Microstructure, Phase Formation, and Stress of Reactively-Deposited Metal Hydride Thin Films

Abstract

Abstract

Pressure induced phase transformation of REH3

“…As for the investigations on the fcc trihydride formation by synthesis from the mixture of corresponding rare earth metal and magnesium [9] or by the sputtering technique [8], the striking feature is that these phases remain stable at normal pressure while our results clearly show the complete reversibility of the transition. How it is possible that the surroundings of magnesium hydride can locally sustain pressure of the order of GPa's to keep the grain of the fcc phase stable remains difficult to understand.…”

“…We have observed the first reversible hexagonal to cubic phase transformation induced by pressure on the bulk erbium trihydride by X-ray "in situ" diffraction study [7]. Our project has been stimulated by Sandia's report in which signs of cubic phase has been detected during the sputtering of erbium in a hydrogen atmosphere [8] on cold deposit. As the sputtering technique inevitably involves creation of high stresses we decided to check the structural properties and existence of the fcc phase of erbium trihydrides under well controlled pressure conditions in a diamond anvil cell.…”

Fabrication processing effects on the microstructure and morphology of erbium film

“…A tensile stress develops due to the mismatched CTE of the substrate-film couple. [32] Yuan et al [28] demonstrated that the lattice constant decreases and is close the bulk one, which indicates that the compressive strains in the In 2 O 3 films are gradually relaxed as the the annealing temperature increases. Zhou et al [23] found that with the increasing annealing temperature, the compressive stress decreases due to the elimination of defects and the grain growth that causes the lateral shrinkage of film and produces a relative tensile stress.…”

“…The evolution of stress in ScD 2 /Cr thin films fabricated by evaporation and high temperature reaction has been reviewed in detail. [32] The reaction of scandium metal with deuterium at the elevated temperature to form a stoichiometric dideuteride phase leads to a large compressive in-plane film stress, resulted from an increased atomic density compared with the as-deposited metal film. A tensile stress develops due to the mismatched CTE of the substrate-film couple.…”

A new thin film photochromic material: Oxygen-containing yttrium hydride

“…The finding of the photochromic effect in oxygen-containing yttrium hydride could provide an opening to a new class of inorganic photochromic compounds. Erbium hydride has also been reported to form an fcc as opposed to hcp lattice when prepared by reactive sputtering [22], and it is probable that this kind of material also exhibits photochromism. Further investigation should be carried out to explore photochromism in other oxygen-containing rare earth hydrides and to enhance the reaction rate and strength of the photochromism in oxygen-containing yttrium hydride.…”