Materials Science

The Thermodynamic Way of Assessing Reversible Metal Hydride Volume Expansion: Getting a Grip on Metal Hydride Formation Overpotential

Roland Hermann Pawelke FOTEC Forschungs- und Technologietransfer GmbH


The relative volume expansion of reversible metal hydride crystals upon formation is determined by means of the van’t Hoff reaction entropy and STP ideal gas parameters, the development of this approach leads to a general method for calculating metal hydride single-crystal density. These results allow highlighting the pressure requirement to hydride phase formation, shown by the example of Ti-NaAlH4.

Version notes

V4: Some minor rephrasing of passages; in equation 13 there was a wrong hydrogen mol number in the sum formula (1+1.5 instead of 1+0.5), however a mistake of no consequence; a nice notion about the relation of the chemical potential solution to the one based on molar volume has been inserted, the space has been created by phrasing the critique of an unthinking positivist vantage point shorter; length is still 3000 words.


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