Systems Based on InN

Some compounds are formed in the In–Ca–N ternary system. Ca ₂ InN crystallizes in the orthorhombic structure with the lattice parameters a = 353.2 ± 0.3, b = 2020.4 ± 1.6, and c = 496.9 ± 0.4 pm at 160 K and a calculated density of 3.915 g⋅cm^–3 (Bailey and DiSalvo 2003). Dark red metallic-looking needles of the title compound were synthesized in sealed Nb tubes from the elements in molten Na with Na₃N as the nitrogen source. Inside an Ar-filled glove box, Na₃N, Ca, In, and Na were placed into a Nb tube, the amounts of which were chosen such that the atomic ratios of Na/In/Ca/N₂ were 6:1.5:1.4:1. The tube was sealed under 0.1 MPa of Ar and then itself sealed inside a fused silica sheath. These starting materials were heated to 800°C in 15 h, remained at temperature for 24 h, and slow cooled to 600°C at 0.2°C⋅h^–1 and then to 200°C at 0.4°C⋅h^–1. At this point, the furnace was shut off and allowed to cool naturally. Unreacted Na was removed by sublimation from a mixture of NaIn, In, and dark red needle crystals by heating the niobium tube to 325°C under a pressure of 0.1 Pa for 8 h. This compound was not detected during the experiments by Kirchner et al. (2005).