Negative thermal expansion of (Al1/3Fe1/3Cr1/3)2(Mo1/2W1/2)3O12 (AFCMW) and low thermal expansion of AFCMW-(Co1/2Ni1/2)(Mo1/2W1/2)O4 with high entropy |
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| Affiliation: | 1. Henan Key Laboratory of Photovoltaic Materials and Research Center of Topological Functional Materials, Henan University, Kaifeng, 475004, China;2. Key Laboratory for Special Functional Materials of Ministry of Education, And School of Materials and Engineering, Henan University, Kaifeng, 475004, China;3. Key Laboratory of Materials Physics of Ministry of Education, And School of Physics and Microelectronics, Zhengzhou University, Zhengzhou, 450052, China |
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| Abstract: | A2Mo3O12 (A-Al, Fe, Cr) have large negative thermal expansion (NTE) coefficients and structural stability but high phase-transition temperatures (PTTs). Herein, we prepared (Al1/3Fe1/3Cr1/3)2(Mo1/2W1/2)3O12 (AFCMW), and found it to have a low NTE coefficient and a low PTT. Furthermore, combination of AFCMW with (Co1/2Ni1/2)(Mo1/2W1/2)O4 (CNMW) afforded an AFCMW–CNMW composite with a low thermal expansion (LTE). We determined that the PTT reductions in A2Mo3O12 are largely due to the high-entropy effect resulting from the introduction of different ions into its A and M sites. Moreover, we found that the low LTE of the AFCMW–CNMW composite is attributable to the opposite thermal expansion behaviours of AFCMW and CNMW. We suggest that the suppressed thermal expansion during the phase transition process of the AFCMW–CNMW composite could be derived from the high-entropy effect resulting from its increased diversity of polyhedra, the influence of Co2+ and Ni2+ dopants, and CNMW-induced lattice distortion. |
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| Keywords: | Negative thermal expansion Phase transition High entropy Low thermal expansion |
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