Feasibility of density and viscosity measurements under ammonothermal conditions

Ammonothermal Synthesis of Nitrides: Recent Developments and Future Perspectives

“…Typically employed materials in different research groups include Inconel 625, Inconel 718,R enØ 41, as well as Haynes 282 alloy. [16,[155][156][157] Exemplarily,a utoclaves with uppert emperature limits of 900 Ka t3 00 MPa or 1100 Ka t 150-170MPa were constructed, dependento nt he respective materials pecifications and the autoclave design ( Figure 11).…”

“…Material properties of such alloys can be tailored by modulation of chemical compositions, as well as by thermal treatment of the raw material using post‐fabrication processes like precipitation hardening. Typically employed materials in different research groups include Inconel 625, Inconel 718, René 41, as well as Haynes 282 alloy . Exemplarily, autoclaves with upper temperature limits of 900 K at 300 MPa or 1100 K at 150–170 MPa were constructed, dependent on the respective material specifications and the autoclave design (Figure ).…”

Decomposition of supercritical ammonia and modeling of supercritical ammonia–nitrogen–hydrogen solutions with applicability toward ammonothermal conditions

“…While some information regarding chemical and physical properties of ammonothermal systems can be extracted from growth runs 14,15,16 , in-situ investigations of the fluid properties 17,18 and modeling of the heat and fluid flow within the system 19,20,21 , currently the understanding is incomplete for the dependence of the equilibrium constant for ammonia decomposition on temperature and pressure at typical ammonothermal growth conditions. Furthermore, an experimentally verified equation of state (EOS) is not available for ammonia at temperatures greater than 700 K. The high temperature EOS is necessary to derive many thermodynamic…”

Determination of GaN solubility in supercritical ammonia with NH4F and NH4Cl mineralizer by in situ x-ray imaging of crystal dissolution

“…A promising method for obtaining high-quality GaN bulk single crystals is solution growth using supercritical ammonia as a solvent, i.e., the ammonothermal method. Despite impressive progress in the ammonothermal growth of bulk GaN crystals was achieved during the last years [4][5][6], further development is still hindered by the lack of fundamental data such as the solubility of GaN, the chemical nature and stability of solved and transported species and the viscosity of the fluid [7][8][9]. These parameters are difficult to investigate due to the challenging process conditions, namely high pressure, high temperature and highly corrosive reaction medium.…”