Voltage tunable dielectric properties of titanium substituted Bi-pyrochlore thin films

(Bi_2-xZn_x)(Nb_xTi_2-x)O₇ (BZNT, 0.1 × 1.0) pyrochlore thin films were prepared on platinized Si substrates using metalorganic deposition process. Broad ranges of solid solutions based on cubic (Bi_1.5Zn_0.5)(Zn_0.5Nb_1.5)O₇ were observed by chemical substitutions, e.g., Bi³⁺ + Ti⁴⁺ = Zn²⁺ + Nb⁵⁺. Crystallization of BZNT thin films started below 600 °C and completed at about 750 °C. The crystal structure, and dielectric characteristics of thin films were investigated using X-ray diffraction, FE-SEM, and LCR-meter. The dielectric constants of BZNT decreased with decreasing Ti content. The resultant solid solutions have dielectric constant in the range of 142-242. Room temperature capacitance-voltage measurements at I MHz demonstrated a tunability of nearly 30 %, with a zero bias tan δ of 0.005. The effect of structural stability on the dielectric properties was also investigated.