High Pressure Synthesis of Marcasite-Type Rhodium Pernitride

Abstract

Marcasite-type rhodium nitride was successfully synthesized in a direct chemical reaction between a rhodium metal and molecular nitrogen at 43.2 GPa using a laser-heated diamond-anvil cell. This material shows a low zero-pressure bulk modulus of K0 = 235(13) GPa, which is much lower than those of other platinum group nitrides. This finding is due to the weaker bonding interaction between metal atoms and quasi-molecular dinitrogen units in the marcasite-type structure, as proposed by theoretical studies.

Diverse ruthenium nitrides stabilized under pressure: a theoretical prediction

“…This value is lower than the measured value 330 GPa17 and the calculated value 343 GPa18, caused by the difference between LDA and GGA methods938. The bulk modulus of Pnnm -RuN 2 is higher than that of RhN 2 (235 GPa)16, although lower than that of PtN 2 (372 GPa)910, IrN 2 (428 GPa)12, and OsN 2 (358 GPa)1218. Besides the highest bulk modulus, Pnnm -RuN 2 also has the highest shear modulus (180 GPa), close to that of PtN 2 (187 GPa)34, while I -4 m 2-RuN has the lowest G value (66 GPa).…”

“…Later on, iridium, osmium and palladium were also found to form pernitrides under pressure12131415. Recently, marcasite-type rhodium and ruthenium pernitrides have been successfully synthesized as well1617. Among these nitrides, IrN 2 was found to have bulk modulus of 428 GPa1218, higher than most of previously synthesized materials.…”

Electronic bonding analyses and mechanical strengths of incompressible tetragonal transition metal dinitrides TMN2 (TM = Ti, Zr, and Hf)

“…Polyhedral view of this tetragonal structure (Fig. 1(b)) reveals that TiN 2 consists of the TiN 8 face-sharing tetragonal antiprisms connected by N-N bonds and stacked along the c -axis, in contrast to the TMN 6 octahedrons in the previous synthesized noble metals pernitrides789101112. Through the full relaxations of both lattice constants and internal atomic coordination, the obtained equilibrium structure parameters for three TMN 2 compounds are listed in Table 1, among which the calculated results for TiN 2 compare well with the available experimental data15.…”

“…and was finally determined to crystallize in the pyrite structure with a stoichiometry of 1:278. Thereafter, there have been considerable researches to search for other transition metal dinitrides, and so far as we know, the OsN 2 89, IrN 2 7910, PdN 2 10, RhN 2 11, and recently RuN 2 12 have been experimentally obtained in a direct chemical reaction between platinum group elements and molecular fluid nitrogen at high pressures and temperatures. The follow-up studies of their structures and mechanical properties have stimulated significant in their potential applications.…”

Synthesis of Arsenopyrite‐Type Rhodium Pernitride RhN2 from a Single‐Source Azide Precursor

“…The first indexing resulted in the orthorhombic lattice parameters ( a = 3.8540, b = 4.7106, c = 2.7068 Å) characteristic for marcasite type structure of rhodium pernitride RhN 2. , However, the detailed analysis of the diffraction pattern revealed several extra features that had to be explained. In particular, we observed that some of the reflections are split (Figure b–d).…”