Strontium adding effects in Pr0.65Ca0.35MnO3

R.D. SANCHEZ; H. SALVA; A. CANEIRO; D. NIEBIESKIKWIAT; P. MONCEAU

JOURNAL DE PHYSIQUE IV

Journal de Physique

Lugar: Paris; Año: 1999 vol. 9 p. 10333 - 10334

1155-4339

The manganese compounds with a perovskite structure are a hot topic in the MaterialsScience due to the high variation of the electrical resistivity under a magnetic fieldcalled colossal magnetoresistance (CMR). This effect is maximum near the Curietemperature (Tc) when the materials become ferromagnetic (FM). Nevertheless, thedouble exchange interaction, that produces this FM state, competes with otherinteractions (as the antiferromagnetic (AFM) superexchange and structural distortions).When these last effects are more important the manganite evolves to an insulator, AFMand in some cases with charge order localization (CO) of Mn3+ and Mn4+. We study thesolid solution Pr0.65SrxCa0.35-xMnO3 with x between x=0 and x=0.20 prepared bydecomposition of metal nitrates route. Our magnetic and transport measurements showhow the CO is destroyed while we add Sr, changing from semiconducting behavior(x=0) to FM metallic (x=0.20). SEM photographs show that all samples have 1-5micrometers grain size. No frequency dependence (33 Hz-33KHz) was observed in x=0sample, indicating that the grain size do not affect the dielectric properties.