Solubility and dissolution kinetics of GaN in supercritical ammonia in presence of ammonoacidic and ammonobasic mineralizers

Solubility and dissolution kinetics of GaN in supercritical ammonia in presence of ammonoacidic and ammonobasic mineralizers

•Solubility and dissolution kinetics of GaN under ammonoacidic and -basic conditions.•Results suggest a significant refinement of raw gravimetric literature data.•Change from normal to retrograde solubility at high temperatures is discussed.•Potentially relevant, reactor-material related sources of...

Full description

Saved in:
Bibliographic Details
Published in:Journal of crystal growth Vol. 479; pp. 59 - 66
Main Authors: Schimmel, Saskia, Koch, Martina, Macher, Philipp, Kimmel, Anna-Carina L., Steigerwald, Thomas G., Alt, Nicolas S.A., Schlücker, Eberhard, Wellmann, Peter
Format: Journal Article
Language:English
Published: Amsterdam Elsevier B.V 01-12-2017
Elsevier BV
Subjects:
A1. Solubility
A1. Solvents
A2. Ammonothermal crystal growth
A2. Growth from solutions
A2. Solvothermal crystal growth
Alkali metals
Ammonia
B1. Gallium compounds
Dissolution
Gallium arsenide
Gravimetry
Reaction kinetics
Solubility
Studies
Thermogravimetric analysis
A1. Solvents
A2. Growth from solutions
B1. Gallium compounds
A2. Ammonothermal crystal growth
A1. Solubility
A2. Solvothermal crystal growth
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:•Solubility and dissolution kinetics of GaN under ammonoacidic and -basic conditions.•Results suggest a significant refinement of raw gravimetric literature data.•Change from normal to retrograde solubility at high temperatures is discussed.•Potentially relevant, reactor-material related sources of errors are addressed. Solubility and dissolution kinetics of GaN are investigated, as they represent essential parameters for ammonothermal crystal growth of GaN. In situ X-ray imaging is applied to monitor the dissolving crystal. Both ammonoacidic and ammonobasic conditions are investigated. Compared to NH4F, the dissolution is generally much slower using NaN3 mineralizer, leading to a much longer time needed to establish a saturated solution. The solubility of GaN at 540°C and 260MPa in supercritical ammonia with a molar concentration of NaN3 of 0.72mmol/ml is determined to be 0.15±0.01mol%. This suggest a severe refinement of raw gravimetric literature data also for alkali metal based mineralizers, as we reported previously for ammonium halide mineralizers. The order of magnitude is in good agreement with refined gravimetric solubility data (Griffiths et al., 2016). The apparent discrepancy between the literature and this work regarding the temperature range in which retrograde solubility occurs is discussed. A possible reason for the occurrence of retrograde solubility at high temperatures is described. The paper is complemented by a section pointing out and partially quantifying potential, reactor-material-dependent sources of errors.
ISSN:0022-0248
1873-5002
DOI:10.1016/j.jcrysgro.2017.09.027