Synthesis and characterisation of a Lanthanide-based dioxide

M.R. ESQUIVEL; E. ZELAYA

ADVANCES IN APPLIED CERAMICS

MANEY PUBLISHING

Lugar: Londres; Año: 2011 vol. 110 p. 219 - 224

1743-6753

In this work, the microstructure and structure of La0.25Ce0.52Nd0.17Pr0.06(OH)3 and La0.25Ce0.52Nd0.17Pr0.06O2 is obtained from Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD) measurements. Space group P63/m is assigned to the structure of La0.25Ce0.52Nd0.17Pr0.06(OH)3.  Lanthanides are assigned to Wyckoff positions 2c. Cell parameters are a = 6.375(5) Å and c = 3.753(5) Å. The thermal decomposition of this compound was studied by Differential Scanning Calorimetry (DSC). The process is exothermal with an enthalpy change (DH°) value of -254 ± 10  kJ.mol-1.  The decomposition kinetics is complex and two global processes with Ea values of (98 ± 4) kJ.mol-1 and (61 ± 2) kJ.mol-1 were observed. The product is a lanthanide dioxide. Space group Fm3m is assigned to the La0.25Ce0.52Nd0.17Pr0.06O2. Lanthanides are distributed in Wyckoff positions 4a. The cell parameter is a = 5.479(5) Å.   Nano-pores in the oxide surface are obtained by using this method and characterized by STEM measurements.