Production and characterisation of multicomponent rare-earth oxide ceramics with high entropy

High entropy systems have opened a broad gate to the materials world with their unique and unusual properties. Their uniqueness originates from four core effects: high entropy, sluggish diffusion, severe lattice distortion, and cocktail effect. The developing trend of this new area has led to a unique point of view, such as high entropy rare earth oxides, the main idea of this study. It has become an attraction point of high entropy systems due to the extraordinary outcomes of rare earth oxide combinations with equal or near equal amounts. Seven compositions were synthesized via ball milling with isopropyl alcohol media. Then synthesized powders were first sintered via Spark Plasma Sintering. After structural characterization, the study process fronted to the Arc Melting due to its absence of research in the literature. Single-phase structure expectations were reached via arc melting and annealing for the HEC5 and HEC7 samples according to the XRD and EDX results. In addition to the structural characterizations, mechanical tests were applied to the SPSed and arc-melted-annealed samples. Arc-melted and annealed samples showed glassy properties. So, hardness tests were ineffective in measuring their hardness due to the unclear indentation marks. On the other hand, SPSed samples were tested to measure hardness and density. While the SPSed samples with Y2O3 had high hardness values (HEC7 ~ 811 MPa), the ones with La2O3 had high-density values (HEC3 ~ 95.34%).