Ultrafast high-temperature sintering of high-entropy (La0.2Nd0.2Sm0.2Eu0.2Gd0.2)2Hf2O7 ceramics with fluorite structure

High-entropy (La0.2Nd0.2Sm0.2Eu0.2Gd0.2)2Hf(2)O(7) (5LaH) hafnate was designed and successfully prepared by the emerging ultrafast high-temperature sintering (UHS) in less than six minutes. The prepared 5LaH has an ultra-high hardness (1089 HV0.3) and an extremely low thermal conductivity of 0.93 W/(mk), which are mainly attributed to the severe lattice distortion inside the high-entropy material. Furthermore, the grain size only grows at a rate of 0.09 mu m/h at 1500 degrees C, which shows hugely sluggish grain growth characteristics. After annealing at 1300 degrees C for 30 h, the 5LaH maintains the initial fluorite structure, which exhibits excellent high-temperature phase stability owing to the higher configurational entropy that causes a decrease in the Gibbs free energy of the high-entropy material system. Therefore, 5LaH has excellent potential as the next-generation thermal barrier coating material, and the UHS has excellent prospects in developing and rapidly synthesizing new ceramic materials.

Automated summary

A high-entropy hafnate material, 5LaH, has been successfully prepared using the ultrafast high-temperature sintering (UHS) technique. It exhibits high hardness, low thermal conductivity, slow grain growth, and excellent high-temperature phase stability. Thus, 5LaH has the potential to be used as the next-generation thermal barrier coating material, and UHS has promising prospects in developing new ceramic materials.