Synthesis of tin(IV) nitride with spinel structure, γ-Sn₃N₄, from the elements and its Raman-spectroscopic examination at high pressures

We report on the synthesis of tin(IV) nitride with spinel structure, γ-Sn₃N₄, from the elements at high pressures and temperatures using a laser-heated diamond anvil cell, and on the Rietveld refinement of the product structure. The procedure described here is, in our opinion, the most reliable method of obtaining high-purity nitrides which are thermodynamically stable only at high pressures. Raman spectroscopy and powder X-ray diffraction were used to characterize the synthesis products. Pressure dependences of the Raman-band frequencies of γ-Sn₃N₄ were measured and used to determine its average mode Grüneisen parameter, 〈γ〉 = 0.95. Using this value, we estimated the thermal-shock resistance of γ-Sn₃N₄ to be about half that of γ-Si₃N₄, which, in turn, is moderately surpassed by β-Si₃N₄, known to be highly thermal-shock resistant. This article is part of the theme issue 'Exploring the length scales, timescales and chemistry of challenging materials (Part 1)'.