Solid State Ionics, Vol.154, 93-100, 2002
Microthermogravimetry in studying the defect and transport phenomena in transition metal sulfides
The chemical diffusion coefficient and point defect concentration in metal-deficit sulfides (Co9-yS8, Ni1-yS and Mn1-yS) has been studied as a function of temperature and sulfur activity using reequilibration and two-stage kinetic methods. Measurements have been carried out in a novel microthermogravimetric apparatus, enabling the mass changes of the sulfidized samples to be determined as a function of time with the accuracy of the order of 10(-6) g. The diffusivity and defect concentration in investigated sulfides have been studied at high temperatures (873-1273 K) in pure sulfur vapours (10(-1)-10(4)) Pa) and H-2-H2S gas mixture with P(S-2) ranging from 10(-5) up to 1 Pa. The results described in the present paper show clearly that the microthermogravimetry may successfully be utilized in studying the defect and transport properties of nonstoichiometric metal sulfides.
Keywords:thermogravimetry;reequilibration kinetics;Rosenburg's method;defect concentration;chemical diffusion