Ion-Induced Nucleation: The Importance of Ionic Polarizability

2010 ◽  
Vol 114 (13) ◽  
pp. 4595-4600 ◽  
Author(s):  
Samuel J. Keasler ◽  
Hyunmi Kim ◽  
Bin Chen
Keyword(s):  
Ionic Polarizability

In-crystal ionic polarizabilities derived by combining experimental and ab initio results

1985 ◽  
Vol 398 (1815) ◽  
pp. 377-393 ◽  
Keyword(s):  
Refractive Index ◽  
Charge Transfer ◽  
Ab Initio ◽  
Empirical Model ◽  
Ionic Polarizability ◽  
Model Calculations ◽  
Ionic Solids ◽  
A Charge ◽  
Refractive Index Data ◽  
Environmental Dependence

It is shown that an empirical model of in-crystal polarizabilities must incorporate the environmentally induced variation of anion polarizabilities. Those of s 2 and p 6 cations can be taken to be constant. Such a model is combined with the ab initio calculation of small cation polarizabilities to extract the polarizabilities of Rb + , Cs + , Tl + , Sr 2+ , Ba 2+ and Pb 2+ from experimental refractive index data. The deficiencies of previous estimates are discussed. The function describing the environmental dependence of halide polarizabilities is found to be transferable between different crystal structures. This does not hold for chalcogenide anions. It is shown that the polarizabilities of d 10 cations are very sensitive to environment. The anisotropy of the purely electrostatic environment increases the polarizability of Ag + in AgF by 4% while model calculations suggest a much larger increase from anisotropic overlap effects. A comparison of the relative merits of an ionic polarizability and a charge-transfer picture of polarization in ionic solids is found to favour the former description.

Effect of ionic polarizability on oxygen diffusion in δ-Bi2O3 from atomistic simulation

Ionics ◽  
2010 ◽  
Vol 16 (4) ◽  
pp. 297-303 ◽  
Author(s):  
Dilpuneet S. Aidhy ◽  
Susan B. Sinnott ◽  
Eric D. Wachsman ◽  
Simon R. Phillpot
Keyword(s):  
Oxygen Diffusion ◽  
Atomistic Simulation ◽  
Ionic Polarizability

Tunability of τf in perovskites and related compounds

2002 ◽  
Vol 17 (8) ◽  
pp. 2033-2040 ◽  
Author(s):  
P. L. Wise ◽  
I. M. Reaney ◽  
W. E. Lee ◽  
D. M. Iddles ◽  
D. S. Cannell ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Resonant Frequency ◽  
Room Temperature ◽  
Structural Phase ◽  
Structural Phase Transitions ◽  
Ionic Polarizability ◽  
Microwave Dielectrics ◽  
Related Compounds ◽  
Range Of Values

Tuning the temperature coefficient of resonant frequency (τf) in microwave dielectrics has been attributed to two main mechanisms: (i) dilution of the average ionic polarizability; (ii) the onset of an octahedral tilt transition above room temperature. The contributions of each mechanism have been isolated using ceramics in the Srn+1TinO3n+1, SrxCa1−x)3Ti2O7, and (SrxCa1−x)TiO3 series. In the Srn+1TinO3n+1 series, relative permittivity (εr) and τf are linearly proportional over a broad range of values, 100–37 and 800–140 ppm/°C, n = 4 and 1, respectively. No structural phase transitions occur on cooling from the prototype symmetry, and the mechanism of tuning is attributed solely to dilution of the average ionic polarizability as the SrO:SrTiO3 ratio increases. Exchanging Ca for Sr in the (SrxCa1−x)3Ti2O7 series resulted in an 80% reduction in the magnitude of τf from +320 to +50 ppm/°C but only 21% in permittivity (58 to 46). The effect was nonlinear and attributed primarily to the onset of a phase transition involving rotations of the octahedra on cooling. Superlattice reflections associated with the octahedral tilt transition have been identified.

Dielectric Properties of Barium Titanate Ceramics with Nano-Sized Domain

2010 ◽  
Vol 445 ◽  
pp. 27-30 ◽  
Author(s):  
Yoichi Kigoshi ◽  
Saki Hatta ◽  
Takashi Teranishi ◽  
Takuya Hoshina ◽  
Hiroaki Takeda ◽  
...  
Keyword(s):  
Grain Size ◽  
Barium Titanate ◽  
Dipole Polarizability ◽  
Ionic Polarizability ◽  
Grain Sizes ◽  
Conventional Sintering ◽  
Rate Controlled ◽  
Titanate Ceramics ◽  
Sintering Method ◽  
Domain Width

Barium titanate (BaTiO3) ceramics with various grain sizes from 0.7 to 13 μm on average were prepared by a conventional sintering method, a two-step sintering method and a rate controlled two-step sintering method. The permittivity of the ceramics was increased with decreasing grain size to 1.1 μm on average. However, the permittivity of the ceramics was decreased when the grain size was below 1 μm. The field emission scanning electron microscope (FE-SEM) observations revealed that the 90º domain width decreased with decreasing the grain size. By ultrawide range dielectric spectra from kHz to THz range of the BaTiO3 ceramics, the domain contribution to the permittivity was investigated. For the BaTiO3 ceramics with grain sizes over 1 μm, the dipole polarizability and the ionic polarizability were enhanced by high domain-wall density. In contrast, for the BaTiO3 ceramics with grain sizes below 1 μm, these polarizabilities were weakened.

Delayed thermal depolarization of Bi0.5Na0.5TiO3-BaTiO3 by doping acceptor Zn2+ with large ionic polarizability

2017 ◽  
Vol 122 (20) ◽  
pp. 204104 ◽  
Author(s):  
Ling Li ◽  
Mankang Zhu ◽  
Kailing Zhou ◽  
Qiumei Wei ◽  
Mupeng Zheng ◽  
...  
Keyword(s):  
Ionic Polarizability
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