Structure and dielectric properties of sputtered bismuth magnesium niobate thin films

摘要

The Bi_(1.5)MgNb_(1.5)O_7 (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 Bi_(1.5)MgNb_(1.5)O_7 cubic pyrochlore thin films with (222) oriented texture exhibited large tunability of-50% at a maximum applied bias field of 1.5 MV/cm, with low dielectric loss of -0.007. The temperature and frequency dependent dielectric measurements indicated that no noticeable dielectric dispersion was detected in BMN cubic pyrochlore thin films.