A Site-Ordered Quadruple Perovskites, RMn3Ni2Mn2O12 with R = Bi, Ce, and Ho, with Different Degrees of B Site Ordering

Alexei A. Belik

doi:10.3390/molecules30081749

Article A Site-Ordered Quadruple Perovskites, RMn3Ni2Mn2O12 with R = Bi, Ce, and Ho, with Different Degrees of B Site Ordering

Alexei A. Belik (National Institute for Materials Science)

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Alexei A. Belik. A Site-Ordered Quadruple Perovskites, RMn3Ni2Mn2O12 with R = Bi, Ce, and Ho, with Different Degrees of B Site Ordering. Molecules. 2025, 30 (8), 1749. https://doi.org/10.3390/molecules30081749

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A-site-ordered quadruple perovskites, AA’3B4O12, can have 3d transition-metal at A’ and B sites and show complex magnetic interactions and behavior. Additional complexity appears when B-site-ordered arrangements are realized in AA’3B2B’2O12. In this work, A-site-ordered quadruple perovskites, RMn3Ni2Mn2O12 with R = Bi, Ce, and Ho, were prepared by a high-pressure, high-temperature method at about 6 GPa and about 1500 K. The R = Bi and Ce samples were found to crystallize in space group Im-3 with a disordered distribution of Ni2+ and Mn4+ cations in one B site. On the other hand, the R = Ho sample crystallized in space group Pn-3 and showed a partial ordering of Ni2+ and Mn4+ cations between two B sites. The structural data (and bond-valence sums) suggest that cerium has the oxidation state +3 that is unusual for such perovskites. Magnetic properties were investigated by magnetic susceptibility and specific heat measurements, which showed the presence of one magnetic transition near 36 K for R = Bi; there was evidence for the presence of two magnetic transitions near 27 K and 33 K for R = Ce and near 10 K and 36 K for R = Ho. Curie-Weiss parameters were estimated for all samples from high-temperature magnetic measurements up to 750 K. The total effective magnetic moment for R = Ce also suggests the presence of Ce3+. Magnetic field of 90 kOe has the largest effect on specific heat of the R = Ho sample, and almost no effects on specific heat of the R = Bi sample.

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