Effects of pulling speed and hot zone temperature on the directional growth of YBa₂Cu₃O_x superconductor

Abstract

The effects of pulling speed and hot zone temperature on the microstructure and the superconducting properties of YBa₂Cu₃O_x sample textured using directional growth of Y₂BaCuO₅, BaCuO₂, and CuO powder mixture were studied. The grain size, the alignment, and the critical current density of the sample were increased as the pulling speed decreased. The sample grown directionally at 1.5 mm h⁻¹ pulling speed consisted of a single grain. The zero resistivity temperature and the critical current density of the sample increased as the hot zone temperature increased up to 1120°C beyond which the sample consisted of Y₂O₃ and impurities and showed resistivity at 77 K. The sample grown directionally at 1.5 mm h⁻¹ pulling speed and at 1120 °C hot zone temperature showed sharp resistivity transition of 91 K zero resistivity and over 6000 Acm⁻². The sample showed well aligned microstructure. Compared to data from another study, the hot zone temperature required to produce maximum critical current density is lower due to low liquid forming temperature.