Strontium vacancy effects upon the physical properties in lacunar Pr0.7Sr0.3-x square xMnO(3) perovskite system

We studied the structural, magnetic and electrical properties of lacunar pe rovskite-type manganese oxides Pr(0.7)Sr(0.3-x)square xMnO3, where 0 less t han or equal to x less than or equal to 0.3. With varying x, the powder X-r ay diffraction patterns could index a rhombohedral and an orthorhombic pero vskite structure. Magnetization measurements versus temperature show that t he samples exhibit a magnetic transition when the temperature decreases. As the A-site vacancy content increases, the magnetic transition temperature shifts to lower values. Resistivity measurements as a function of temperatu re show a semiconducting-metallic transition when the temperature decreases for 0 less than or equal to x less than or equal to 0.1 and a semiconducto r-like behaviour in the range x greater than or equal to 0.15. The resistiv ity of the samples increases with x. The sample Pr(0.7)Sr(0.2)square 0.1MnO 3 shows a ferromagnetic insulator behaviour below a spin-canted ferromagnet ic temperature (T-FC).