Equations of state of rhodium, iridium and their alloys up to 70 GPa

Abstract

Thermal decomposition of (NH4)2[OsxPt1-xCl6] as single-source precursors for Os-Pt binary alloys has been investigated under ambient and high pressure up to 40 GPa. Thermal decomposition of mixed-metal (NH4)2[OsxPt1-xCl6] precursor in hydrogen atmosphere (reductive environment) under ambient pressure results in formation of β-trans-[Pt(NH3)2Cl2] and α-trans-[Pt(NH3)2Cl2] crystalline intermediates as well as single and twophase Os-Pt binary alloys. For the first time, direct thermal decomposition of coordination compound under pressure has been investigated. A formation of pure metallic alloys from single-source precursors under pressure has been shown. Miscibility between fccand hcpstructured alloys has been probed up to 50 GPa by in situ high-pressure X-ray diffraction. Miscibility gap between fccand hcp-structured alloys does not change its positions with pressure up to at least 50 GPa.

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

“…[2,10,13,34] We were able to find the orientation matrices of several grains of the new phase. The [27] 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. [6,35] However, the detailed analysis of the diffraction pattern revealed several extra features that had to be explained.…”

Face-Centered Cubic Refractory Alloys Prepared from Single-Source Precursors

“…Recently, single-source precursors strategy has been applied to access high-entropy alloys based on platinum group metals. The strategy requires a synthesis of coordination compounds from water solutions and their further thermal decomposition in a hydrogen flow based on the following principle general scheme [1]: in water solution: a[Ir(NH 3 ) 5 Cl]Cl 2 + b[Rh(NH 3 ) 5 Cl]Cl 2 + (1-a-b)[Ru(NH 3 ) 5 2 O respectively. Details about the synthesis of solid-state precursors and alloys can be found in our earlier publications [8,10].…”

“…Their low compressibility might be compared only with diamond [2][3][4]. Previously, several binary and multicomponent refractory systems of fccand hcp-structured alloys were investigated under extreme conditions [5][6][7][8]. It has been shown that all known platinum group alloys do not show any temperature and/or pressure induced phase transitions.…”

“…Ultra-incompressible alloys with Re, Os (hcp) and Ir (fcc) were investigated in detail up to 140 GPa; nevertheless, compressibility of fcc-structured alloys of metals with high compressibility such as Rh and Pd were not investigated so far. Among fcc-structured alloys, only fcc-Ir 0.42 Rh 0.58 has been investigated up to 57 GPa at room temperature [5].In the current study, we report synthesis of fcc-Ir 0.50 Pt 0.50 , fcc-Rh 0.66 Pt 0.33 and fcc-Rh 0.50 Pd 0.50 binary alloys from [Ir(NH 3 ) 5 Cl][PtCl 6 ], [Ir(NH 3 ) 5 Cl][PtBr 6 ], [Rh(NH 3 ) 5 Cl] 2 [PtCl 6 ]Cl 2 and [Rh(NH 3 ) 5 Cl][PdCl 4 ]·H 2 O, respectively, as single-source precursors under low temperature.Investigation of fcc-Ir 0.50 Pt 0.50 , fcc-Rh 0.66 Pt 0.33 and fcc-Rh 0.50 Pd 0.50 binary alloys under hydrostatic compression up to 50 GPa in diamond anvil cells allow us to obtain bulk moduli for fcc-structured binary alloys. Equations of state, thermal expansion and pressure compressibility for known refractory high-entropy alloys can be validated with experimental data obtained for fcc-structured refractory binaries.…”

“…Ultra-incompressible alloys with Re, Os (hcp) and Ir (fcc) were investigated in detail up to 140 GPa; nevertheless, compressibility of fcc-structured alloys of metals with high compressibility such as Rh and Pd were not investigated so far. Among fcc-structured alloys, only fcc-Ir 0.42 Rh 0.58 has been investigated up to 57 GPa at room temperature [5].…”