Diffuse phase transitions in ferroelectric ultrathin films from first principles

2010 ◽  
Vol 81 (9) ◽  
Author(s):  
S. Bin-Omran ◽  
I. Kornev ◽  
I. Ponomareva ◽  
L. Bellaiche
Keyword(s):  
Phase Transitions ◽  
Ultrathin Films ◽  
First Principles ◽  
Diffuse Phase

A first-principles study of phase transitions in ultrathin films of BaTiO3

Pramana ◽  
2008 ◽  
Vol 70 (2) ◽  
pp. 263-270 ◽  
Author(s):  
J. Paul ◽  
T. Nishimatsu ◽  
Y. Kawazoe ◽  
U. V. Waghmare
Keyword(s):  
Phase Transitions ◽  
Ultrathin Films ◽  
First Principles ◽  
First Principles Study

PREDICTION OF DIELECTRIC DISPERSION FOR LEAD BASED PEROVSKITES AND STUDY OF LOCAL DIELECTRIC RESPONSE IN 0.75Pb(Mg1/3Nb2/3)O3–0.25PbTiO3

2012 ◽  
Vol 02 (02) ◽  
pp. 1241009 ◽  
Author(s):  
ILYA GRINBERG ◽  
HIROYUKI TAKENAKA ◽  
YOUNG-HAN SHIN ◽  
ANDREW M. RAPPE
Keyword(s):  
Dielectric Constant ◽  
Phase Transitions ◽  
First Principles ◽  
Local Structure ◽  
Dielectric Response ◽  
Dielectric Dispersion ◽  
Response Properties ◽  
Structure And Dynamics ◽  
Diffuse Phase

Relaxors exhibit unique dielectric response properties such as diffuse phase transitions and strong dispersion of the dielectric constant. The origin of these properties is still not fully understood. Here, we review our work on using first-principles-based methods to elucidate the connections between composition, local structure and dynamics in Pb -based relaxors.

Structural phase transitions of LaScO3 from first principles

2021 ◽  
Vol 26 ◽  
pp. 102048
Author(s):  
Craig A.J. Fisher ◽  
Ayako Taguchi ◽  
Takafumi Ogawa ◽  
Akihide Kuwabara
Keyword(s):  
Phase Transitions ◽  
First Principles ◽  
Structural Phase ◽  
Structural Phase Transitions

Crystal structure, compressibility and possible phase transitions in \boldvarepsilon-FeSi studied by first-principles pseudopotential calculations

1999 ◽  
Vol 55 (4) ◽  
pp. 484-493 ◽  
Author(s):  
Lidunka Vočadlo ◽  
Geoffrey D. Price ◽  
I. G. Wood
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Phase Transitions ◽  
First Principles ◽  
Stable Phase ◽  
Third Order ◽  
First Derivative ◽  
Pseudopotential Calculations ◽  
Cscl Type ◽  
Murnaghan Equation

An investigation of the relative stability of the FeSi structure and of some hypothetical polymorphs of FeSi has been made by first-principles pseudopotential calculations. It has been shown that the observed distortion from ideal sevenfold coordination is essential in stabilizing the FeSi structure relative to one of the CsCl type. Application of high pressure to FeSi is predicted to produce a structure having nearly perfect sevenfold coordination. However, it appears that FeSi having a CsCl-type structure will be the thermodynamically most stable phase for pressures greater than 13 GPa. Fitting of the calculated internal energy vs volume for the FeSi structure to a third-order Birch–Murnaghan equation of state led to values, at T = 0 K, for the bulk modulus, K 0, and for its first derivative with respect to pressure, K 0′, of 227 GPa and 3.9, respectively.

Grain-Size Effects on Diffuse Phase Transitions of Batio3 Ceramics Obtained by Alkoxide Precursors

1994 ◽  
Vol 346 ◽  
Author(s):  
R. P. S. M. Lobo ◽  
R. L. Moreira ◽  
N. D. S. Mohallem
Keyword(s):  
Grain Size ◽  
Phase Transitions ◽  
Barium Titanate ◽  
Size Effects ◽  
Sol Gel ◽  
Simple Relationship ◽  
Titanate Ceramics ◽  
Charged Defects ◽  
Alkoxide Precursors ◽  
Diffuse Phase

ABSTRACTBarium titanate ceramics have been obtained by sol-gel methods. The dielectric investigations of these materials revealed the existence of diffuse ferroelectric transitions. By using a phenomenological model, we could demonstrate the existence of a simple relationship between the diffuse character of the transition and the sample grain-size. This effect has been attributed to interactions between charged defects on the grain surfaces and the spontaneous polarization of the material.

scholarly journals Prediction of 10-fold coordinated TiO2 and SiO2 structures at multimegabar pressures

2015 ◽  
Vol 112 (22) ◽  
pp. 6898-6901 ◽  
Author(s):  
Matthew J. Lyle ◽  
Chris J. Pickard ◽  
Richard J. Needs
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Electronic Properties ◽  
First Principles ◽  
Pressure Range ◽  
Extrasolar Planets ◽  
Equations Of State ◽  
Space Group ◽  
P Type ◽  
Pressure Phase

We predict by first-principles methods a phase transition in TiO2 at 6.5 Mbar from the Fe2P-type polymorph to a ten-coordinated structure with space group I4/mmm. This is the first report, to our knowledge, of the pressure-induced phase transition to the I4/mmm structure among all dioxide compounds. The I4/mmm structure was found to be up to 3.3% denser across all pressures investigated. Significant differences were found in the electronic properties of the two structures, and the metallization of TiO2 was calculated to occur concomitantly with the phase transition to I4/mmm. The implications of our findings were extended to SiO2, and an analogous Fe2P-type to I4/mmm transition was found to occur at 10 TPa. This is consistent with the lower-pressure phase transitions of TiO2, which are well-established models for the phase transitions in other AX2 compounds, including SiO2. As in TiO2, the transition to I4/mmm corresponds to the metallization of SiO2. This transformation is in the pressure range reached in the interiors of recently discovered extrasolar planets and calls for a reformulation of the equations of state used to model them.

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