In-situ Raman spectroscopy study of thermal mismatch stress and negative thermal expansion behaviours of ZrW2O8 in ZrW2O8/Al composite

- Effective heat treatment temperature can be got from temperature dependent Raman spectra.
- The Raman bands of ZrW2O8 will suffer frequency shift under thermal stress and different bands show diverse trends.
- The Raman frequency shift can be estimated and in good agreement with experimental results.
- We establish a novel method to measure NTE materials' CTE by measuring Raman frequency shift and Grüneisen parameter.

Negative thermal expansion materials with open frame structure were easy to undergo phase transformation under high thermal mismatch stress. In this work, a large amount of γ-phase was found in ZrW2O8/Al composite, presenting great fluctuations. Based on the temperature-dependent Raman spectroscopy and theoretical calculation, the accurate heat-treatment temperature was used to eliminate γ-phase and low thermal expansion composite without abnormal expansion was obtained. The Raman frequency shift caused by the thermal stress was quantitatively analyzed. The negative thermal expansion material's thermal expansion was estimated with Raman peak shift.

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