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High-entropy single-phase rare earth titanates (RE 0.2 Gd 0.2 Ho 0.2 Er 0.2 Yb 0.2 ) 2 Ti 2 O 7 (RE = Sm, Y, Lu) were designed and synthesized successfully, in which their lattice distortion was quantitatively described by mass disorder and size disorder. It is worth mentioning that (Y 0.2 Gd 0.2 Ho 0.2 Er 0.2 Yb 0.2 ) 2 Ti 2 O 7 could obtain the low thermal conductivity (1.51 W⋅m −1 ⋅K −1 , 1500 • C), high thermal expansion coefficient (average, 11.69×10 −6 K −1 , RT ∼1500 • C) and excellent high-temperature stability. In addition, the relationship between the microstructure and thermal transport behaviors has been studied at the atomic scale. Due to the disorder of A-site ions, severe lattice distortion occurred in specific crystal planes, and the large mass difference between Y 3+ and other RE 3+ further causes mass fluctuation and results in lower thermal conductivity. Compared with YSZ, the high-entropy rare earth titanate (Y 0.2 Gd 0.2 Ho 0.2 Er 0.2 Yb 0.2 ) 2 Ti 2 O 7 has lower thermal conductivity, higher thermal expansion coefficient, and excellent high-temperature stability, which has great potential for application in the thermal protection field.

CsPbX3 (X=Cl, Br, I) semiconductor nanocrystals (NCs) have excellent optical and photoelectric properties, and are potential core materials for various photoelectric devices. However, the toxicity of Pb and instability have been the key limitations to application of NCs. Herein, using MnBr2 and MnBr2·4H2O as manganese sources, heavy Mn-doped CsPbBr3 (Mn:CsPbBr3) NCs are synthesized by high-energy ball grinding, which avoids high temperature, a large number of polar solvents and atmosphere protection required in traditional liquid phase methods. However, when MnBr2·4H2O is used as the raw material, infinite solid solution doping can be achieved, and the synthesized Mn:CsPbBr3 NCs show stronger PL intensity and stability. The reason is that presence of crystal water plays a similar role to wet milling in the ball milling process, and can promote the passivation effect of oleylamine (OAm) on nanocrystal defects and the connection between them. In addition, a simple, low-cost, easy to operate and beneficial to commercial production method for the preparation of Mn:CsPbBr3 NCs/EVA flexible films is proposed, which can effectively improve the stability of Mn:CsPbBr3 NCs. This study is expected to provide an effective way for the synthesis and stability improvement of CsPbX3 NCs doped with different ions.

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