Preprint Article Version 2 This version is not peer-reviewed

Comparative Study of the Reactivity of the Tungsten Oxides WO2 and WO3 with Beryllium at Temperatures up to 1273 K

Version 1 : Received: 30 June 2019 / Approved: 2 July 2019 / Online: 2 July 2019 (03:55:52 CEST)
Version 2 : Received: 10 September 2019 / Approved: 10 September 2019 / Online: 10 September 2019 (08:09:51 CEST)

A peer-reviewed article of this Preprint also exists.

Köppen, M. Comparative Study of the Reactivity of the Tungsten Oxides WO2 and WO3 with Beryllium at Temperatures up to 1273 K. Condens. Matter 2019, 4, 82. Köppen, M. Comparative Study of the Reactivity of the Tungsten Oxides WO2 and WO3 with Beryllium at Temperatures up to 1273 K. Condens. Matter 2019, 4, 82.

Journal reference: Condens. Matter 2019, 4, 82
DOI: 10.3390/condmat4030082

Abstract

Tungsten oxides play a pivotal role in a variety of modern technologies e.g., switchable glasses, wastewater treatment, and modern gas sensors. Metallic tungsten is used as armor material, for e.g., gas turbines as well as future fusion power devices. In the first case, oxides are desired as functional materials, while in the second case, oxides can lead to catastrophic failures, so avoiding the oxidation of tungsten is desired. In both cases, it is crucial to understand the reactivity of tungsten oxides with other chemicals. In this study, the different reactivities of tungsten oxides with the highly-oxophilic beryllium are studied and compared. Tungsten-(IV)-oxide and tungsten-(VI)-oxide layers are prepared on a tungsten substrate. In the next step, a thin film of beryllium is evaporated on the samples. In consecutive steps, the sample is heated in steps of 100 K from r. t. to 1273 K. The chemical composition is investigated after each experimental step by high-resolution X-ray photoelectron spectroscopy (XPS) of all involved core levels as well as the valence band. A model is developed to analyze the chemical reactions after each step. In this study, we find that tungsten trioxide was already reduced by beryllium at r. t. and started to react to form the ternary compounds BeWO3 and BeWO4 at temperatures starting from 673 K. However, tungsten dioxide is resistant to reduction at temperatures of up to 1173 K. In conclusion, we find WO2 to be much more chemically resistant to the reduction agent Be than WO3.

Subject Areas

X-ray photoelectron spectroscopy; physical vapor deposition; X-ray diffraction; tungsten oxide; tungsten dioxide; tungsten trioxide; beryllium; tungstate; tungsten bronze

Comments (1)

Comment 1
Received: 10 September 2019
Commenter: Martin Köppen
Commenter's Conflict of Interests: Author
Comment: Dear editors and readers, I'm pleased to present the latest version of my article. This version is peer-reviewed.
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