Medium-entropy (Me,Ti)0.1(Zr,Hf,Ce)0.9O2 (Me = Y and Ta): Promising thermal barrier materials for high-temperature thermal radiation shielding and CMAS blocking

•Two medium-entropy (ME) oxide ceramics, ME (Y,Ti)0.1(Zr,Hf,Ce)0.9O2 and ME (Ta,Ti)0.1(Zr,Hf,Ce)0.9O2, were designed and prepared successfully.•Good high-temperature thermal radiation shielding performance and CMAS resistance of the two ME oxides were demonstrated for the first time.•The relationship between high-temperature thermal radiation shielding performance, i.e., infrared absorbance at the waveband of 1 to 5 μm and band gap in ME (Me,Ti)0.1(Zr,Hf,Ce)0.9O2 (Me= Y and Ta) was investigated systematically.•The mechanism for the CMAS corrosion resistance was proposed for ME (Me,Ti)0.1(Zr,Hf,Ce)0.9O2 (Me= Y and Ta).