S. Yamamichi et al., (BA+SR) TI RATIO DEPENDENCE OF THE DIELECTRIC-PROPERTIES FOR (BA.05SR0.5)TIO3 THIN-FILMS PREPARED BY ION-BEAM SPUTTERING/, Applied physics letters, 64(13), 1994, pp. 1644-1646
(Ba0.5Sr0.5)TiO3 thin films were prepared by ion beam sputtering from
powder targets with (Ba + Sr)/Ti ratios ranging from 0.80 to 1.50. All
of the perovskite (Ba,Sr)TiO3 films were single phase except for the
film with a (Ba + Sr)/Ti ratio of 1.41. The dielectric constant values
notably depended on the (Ba + Sr)/Ti ratio for films thicker than 70
nm. The highest dielectric constant of 580 was achieved for the 5% (Ba
+ Sr) rich film. This (Ba + Sr)/Ti ratio dependence was diminished by
the thickness dependence for thinner films. The grain sizes for the 9
% (Ba + Sr) rich film and for the 6% (Ba + Sr) poor film ranged from 7
0 to 100 nm and from 30 to 60 nm, respectively. This grain size differ
ence could explain why slightly A-site rich (Ba,Sr)TiO3 films have a l
arger dielectric constant than A-site poor films.