Strain-induced modification in microstructure and electrical properties of polycrystalline LaNiO3-δ films

In the present work, lanthanum nickel oxide (LaNiO3-delta) thin films are prepared with the sol-gel multilayer coating method. Substrates with different thermal expansion coefficients are chosen to introduce thermal strain into the polycrystalline LaNiO3-delta ( LNO) films. The effects of strain on the microstructure and electrical properties of LNO films are investigated. The results show that with increasing magnitude of strain, except for the change in lattice constant, an increase in defects in LNO films might occur. Furthermore, the resistivity of LNO films firstly decreases as the strain evolves from tensile to compressive, and then, increases again with the increasing compressive strain. The anomalous change in the both resistivity and transport behavior of LNO films under different strains is ascribed to the combined effects of the varying lattice constant and oxygen vacancy density.