Anomalous structural transformations of Gd-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=- nanopowders obtained in the combustion mode by the glycine-nitrate method

Abstract

The structural states of Gd2O3 and Gd2O3 : 2% Eu3+ synthesized by the glycine-nitrate method were studied. As a result of this synthesis, in addition to the known cubic modification of gadolinium oxide, two new previously unknown phases are formed. The first phase is formed during prolonged exposure at room temperature of the initial nanocrystalline cubic structure obtained at a synthesis temperature of 650oC. The second phase has orthorhombic syngony and is formed during either long-term synthesis at a temperature of 650oC, or short-term syntheses at a higher temperature. Both phases pass into the traditional cubic modification during further high-temperature annealing. In addition, the effect of structural "infection" was found, which consists in the fact that during annealing of the cubic phase of Gd2O3 doped with Eu3+ ions in the range of 800-1100oC, its partial transition into the monoclinic phase occurs, which disappears with a further increase in the annealing temperature. Keywords: synthesis of Gd2O3, glycine-nitrate method, nanocrystalline state, X-ray diffraction research methods, phase transitions.