In the context of our efforts to develop hydrogen gas sensors, two samples of ternary CuWO4 with the same crystalline structure have been prepared by two different non-equilibrium techniques. We show that the materials' structure is significantly different from the known stable one, and we identify that it is very similar to that of previously reported {\gamma}-CuMoO4. We use ab initio calculations to confirm that the newly identified phase, {\gamma}-CuWO4, represents a local energy minimum. We present very similar calculated and measured lattice constants and X-ray diffractograms. We make a case that the low-temperature formation of the metastable {\gamma}-CuWO4 phase is facilitated by easier kinetics and/or by Cu-rich composition of our samples, and we show that it converts to the stable phase after annealing to 600 {\deg}C.
@article{arxiv.2501.03036,
title = {New polymorph {\gamma}-CuWO4 inspired by {\gamma}-CuMoO4: experimental identification and theoretical verification},
author = {Jiri Houska and Stanislav Haviar and Jiri Capek and Radomir Cerstvy and Kalyani Shaji and Nirmal Kumar and Petr Zeman},
journal= {arXiv preprint arXiv:2501.03036},
year = {2025}
}