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M. L. CRAUS1,2,* , N. CORNEI3, C. MITA3, M. LOZOVAN1
Manganese perovskites, Re1-xAlkxMnO3 (Re= rare earth; Alk= alkali earth/alkali elements) were intensively investigated in the last ten years, due to the observed colossal magnetoresistance (CMR) near the ferromagnetic-paramagnetic transition temperature. The CMR effect is most prominent for x≈0.3. It is observed a correlation between the radius and distribution of the cations in the unit cell, on one side, and physical properties on other side for La0.54Ho0.11Ca0.35-xNaxMn1-yCuyO3 manganites, obtained by sol-gel method. Powders resulted from gel calcinations were presintered and finally sintered at 1200°C in air and investigated by X-ray analysis to determine begin of solid-state reaction, the phase composition, and other microstructure parameters. XRD data were handled with DICVOL, CellRef and Rietveld type programs. Magnetic were performed with a Foner type magnetometer between 77 and 600 K. The sintered samples contain only perovskite phases. The substitution of Ca with Na leads to a decrease of the unit cell volume, while the Cu substitution produced a non-monotonous variation of the unit cell. We discussed the dependence between the tolerance factor (experimental and calculated) and the chemical disorder degree, on one side, and the Curie temperature on other side.
Magnetoresistance, Crystalline and magnetic structure, Manganites.
M. L. CRAUS, N. CORNEI, C. MITA, M. LOZOVAN, Microstructure of La0.54Ho0.11Ca0.35-xNaxMn1-yCuyO3 manganites, Optoelectronics and Advanced Materials - Rapid Communications, 2, 1, January 2008, pp.33-36 (2008).
Submitted at: Nov. 30, 2007
Accepted at: Jan. 16, 2008
Optoelectronics and Advanced Materials - Rapid Communications
(2024): Impact Factor = 0.4 - Journal Citation Reports (Clarivate Analytics, 2025)
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