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Title: First principles study of substituents in KTaO{sub 3}

Abstract

The structural properties, energetics, and dynamics of Ca{sup 2+} and Mn{sup 2+} substituents in KTaO{sub 3} are investigated from first principles. It is found that Ca substitutes for both K and Ta ions. Oxygen vacancies bind to isolated Ca ions residing at Ta-sites, causing off-center Ca displacement and forming large dipoles. There is also evidence that oppositely charged defects may cluster together. The calculations predict that the activation energy for dipole reorientation via oxygen vacancy hopping within the first neighbor shell of Ta-substituting Ca or Mn exceeds 2 eV. On the other hand, Mn{sup 2+} substituting at the K-site displaces off center along the (100) direction, also forming a dipole. This dipole can reorient via Mn hopping motion with an activation energy of {approximately} 0.18 eV, in reasonable agreement with experiments. The authors argue that, in general, metal ion hopping at the A-site, not oxygen vacancy hopping, is responsible for the small activation energies found in experiments.

Authors:
Publication Date:
Research Org.:
Sandia National Labs., Albuquerque, NM (US); Sandia National Labs., Livermore, CA (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
755614
Report Number(s):
SAND2000-1254J
TRN: AH200021%%358
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Journal Article
Journal Name:
Physical Review B
Additional Journal Information:
Other Information: Submitted to Physical Review B; PBD: 17 May 2000
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CRYSTAL STRUCTURE; CALCIUM; MANGANESE; TANTALATES; POTASSIUM COMPOUNDS; CRYSTAL DOPING

Citation Formats

LEUNG,KEVIN. First principles study of substituents in KTaO{sub 3}. United States: N. p., 2000. Web.
LEUNG,KEVIN. First principles study of substituents in KTaO{sub 3}. United States.
LEUNG,KEVIN. Wed . "First principles study of substituents in KTaO{sub 3}". United States. https://www.osti.gov/servlets/purl/755614.
@article{osti_755614,
title = {First principles study of substituents in KTaO{sub 3}},
author = {LEUNG,KEVIN},
abstractNote = {The structural properties, energetics, and dynamics of Ca{sup 2+} and Mn{sup 2+} substituents in KTaO{sub 3} are investigated from first principles. It is found that Ca substitutes for both K and Ta ions. Oxygen vacancies bind to isolated Ca ions residing at Ta-sites, causing off-center Ca displacement and forming large dipoles. There is also evidence that oppositely charged defects may cluster together. The calculations predict that the activation energy for dipole reorientation via oxygen vacancy hopping within the first neighbor shell of Ta-substituting Ca or Mn exceeds 2 eV. On the other hand, Mn{sup 2+} substituting at the K-site displaces off center along the (100) direction, also forming a dipole. This dipole can reorient via Mn hopping motion with an activation energy of {approximately} 0.18 eV, in reasonable agreement with experiments. The authors argue that, in general, metal ion hopping at the A-site, not oxygen vacancy hopping, is responsible for the small activation energies found in experiments.},
doi = {},
journal = {Physical Review B},
number = ,
volume = ,
place = {United States},
year = {2000},
month = {5}
}