Effect of water on the glass transition of a potassium-magnesium carbonate melt

Weidendorfer, Daniel, Hess, Kai-Uwe, Ruhekenya, Ruben M., Schawe, Jürgen E. K., Wilding, Martin C. and Dingwell, Donald B. 2023. Effect of water on the glass transition of a potassium-magnesium carbonate melt. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 381 (2258) , 20220355. 10.1098/rsta.2022.0355

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Abstract

Calorimetric measurements of the glass transition temperatures (Tg) of hydrous carbonate melts are reported on a near-eutectic composition of 55 mol% K2CO3 – 45 mol% MgCO3 with up to 42 mol% bulk H2O dissolved in the carbonate melt. Hydrous melts were quenched from 750°C to transparent and crystal-free glasses and were subsequently analysed for water content before and after measuring Tg by high-sensitivity differential scanning calorimetry. The glass transition and limited fictive temperatures as a function of the water content were determined at 10 K/min cooling/heating rates resulting in Tg ranging from 245°C at nominally anhydrous conditions to 83°C in the presence of 42 mol% H2O in the glass. Through a generalized Gordon–Taylor analysis, the factors k (7.27), k0 (3.2) and the interaction parameter Ax (0.49) were derived. The limited fictive temperature of a hypothetically, zero water containing 55 mol% K2CO3 – 45 mol% MgCO3 glass is 232 ± 5°C (505 K). The high value of the interaction parameter A indicates strong specific molecular interactions between water and the carbonates in the glassy state and a large decrease in the excess enthalpy of mixing during the conversion of the glassy into the liquid state at the glass transition. This article is part of the theme issue 'Exploring the length scales, timescales and chemistry of challenging materials (Part 1)'.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Chemistry
Publisher:	The Royal Society
ISSN:	1364-503X
Date of Acceptance:	5 June 2023
Last Modified:	11 Feb 2025 15:00
URI:	https://orca.cardiff.ac.uk/id/eprint/175859

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