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Lynette Keeney - One of the best experts on this subject based on the ideXlab platform.
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compositional tuning of the Aurivillius Phase material bi 5 ti 3 2 x fe 1 x nb x o 15 0 x 0 4 grown by chemical solution deposition and its influence on the structural magnetic and optical properties of the material
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 2021Co-Authors: Jennifer Halpin, Tuhin Maity, Martyn E. Pemble, Michael Schmidt, Lynette KeeneyAbstract:A series of Aurivillius Phase materials, Bi5Ti $_{{{3} -{ }{2}}{x}}$ Fe $_{{{1} +{ }}{x}}$ Nb x O15 ( $\text {x} = {0}$ , 0.1, 0.2, 0.3, and 0.4), was fabricated by chemical solution deposition. The effects of aliovalent substitution for the successful inclusion of Fe $^{{3}+}$ and Nb $^{{5}+}$ by replacing Ti $^{{4}+}$ were explored as a potential mechanism for increasing magnetic ion content within the material. The structural, optical, piezoelectric, and magnetic properties of the materials were investigated. It was found that a limit of ${x} = {0.1}$ was achieved before the appearance of secondary Phases as determined by the X-ray diffraction. Absorption in the visible region increased with increasing values of ${x}$ corresponding to the transition from the valence band to the conduction band of the Fe- ${e}_{{\text {g}}}$ energy level. Piezoresponse force microscopy measurements demonstrated that the lateral piezoelectric response increased with increasing values of ${x}$ . Magnetic measurements of Bi5Ti2.8Fe1.1Nb0.1O15 exhibited a weak ferromagnetic response at 2, 150, and 300 K of 2.2, 1.6, and 1.5 emu/cm3 with ${H}_{c}$ of $\sim 40$ , 36, and 34 Oe, respectively. The remanent magnetization ${M}_{R}$ of this sample was found to be higher than the range of reported values for the Bi5Ti3Fe1O15 parent Phase. Elemental analysis of this sample by energy-dispersive X-ray analysis did not provide any evidence for the presence of iron-rich secondary Phases. However, it is noted that a series of measurements at varying sample volumes and instrument resolutions is still required in order to put a defined confidence level on the Bi5Ti2.8Fe1.1Nb0.1O15 material being a single-Phase multiferroic.
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Compositional Tuning of the Aurivillius Phase Material Bi5Ti3−2xFe1+xNbxO15 (0 ≤ x ≤ 0.4) Grown by Chemical Solution Deposition and its Influence on the Structural, Magnetic, and Optical Properties of the Material
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 2021Co-Authors: Jennifer C. Halpin, Tuhin Maity, Martyn E. Pemble, Michael Schmidt, Lynette KeeneyAbstract:A series of Aurivillius Phase materials,Bi5Ti3-2xFe1+xNbxO15 (x = 0, 0.1, 0.2, 0.3, and 0.4), was fabricated by chemical solution deposition. The effects of aliovalent substitution for the successful inclusion of Fe3+ and Nb5+ by replacing Ti4+ were explored as a potential mechanism for increasing magnetic ion content within the material. The structural, optical, piezoelectric, and magnetic properties of the materials were investigated. It was found that a limit of x = 0.1 was achieved before the appearance of secondary Phases as determined by the X-ray diffraction. Absorption in the visible region increased with increasing values of x corresponding to the transition from the valence band to the conduction band of the Fe-eg energy level. Piezoresponse force microscopy measurements demonstrated that the lateral piezoelectric response increased with increasing values of x. Magnetic measurements of Bi5Ti3-2xFe1+xNbxO15 exhibited a weak ferromagnetic response at 2, 150, and 300 K of 2.2, 1.6, and 1.5 emu/cm3 with Hc of ~40, 36, and 34 Oe, respectively. The remanent magnetization MR of this sample was found to be higher than the range of reported values for the Bi5Ti3Fe1O15 parent Phase. Elemental analysis of this sample by energy-dispersive X-ray analysis did not provide any evidence for the presence of iron-rich secondary Phases. However, it is noted that a series of measurements at varying sample volumes and instrument resolutions is still required in order to put a defined confidence levelon the Bi5Ti2.8Fe1.1Nb0.1O15 material being a single-Phase multiferroic.
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compositional tuning of the Aurivillius Phase material bi5ti3 2xfe1 xnbxo15 0 x 0 4 grown by chemical solution deposition and its influence on the structural magnetic and optical properties of the material
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 2020Co-Authors: Jennifer Halpin, Tuhin Maity, Martyn E. Pemble, Michael Schmidt, Lynette KeeneyAbstract:A series of Aurivillius Phase materials, Bi5Ti3-2xFe1+xNbxO15 (x = 0, 0.1, 0.2, 0.3 and 0.4), was fabricated by chemical solution deposition. The effects of aliovalent substitution for the successful inclusion of Fe3+ and Nb5+ by replacing Ti4+ was explored as a potential mechanism for increasing magnetic ion content within the material. The structural, optical, piezoelectric and magnetic properties of the materials were investigated. It was found that a limit of x = 0.1 was achieved before the appearance of secondary Phases as determined by X-ray diffraction. Absorption in the visible region increased with increasing values of x corresponding to the transition from the valence band to the conduction band of the Fe-eg energy level. Piezoresponse force microscopy measurements demonstrated that the lateral piezoelectric response increased with increasing values of x. Magnetic measurements of Bi5Ti2.8Fe1.1Nb0.1O15 exhibited a weak ferromagnetic response at 2K, 150 and 300K of 2.2, 1.6, 1.5 emu/cm3 with Hc ∼ 40, 36, 34 Oe respectively. The remanent magnetisation, MR, of this sample was found to be higher than the range of reported values for the Bi5Ti3Fe1O15 parent Phase. Elemental analysis of this sample by energy dispersive X-ray analysis did not provide any evidence for the presence of ironrich secondary Phases. However, it is noted that a series of measurements at varying sample volumes and instrument resolutions is still required to in order to put a defined confidence level on the Bi5Ti2.8Fe1.1Nb0.1O15 material being a single-Phase multiferroic.
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Direct visualization of magnetic-field-induced magnetoelectric switching in multiferroic Aurivillius Phase thin films
Journal of the American Ceramic Society, 2016Co-Authors: Ahmad Faraz, Martyn E. Pemble, Roger W. Whatmore, Tuhin Maity, Michael Schmidt, Nitin Deepak, Saibal Roy, Lynette KeeneyAbstract:Multiferroic materials displaying coupled ferroelectric and ferromagnetic order parameters could provide a means for data storage whereby bits could be written electrically and read magnetically, or vice versa. Thin films of Aurivillius Phase Bi6Ti2.8Fe1.52Mn0.68O18, previously prepared by a chemical solution deposition (CSD) technique, are multiferroics demonstrating magnetoelectric coupling at room temperature. Here, we demonstrate the growth of a similar composition, Bi6Ti2.99Fe1.46Mn0.55O18, via the liquid injection chemical vapor deposition technique. High-resolution magnetic measurements reveal a considerably higher in-plane ferromagnetic signature than CSD grown films (MS=24.25 emu/g (215 emu/cm3), MR=9.916 emu/g (81.5 emu/cm3), HC=170 Oe). A statistical analysis of the results from a thorough microstructural examination of the samples, allows us to conclude that the ferromagnetic signature can be attributed to the Aurivillius Phase, with a confidence level of 99.95%. In addition, we report the direct piezoresponse force microscopy visualization of ferroelectric switching while going through a full in-plane magnetic field cycle, where increased volumes (8.6% to 14% compared with 4% to 7% for the CSD-grown films) of the film engage in magnetoelectric coupling and demonstrate both irreversible and reversible magnetoelectric domain switching.
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tunable nanoscale structural disorder in Aurivillius Phase n 3 bi4ti3o12 thin films and their role in the transformation to n 4 bi5ti3feo15 Phase
Journal of Materials Chemistry C, 2015Co-Authors: Lynette Keeney, Martyn E. Pemble, Roger W. Whatmore, Nitin Deepak, Patrick B. CarolanAbstract:Naturally super-latticed Aurivillius Phase ferroelectrics can accommodate various magnetic ions, opening up the possibility of making new room temperature multiferroics. Here, we studied the growth of single-Phase Aurivillius Phase Bi5Ti3FeO15 (BTFO) thin films, grown onto single crystalline SrTiO3 (STO) substrates, by doping Bi4Ti3O12 (BTO) with iron by liquid injection metal–organic chemical vapour deposition. The crystalline properties of the resulting films were characterized by X-ray diffraction and transmission electron microscopy. It has been found that the structural properties of the films depend strongly on the relative iron and titanium precursor injection volumes. Nanoscale structural disorder starts to occur in BTO films on the onset of iron precursor flow. A small iron precursor flow causes the formation of half-unit cells of BTFO inside BTO lattice, which in turns causes disorder in BTO films. This disorder can be tuned by varying iron content in the film. Atomic force microscopy shows how the growth mode switches from island growth to layer-by-layer growth mode as the composition changes from BTO to BTFO.
Haixue Yan - One of the best experts on this subject based on the ideXlab platform.
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cobalt induced structural modulation in multiferroic Aurivillius Phase oxides
Journal of Materials Chemistry C, 2020Co-Authors: Vladimir Koval, Giuseppe Viola, Yurong Shi, I Skorvanek, R Bures, Karel Saksl, P Roupcova, M Zhang, Ch Jia, Haixue YanAbstract:Attaining robust magnetic long-range order in ferroelectric Aurivillius-Phase oxides at room temperature has recently attracted considerable attention of materials scientists and engineers for the development of magnetoelectric-active materials in microelectronics and spintronics. Here, we report the structural evolution and its relation to the macroscopic magnetization of a series of samples of Aurivillius (Bi4.3Gd0.7)(Fe1−xCox)1+yTi3−2yNbyO15 (x = 0, 0.3, 0.5 and y = 0, 0.3) compounds prepared by a solid state reaction, aiming at shedding light on the Co substitution-induced ferromagnetism at room temperature and above. The Co-free composition showed a single-Phase four-layered Aurivillius structure (space group A21am), while the Co substitution was found to give rise to a mixed-layer structure composed of four- and three-layered Phases. Rietveld analysis of the synchrotron X-ray diffraction data showed that the reduction in the number of layers across the Aurivillius morphotropic transition boundary is accompanied by a structural Phase transformation from A21am to B2cb. The disordered intergrowth of these Phases was evidenced by high-resolution transmission electron microscopy and found to originate from a nanoscale structural modulation occurring at the interface between the two Phases. A sextet suggesting long-range magnetic ordering in the doped samples was deduced from Mossbauer spectra. Magnetic-property measurements, indeed, confirmed a ferromagnetic state of these samples at elevated temperatures. The highest values of the remanent and saturation magnetization at room temperature were obtained for the compositions with x = 0.3, in which the occurrence and enhancement of the magnetization can be attributed to the ferromagnetic clustering of the FeO6 and CoO6 octahedra and, partly, also to spin canting effects and/or a double-exchange magnetic interaction between the mixed valence cobalt through oxygen. The cooperative freezing of randomly distributed Fe–O–Co clusters is suggested to be responsible for the spin glass-like behaviour observed at low temperatures. The occurrence and enhancement of the magnetization in the ferroelectric Co-doped Aurivillius ceramics are attributed, respectively, to the structural modulation and the population of the ferromagnetic clusters near the interface of the four- and three-layered Phases.
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Ferroelectric and photocatalytic properties of Aurivillius Phase Ca2Bi4Ti5O18
2020Co-Authors: Yaqiong Wang, Hongtao Zhang, Man Zhang, Haixue YanAbstract:Aurivillius Phase Ca2Bi4Ti5O18 powders with micrometer size were produced by solidstate reaction. X-ray diffraction revealed that the powders had polar orthorhombic structure with space group of B2cb. Ca2Bi4Ti5O18 ceramic exhibited frequency independent dielectric anomaly at 774 °C. The piezoelectric coefficient d33 value of poled Ca2Bi4Ti5O18 pellets was 0.7±0.2 pC/N. Both frequency independent dielectric anomaly and detectable d33 value clearly indicated that Ca2Bi4Ti5O18 is a ferroelectric material with Curie point of 774 ℃. UV–vis absorption spectra revealed that Ca2Bi4Ti5O18 had a direct band gap of 3.2 eV. Photocatalytic activity of the Ca2Bi4Ti5O18 powders was examined by degradation of rhodamine B (RhB) under simulated solar light. 16% of RhB solution was degraded by Ca2Bi4Ti5O18 powders after 4 h UV-vis irradiation. With Ag nanoparticles deposited on the Ca2Bi4Ti5O18 powders surface, 50% of RhB were degraded under the same irradiation condition. The fitted degradation rate constant of Ag decorated Ca2Bi4Ti5O18 was 4 times higher than that of bare Ca2Bi4Ti5O18. This work suggested that the Aurivillius ferroelectric Ca2Bi4Ti5O18 is a promising candidate for photocatalytic applications
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spark plasma sintering of grain oriented sr2bi4ti5o18 Aurivillius Phase ceramics
Journal of Alloys and Compounds, 2019Co-Authors: Jun Cao, Giuseppe Viola, Haixue YanAbstract:Abstract To improve dielectric, piezoelectric and ferroelectric properties of Sr2Bi4Ti5O18 ceramics, highly textured, dense ceramics are required. Highly grain-oriented Sr2Bi4Ti5O18 textured ceramics were prepared by pressure-assisted spark plasma sintering. The textured ceramics exhibited crystallographic anisotropy with c-axis oriented grains (Lotgering factor of 71%). The dielectric permittivity, piezoelectric constant and ferroelectric remnant polarization measured on the ceramics in the direction perpendicular to the pressure applied during sintering are higher than those along the parallel direction. These improved properties are related to the preferred polarization rotation in the textured microstructures prepared during spark plasma sintering.
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Room temperature magnetoelectric coupling in intrinsic multiferroic Aurivillius Phase textured ceramics
Dalton Transactions, 2016Co-Authors: Zhipeng Gao, Giuseppe Viola, Vladimir Koval, Amit Mahajan, Chenglong Jia, Ce-wen Nan, Haixue YanAbstract:Spark plasma sintering was employed in order to obtain textured Aurivillius Phase ceramics that simultaneously exhibit ferroelectric and ferromagnetic properties at room temperature. The sintered multiferroics are layer-structured, nearly single-Phase materials. Although a small amount of the secondary Phase consisting of magnetic Co and Fe was detected by SEM/EDX, a majority of the observed ferromagnetic behaviour was attributed to the Aurivillius Phase Bi4.25La0.75Ti3Fe0.5Co0.5O15 based on the observed magnetic anisotropy. The ferroelectric switching was demonstrated to exist in the Aurivillius Phase ceramics by measuring the current peaks upon electric field reversal. Piezoresponse force microscopy at room temperature revelaed substantial changes of the ferroelectric domain structure when the Aurivillius Phase material is subjected to an external magnetic field.
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the contribution of electrical conductivity dielectric permittivity and domain switching in ferroelectric hysteresis loops
Journal of Advanced Dielectrics, 2011Co-Authors: Haixue Yan, Zhipeng Gao, Giuseppe Viola, Hongtao Zhang, Huanpo Ning, Fawad Inam, Qinghui Jiang, Tao Zeng, Michael J. ReeceAbstract:Triangular voltage waveform was employed to distinguish the contributions of dielectric permittivity, electric conductivity and domain switching in current-electric field curves. At the same time, it is shown how those contributions can affect the shape of the electric displacement — electric field loops (D–E loops). The effects of frequency, temperature and microstructure (point defects, grain size and texture) on the ferroelectric properties of several ferroelectric compositions is reported, including: BaTiO3; lead zirconate titanate (PZT); lead-free Na0.5K0.5NbO3; perovskite-like layer structured A2B2O7 with super high Curie point (Tc); Aurivillius Phase ferroelectric Bi3.15Nd0.5Ti3O12; and multiferroic Bi0.89La0.05Tb0.06FeO3. This systematic study provides an instructive outline in the measurement of ferroelectric properties and the analysis and interpretation of experimental data.
Roger W. Whatmore - One of the best experts on this subject based on the ideXlab platform.
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Direct visualization of magnetic-field-induced magnetoelectric switching in multiferroic Aurivillius Phase thin films
Journal of the American Ceramic Society, 2016Co-Authors: Ahmad Faraz, Martyn E. Pemble, Roger W. Whatmore, Tuhin Maity, Michael Schmidt, Nitin Deepak, Saibal Roy, Lynette KeeneyAbstract:Multiferroic materials displaying coupled ferroelectric and ferromagnetic order parameters could provide a means for data storage whereby bits could be written electrically and read magnetically, or vice versa. Thin films of Aurivillius Phase Bi6Ti2.8Fe1.52Mn0.68O18, previously prepared by a chemical solution deposition (CSD) technique, are multiferroics demonstrating magnetoelectric coupling at room temperature. Here, we demonstrate the growth of a similar composition, Bi6Ti2.99Fe1.46Mn0.55O18, via the liquid injection chemical vapor deposition technique. High-resolution magnetic measurements reveal a considerably higher in-plane ferromagnetic signature than CSD grown films (MS=24.25 emu/g (215 emu/cm3), MR=9.916 emu/g (81.5 emu/cm3), HC=170 Oe). A statistical analysis of the results from a thorough microstructural examination of the samples, allows us to conclude that the ferromagnetic signature can be attributed to the Aurivillius Phase, with a confidence level of 99.95%. In addition, we report the direct piezoresponse force microscopy visualization of ferroelectric switching while going through a full in-plane magnetic field cycle, where increased volumes (8.6% to 14% compared with 4% to 7% for the CSD-grown films) of the film engage in magnetoelectric coupling and demonstrate both irreversible and reversible magnetoelectric domain switching.
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tunable nanoscale structural disorder in Aurivillius Phase n 3 bi4ti3o12 thin films and their role in the transformation to n 4 bi5ti3feo15 Phase
Journal of Materials Chemistry C, 2015Co-Authors: Lynette Keeney, Martyn E. Pemble, Roger W. Whatmore, Nitin Deepak, Patrick B. CarolanAbstract:Naturally super-latticed Aurivillius Phase ferroelectrics can accommodate various magnetic ions, opening up the possibility of making new room temperature multiferroics. Here, we studied the growth of single-Phase Aurivillius Phase Bi5Ti3FeO15 (BTFO) thin films, grown onto single crystalline SrTiO3 (STO) substrates, by doping Bi4Ti3O12 (BTO) with iron by liquid injection metal–organic chemical vapour deposition. The crystalline properties of the resulting films were characterized by X-ray diffraction and transmission electron microscopy. It has been found that the structural properties of the films depend strongly on the relative iron and titanium precursor injection volumes. Nanoscale structural disorder starts to occur in BTO films on the onset of iron precursor flow. A small iron precursor flow causes the formation of half-unit cells of BTFO inside BTO lattice, which in turns causes disorder in BTO films. This disorder can be tuned by varying iron content in the film. Atomic force microscopy shows how the growth mode switches from island growth to layer-by-layer growth mode as the composition changes from BTO to BTFO.
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The structural and piezoresponse properties of c-axis-oriented Aurivillius Phase Bi5Ti3FeO15 thin films deposited by atomic vapor deposition
Applied Physics Letters, 2012Co-Authors: Panfeng F. Zhang, Lynette Keeney, Martyn E. Pemble, Nitin Deepak, Roger W. WhatmoreAbstract:The deposition by atomic vapor deposition of highly c-axis-oriented Aurivillius Phase Bi5Ti3FeO15 (BTFO) thin films on (100) Si substrates is reported. Partially crystallized BTFO films with c-axis perpendicular to the substrate surface were first deposited at 610 °C (8% excess Bi), and subsequently annealed at 820 °C to get stoichiometric composition. After annealing, the films were highly c-axis-oriented, showing only (00l) peaks in x-ray diffraction (XRD), up to (0024). Transmission electron microscopy (TEM) confirms the BTFO film has a clear layered structure, and the bismuth oxide layer interleaves the four-block pseudoperovskite layer, indicating the n = 4 Aurivillius Phase structure. Piezoresponse force microscopy measurements indicate strong in-plane piezoelectric response, consistent with the c-axis layered structure, shown by XRD and TEM.
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room temperature ferroelectric and magnetic investigations and detailed Phase analysis of Aurivillius Phase bi5ti3fe0 7co0 3o15 thin films
Journal of Applied Physics, 2012Co-Authors: Lynette Keeney, Panfeng F. Zhang, Martyn E. Pemble, Michael Schmidt, Nitin Deepak, Saibal Roy, Santosh Kulkarni, Nikolay Petkov, S A Cavill, Roger W. WhatmoreAbstract:Aurivillius Phase Bi5Ti3Fe0.7Co0.3O15 (BTF7C3O) thin films on α-quartz substrates were fabricated by a chemical solution deposition method and the room temperature ferroelectric and magnetic properties of this candidate multiferroic were compared with those of thin films of Mn3+ substituted, Bi5Ti3Fe0.7Mn0.3O15 (BTF7M3O). Vertical and lateral piezoresponse force microscopy (PFM) measurements of the films conclusively demonstrate that BTF7C3O and BTF7M3O thin films are piezoelectric and ferroelectric at room temperature, with the major polarization vector in the lateral plane of the films. No net magnetization was observed for the in-plane superconducting quantum interference device (SQUID) magnetometry measurements of BTF7M3O thin films. In contrast, SQUID measurements of the BTF7C3O films clearly demonstrated ferromagnetic behavior, with a remanent magnetization, Br, of 6.37 emu/cm3 (or 804 memu/g), remanent moment = 4.99 × 10−5 emu. The BTF7C3O films were scrutinized by x-ray diffraction, high resolutio...
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room temperature electromechanical and magnetic investigations of ferroelectric Aurivillius Phase bi5ti3 fexmn1 x o15 x 1 and 0 7 chemical solution deposited thin films
Journal of Applied Physics, 2012Co-Authors: Lynette Keeney, Claudia Groh, Martyn E. Pemble, Saibal Roy, Santosh Kulkarni, Roger W. WhatmoreAbstract:Aurivillius Phase thin films of Bi5Ti3(FexMn1−x)O15 with x = 1 (Bi5Ti3FeO15) and 0.7 (Bi5Ti3Fe0.7Mn0.3O15) on SiO2-Si(100) and Pt/Ti/SiO2-Si substrates were fabricated by chemical solution deposition. The method was optimized in order to suppress formation of pyrochlore Phase Bi2Ti2O7 and improve crystallinity. The structural properties of the films were examined by x-ray diffraction, scanning electron microscopy, and atomic force microscopy. Optimum crystallinity and pyrochlore Phase suppression was achieved by the addition of 15 to 25 mol. % excess bismuth to the sols. Based on this study, 17.5 mol. % excess bismuth was used in the preparation of Bi2Ti2O7-free films of Bi5Ti3FeO15 on SrTiO3(100) and NdGaO3(001) substrates, confirming the suppression of pyrochlore Phase using this excess of bismuth. Thirty percent of the Fe3+ ions in Bi5Ti3FeO15 was substituted with Mn3+ ions to form Bi2Ti2O7-free thin films of Bi5Ti3Fe0.7Mn0.3O15 on Pt/Ti/SiO2-Si, SiO2-Si(100), SrTiO3(100), and NdGaO3(001) substrates. B...
Martyn E. Pemble - One of the best experts on this subject based on the ideXlab platform.
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compositional tuning of the Aurivillius Phase material bi 5 ti 3 2 x fe 1 x nb x o 15 0 x 0 4 grown by chemical solution deposition and its influence on the structural magnetic and optical properties of the material
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 2021Co-Authors: Jennifer Halpin, Tuhin Maity, Martyn E. Pemble, Michael Schmidt, Lynette KeeneyAbstract:A series of Aurivillius Phase materials, Bi5Ti $_{{{3} -{ }{2}}{x}}$ Fe $_{{{1} +{ }}{x}}$ Nb x O15 ( $\text {x} = {0}$ , 0.1, 0.2, 0.3, and 0.4), was fabricated by chemical solution deposition. The effects of aliovalent substitution for the successful inclusion of Fe $^{{3}+}$ and Nb $^{{5}+}$ by replacing Ti $^{{4}+}$ were explored as a potential mechanism for increasing magnetic ion content within the material. The structural, optical, piezoelectric, and magnetic properties of the materials were investigated. It was found that a limit of ${x} = {0.1}$ was achieved before the appearance of secondary Phases as determined by the X-ray diffraction. Absorption in the visible region increased with increasing values of ${x}$ corresponding to the transition from the valence band to the conduction band of the Fe- ${e}_{{\text {g}}}$ energy level. Piezoresponse force microscopy measurements demonstrated that the lateral piezoelectric response increased with increasing values of ${x}$ . Magnetic measurements of Bi5Ti2.8Fe1.1Nb0.1O15 exhibited a weak ferromagnetic response at 2, 150, and 300 K of 2.2, 1.6, and 1.5 emu/cm3 with ${H}_{c}$ of $\sim 40$ , 36, and 34 Oe, respectively. The remanent magnetization ${M}_{R}$ of this sample was found to be higher than the range of reported values for the Bi5Ti3Fe1O15 parent Phase. Elemental analysis of this sample by energy-dispersive X-ray analysis did not provide any evidence for the presence of iron-rich secondary Phases. However, it is noted that a series of measurements at varying sample volumes and instrument resolutions is still required in order to put a defined confidence level on the Bi5Ti2.8Fe1.1Nb0.1O15 material being a single-Phase multiferroic.
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Compositional Tuning of the Aurivillius Phase Material Bi5Ti3−2xFe1+xNbxO15 (0 ≤ x ≤ 0.4) Grown by Chemical Solution Deposition and its Influence on the Structural, Magnetic, and Optical Properties of the Material
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 2021Co-Authors: Jennifer C. Halpin, Tuhin Maity, Martyn E. Pemble, Michael Schmidt, Lynette KeeneyAbstract:A series of Aurivillius Phase materials,Bi5Ti3-2xFe1+xNbxO15 (x = 0, 0.1, 0.2, 0.3, and 0.4), was fabricated by chemical solution deposition. The effects of aliovalent substitution for the successful inclusion of Fe3+ and Nb5+ by replacing Ti4+ were explored as a potential mechanism for increasing magnetic ion content within the material. The structural, optical, piezoelectric, and magnetic properties of the materials were investigated. It was found that a limit of x = 0.1 was achieved before the appearance of secondary Phases as determined by the X-ray diffraction. Absorption in the visible region increased with increasing values of x corresponding to the transition from the valence band to the conduction band of the Fe-eg energy level. Piezoresponse force microscopy measurements demonstrated that the lateral piezoelectric response increased with increasing values of x. Magnetic measurements of Bi5Ti3-2xFe1+xNbxO15 exhibited a weak ferromagnetic response at 2, 150, and 300 K of 2.2, 1.6, and 1.5 emu/cm3 with Hc of ~40, 36, and 34 Oe, respectively. The remanent magnetization MR of this sample was found to be higher than the range of reported values for the Bi5Ti3Fe1O15 parent Phase. Elemental analysis of this sample by energy-dispersive X-ray analysis did not provide any evidence for the presence of iron-rich secondary Phases. However, it is noted that a series of measurements at varying sample volumes and instrument resolutions is still required in order to put a defined confidence levelon the Bi5Ti2.8Fe1.1Nb0.1O15 material being a single-Phase multiferroic.
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compositional tuning of the Aurivillius Phase material bi5ti3 2xfe1 xnbxo15 0 x 0 4 grown by chemical solution deposition and its influence on the structural magnetic and optical properties of the material
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 2020Co-Authors: Jennifer Halpin, Tuhin Maity, Martyn E. Pemble, Michael Schmidt, Lynette KeeneyAbstract:A series of Aurivillius Phase materials, Bi5Ti3-2xFe1+xNbxO15 (x = 0, 0.1, 0.2, 0.3 and 0.4), was fabricated by chemical solution deposition. The effects of aliovalent substitution for the successful inclusion of Fe3+ and Nb5+ by replacing Ti4+ was explored as a potential mechanism for increasing magnetic ion content within the material. The structural, optical, piezoelectric and magnetic properties of the materials were investigated. It was found that a limit of x = 0.1 was achieved before the appearance of secondary Phases as determined by X-ray diffraction. Absorption in the visible region increased with increasing values of x corresponding to the transition from the valence band to the conduction band of the Fe-eg energy level. Piezoresponse force microscopy measurements demonstrated that the lateral piezoelectric response increased with increasing values of x. Magnetic measurements of Bi5Ti2.8Fe1.1Nb0.1O15 exhibited a weak ferromagnetic response at 2K, 150 and 300K of 2.2, 1.6, 1.5 emu/cm3 with Hc ∼ 40, 36, 34 Oe respectively. The remanent magnetisation, MR, of this sample was found to be higher than the range of reported values for the Bi5Ti3Fe1O15 parent Phase. Elemental analysis of this sample by energy dispersive X-ray analysis did not provide any evidence for the presence of ironrich secondary Phases. However, it is noted that a series of measurements at varying sample volumes and instrument resolutions is still required to in order to put a defined confidence level on the Bi5Ti2.8Fe1.1Nb0.1O15 material being a single-Phase multiferroic.
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Direct visualization of magnetic-field-induced magnetoelectric switching in multiferroic Aurivillius Phase thin films
Journal of the American Ceramic Society, 2016Co-Authors: Ahmad Faraz, Martyn E. Pemble, Roger W. Whatmore, Tuhin Maity, Michael Schmidt, Nitin Deepak, Saibal Roy, Lynette KeeneyAbstract:Multiferroic materials displaying coupled ferroelectric and ferromagnetic order parameters could provide a means for data storage whereby bits could be written electrically and read magnetically, or vice versa. Thin films of Aurivillius Phase Bi6Ti2.8Fe1.52Mn0.68O18, previously prepared by a chemical solution deposition (CSD) technique, are multiferroics demonstrating magnetoelectric coupling at room temperature. Here, we demonstrate the growth of a similar composition, Bi6Ti2.99Fe1.46Mn0.55O18, via the liquid injection chemical vapor deposition technique. High-resolution magnetic measurements reveal a considerably higher in-plane ferromagnetic signature than CSD grown films (MS=24.25 emu/g (215 emu/cm3), MR=9.916 emu/g (81.5 emu/cm3), HC=170 Oe). A statistical analysis of the results from a thorough microstructural examination of the samples, allows us to conclude that the ferromagnetic signature can be attributed to the Aurivillius Phase, with a confidence level of 99.95%. In addition, we report the direct piezoresponse force microscopy visualization of ferroelectric switching while going through a full in-plane magnetic field cycle, where increased volumes (8.6% to 14% compared with 4% to 7% for the CSD-grown films) of the film engage in magnetoelectric coupling and demonstrate both irreversible and reversible magnetoelectric domain switching.
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tunable nanoscale structural disorder in Aurivillius Phase n 3 bi4ti3o12 thin films and their role in the transformation to n 4 bi5ti3feo15 Phase
Journal of Materials Chemistry C, 2015Co-Authors: Lynette Keeney, Martyn E. Pemble, Roger W. Whatmore, Nitin Deepak, Patrick B. CarolanAbstract:Naturally super-latticed Aurivillius Phase ferroelectrics can accommodate various magnetic ions, opening up the possibility of making new room temperature multiferroics. Here, we studied the growth of single-Phase Aurivillius Phase Bi5Ti3FeO15 (BTFO) thin films, grown onto single crystalline SrTiO3 (STO) substrates, by doping Bi4Ti3O12 (BTO) with iron by liquid injection metal–organic chemical vapour deposition. The crystalline properties of the resulting films were characterized by X-ray diffraction and transmission electron microscopy. It has been found that the structural properties of the films depend strongly on the relative iron and titanium precursor injection volumes. Nanoscale structural disorder starts to occur in BTO films on the onset of iron precursor flow. A small iron precursor flow causes the formation of half-unit cells of BTFO inside BTO lattice, which in turns causes disorder in BTO films. This disorder can be tuned by varying iron content in the film. Atomic force microscopy shows how the growth mode switches from island growth to layer-by-layer growth mode as the composition changes from BTO to BTFO.
Yoshiyuki Sugahara - One of the best experts on this subject based on the ideXlab platform.
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a layered tungstic acid h2w2o7 nh2o with a double octahedral sheet structure conversion process from an Aurivillius Phase bi2w2o9 and structural characterization
Inorganic Chemistry, 2003Co-Authors: Manabu Kudo, Wataru Sugimoto, Hajime Ohkawa, Nobuhiro Kumada, Zheng Liu, Osamu Terasaki, Yoshiyuki SugaharaAbstract:The conversion process of an Aurivillius Phase, Bi2W2O9, into a layered tungstic acid by hydrochloric acid treatment has been investigated, and resultant H2W2O7·nH2O has been fully characterized. The c parameter of Bi2W2O9 [2.37063(5) nm] decreases to 2.21(1) nm in an acid-treated product dried at ambient temperature. The a and b parameters of Bi2W2O9 [a = 0.54377(1) nm and b = 0.54166(1) nm] also decrease slightly to a = 0.524(1) nm and b = 0.513(1) nm in the acid-treated product dried at ambient temperature, indicating structural changes in the ReO3-like slabs in Bi2W2O9 upon acid treatment. Drying at 120 °C leads to a further decrease in the c parameter [1.86(1) nm] with no notable change in the a and b parameters [a = 0.5249(2) nm and b = 0.513(2) nm]. The formation of an expandable layered structure is demonstrated by the successful intercalation of n-octylamine [interlayer distance 2.597(9) nm] and n-dodecylamine [interlayer distance 3.56(2) nm]. The compositions of the acid-treated products are det...
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a layered tungstic acid h2w2o7 nh2o with a double octahedral sheet structure conversion process from an Aurivillius Phase bi2w2o9 and structural characterization
Inorganic Chemistry, 2003Co-Authors: Manabu Kudo, Wataru Sugimoto, Hajime Ohkawa, Nobuhiro Kumada, Zheng Liu, Osamu Terasaki, Yoshiyuki SugaharaAbstract:The conversion process of an Aurivillius Phase, Bi(2)W(2)O(9), into a layered tungstic acid by hydrochloric acid treatment has been investigated, and resultant H(2)W(2)O(7) x nH(2)O has been fully characterized. The c parameter of Bi(2)W(2)O(9) [2.37063(5) nm] decreases to 2.21(1) nm in an acid-treated product dried at ambient temperature. The a and b parameters of Bi(2)W(2)O(9) [a = 0.54377(1) nm and b = 0.54166(1) nm] also decrease slightly to a = 0.524(1) nm and b = 0.513(1) nm in the acid-treated product dried at ambient temperature, indicating structural changes in the ReO(3)-like slabs in Bi(2)W(2)O(9) upon acid treatment. Drying at 120 degrees C leads to a further decrease in the c parameter [1.86(1) nm] with no notable change in the a and b parameters [a = 0.5249(2) nm and b = 0.513(2) nm]. The formation of an expandable layered structure is demonstrated by the successful intercalation of n-octylamine [interlayer distance 2.597(9) nm] and n-dodecylamine [interlayer distance 3.56(2) nm]. The compositions of the acid-treated products are determined to be H(2)W(2)O(7) x nH(2)O typically with n = 0.58 for the air-dried product and n = 0 for the product dried at 120 degrees C. As a consequence, the composition of the layer is H(2)W(2)O(7), and the decrease in the c parameter upon drying is ascribable to the loss of interlayer water. Scanning electron microscopy reveals no morphological change during acid treatment, which strongly suggests a selective leaching of the bismuth oxide sheets as a reaction mechanism. High-resolution transmission electron microscopy (HREM) observation of the acid-treated product shows consistency with a structural model for H(2)W(2)O(7), derived from Bi(2)W(2)O(9) through removal of the bismuth oxide sheets and contraction along the c axis. HREM observation also reveals that the WO(6) octahedra arrangement changes slightly with acid treatment. A one-dimensional electron density map projected on the c axis for the product dried at 120 degrees C, H(2)W(2)O(7), shows good consistency with that calculated for the structural model.
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intercalation behavior of n alkylamines into a protonated form of a layered perovskite derived from Aurivillius Phase bi2srta2o9
Chemistry of Materials, 2003Co-Authors: Yu Tsunoda, Wataru Sugimoto, Yoshiyuki SugaharaAbstract:Intercalation behavior of n-alkylamines into a protonated form of a layered perovskite, H1.8[Sr0.8Bi0.2Ta2O7], derived from an Aurivillius Phase, Bi2SrTa2O9, has been investigated. H1.8[Sr0.8Bi0.2Ta2O7] can accommodate n-alkylamines (CmHm+1NH2; m = 4, 8, 12, 18) to form intercalation compounds via an acid−base mechanism. The interlayer distance increases to 2.071(2) (m = 4), 2.840(9) (m = 8 ), 3.83(1) (m = 12), and 5.17(2) (m = 18) nm. In contrast, H1.8[Sr0.8Bi0.2Ta2O7] does not form any intercalation compound with pyridine, which is a weaker base, indicating that the protons in H1.8[Sr0.8Bi0.2Ta2O7] are weakly acidic. The IR spectra of the intercalation compounds with n-alkylamines (m = 12 and 18) clearly show that n-alkyl chains possess an all-trans conformation. A linear relationship is observed between the interlayer distance and the number of carbon atoms in n-alkyl chains, and this corresponds to a bilayer arrangement of the n-alkyl chains with a tilt angle of 60°. Despite the relatively high proton...
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preparation and hrem characterization of a protonated form of a layered perovskite tantalate from an Aurivillius Phase bi2srta2o9 via acid treatment
Inorganic Chemistry, 2001Co-Authors: Yu Tsunoda, Wataru Sugimoto, Masashi Shirata, Zheng Liu, Osamu Terasaki, Kazuyuki Kuroda, Yoshiyuki SugaharaAbstract:An Aurivillius Phase, Bi(2)SrTa(2)O(9), which consists of perovskite-like slabs and bismuth oxide sheets, was treated with 3 M hydrochloric acid for 72 h, and the resultant product was characterized. Scanning electron microscopy investigation indicated that no morphological change occurred during the acid treatment. X-ray diffraction (XRD) analysis revealed that the product exhibited tetragonal symmetry with a = 0.391 +/- 0.004 nm and c = 0.98 +/- 0.01 nm, and the a parameter is consistent with a typical value for cubic perovskite oxides. High-resolution electron microscopy (HREM) observations along both [001] and [010] showed that the structure of the perovskite-like slabs in Bi(2)SrTa(2)O(9) was retained after the acid treatment. The compositional analyses revealed the loss of a large portion of bismuth and a part of strontium (present in the bismuth oxide sheets due to B Sr disorder) and the introduction of protons. These observations indicate that the bismuth oxide sheets in Bi(2)SrTa(2)O(9) were selectively leached and that protons were introduced into the interlayer space to form a protonated layered perovskite, H(1.8)[Sr(0.8)Bi(0.2)Ta(2)O(7)]. Though diffraction techniques (XRD and electron diffraction) demonstrated that an average structure of H(1.8)[Sr(0.8)Bi(0.2)Ta(2)O(7)] consisted of perovskite-like slabs stacked without displacement, HREM observation along [010] demonstrated that both a simple stacking sequence without displacement (P-type) and a stacking sequence with a relative displacement by (a + b)/2 (I-type) were present in H(1.8)[Sr(0.8)Bi(0.2)Ta(2)O(7)].
