Preparation, structure and properties of La0.67Pb0.33(Mn1-xCox)O3-δ

• Published in: Applied physics. A, Materials science & processing Vol. 90; no. 2; pp. 359 - 365
• Main Authors: Gritzner, G., Ammer, J., Kellner, K., Kavečanský, V., Mihalik, M., Maťaš, S., Zentková, M.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.02.2008; Springer
• Subjects: Characterization and Evaluation of Materials; Condensed Matter Physics; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Machines; Magnetic properties and materials; Magnetotransport phenomena, materials for magnetotransport; Manganites; Manufacturing; Nanotechnology; Optical and Electronic Materials; Physics; Physics and Astronomy; Processes; Surfaces and Interfaces; Thin Films; Ferromagnetic Transition; Magnetic Phase Transition; Weiss Temperature; Effective Magnetic Moment; Paramagnetic Curie Temperature; Curie point; Impurity density; Metal-insulator transition; Magnetic moments; Magnetic hysteresis; XRD; Magnetic transitions; Heat treatments; Trigonal lattices; Paramagnetic materials; Anomaly; Cobalt additions; Magnetoresistance; Ferromagnetic-paramagnetic transitions; Manganites; Saturation magnetization
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-007-4284-2

La 0.67 Pb 0.33 (Mn 1-x Co x )O 3-δ ceramics with x=0, 0.01, 0.03, 0.06, 0.1 and 0.15 have been prepared in a two-step procedure. Precursor gels were made by the wet chemical malic acid method. The gels were calcined and then converted into ceramics by heat treatment at 950 °C and 1000 °C in air. X-ray diffraction showed that the compounds were phase pure. The crystal structure symmetry of the compounds was confirmed to be rhombohedral (space group R3̄c) for the whole investigated range of x. All compounds undergo a paramagnetic–ferromagnetic phase transition between 335 K and 225 K. The basic magnetic characteristics such as the Curie temperature , the paramagnetic Curie temperature θ, the effective magnetic moment and the saturated magnetization decrease with increasing Co doping. The ferromagnetic transition is accompanied by an anomaly in the electrical resistance for all compounds. The high-temperature insulator–metal transitions ( ) do not coincide with the relevant . A large magnetoresistance peak of about 15% was observed for all compounds at .