Synthesis of lanthanide manganites LnMnO3 and LnMn2O5 from individual molecular precursors

Abstract

Methods for the synthesis of lanthanide manganites LnMnO3 and LnMn2O5 from individual molecular precursors were developed. The thermolysis of the neodymium complex from the series of [Mn3Ln2(Piv)10(NO3)2(MeCN)2] n compounds (Ln = Nd (1), Sm (2), Eu (3), Gd(4)) was shown to yield a NdMnO3–NdMn2O5 (1: 1) mixture. NdMnO3–NdMn2O5 films on Y2O3-doped ZrO2 were obtained from solutions of the neodymium complex using the temperature program providing a constant gas liberation rate. The thermolysis of several series of lanthanide carboxylates containing the cymantrene moiety (Cym = (η5-C5H4)Mn(CO)3) was studied. The thermolysis of these compounds was shown to quantitatively yield LnMn2O5–Mn2O3 mixtures or LnMn2O5 and LnMnO3 phases, and the composition of the product was governed by the Ln: Mn atomic ratio in the initial complex. The conditions for the synthesis of polycrystalline LnMn2O5 samples from [Ln2(OOCCym)4(NO3)2(DME)2] and LnMnO3 samples from [Ln(Cym-COO)(acac)2(H2O)] n were optimized, and the magnetic behavior of the synthesized LnMn2O5 (Ln = Eu, Tb, Y) and LnMnO3 (Ln = Ho, Er) phases was studied in detail within a wide range of temperatures.