Results of calorimetric investigations performed on two groups of glasses, viz. As-Te-Se and Ge-As-Se, are described. The glass transition temperatureT_g and specific heat at constant pressureC_p of these two families of glasses have been determined using a differential scanning calorimeter. The composition dependence of glass transition temperature and variation of heat capacity during transition are discussed.

The double sulfate family (ABSO₄), where A and B are alkali metal cations, is the object of great interest owing to the complexity and richness of its sequence of phase transition induced by temperature variation. A new sulfate salt characterized by the presence of water molecule in the unit cell with the chemical formula, Li₂Na₃(SO₄)₂.6H₂O (LSSW), was obtained. The ultrasonic velocity measurement was done with pulse echo overlap technique [PEO]. All the six second order elastic stiffness constants, 𝐶₁₁ = 𝐶₂₂, 𝐶₃₃, 𝐶₄₄ = 𝐶₅₅, 𝐶₁₂, 𝐶₁₄ and 𝐶₁₃ = 𝐶₂₃ are reported for the first time. The anisotropy in the elastic properties of the crystal are well explained by the pictorial representation of the polar plots of phase velocity, slowness, Young’s modulus and linear compressibility in 𝑎–𝑏 and 𝑎–𝑐 planes.

The double sulfate family of (ABSO₄) where A and B are alkali metal cations, is the object of great interest owing to the complexity and richness of its sequence of phase transition induced by temperature variation. A new sulfate salt characterized by the presence of water molecule in the unit cell with the chemical formula, Li₂Na₃(SO₄)₂.6H₂O (LSSW), was obtained. The ultrasonic velocity measurement was done with pulse echo overlap technique [PEO]. All the six second order elastic stiffness constants, 𝐶₁₁ = 𝐶₂₂, 𝐶₃₃, 𝐶₄₄ = 𝐶₅₅, 𝐶₁₂, 𝐶₁₄ and 𝐶₁₃ = 𝐶₂₃, are reported for the first time. The anisotropy in the elastic properties of the crystal are well explained by the pictorial representation of the surface plots of phase velocity, slowness, Young’s modulus and linear compressibility in 𝑎–𝑏 and 𝑎–𝑐 planes.