Thermal and spectroscopy studies of Ag2SO4 and LiAgSO4

Abstract

A comparative study is conducted on the structure, electronic and spectroscopic properties of Ag 2 SO 4 and LiAgSO 4 . Both the sulphates crystallise in an orthorhombic structure with the same space group of Fddd (70). A red shift in Raman modes indicates the stiffness of the crystal Ag 2 SO 4 over LiAgSO 4 . From ESR, it is observed that these sulphates has Mn 2+ impurities leading to the g av = 2.1040 at a field of 3255 G. This indicates that the Mn 2+ ions have an environment close to octahedral symmetry. The g value corresponding to Ag 2 SO 4 is 2.3005. The endothermic peaks in LiAgSO 4 at 388.8 and 420 0 C are due to the formation of BCC structure of LiAgSO 4 . The peak at 420.9 0 C in Ag 2 SO 4 may be due to the phase transition of β-Ag 2 SO 4 particles to α-Ag 2 SO 4 on heating.

Structure, Thermal Stability, and Spectroscopic Properties of Triclinic Double Sulfate AgEu(SO4)2 with Isolated SO4 Groups

“…To evaluate the solid-phase interaction between Ag 2 SO 4 and Eu 2 (SO 4 ) 3 used as starting materials as well as to see the stability of the formed double sulfate AgEu­(SO 4 ) 2 , the behavior of an equimolar mixture of Ag 2 SO 4 and Eu 2 (SO 4 ) 3 (Figure a) and stoichiometric AgEu­(SO 4 ) 2 (Figure b) on heating in the air was studied by differential scanning calorimetry (DSC). The thermograms contains a large number of thermal effects, among them, several effects are known (A, D, E, and F). − The effects B and C are observed for the first time in the present study. The interpretation of thermal effects and corresponding reactions are given in Table .…”

“…However, the sample mass does not change. According to the literature, this transformation corresponds to a polymorphous transition of the rhombic modification of silver sulfate to hexagonal form. − The exothermic peak (B) originating at 874.5 K is not accompanied by a change in the sample mass. Earlier, when Ag 2 SO 4 and Eu 2 (SO 4 ) 3 were studied individually, no similar effect was observed. , Accounting for this, the effect (B) is interpreted as a chemical interaction of the Ag 2 SO 4 and Eu 2 (SO 4 ) 3 components, leading to the formation of a new complex sulfate AgEu­(SO 4 ) 2 .…”