Crystal structure, composition and valence state of cations in mixed-valence A1-xCdxMnO3 (A=Pr, La) ceramics

Complex manganites A 1−x Cd x MnO 3 (A = Pr, La) are synthesized by solid state reaction method. X-ray diffraction, scanning electron microscopy and energy-dispersive analysis are applied to study their crystal structure, surface morphology, elemental and phase composition. X-ray photoelectron spectroscopy (XPS) methods are used to study the charge states of Pr and La cations, as well as to quantify the fractions of coexisting Mn 3+ and Mn 4+ ions. La3d-, La4d-, Pr4d- и Mn2p-spectra of La 3+ , Pr 3+ , Mn 3+ and Mn 4+ ions are calculated in the isolated–ion approximation with accounting for multiplet splitting and charge transfer effect. Good agreement with the experiment is obtained. The relative fractions of trivalent and tetravalent manganese ions in La 0.45 Cd 0.78 Mn 0,9 O 2.86 and Pr 0.50 Cd 0.76 Mn 0.86 O 2.88 samples are determined by fitting the Mn2p spectra by superposition of experimental spectra containing only Mn 3+ , and only Mn 4+ ions; they were found to be 0.71Mn 3+ /0.29Mn 4+ and 0.54Mn 3+ /0.46Mn 4+ , respectively.