splitting. A perovskite bismuth ferrite oxide (BiFeO3) thin film has been synthesized and deposited onto a fluorine-doped tin oxide (FTO) coated glass substrate by the sol-gel process. The thickness of thin film has been tuned by applying different spin coating cycles. The photoelectrochemical properties of the bismuth ferrite oxide (BFO) film have been investigated. The BFO photoanode exhibits the n-type behavior with a flat band potential of 0.36 V versus the reversible hydrogen electrode (RHE). The BFO film possesses a band gap about 2.0 eV, which is favorable for photoelectrochemical water splitting. Among the three BFO thin film samples prepared, five spin cycles achieved the highest photocurrent. The results show that the BFO film photoanode is very stable and capable of generating hydrogen through photoelectrochemical water splitting. However, an improvement in the photocurrent needs to be studied through the use of co-catalyst and metal transition doping. The knowledge obtained from our findings can be used for development of metal oxide based materials for solar fuel generation. TABLE OF CONTENTS ABSTRACT II ACKNOWLEDGMENTS III TABLE OF CONTENTS IV TABLES OF FIGURES VI 1. INTRODUCTION 1.1. BACKGROUND 1.2. MOTIVATION AND OBJECTIVES 1.3. SIGNIFICANCE 2. LITERATURE REVIEW 2.1. INTRODUCTION 2.2. GENERAL INTRODUCTION TO HYDROGEN FUEL GENERATION 2.2.1. HYDROGEN FUEL PRODUCTION FROM FOSSIL FUELS 2.2.2. HYDROGEN FUEL PRODUCTION FROM SOLAR ENERGY 2.3. PRINCIPLE OF PHOTOCATALYTIC WATER SPLITTING 2.3.1. PROCESS OF PHOTOCATALYTIC WATER SPLITTING 2.3.2. FUNDAMENTAL THEORY OF PHOTOCATALYTIC WATER SPLITTING 2.4. PEROVSKITE METAL OXIDE MATERIALS AS PHOTOCATALYSTS 2.4.1. STRUCTURE OF PEROVSKITE METAL OXIDE 2.4.2. PEROVSKITE MATERIALS IN PHOTOCATALYSIS 2.5. PEROVSKITE BISMUTH FERRITE OXIDE 2.5.1. STRUCTURE OF BISMUTH FERRITE OXIDE 2.5.2. SYNTHESIS OF BISMUTH FERRITE OXIDE BY DIFFERENT ROUTES 3. BISMUTH FERRITE OXIDE THIN FILM SYNTHESIS AND CHARACTERIZATION 3.1 INTRODUCTION 3.2 EXPERIMENTAL SECTION 3.2.1 PREPARATION OF BIFEO3 PRECURSOR 3.2.2 DEPOSITION OF BIFEO3 THIN FILM iv 3.3 CHARACTERIZATION OF THE BFO THIN FILM 3.4 RESULTS AND DISCUSSION 3.4.1 MORPHOLOGY AND CRYSTAL STRUCTURE OF THE BIFEO3 THIN FILM 3.4.3 CHEMICAL STATE AND ELECTRONIC STRUCTURE OF BIFEO3 FILMS 3.4.4 OPTICAL ABSORPTION OF BIFEO3 THIN FILM 4. PHOTOELECTROCHEMICAL TESTING OF BISMUTH FERRITE OXIDE THIN FILMS 38

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Effects of excess Bi on structure and electrical properties of BiFeO3 thin films deposited on indium tin oxide substrate using sol–gel method

Cited by 12 publications

References 30 publications

Effect of annealing atmosphere on leakage and dielectric characteristics of multiferroic gallium ferrite

Effect of annealing atmosphere on leakage and dielectric characteristics of multiferroic gallium ferrite

Nonstoichiometry, Structure, and Properties of BiFeO₃ Films

Synthesis of Bismuth Ferrite for Photoelectrochemical Water Splitting

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Effects of excess Bi on structure and electrical properties of BiFeO3 thin films deposited on indium tin oxide substrate using sol–gel method

Cited by 12 publications

References 30 publications

Effect of annealing atmosphere on leakage and dielectric characteristics of multiferroic gallium ferrite

Effect of annealing atmosphere on leakage and dielectric characteristics of multiferroic gallium ferrite

Nonstoichiometry, Structure, and Properties of BiFeO3 Films

Synthesis of Bismuth Ferrite for Photoelectrochemical Water Splitting

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Product

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Nonstoichiometry, Structure, and Properties of BiFeO₃ Films