First Principles Calculation of the Structure and Dielectric Properties of Bi2Ti2O7
Citation:
Charles H. Patterson, First Principles Calculation of the Structure and Dielectric Properties of Bi2Ti2O7, Physical Review B, 82, 15, 2010, 155103-Download Item:
Abstract:
The structure, vibrational modes, and phonon contribution to the dielectric function of the pyrochlore
Bi
2
Ti
2
O
6
O
were calculated using first-principles methods. Total-energy minimization calculations were per-
formed for Bi
2
Ti
2
O
6
O
in a unit cell containing 88 ions, which had the ideal, cubic pyrochlore structure as the
initial configuration. No symmetry constraints were imposed during this relaxation. Subsequent symmetry
analysis of the relaxed structure found
Pna
2
1
space-group symmetry in a 44 ion unit cell. This structure
contains Bi ions with two types of eightfold coordination by O and O
ions. Vibrational modes and the
dielectric function were calculated for the
Fd
3
̄
m
,
Pna
2
1
, and
P
1
structures. The crystal structure obtained by
total-energy minimization is compared to structural data from reverse Monte Carlo analysis of neutron total
scattering data. The imaginary part of the dielectric function derived from vibrational mode calculations is
compared to dielectric function data for several related pyrochlores. Phonons which make the largest contri-
butions to the dielectric constant are identified and analyzed.
Sponsor
Grant Number
Science Foundation Ireland (SFI)
RFP/09/MTR2295
Author's Homepage:
http://people.tcd.ie/cpttrsonDescription:
PUBLISHED
Author: PATTERSON, CHARLES
Type of material:
Journal ArticleCollections
Series/Report no:
Physical Review B82
15
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Full text availableKeywords:
PhysicsSubject (TCD):
Nanoscience & MaterialsDOI:
http://dx.doi.org/10.1103/PhysRevB.82.155103Metadata
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