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Title: Theoretical study of hydration in Y{sub 2}Mo{sub 3}O{sub 12}: Effects on structure and negative thermal expansion

We report ab-initio calculations of water absorption in Y{sub 2}Mo{sub 3}O{sub 12}. The absorption geometry of H{sub 2}O in Y{sub 2}Mo{sub 3}O{sub 12} and the binding property between H{sub 2}O and Y{sub 2}Mo{sub 3}O{sub 12} have been first identified. Our calculated results show that water is chemisorbed in Y{sub 2}Mo{sub 3}O{sub 12} with O of the water binding to the Y{sup 3+} cation, which is further strengthened by hydrogen bonding between each of the hydrogen atoms of H{sub 2}O and the bridge O in Y{sub 2}Mo{sub 3}O{sub 12}, shared by polyhedrons YO{sub 6} and MoO{sub 4}. The absorption of water leads to a reduced angle of Y-O-Mo and shortened Y-Mo distance, and consequently volume contraction of the material, almost linearly with the increasing number of water molecules per unit cell, up to eight in total. In addition, our phonon calculation show that the transverse vibration of Y-O-Mo is restricted due to water absorption, which in turn hinders the NTE, as it is mainly originated from this vibrational mode. Our results clarify further the fundamental mechanisms of the large volume shrinkage and the lost NTE of the framework oxide due to water absorption.
Authors:
; ; ;  [1] ;  [2]
  1. International Laboratory for Quantum Functional Materials of Henan, and School of Physics and Engineering, Zhengzhou University, Zhengzhou, 450001 (China)
  2. Department of Chemistry, University College London, London WC1H 0AJ (United Kingdom)
Publication Date:
OSTI Identifier:
22454456
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Advances; Journal Volume: 5; Journal Issue: 2; Other Information: (c) 2015 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ABSORPTION; BONDING; CATIONS; CHEMISORPTION; HYDRATION; HYDROGEN; MOLECULES; MOLYBDATES; OXIDES; SHRINKAGE; THERMAL EXPANSION; WATER; YTTRIUM IONS