Synthesis of tin(IV) nitride with spinel structure, γ -Sn 3 N 4 , from the elements and its Raman-spectroscopic examination at high pressures.

We report on the synthesis of tin(IV) nitride with spinel structure, γ -Sn 3 N 4 , 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 -Sn 3 N 4 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 -Sn 3 N 4 to be about half that of γ -Si 3 N 4 , which, in turn, is moderately surpassed by β -Si 3 N 4 , 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)'.