Tuning the hydrogen desorption of Mg(BH4)2 through Zn alloying

D. Harrison and T. Thonhauser
Phys. Rev. B 90, 125152 – Published 29 September 2014

Abstract

We study the effect of Zn alloying on the hydrogen desorption properties of Mg(BH4)2 using ab initio simulations. In particular, we investigate formation/reaction enthalpies/entropies for a number of compounds and reactions at a wide range of temperatures and Zn concentrations in Mg1xZnx(BH4)2. Our results show that the thermodynamic stability of the resulting material can be significantly lowered through Zn alloying. We find, e.g., that the solid solution Mg2/3Zn1/3(BH4)2 has a reaction enthalpy for the complete hydrogen desorption of only 25.3 kJ/mol H2—a lowering of 15 kJ/mol H2 compared to the pure phase and a corresponding lowering in critical temperature of 123 K. In addition, we find that the enthalpy of mixing is rather small and show that the decrease in reaction enthalpy with Zn concentration is approximately linear.

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  • Received 21 March 2014
  • Revised 10 July 2014

DOI:https://doi.org/10.1103/PhysRevB.90.125152

©2014 American Physical Society

Authors & Affiliations

D. Harrison and T. Thonhauser*

  • Department of Physics, Wake Forest University, Winston-Salem, North Carolina 27109, USA

  • *thonhauser@wfu.edu

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Issue

Vol. 90, Iss. 12 — 15 September 2014

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