V. Jordanovska et J. Siftar, SYNTHESIS AND THERMAL-DECOMPOSITION OF SOME RARE-EARTH TETRAMETHYLAMMONIUM DOUBLE SULFATES, Journal of thermal analysis, 44(3), 1995, pp. 655-661
When reaction mixtures of rare earth(III) sulphates and tetramethylamm
onium sulphate in molar ratios of from 1:4 to 1:12 were evaporated at
ambient temperature and the concentrated reaction mixture was treated
with ethanol, double sulphates with general empirical formula (CH3)(4)
NLn(SO4)(2) . 2H2O (Ln = Ho-Lu and Y) were obtained as reaction produc
ts. The crystalline products were identified by quantitative analysis,
X-ray powder diffraction patterns and TG, DTG and DTA analysis. They
were found to be isostructural. Their thermal decomposition look place
in three stages. The temperature range of the dehydration mainly decr
eased from Ho to Lu. The thermal decomposition in the second and third
stages occurred with many thermal events. As final product, Ln(2)O(SO
4)(2) was obtained.