Hydrothermal Synthesis and Study of the Properties of the System ZrW_2-xMo_xO₇(OH)₂·2H₂O (0≤x≤2)

Abstract:

The ZrW_2-xMo_xO₈ (0≤x≤2) system has a unique property - a negative coefficient of thermal expansion (CTE), that is it shrinks when heated. Such materials solve the problem of undesirable thermal expansion of composites in many areas. In contradistinction to ZrW₂O₈ and ZrMo₂O₈, this system has anomalously low CTE values [1,2] and adverse phase transition is shifted to a lower temperature, unlikely area for operation [3,4]. At the same time, the fundamental question remains about the mechanism of formation of ZrW_2-xMo_xO₈(0≤x≤2). According to [5,6], pure cubic ZrW₂O₈ and ZrMo₂O₈ are obtained by thermal decomposition of the precursor ZrM₂O₇(OH)₂· 2H₂O, where (M = Mo, W). However, the structure of the precursor is extremely sensitive to various changes in the synthesis process. To date, there are a number of works devoted to the hydrothermal synthesis of precursors ZrW_2-xMo_xO₇(OH)₂·2H₂O (0≤x≤2) solid solutions, however, not all formulations were obtained during the hydrothermal reaction. The study of their thermal properties, as well as structural and phase transformations are not fully studied. Within the paper it was first time proposed to obtain full number of nanosized materials by the hydrothermal method and also to study the nature of the thermal expansion of each member of the solid solution. The obtained data will solve many technical problems associated with dimensional nonvariance in the electronic, oil and gas, optical industry, medicine and rocket engineering.

• Periodical: Key Engineering Materials (Volume 806)
• Pages: 118-123
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.806.118
• Online since: June 2019
• Authors: Mariya Yu. Petrushina, Elena Dedova, Alexander Gubanov, Natalya Ruban, Anastasya Kirilovich, Polina Topchian, Arseniy Portnyagin*
• Keywords: Hydrothermal Method, Negative Thermal Expansion, Phase Transition, Solid Solution

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