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Characterization of bismuth titanate ceramics derived by mechanochemical synthesis  [PDF]
Lazarevi? Z.?.,Stojanovi? B.D.,Paiva-Santos C.O.,Rom?evi? N.?.
Science of Sintering , 2007, DOI: 10.2298/sos0703267l
Abstract: Bismuth titanate, Bi4Ti3O12 (BIT) nanosized powders have been successfully synthesized via high energy mechanochemical activation. The phase formation of BIT, crystal structure, microstructure, crystallite size and specific surface area were followed by XRD, scanning electron microscopy (SEM) and the BET specific surface area measurements. The BIT milled 2 h shows the orthorhombic crystalline structure with small amount of amorphous phase. The microstructure of Bi4Ti3O12 ceramics sintered at 1000°C for 12h exhibit plate-like grain structure.
Optical Anisotropy in Bismuth Titanate: An Experimental and Theoretical Study  [PDF]
Amritendu Roy,Rajendra Prasad,Sushil Auluck,Ashish Garg
Physics , 2013, DOI: 10.1063/1.4870460
Abstract: We report experimental and theoretical investigation of anisotropy in optical properties and their origin in the ferroelectric and paraelectric phases of bismuth titanate. Room temperature ellipsometric measurements performed on pulsed laser deposited bismuth titanate thin films of different orientations show anisotropy in the dielectric and optical constants, Subsequent first-principles calculations performed on the ground state structures of ferroelectric and high temperature paraelectric phases of bismuth titanate show that the material demonstrates anisotropic optical behavior in both ferroelectric and paraelectric phases. We further show that O 2p to Ti 3d transition is the primary origin of optical activity of the material while optical anisotropy results from the asymmetrically oriented Ti-O bonds in TiO6 octehdra in the unit cell.
Study of barium bismuth titanate prepared by mechanochemical synthesis  [PDF]
Lazarevi? Z.?.,Bobi? J.,Rom?evi? N.?.,Paunovi? N.
Science of Sintering , 2009, DOI: 10.2298/sos0903329l
Abstract: Barium-bismuth titanate, BaBi4Ti4O15 (BBT), a member of Aurivillius bismuth-based layer-structure perovskites, was prepared from stoichiometric amounts of barium titanate and bismuth titanate obtained via mechanochemical synthesis. Mechanochemical synthesis was performed in air atmosphere in a planetary ball mill. The reaction mechanism of BaBi4Ti4O15 and the preparation and characteristics of BBT ceramic powders were studied using XRD, Raman spectroscopy, particle analysis and SEM. The Bi-layered perovskite structure of BaBi4Ti4O15 ceramic forms at 1100 °C for 4 h without a pre-calcination step. The microstructure of BaBi4Ti4O15 exhibits plate-like grains typical for the Bi-layered structured material and spherical and polygonal grains. The Ba2+ addition leads to changes in the microstructure development, particularly in the change of the average grain size.
Engineering Polarization Rotation in Ferroelectric Bismuth Titanate  [PDF]
Amritendu Roy,Rajendra Prasad,Sushil Auluck,Ashish Garg
Physics , 2013, DOI: 10.1063/1.4804367
Abstract: Here, we report a combined experimental-theoretical study showing that collective application of rare earth doping on A-site and epitaxial strain to ferroelectric bismuth titanate does not lead to a very large c-axis polarization as reported previously. Further first principles calculations based on the examination of polarization tensor suggest that simultaneous Bi and Ti site doping could result in moderate polarization along c-axis of bismuth titanate which is typically a preferential axis of film growth and thus enabling c axis oriented films to have appreciable polarization. This approach could also be applicable to other ferroic oxides where one can correlate the doping, epitaxial strain, and polarization to design materials compositions resulting in epitaxial films grown along desired directions yielding substantial polarization.
An approach to analyzing synthesis, structure and properties of bismuth titanate ceramics  [PDF]
Lazarevi? Z.,Stojanovi? B.D.,Varela J.A.
Science of Sintering , 2005, DOI: 10.2298/sos0503199l
Abstract: The family of bismuth titanate, Bi4Ti3O12 (BIT) layered-structured ferroelectrics materials is attractive from the viewpoint of their application as electronic materials such as dielectrics, piezoelectrics and pyroelectrics, because they are characterized by good stability of piezoelectric properties, a high Curie temperature and a good resistance vs temperature. Bismuth titanate (Bi4Ti3O12) powders can be prepared using different methods, depending if the creation will be film coating or ceramics. The structure and properties of bismuth titanate materials show a significance dependence on the applied synthesis method. In this review paper, we made an attempt to give an approach to analyzing the structure, synthesis methods and properties of bismuth titanate ferroelectrics materials. .
Effect of synthesis route on the microstructure of SiO2 doped bismuth titanate ceramics  [PDF]
Elena P. Kashchieva,Milena Z. Krapchanska,Stanislav S. Slavov,Yanko B. Dimitriev
Processing and Application of Ceramics , 2009,
Abstract: Synthesis and characterization of SiO2 doped bismuth titanate ceramics were investigated. Four investigated compositions belonging to the system Bi2O3-TiO2-SiO2 are located in the section Bi4Ti3O12-SiO2, near by it and in the binary Bi2O3-TiO2 system. Melt quenching was applied for synthesis of SiO2 doped bismuth titanate ceramics and for the sample 40Bi2O3·60TiO2. The binary sample 70Bi2O3·30TiO2 is prepared by gradient heating of bulk materials near the liquidus temperature (modified solid state reaction). The influence of the thermal treatment on the phase formation and microstructure was evaluated using XRD, EDS and SEM. The binary samples prepared by solid state reaction at low temperature (1000°C) possess poly-phased dense microstructure, while secondary crystallization combined with porosity formation is typical for the sample obtained at high temperature (1150°C). The ternary Bi2O3-TiO2-SiO2 samples, obtained by supercooling of the melts down to room temperature, are thermally treated at 700, 800°C. They consist of elongated crystals in amorphous matrix. The crystals have lower Bi2O3-content and higher TiO2-content than the nominal batch composition. The XRD data show that the main crystalline phases in the ceramics produced by melt quenching method and solid state reaction are β-Bi2O3, Bi4Ti3O12 and one unknown new phase. It is proved that the applied methods of synthesis are suitable for generation of different microstructures in the bulk SiO2 doped bismuth titanate ceramics, which is promising basis for modification of their electrical properties.
Review - Fabrication of crystal-oriented barium-bismuth titanate ceramics in high magnetic field and subsequent reaction sintering
Satoshi Tanaka, Yusuke Tomita, Ryoichi Furushima, Hiroyuki Shimizu, Yutaka Doshida and Keizo Uematsu
Science and Technology of Advanced Materials , 2009,
Abstract: High magnetic field was applied to fabricate novel lead-free piezoelectric ceramics with a textured structure. A compact of crystallographically oriented grains was prepared by dry forming in a high magnetic field from a mixed slurry of bismuth titanate and barium titanate powders. Bismuth titanate particles with a size of about 1 μ m were used as the host material. In the forming process, the slurry was poured into a mold and set in a magnetic field of 10 T until completely dried. Bismuth titanate particles were highly oriented in the slurry under the magnetic field. The dried powder compact consisted of highly oriented bismuth titanate particles and randomly oriented barium titanate particles. Barium bismuth titanate ceramics with a- and b-axis orientations were successfully produced from the dried compact by sintering at temperatures above 1100 ° C.
Synthesis and characterization of Ce and La modi ed bismuth titanate  [PDF]
Nikolina Pavlovi?,Dejan Kancko,Katalin Mészáros Szécsényi,Vladimir V. Srdi?
Processing and Application of Ceramics , 2009,
Abstract: Bismuth titanate based nanopowders with the different content of La or Ce were synthesized by the modi ed sol-gel method. After calcination at 600°C, in addition to Aurivillius layered structure, a small quantity of cubic pyrochlore phase was detected in the La modi ed powders, while this second phase was much more pronounced in the Ce substituted powders. In fact, as the powder with the highest amount of Ce (Bi3CeTi3O12) has the pure pyrochlore phase it seems that the presence of Ce stabilizes the formation of this phase. This different in uence of cerium and lanthanum could be explained by the incorporation of their ions on the different sites in the titanate structure. Bismuth titanate based ceramics, sintered at 1050°C/2h, had densities above 93% of theoretical density and characteristic plate-like grain morphology. Small quantity of cubic pyrochlore phase was detected only in the Ce modi ed bismuth titanate ceramics. On the other hand, lanthanum addition caused formation of smaller grain size with pronounced plate-like morphology.
Phase Stability in Ferroelectric Bismuth Titanate: A First Principles Study  [PDF]
Anurag Shrinagar,Ashish Garg,Rajendra Prasad
Physics , 2007,
Abstract: Experimental data on the structure of ferroelectric oxide Bismuth Titanate suggests two different kinds of structures i.e. orthorhombic and monoclinic. We have performed density functional theory (DFT) based first principle calculations to determine the ground state structure of bismuth titanate, based on experimentally observed monoclinic and orthorhombic phases of Bi4Ti3O12. Both of these phases are optimized to zero pressure and lattice parameters were determined as a = 5.4370 Ang, b = 5.4260 Ang, c = 32.6833 Ang and Z = 4 for structure with space group B2cb and a = 5.4289 Ang, b = 5.4077 Ang, c = 32.8762 Ang, b = 90.08 deg and Z = 4 for the structure with space group B1a1 . Static and dynamic calculations show that the monoclinic structure with the space group B1a1 is the ground state structure. It is noted that small difference in the energies of both structures could be a factor behind experimental observation of either of the structure.
Dielectric and Piezoelectric Properties of Sodium Bismuth Titanate Ceramics with KCe Substitution

XU Jian-Xiu,ZHAO Liang,ZHANG Cheng-Ju,

中国物理快报 , 2008,
Abstract: The piezoelectric properties of the (KCe)-substituted sodium bismuth titanate (Na0.5Bi4.5Ti4O15, NBT) piezoelectric ceramics are investigated. The piezoelectric properties of NBT ceramics are significantly enhanced by (KCe) substitution. The Curie temperature Tc, and piezoelectric coefficient d33 for the (KCe)-substituted NBT are found to be 663oC, and 27pC/N, respectively. Dielectric and annealing spectroscopy resent that the (KCe) co-substituted NBT piezoelectric ceramics possess stable piezoelectric properties.
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