Publication No.50



A. Stashans, J. Chimborazo.  Effect of interstitial hydrogen on structural 
and electronic properties in BaTiO3 - Phil. Mag. B, 2002, Vol. 82,
p. 1145-1154.

Abstract:
	We investigate the geometry and electronic structure of an interstitial 
H atom in the BaTiO3 crystal considering both cubic and tetragonal 
crystallographic lattices. A quantum-chemical method based on the Hartree-
Fock formalism is used throughout the study. Interstitial H is found to 
bind to one of the O atoms, forming the so-called OH group. At equilibrium, 
the O-H distances are found to be 0.89 � and 0.91 � for cubic and tetragonal 
lattices respectively. The performed automated geometry optimization 
procedure of the defective region shows considerable outward movements 
of atoms closest to the impurity. The role of the H impurity in ferroelectric 
polarization in the BaTiO3 crystal is analysed using the results obtained 
in connection with the available experimental data on ferroelectric 
perovskites. 




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