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In situ monitoring of hydrothermal reactions by X‐ray diffraction with Bragg–Brentano geometry
Author(s) -
Mesecke Karsten,
Malorny Winfried,
Warr Laurence N.
Publication year - 2020
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s1600576720006019
Subject(s) - dissolution , autoclave , hydrothermal circulation , diffractometer , materials science , crystallization , quartz , diffraction , cementitious , x ray , in situ , hydrothermal synthesis , crystal (programming language) , powder diffraction , nanocrystalline material , crystallography , mineralogy , chemistry , crystal structure , chemical engineering , optics , composite material , physics , cement , metallurgy , organic chemistry , programming language , computer science , engineering
This note describes an autoclave chamber developed and constructed by Anton Paar and its application for in situ experiments under hydrothermal conditions. Reactions of crystalline phases can be studied by successive in situ measurements on a conventional laboratory X‐ray diffractometer with Bragg–Brentano geometry at temperatures <483 K and saturated vapour pressure <2 MPa. Variations in the intensity of X‐ray diffraction reflections of both reactants and products provide quantitative information for studying the reaction kinetics of both dissolution and crystal growth. Feasibility is demonstrated by studying a cementitious mixture used for autoclaved aerated concrete production. During a period of 5.7 h at 466 K and 1.35 MPa, the crystallization of torbermorite and the partial consumption of quartz were monitored.