Oxysulfate/oxysulfide of Tb3+ obtained by thermal decomposition of terbium sulfate hydrates under different atmospheres

Abstract

The terbium oxysulfate/oxysulfide Tb 2 O 2 SO 4 / Tb 2 O 2 S were prepared from two different precursors: Tb(DAS) 3 Á2H 2 O and Tb 2 (SO 4 ) 3 Á8H 2 O, utilizing two different atmospheres of thermal decomposition. The reaction of Tb 4 O 7 with aqueous solution of H 2 SO 4 (2 mol L -1 ) produces Tb 2 (SO 4 ) 3 Á8H 2 O; after isolation and purification, it was reacted with Ba(DAS) 2 ÁH 2 O in aqueous solution to produce Tb 2 (DAS) 3 Á2H 2 O precursor. Both of the terbium sulfonate Tb(DAS) 3 Á2H 2 O and terbium sulfate Tb 2 (SO 4 ) 3 Á 8H 2 O precursors were analyzed in two different atmospheres of thermal treatment; in air atmosphere, terbium oxysulfate Tb 2 O 2 SO 4 was obtained as the end product; and in reducing (CO) atmosphere, terbium oxysulfide Tb 2 O 2 S one was obtained. Thus, it was observed that the change of precursor can result in obtaining different size of particles. Moreover, it was also observed that the terbium oxysulfate Tb 2 O 2 SO 4 obtained from sulfonate precursor at 1223 K, while from sulfate one at 1323 K. Similarly, the terbium oxysulfide Tb 2 O 2 S obtained from both sulfonate and sulfate precursors did not show significant difference, at 1013 K from sulfonate and 1033 K from sulfate precursor.