The ternary system CePO4−NaPO3−Ce(PO3)3 was investigated by differential thermal analysis, powder X-ray diffraction and microscopy in reflected light. Two double
phosphates, NaCeP2O7 and NaCe(PO3)4, occur in this system. Both NaCeP2O7 and NaCe(PO3)4 melt incongruently, at 800 and 865°C, respectively. Two systems, NaCeP2O7−NaCe(PO3)4 and CePO4−NaCe(PO3)4, were found to occur in this region. Their phase diagrams are presented.
Authors:Y. Kitazawa, Y. Kunimoto, M. Wakihara, and M. Taniguchi
The phase diagram of the La-S-O system at 1073 K was established with the vacuum seal technique. Six phases exist at this temperature: La2O3 (B-type), LaS2, La2S3, La2O2SO4, La2O2S and La2O2S2. The thermodynamic functions for the reaction La2O2SO4=La2O3+SO2+1/2 O2 were determined by using the emf method at temperatures from 1123 to 1373 K. The mechanisms of the oxidation reactions in the La-S-O system under different partial pressures of oxygen (−4.4 < log
<−0.7) were also investigated by means of DTA, TG and powder X-ray diffractometry.
Authors:V. Vassilev, L. Aljihmani, and V. Parvanova
The phase diagram of the system Ag4SSe–As2Se3
is studied by means of X-ray diffraction, differential thermal analyses and
measurements of the microhardness and the density of the materials. The unit-cell
parameters of the intermediate phases 3Ag4SSeAs2Se3
(phase A) and Ag4SSe2As2Se3
(phase B) are determined as follows for phase A: a=4.495
, b=3.990 , c=4.042
, α=89.05, β=108.98, γ=92.93; for phase
B: a=4.463 , b=4.136
, c=3.752 , α=118.60,
β=104.46, γ=83.14. The phase 3Ag4SSeAs2Se3
have a polymorphic transition α↔β consequently at 105 and 120C.
The phase A melts incongruently at 390C and phase B congruently at the