Preparation and properties of La _0.67Pb _0.33(Mn _1-xFe _x)O ₃ compounds

La0.67Pb0.33(Mn1-xFex)O3 materials with x = 0, 0.01, 0.03, 0.06, 0.1, 0.15 have been prepared by a wet chemical malic acid gel method followed by heat treatment at 1000 °C in air or oxygen. X-ray diffraction showed that the compounds were phase pure. The crystal structure of the compounds were interpreted in the rhombohedral space group (R3c). The temperature dependence of the resistance depended strongly on the Fe-content and showed metal–insulator transitions for all compounds. The Curie temperatures were determined from the dependence of the magnetization on the temperature and on the magnetic field. Both the Curie temperatures and saturation magnetic moments decreased linearly with increasing iron content. The metal–insulator transitions did not coincide with the relevant Curie temperatures. Reasons for this behavior are discussed