Douglass S. Kalika, David W. Giles, et al.
Journal of Rheology
The enthalpies of solution in molten 2PbO · B2O3 at 704°C of Nd2CuO4 (T′), (La1-x Ndx)2CuO4 (T or T′), (La0.60Dy0.35Ce0.05)2CuO 4 (T′ and T*), and (La0.60Dy0.35Th0.05)2CuO 4 (T′- and T*) have been measured. The enthalpy of formation (from oxides) at 700°C of (La1-x Ndx)2CuO4 (0 ≤ x ≤ 1) varies from -20 to -7 kJ mol-1, depending on composition. The enthalpy of the T′ to T transition in (La0.75 Nd0.25)2CuO4 is +6.3 ± 2.8 kJ mol-1. Extrapolated enthalpies of transition from T′ to T are +3 ± 8 kJ mol-1 for La2CuO4 and +28 ± 10 kJ mol-1 for Nd2CuO4. The enthalpy of mixing in the T′ phase of (La1-x Ndx)2 CuO4 is positive, with a regular enthalpy interaction parameter of + 51.8 kJ mol-1. The positive enthalpy of mixing argues against cation ordering being important in this system. The enthalpies of transition of T* to T′ of (La0.6Dy0.35Th0.05)2CuO4 and (La0.6Dy0.35Ce0.05)2CuO4 are +38 ± 5 and +51 ± 6 kJ mol-1, respectively. There is a linear dependence of the enthalpy of transition (ΔH) between T′ and T (or T* and T′) phases on the volume of transition (ΔV), ΔH (kJ mol-1) = 37.4 + 9.27 ΔV (cm3 mol-1). © 1993 Academic Press, Inc.
Douglass S. Kalika, David W. Giles, et al.
Journal of Rheology
A. Krol, C.J. Sher, et al.
Surface Science
J.A. Barker, D. Henderson, et al.
Molecular Physics
C.M. Brown, L. Cristofolini, et al.
Chemistry of Materials