Heavily doped high-entropy A2B2O7 pyrochlore

A novel class of high-entropy pyrochlore compounds with multiple elements at the A and B site positions (A(2)B(2)O(7)) was successfully obtained. Powders with (La1/7Sm1/7Nd1/7Pr1/7Y1/7Gd1/7Yb1/7)(2)(Sn1/3Hf1/3Zr1/3)(2)O-7 nominal composition were fabricated from pure metal oxides obtained through a reaction of metal nitrates (for site A) and metal chlorides (for site B) with sodium hydroxide during the solid-state displacement reaction (SSDR). The phase evolution was analyzed using XRD method. During the thermal treatment of ten individual metal oxides, the single pyrochlore phase was created. The present study showed that the high density (98 %TD) ceramics with a hardness of 8.1 GPa was successfully obtained after pressureless sintering at 1650 degrees C for 4 h. Results of the Raman study and the Rietveld structural refinement showed that sintered high-entropy ceramics is characterized by a single-phase pyrochlore structure, which was investigated in detail.