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Abstract
Abstract
In the present 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 and X-ray diffraction 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. The process is exothermal with an enthalpy change ΔH° value of −254±10 kJ mol−1. The decomposition kinetics is complex and two global processes with Ea values of 98±4 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. Nanopores in the oxide surface are obtained using this method and characterised by STEM measurements.
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The authors wish to thank Dr D. Schryvers for helpful discussion of TEM results. M. R. Esquivel wishes to thank the Agencia Nacional de Promoción Científica y Tecnológica of Argentina (project no. PICT N° 33473), Universidad Nacional de Cuyo of Argentina (project no. 06/C310) and Comisión Nacional of Energía Atómica of Argentina for partial financial support. E. Zelaya thanks the support of a Bijzonder Onderzoeksfonds project of the University of Antwerp.