Structure and dielectric properties of sputtered bismuth magnesium niobate thin films

The Bi1.5MgNb1.5O7 (BMN) thin films were prepared on platinum coated sapphire by rf magnetron sputter deposition. Effects of substrate temperature, sputter pressure and O-2/(O-2 + Ar) mixing ratio on phase structures and dielectric properties of thin films were investigated. The results indicated that sufficiently high substrate temperature and low sputter pressure would facilitate the formation of cubic pyrochlore in BMN thin films. Meanwhile, the appropriate O-2/(O-2 + Ar) mixing ratio of sputter atmosphere was required. The deposited Bi1.5MgNb1.5O7 cubic pyrochlore thin films with (222) oriented texture exhibited large tunability of similar to 50% at a maximum applied bias field of 1.5 MV/cm, with low dielectric loss of similar to 0.007. The temperature and frequency dependent dielectric measurements indicated that no noticeable dielectric dispersion was detected in BMN cubic pyrochlore thin films. (C) 2012 Elsevier B. V. All rights reserved.