Preparation of new heteronuclear (NH_4)RE[Fe~(II)(CN)_6]?nH_2O complexes (RE = La, Ce, Pr, Nd, Sm, Gd, Dy, Y, Er, Lu) and their low-temperature decomposition for perovskite-type oxide

摘要

New heteronuclear (NH_4)RE~(III)[Fe~(II)(CN)_6]?nH_2O complexes (RE = La, Ce, Pr, Nd, Sm, Gd, Dy, Y, Er, Lu) were synthesized and their thermal decomposition products were investigated. The crystal structure of (NH_4)RE[Fe~(II)(CN)_6]?nH_2O would be a hexagonal unit cell (space group: P6_3/ m), which was the same as that of La[Fe~(III)(CN)_6]-5H_2O. The hydration number n = 4 was estimated by TG results for all the RE complexes. The lattice constants depended on the ionic radius of the RE~(3+) ion for the heteronuclear complexes. The single phase of the perovskite type materials was directly obtained by decomposition of the heteronuclear complexes for RE = La, Pr, Nd, Sm, and Gd. A mixture of CeO_2 and Fe_2O_3 was formed for RE = Ce because of its oxidation to Ce~(4+). In the case of RE = Dy, Y, Er, and Lu complexes, the perovskite type materials formed at higher temperature via. mixed oxides such as RE_2O_3 and RE_4Fe_5O_(13) due to the small RE~(3+) ionic radius.