(BA+SR) TI RATIO DEPENDENCE OF THE DIELECTRIC-PROPERTIES FOR (BA.05SR0.5)TIO3 THIN-FILMS PREPARED BY ION-BEAM SPUTTERING/

(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.