Modified top-seeded melt growth for large sized Y1−xCaxBa2Cu3Oy crystals

Abstract

By employing modified top-seeded melt growth, a sizable Y_1−xCa_xBa₂Cu₃O_y (Ca–YBCO) crystal (16 mm in diameter) with a high doping level was grown for the first time. The crystal is a substance of remarkable importance in the study of superconductivity, distinctively by neutron scattering experiments. Firstly, our findings show that the addition of CaCO₃ to the precursors significantly changes the liquid properties, leading to serious liquid loss. In consequence, as-grown samples are unexpectedly characterized by an incomplete growth and a high density of the Y211 phase. Furthermore, a series of experiments have been conducted to improve growth conditions. Our results prove that by using a novel sample construction, setting thin pellets underneath and on top of the main pellet as a liquid reservoir, the aforementioned problems can be effectively solved. As a result, a fully-grown Ca–YBCO crystal with less Y211 particles was achieved.