The ternary system Na2O–ZnO–WO3: Compounds and phase relationships

The subsolidus phase relationships of ternary system Na2O–ZnO–WO3 have been investigated by X-ray diffraction (XRD) and differential thermal analyzer (DTA). All the samples were synthesized in the temperature range from 530 to 850 °C in air. There are one ternary compound and five binary compounds in the Na2O–ZnO–WO3 system, which can be divided into eight three-phase regions. The crystal structure of the ternary compound Na3.6Zn1.2(WO4)3 is determined by single-crystal structure analysis method. It belongs to triclinic system with space group P1¯ and lattice constants a = 7.237 (5) Å, b = 9.172 (6) Å, c = 9.339 (6) Å and α = 94.920 (4)°, β = 105.772 (9)°, γ = 103.531 (8)°, Z = 2. DTA analyses indicate that the compound Na2WO4 is not suitable to be the flux for ZnO crystal growth below 1250 °C, since no liquidus was observed in the system before 1250 °C.