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
In the ternary system La2O3-P2O5-Na2O the partial system La2O3-Na4La2P4O15-LaPO4 has been examined by the thermal, dilatometric X-ray and microscopic analyses and its phase diagram provided. The lanthanum oxyphosphate La3PO7 melts incongruently at the 1590°C temperature and crystallizes in a monoclinic systema=11.20 Å,b=11.94 Å,c=7.01 Å,γ=93.79 andV=936.97 Å3.
The behaviour of V2O5 against FeVMoO7 up to 1000 °C in the whole range of component concentrations was investigated using DTA and X-ray powder diffraction methods. The experimental results are presented in the form of a phase diagram.
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.