Effect of La substitution on the microstructure and dielectric properties of the sol–gel derived BaZr0.2Ti0.8O3 thin films

Abstract

A-site deficient Ba1−xLa2x/3(Zr0.2Ti0.8)O3 (BLZT) thin films with x=0.00, 0.004, 0.006, 0.008, 0.02, 0.06 were processed using a sol–gel technique. X-ray diffraction analysis was used to investigate phase evolution of BLZT films with temperature. Scanning electron microscopy and atomic force microscopy were used to investigate the microstructure and surface topography of the fabricated BLZT thin films. The samples with x=0.00–0.008 showed a homogeneous grain size distribution and uniform surface morphology; however, a certain degree of agglomeration was observed for the samples with x>0.008 which increased with increasing La content. The magnitude of root mean square for the samples with x=0.00, 0.004, 0.006, 0.008, 0.02 and 0.06 was recorded to be 3.53nm, 3.06nm, 2.32nm, 2.02nm, 3.36nm and 4.71nm, respectively. Relative permittivity (ɛr) was observed to decrease with increasing temperature, and increased non-linearly with an increase in La content. Dielectric dispersion was observed for all the BLZT samples and εr decreased with increasing frequency.