LAUSR

Abstract In order to realize the effect of Mn doping on dielectric behavior and optical band gap (Eg) of Lanthanum Gallate; pure and Mn doped LaGaO3 samples were prepared. The phase purity of these samples was confirmed by x-ray diffraction experiments. It was found that all samples possess orthorhombic structure. Room temperature (RT) dielectric response and Eg of LaGa1−xMnxO3 (LGMO) with, x = 0.0 to 0.9, has been recorded using impedance analyzer (LCR meter) and diffuse reflectance spectroscopy respectively. It has been observed that at RT, pure LaGaO3 exhibits moderate dielectric constant (ε′ ≈ 25) with very low dielectric loss (tan δ). Interestingly, the value of RT ε′ significantly increases with Mn doping whereas tan δ remains relatively low upto x = 0.4 and increases abruptly x > 0.4. The observed increase in ε′ and tan δ with Mn doping has been understood in terms of structural coherency and systematic decrease in Eg. A shift in ε′-anomaly (tan δ-peak) with increasing Mn percentage and low frequency large ε′ were also observed in Mn doped LGO. Both of these effects have been understood in terms of coexisting Mn3+ and Mn4+ ions. The LGMO samples (x ≤ 0.4) showing high value of ε′ and very low tan δ can be suitable candidates for capacitive applications.