[NiEn(3)](MoO(4))(0.5)(WO(4))(0.5) Co-Crystals as Single-Source Precursors for Ternary Refractory Ni–Mo–W Alloys

The co-crystallisation of [NiEn(3)](NO(3))(2) (En = ethylenediamine) with Na(2)MoO(4) and Na(2)WO(4) from a water solution results in the formation of [NiEn(3)](MoO(4))(0.5)(WO(4))(0.5) co-crystals. According to the X-ray diffraction analysis of eight single crystals, the parameters of the hexagonal unit cell (space group P–31c, Z = 2) vary in the following intervals: a = 9.2332(3)–9.2566(6); c = 9.9512(12)–9.9753(7) Å with the Mo/W ratio changing from 0.513(3)/0.487(3) to 0.078(4)/0.895(9). The thermal decomposition of [NiEn(3)](MoO(4))(0.5)(WO(4))(0.5) individual crystals obtained by co-crystallisation was performed in He and H(2) atmospheres. The ex situ X-ray study of thermal decomposition products shows the formation of nanocrystalline refractory alloys and carbide composites containing ternary Ni–Mo–W phases. The formation of carbon–nitride phases at certain stages of heating up to 1000 °C were shown.