Preparation-dependent properties of Ca(Cu,Mn)7O12 CMR materials |
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Authors: | D.M. Itkis A.M. Balagurov A.S. Sinitskii |
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Affiliation: | a Faculty of Materials Science, Moscow State University, 119992 Moscow, Russia b Faculty of Chemistry, Moscow State University, 119992 Moscow, Russia c Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, 141980 Dubna, Russia |
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Abstract: | Both magnetic ordering temperatures and lattice constants were observed to be a function of preparation temperature for single-phase CaCuMn6O12 CMR ceramics of the same cation, oxygen composition and crystal structure. It was found for the first time that higher preparation temperatures result in a linear increase of a cubic cell parameter a, , and in a sharp decrease of magnetic ordering temperatures , by about , for quenched samples. High resolution NPD experiments have shown the presence of antisite defects resulting in partial occupation of octahedral (8c) sites by Cu2+ at higher preparation temperatures as never assumed for an ideal structure. The data obtained give a new insight to the problem of functional properties reproducibility suggesting stronger requirements for the production control of CMR materials. |
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Keywords: | 61.12.Ld 61.72.Dd |
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