S.C. Parida

Calorimetric studies on uranium molybdate

Abstract Enthalpy increment measurements on UMoO6(s) have been carried out using a high-temperature Calvet micro-calorimeter in the temperature range 299 to 1000 K. The enthalpy increments were least squares analyzed using Shomate’s method. The complete thermodynamic information for UMoO6(s) has been computed. The enthalpy increment expression for UMoO6(s) as a function of temperature is given by H o (T)−H o (298.15 K )( J mol −1 )=−53928.8+158.65T( K )+21.443×10 −3 T 2 ( K )+14.077×10 5 /T( K ).

Thermodynamic studies on SrThO3(s)

Abstract The Gibbs energy of formation of SrThO3(s) has been determined using e.m.f. and manometric techniques. In the e.m.f. method, two fluoride cells have been constructed to determine ΔfG0m(SrThO3,s,T) using CaF2(s) as a solid electrolyte. The cells used are: (−) O 2 ( g ), Pt / SrO ( s )+ SrF 2 ( s )// CaF 2 //( SrThO 3 ( s )+ ThO 2 ( s )+ SrF 2 ( s )/ Pt , O 2 ( g )(+), ( I ) (−) O 2 ( g ), Pt / SrThO 3 ( s )+ SrF 2 ( s )+ ThO 2 ( s )// CaF 2 ( s )// CaO ( s )+ CaF 2 ( s )/ Pt , O 2 ( g )(+). ( II ) The observed e.m.f. values are represented by following respective expressions: E ( V )±0.0001=0.0998+3.254×10 −5 T ( K ), ( Cell I ) E ( V )±0.0001=0.0285−6.37×10 −5 T ( K ). ( Cell II ) From the measured e.m.f. values of the cells and the ΔfG0m(T) values from the literature, ΔfG0m(SrThO3,s,T) have been calculated and are respectively given as Δ f G 0 m ( SrThO 3 , s ,T)±10 kJ mol −1 =−1829.2+0.2735T ( K ) (978⩽T ( K )⩽1154), ( Cell I ) Δ f G 0 ( SrThO 3 , s ,T)±20 kJ mol −1 =−1853.5+0.2867T ( K ) (1008⩽T ( K )⩽1168). ( Cell II ) In the manometric technique, equilibrium CO2(g) pressures are measured over the three phase mixture: {SrThO3(s)+SrCO3(s)+ThO2(s)} using a mercury manometer from 1075 to 1197 K. The corresponding Gibbs energy as a function of temperature is given by Δ f G 0 m ( SrThO 3 , s ,T)( kJ mol −1 )±14=−1865.4+0.3086T ( K ).

Thermodynamic properties of SmFeO3(s) and Sm3Fe5O12(s)

AbstractThe enthalpy increments and the standard molar Gibbs energy (G) of formation of SmFeO3(s) and Sm3Fe5O12(s) have been measured using a Calvet micro-calorimeter and a solid oxide galvanic cell, respectively. A λ-type transition, related to magnetic order-disorder transformation (antiferromagnetic to paramagnetic), is apparent from the heat capacity data at ∼673 K for SmFeO3(s) and at ∼560 K for Sm3Fe5O12(s). Enthalpy increment data for SmFeO3(s) and Sm3Fe5O12(s), except in the vicinity of λ-transition, can be represented by the following polynomial expressions:

Thermodynamic studies on Al–U–Zr alloy

\begin{gathered} \{ H^0 _m (T) - H^0 _m (298.15K)\{ /J mol^{ - 1} ( \pm 1.2\% ) = - 54532.8 + 147.4 \cdot (T/K) + 1.2 \cdot 10^{ - 4} \cdot (T/K)^2 \hfill \\ + 3.154 \cdot 10^6 \cdot (T/K)^{ - 1} ;(298.15 \leqslant T/K \leqslant 1000) \hfill \\ \end{gathered}

Solid-state synthesis and heat capacity measurements of ceramic compounds LiAlSiO4, LiAlSi2O6, LiAlSi3O8, and LiAlSi4O10

for SmFeO3(s), and

Standard molar Gibbs energy of formation of Ba3Te2O9(s) by transpiration technique

\begin{gathered} \{ H^0 _m (T) - H^0 _m (298.15K)\} /J mol^{ - 1} ( \pm 1.4\% ) = - 192763 + 554.7 \cdot (T/K) + 2.0 \cdot 10^{ - 6} \cdot (T/K)^2 \hfill \\ + 8.161 \cdot 10^6 \cdot (T/K)^{ - 1} ;(298.15 \leqslant T/K \leqslant 1000) \hfill \\ \end{gathered}