ENTHALPIES OF MIXING IN THE DYCL3-NACL, DYCL3-KCL AND DYCL3-PRCL3 LIQUID-SYSTEMS

The molar enthalpies of mixing (DELTA(mix)H(m)) in the DyCl3-NaCl, DyCl3-KCl and DyCl3-PrCl3 liquid binary systems were measured at temperatures of 1100, 1070 and 1074 K respectively over the whole composition range under argon at atmospheric pressure. The apparatus used was a Calvet-type high temperature microcalorimeter and mixing of the two liquid components was achieved by the ampoule break-off technique; the experimental uncertainties were about 6% (DyCl3-NaCl, DyCl3-KCl) and 10% (DyCl3-PrCl3). For the first two systems, the enthalpies of mixing are negative over the whole composition range, with minima at x(DyCl3) almost-equal-to 0.3 of about -8 and -21 kJ mol-1 respectively. In the DyCl3-PrCl3 system the enthalpy-of-mixing values are positive, with a maximum at x(DyCl3) almost-equal-to 0.4 of about 760 J mol-1. The least-squares coefficients A, B, C and D of the equation for the interaction parameter lambda (kJ mol-1) = A + Bx + Cx2 + Dx3 are presented.