Structure, magnetic and electrical properties in the praseodymium deficient Pr0.8-x□xSr0.2MnO3 manganites oxides

Structural, magnetic and electrical properties of Pr deficient Pr(0.8-x)rectangle(x)Sr(0.2)MnO(2) (0 less than or equal to x less than or equal to 0.2) samples have been investigated. Powder X-ray diffraction patterns are indexed in the orthorhombic perovskite system with Pnma space group. The unit cell volume decreases with increasing vacancy contents. The investigated samples exhibit a ferromagnetic to paramagnetic transition with increasing temperature. The highest obtained value of the Curie temperature is about 190 K. The presence of vacancies in structure increases the Curie temperature. At low vacancy concentrations a semiconductor like behaviour was observed. However, for x greater than or equal to 0.15, the samples exhibit a semiconducting to metallic transition with decreasing temperature. (C) 2002 Elsevier Science B.V. All rights reserved.