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High entropy oxides (HEOs) have recently gained a great deal of attention for their enhanced thermal properties. However, one of the biggest limitations for these systems has been low electrical conductivity; limiting their potential as thermoelectrics[1-4]. Recently, a new HEO, (Mn,Fe,Co,Ni,Cu,Zn)WO₄ (AWO₄), was reported where the high configurational entropy drove the material from an insulating to a semiconducting state[5]. Improved thermal properties combined with its semiconducting behavior makes AWO₄ ideal for studying the behavior of thermal conductivity in a first of its kind, phonon-glass electron-crystal HEO system. Further, if these properties persist over a wide temperature range, then the material has potential for use in industrial applications. In this talk, we report ultra-low thermal conductivity in semiconducting AWO₄ over a wide temperature range. We observe a substantial suppression of thermal conductivity as compared to the parent phases due to increased defect scattering and compare these results with theoretical predictions. We also report magnetothermal conductivity of AWO₄ showing at high temperatures a suppression of the electronic contribution to thermal conductivity under applied B field and at low temperature an enhancement of the phonon contribution due to reduced phonon-magnon scattering.

1. Oses, Corey, Cormac Toher, and Stefano Curtarolo. Nature Reviews Materials 5.4 (2020): 295-309.

2. Musicó, Brianna L., et al. APL Materials 8.4 (2020).

3. Zheng, Yunpeng, et al. Journal of Advanced Ceramics 10 (2021): 377-384.

4. Toher, Cormac, et al. MRS Bulletin 47.2 (2022): 194-202.

5. Katzbaer, Rowan R., et al. Inorganic Chemistry (2023).