NEUTRON-POWDER-DIFFRACTION STUDY OF THE MAGNETIC AND STRUCTURAL-PROPERTIES OF PR-0.6(CA1-XSRX)0.4MNO3 (0LESS-THAN-OR-EQUAL-TOXLESS-THAN-OR-EQUAL-TO1)

We present the results of a neutron-powder-diffraction study in which we have examined the magnetic and structural properties of Pr-0.6(Ca1- xSrx)(0.4)MnO3 (0 less than or equal to x less than or equal to 1) as a function of doping concentration x and temperature. For x less than or equal to 0.15 charge ordering and a Jahn-Teller distortion below 25 0 K are evident from rapid changes in the lattice parameters and bond lengths as a function of temperature and a transition from a high-temp erature orthorhombic to a low-temperature monoclinic structure. For x = 0.0 the system orders antiferromagnetically at T-N = 170 K. At low t emperature the system has a canted CLS structure. As the temperature a pproaches T-N there is a transition to a collinear magnetic arrangemen t. For Sr doping of up to x = 0.15 the magnetic transition temperature remains almost constant but the magnetic arrangement now has a ferrom agnetic component which persists up to T-N. For x > 0.15 the charge or dering is removed and the lattice parameters show a more normal temper ature dependence. The materials are now simple ferromagnets and the fe rromagnetic transition temperature T-C increases rapidly with x.