Enhanced tunability of Bi3/2MNb3/2O7 (M=Zn, Mg, Ni) thin films

Cubic pyrochlore Bi3/2ZnNb3/2O7, Bi3/2Zn1/2Mg1/2Nb3/2O7 and Bi3/2Zn1/3Mg1/3Ni1/3Nb3/2O7 thin films were fabricated on Au/Ti/SiO2/Si (100) substrates using a chemical solution spin coating process. Tunability of Bi3/2ZnNb3/2O7 thin films was improved from 22% to 35% by substituting Mg2+ and Ni2+ for Zn2+ at a bias field of ∼1 MV/cm. Dielectric loss of thin films remained below 0.004 at 1 MHz and was almost independent of Mg2+ and Ni2+ doping and bias field. Effects of Mg2+ and Ni2+ substitution on the tunability were discussed based on Raman spectral analyses. The F2g(1) mode correlated with the vibration of A–O bond significantly influenced the tunability of thin films.

► Effects of Mg2+ and Ni2+ substitution on the dielectric properties, tunability and Raman modes of Bi3/2ZnNb3/2O7 thin films were studied.
► Tunability of Bi3/2ZnNb3/2O7 thin films was improved from 22% to 35% by substituting Mg2+ and Ni2+ for Zn2+ at a bias field of ∼1 MV/cm.
► F2g(1) mode correlated with the vibration of A–O bond significantly influenced the tunability of thin films.