Physical investigations on LaMn1−xNixO3 perovskite sprayed thin films along with surface magnetic applications

Abstract

This paper deals with the results on the structural, electrical, vibrational and optical properties of LaMn1−xNixO3 (0 ≤ x ≤ 0.3) thin films prepared by the spray pyrolysis technique on glass substrates at 460 °C using (LaCl3·7H2O), (MnCl2·4H2O) and (NiCl2·6H2O) as precursors. First, XRD analysis shows an orthorhombic structure of all prepared thin films. Second, room temperature Raman spectra showed broad and intense bands characteristic of LaMnO3 parent compound modes. An important shift to higher frequencies was observed and attributed to disorder induced by Ni composition and Frenkel defects associated to the formation of vacancy and interstitial oxygen sites. The optical measurements show that the optical band gap energy value varies sparsely in terms of Ni content. On the other hand, the electric conductivity measurements were investigated using the impedance spectroscopy technique in the frequency range 5 Hz–10 MHz at various temperatures (410–500 °C). AC conductivity of LaMn1−xNixO3 thin films is found to follow the Jonsher law. The temperature dependence of the AC conductivity is consistent with the correlated barrier-hopping model with activation energy Ea varying in (0.70–1.29) eV domain. Finally, the magnetic hysteresis loops of such films exhibit obvious ferromagnetic behavior with a high dependency with Ni content particularly the coercivity value (Hc) increases with Ni concentration.