Mechanical Properties of $\hbox {REBa}_{2}\hbox {Cu}_{3} \hbox {O}_{7 - \delta }$ Superconductor With RE Obtained From Xenotime Mineral

The mechanical properties of REBa₂Cu₃O_7-δ super conductor samples produced by different processing routes are compared, where RE corresponds to a natural mixture of rare-earth (RE) elements extracted from xenotime mineral. Xeno time can be used as a precursor for RE oxides that are used to produce electrotechnical devices that do not demand high-purity yttrium or other pure lanthanide element on Y site. The different processing routes lead to the production of polycrystalline, melt textured, and single-crystal samples. Hardness, elastic modulus, and indentation fracture toughness were measured by instrumented indentation and conventional Vickers microindentation. The highest hardness and elastic modulus are of the melt-textured samples because of their microstructure of 211 inclusions and pores embedded in the 123 matrix. The lowest hardness is observed for the polycrystalline sample due to its high porosity. The lowest elastic modulus is of the single crystal. Indentation fracture toughness for melt-textured and single-crystal samples are in the range of literature values (~1 MPa.m^1/2). Our results indicate that melt-textured REBa₂Cu₃O_7-δ samples have the most favor able mechanical properties for technological applications.