ENHANCED TUNABILITY AND RELAXOR CHARACTERISTICS IN CALCIUM SUBSTITUTED BARIUM ZIRCONIUM TITANATE THIN FILMS

ABSTRACT

Thin films of BaZr_0.25Ti_0.75O₃ in which Ba^{2 +} is partially substituted by Ca^{2 +} are prepared by a sol-gel method. Phases and dielectric properties of the films are studied.The crystal structure of BaZr_0.25Ti_0.75O₃ is cubic and does not change with Ca substitution upto x = 0.25 in Ba_1-xCa_xZr_0.25Ti_0.75O₃. A change from a normal to relaxor behavior is observed for x = 0.20 as indicated by a change in the frequency of dielectric maxima with temperature and other parameters.The dielectric constant and transition temperatures are found to increase with increasing Ca substitution. A tunabilty of 71%, much higher than reported in literature for this material, is observed for x = 0.1 i.e for Ba_0.9Ca_0.1Zr_0.25Ti_0.75O₃.

Keywords::

• Ferroelectrics
• relaxor
• tunability