Mixed layered Aurivillius phases

Author(s):  
Rajnish Kurchania ◽  
Oroosa Subohi
Keyword(s):  
2019 ◽  
Author(s):  
Kazuki Morita ◽  
Ji-Sang Park ◽  
Sunghyun Kim ◽  
Kenji Yasuoka ◽  
Aron Walsh

The Aurivillius phases of complex bismuth oxides have attracted considerable attention due to their lattice polarization (ferroelectricity) and photocatalytic activity. We report a first-principles exploration of Bi<sub>2</sub>WO<sub>6</sub> and the replacement of W<sup>6+</sup> by pentavalent (Nb<sup>5+</sup>, Ta<sup>5+</sup>) and tetravalent (Ti<sup>4+</sup>, Sn<sup>4+</sup>) ions, with charge neutrality maintained by the formation of a mixed-anion oxyhalide sublattice. We find that Bi<sub>2</sub>SnO<sub>4</sub>F<sub>2</sub> is thermodynamically unstable, in contrast to Bi<sub>2</sub>TaO<sub>5</sub>F, Bi<sub>2</sub>NbO<sub>5</sub>F and Bi<sub>2</sub>TiO<sub>4</sub>F<sub>2</sub>. The electric dipoles introduced by chemical substitutions in the parent compound are found to suppress the spontaneous polarization from 61.55 μC/cm<sup>2</sup> to below 15.50 μC/cm<sup>2</sup>. Analysis of the trends in electronic structure, surface structure, and ionization potentials are reported. This family of materials can be further extended with control of layer thicknesses and choice of compensating halide species.<br>


1999 ◽  
Vol 9 (6) ◽  
pp. 1319-1322 ◽  
Author(s):  
Jean-Claude Champarnaud-Mesjard ◽  
Bernard Frit ◽  
Akiteru Watanabe

1996 ◽  
Vol 125 (1) ◽  
pp. 54-62 ◽  
Author(s):  
Svetlana Sorokina ◽  
Renée Enjalbert ◽  
Pierre Baules ◽  
Alicia Castro ◽  
Jean Galy

Author(s):  
Ilona Bella ◽  
Tio Putra Wendari ◽  
Novesar Jamarun ◽  
Nandang Mufti ◽  
Zulhadjri

In this study, the double-layered Aurivillius phases CaBi2Ta2O9 (CBT) and PbBi2Ta2O9 (PBT) were prepared through a hydrothermal route with NaOH as a mineralizer. XRD analysis confirmed that the CBT and PBT compounds were successfully formed and adopted an orthorhombic crystal structure with an [Formula: see text]21am symmetry. Le Bail refinements of XRD data indicated that the unit cell volume of CBT was smaller than PBT and is associated with the smaller ionic radius of Ca[Formula: see text] compared to Pb[Formula: see text]. The surface morphology of both samples, as determined using SEM, demonstrated plate-like grains with anisotropic grain growth. It was found that the different ionic radii of [Formula: see text]-site cations (Ca[Formula: see text] and Pb[Formula: see text] strongly affected the structural, optical and electrical properties of the Aurivillius phase. The occupation of smaller Ca[Formula: see text] cations induced a higher structural distortion, which resulted in higher bandgap ([Formula: see text] energy and ferroelectric transition temperature ([Formula: see text] of CBT, compared to those of PBT.


2011 ◽  
Vol 105 (1) ◽  
pp. 81-88 ◽  
Author(s):  
S. Bin Anooz ◽  
J. Schwarzkopf ◽  
P. Petrik ◽  
M. Schmidbauer ◽  
A. Duk ◽  
...  

2011 ◽  
Vol 43 (2) ◽  
pp. 139-150 ◽  
Author(s):  
Zulhadjri Zulhadjri ◽  
B. Prijamboedi ◽  
A. A. Nugroho ◽  
N. Mufti ◽  
Ismunandar Ismunandar

2001 ◽  
Vol 16 (11) ◽  
pp. 3139-3149 ◽  
Author(s):  
Donají Y. Suárez ◽  
Ian M. Reaney ◽  
William E. Lee

The structures and microstructures of a range of Aurivillius phases were investigated by transmission electron microscopy. Systematic rows of superlattice reflections arising from tilting of octahedra around the c axis were identified, and their intensities at room temperature were shown to diminish as the tolerance factor (t) of the perovskite blocks increased. For compounds with t's approaching 1, no superlattice reflections were observed. the paraelectric-to-ferroelectric phase transition temperature (Tc) was monitored through permittivity measurements as a function of temperature, and Tc was also shown to decrease as t increased. Consequently, the onset of octahedral tilting and Tc appeared to be strongly related Aurivillius phases. Planar defects arising from the structural phase transitions and from stacking irregularities were also discussed.


2001 ◽  
Vol 666 ◽  
Author(s):  
Yun-Mo Sung ◽  
Woo-Chul Kwack

ABSTRACTPhase formation characteristics of Sr0.7Bi2.4Ta2O9 (SBT) powder, synthesized via sol-gel and pyrolysis process, was investigated by using thermal analysis. Each of the two exotherms, appearing in differential thermal analysis (DTA) scan curves, was identified as crystallization of fluorite phase and transformation of fluorite to aurivillius phase, respectively by using x-ray diffraction (XRD). By applying non-isothermal kinetic analyses to the DTA results, activation energy values for the formation of fluorite and aurivillius phases were determined as 192 and 375 kJ/mol, respectively and Avrami exponent values for each reaction were determined as 0.91 and 0.96, respectively. These activation energy and Avrami exponent values were discussed in detail to understand phase formation mechanism in SBT system.


ChemInform ◽  
1989 ◽  
Vol 20 (34) ◽  
Author(s):  
K. A. YEE ◽  
T. A. ALBRIGHT ◽  
D. JUNG ◽  
M.-H. WHANGBO

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