High-pressure chemistry of nitride-based materials

Abstract

Besides temperature at one atmosphere, the applied pressure is another important parameter for influencing and controlling reaction pathways and final reaction products. This is relevant not only for the genesis of natural minerals, but also for synthetic chemical products and technological materials. The present critical review (316 references) highlights recent developments that utilise high pressures and high-temperatures for the synthesis of new materials with unique properties, such as high hardness, or interesting magnetic or optoelectronic features. Novel metal nitrides, oxonitrides as well as the new class of nitride-diazenide compounds, all formed under high-pressure conditions, are highlighted. Pure oxides and carbides are not considered here. Moreover, syntheses under high-pressure conditions require special equipment and preparation techniques, completely different from those used for conventional synthetic approaches at ambient pressure. Therefore, we also summarize the high-pressure techniques used for the synthesis of new materials on a laboratory scale. In particular, our attention is focused on reactive gas pressure devices with pressures between 1.2 and 600 MPa, multi-anvil apparatus at P < 25 GPa and the diamond anvil cell, which allows work at pressures of 100 GPa and higher. For example, some of these techniques have been successfully upgraded to an industrial scale for the synthesis of diamond and cubic boron nitride.

Li+ Ion Conductors with Adamantane‐Type Nitridophosphate Anions β‐Li10P4N10 and Li13P4N10X3 with X=Cl, Br

“…The ampoules were heated for 120 h[ Eqs. (1), (2), and (4) (4)]. A ll syntheses yielded ac olorless powder containing dark traces of Li 3 P. To obtain phase-pure products, the traces of Li 3 Pw ere removed by washing with dry ethanol.…”

“…b-Li 10 P 4 N 10 crystallizes in the trigonal space group R3w ith lattice parameters a = 8.71929 (8) and c = 21.4656 (2) .F urther crystallographic data (atomicp ositions, isotropic displacement parameters) are given in the Supporting Information. During the structure determination of b-Li 10 P 4 N 10 ,d ifferent space groups weret ested and compared.…”

“…[1][2][3][4][5][6] Nitridophosphates are of particular interest due to their structural variability.T he ability to form different linking patterns of corner-and/oredge-sharing PN 4 tetrahedra as primary building units leads to av ariety of complex structures and allows materials to be optimized for many purposes. [7][8][9][10][11] Synthetic approaches to nitridophosphates are somewhat challenging due to the limited thermal stability of the starting materials (e.g.,P 3 N 5 decomposes above 850 8C).…”

Electronic structure, stability, and mechanism of the decohesion and shear of interfaces in superhard nanocomposites and heterostructures

“…46͒ or high-pressure phases, such as the Stishovit phase of silica and the spinel phases of the fourth group elements, such as ␥-Si 3 N 4 , ␥-Ge 3 N 4 , ␥-͑Si 1−x Ge x ͒ 3 N 4 and ␥-Sn 3 N 4 . 47,48 The spinel structure consists of 8 f.u. of a total of 56 atoms of which eight cations ͑Si, Ge, Sn͒ are in tetrahedral ͑fourfold coordinated to N͒ and 16 in octahedral ͑sixfold coordinated to N͒ sites, whereas nitrogen is fourfold coordinated to the cations.…”

Effects of structural differences in starting materials on the formation behavior of cubic silicon nitride by shock compression

“…1)3) Cubic silicon nitride (c-Si 3 N 4 ) with a spinel structure, discovered in 1999, 4) is a typical high-pressure phase with excellent hardness. So far, three methods have been developed for high-pressure synthesis of c-Si 3 N 4 .…”