Determination of Standard Gibbs Energy of Formation of Al<SUB>2</SUB>Nd by Solution Calorimetry and Heat Capacity Measurement from Near Absolute Zero Kelvin

Abstract

The thermodynamic properties of Al 2 Nd were investigated by calorimetry. The standard entropy of formation of Al 2 Nd at 298 K, Á f S o 298 (Al 2 Nd), was determined from measuring the heat capacities, C p , from near absolute zero (2 K) to 300 K by the relaxation method.

Temperature dependence of standard Gibbs energy of formation of Al2Nd from near absolute 0K to room temperature

“…1 are the calculated C p (Al 0.667 Nd 0.333 ) using the coefficients of the polynomials shown in Table 5 obtained in the previous work [8]. As described in the previous work [8], there are two -type peaks, P 1 and P 2 , at the temperatures of 71.8 and 3.91 K. Table 6. Open circle symbols in Fig.…”

“…C p (Al 0.667 Nd 0.333 ) was obtained in our previous work, [8] and C p (Al) and C p (Nd) were measured and fitted to polynomials as mentioned above. …”

“…already reported about the determination of the standard entropy of formation at 298 K, f S • 298 , of Al 11 Nd 3 (Al 0.786 Nd 0.214 ) by measuring the heat capacities, C p , from near absolute zero (2 K) to 300 K by the relaxation method [7], and the determination of f S • 298 , the standard enthalpy of formation at 298 K, f H • 298 , and the standard Gibbs energy of formation at 298 K, f G • 298 , of Al 2 Nd by heat capacity measurement and solution calorimetry in hydrochloric acid solution [8]. In this paper, the standard Gibbs energy of formation as a function of temperature of Al 2 Nd, f G • T (Al 2 Nd), in the temperature range from near absolute 0 K to room temperature was determined by combining the measurements of heat capacities, C p , of pure aluminium and neodymium using the relaxation method with the thermodynamic data of Al 2 Nd in our previous work [8].…”

Thermodynamic Properties of AlNd Determined by Low Temperature Heat Capacity Measurements

“…We have previously reported the thermodynamic properties of the intermetallic compounds Al 11 Nd 3 and Al 2 Nd [4][5][6] in the Al-Nd binary system. The standard entropy of formation, Á f S o 298 , of Al 11 Nd 3 at 298 K was determined by measuring the heat capacity, C p , from near absolute zero (2 K) to 300 K 5) using the relaxation method.…”

“…[7][8][9][10] In the case of Al 2 Nd, Á f S o 298 , the standard enthalpy of formation at 298 K, Á f H o 298 , and the standard Gibbs energy of formation at 298 K, Á f G o 298 , were determined by heat capacity measurement and solution calorimetry in hydrochloric acid solution. 4) Furthermore, the standard Gibbs energy of formation as a function of temperature, Á f G o T , of Al 2 Nd was determined using the C p polynomials of pure aluminum and pure neodymium. 6) During the measurement of C p of these AlNd intermetallic compounds, several peaks probably caused by magnetic transitions were found on the C p curves.…”