Synthesis of new double perovskites La1.98Mn1.11Mo0.89O5.93 and La1.92Mn1.29Mo0.71O5.84: characterization of structural and magnetic properties

V.C. FUERTES; M.C. BLANCO; D.G. FRANCO; G. TIRAO; V.M. NASSIF; G. NIEVAS; R. CARBONIO

JOURNAL OF ALLOYS AND COMPOUNDS

ELSEVIER SCIENCE SA

Lugar: Amsterdam; Año: 2016 vol. 681 p. 444 - 454

0925-8388

The synthesis, structural and magnetic characterization of two new perovskitesLa1.98Mn1.11Mo0.89O5.93 and La1.92Mn1.29Mo0.71O5.84 are reported. Combined Rietveldrefinements of X-ray and neutron powder diffraction data indicate that both samplesare monoclinic perovskites with space group P21/n. The distribution of the transitionmetals over the octahedral sites is highly ordered: Mn preferentially occupies 2c sites,while Mo mostly occupies 2d sites. Mn oxidation states were determined by means ofhigh resolution Kβ Emission Spectroscopy. The susceptibility as a function oftemperature measurements and hysteresis loops show complex magnetic behaviour ofboth perovskites. The refined magnetic cells indicate that La1.98Mn1.11Mo0.89O5.93 isferrimagnetic as a result of the antiferromagnetic coupling of two ferromagnetic sublatticesassociated to 2d and 2c sites, while La1.92Mn1.29Mo0.71O5.84 is ferromagnetic dueto ferromagnetic alignment of the two sub-lattices. The magnetic overall behaviour ofthe latter perovskite is interpreted in terms of delocalization of magnetic momentsarising from ferromagnetic double-exchange interactions between Mn2+ and Mn3+.