Annealing effect on the characteristics of La0.67Sr0.33MnO3 polycrystalline thin films produced by the sol–gel dip-coating process

The effect of annealing temperature on selected characteristics of polycrystalline La 0.67 Sr 0.33 MnO 3 films, which have been produced on quartz substrates, was investigated. X-Ray powder diffraction patterns showed that the phase formation started at 873 K and all the films had perovskite structure. By increasing the annealing temperature, the lattice parameters were decreased. Scanning electron microscope indicated that the film thicknesses were approximately 3 μm and the average grain size of the samples varied between 30–100, 50–110, 70–120, and 100–150 nm for films annealed at 873, 973, 1,073, and 1,173 K, respectively. All the films showed a paramagnetic–ferromagnetic (T C ) and metal–insulator (T IM ) phase transition. The T C indicated a small variation [from 131 K (S4) to 124 K (S1)] as a function of annealing temperature, whereas the T IM went down from 212 K (S4) to 110 K (S1), a strong decrease of 102 K. A colossal magneto resistance with magneto resistance ratios of 130, 139, 156, and 163% were observed near T C and at 6 T magnetic field.