On the application of new equations to derive acoustic, thermodynamic and other properties of iron phosphate semiconducting glass

Abstract

We made an exhaustive study of semiconducting (Fe₂O₃)_0.38(P₂O₅)_0.62 glass and derived several important properties. They are in satisfactory agreement with experiment for those found in literature, and the other values obtained by different methods are found to be interconsistent. Using Thurston's equations and the pressure derivative of βand δ, Bhatia-Singh's parameters, we have calculated and compared the pressure derivatives of second order elastic constants. Gruneisen gammas (γ_g^L, γ_g^T, γ_g^el, γ_g^th) are calculated using various methods. Pressure derivative of bulk modulus (C₁) was evaluated assuming hard sphere model, and effective packing fraction (η_eff) was obtained from the compressibility equation of state. C₁' [≡(dC₁/dP)_T]=2(γ_g^th) was calculated using the compressibility equation of state, and from β and δ. (γ_g^th) and (γ_g^th)' [=dγ_g^th/dP] is important in superconducting studies, and in the evaluation of the second Gruneisen constant. Using Einstein and Debye's equation, molar heat capacity was evaluated. Second Gruneisen constant Q [=(∂ln γg/∂ln V)_T] and Anderson-Gruneisen parameter δ_AG [=-1/αK_T(∂ K_T/∂T)_P] was also evaluated. Smith-Nath-DeLaunay's (SND) equation was used to obtain absorption band position. Phonon frequencies were calculated using Bhatia-Singh's equations for the evaluation of C₁₁ and C₄₄. We made a self consistent check in the calculation of C₁₁ and C₄₄ from the slopes of ω_L(k) and ω_T(k) at low k values.