Thermogravimetry study of Gd2O3 Chlorination . Kinetics and characterization of Gadolinium Oxychloride

F. J. POMIRO; G. G. FOUGA; J.P. GAVIRÍA; A. E. BOHÉ

JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY

SPRINGER

Año: 2015

1388-6150

The reaction between Gd2O3(s) and Cl2(g) was studied in a high resolutionthermogravimetric system. The reaction product was GdOCl, which it was the uniquesolid phase produced in all the temperature range. The GdOCl is subsequentlychlorinated producing GdCl3 for temperatures above 1123 K. The system is underchemical control for temperatures below to 723 K. It was found that the reaction orderwith respect to the chorine partial pressure is 0.77 and the activation energy is 132kJ·mol-1 for the temperature range of 623 K to 723 K. The global rate equation wasdeveloped. The GdOCl obtained was characterized by X-ray diffraction, scanningelectron microscopy and magnetic measurements. The structure of GdOCl was refinedwith the Rietveld method and it crystallized in a tetragonal form of REOX possessingthe Matlockite-type (PbFCl) structure. The magnetic measurements indicated that thesample is paramagnetic at all the measurement range. The parameters of the Curie-Weiss law obtained were: θ = -12.0 K , C = 7.9592 emu∙K∙mol-1 and μeff = 7.98μB.