A method for preparing large-scale high-temperature superconducting single crystals

Abstract

The invention discloses a method for preparing a large-scale high-temperature superconducting single crystal, comprising steps: (a) adding BaCO 3 powder and CuO powder were compounded, wet-milled and sintered to obtain Ba‑Cu‑O powder; (b) Ba‑Cu‑O powder was added to RE 2 o 3 Crucible heated to the first temperature, and continue to keep warm, to obtain RE-Ba-Cu-O solution, and then cooled to the second temperature; (c) using the REBCO / MgO film as the seed crystal, first in the RE-Ba-Cu-O solution at the second temperature The ‑Cu‑O solution pulling method was used to grow for 10 to 20 hours, and then the slow cooling rate of the solution was set to 0.2 to 2.0°C / h, and the obtained REBCO single crystal continued to grow by the pulling method for 50 to 100 hours. The invention introduces a slow cooling process at the growth temperature to continuously increase the supersaturation of the solution, which is beneficial to increasing the growth rate of single crystals and preparing large-scale REBCO high-temperature superconducting single crystals.

Description

technical field [0001] The invention relates to the preparation of high-temperature superconducting materials, in particular to a method for preparing large-scale high-temperature superconducting single crystals. Background technique [0002] Since REBa 2 Cu 3 o 7-δ (RE-Ba-Cu-O or REBCO for short, where RE=Y, Sm, Gd, Nd, etc.) High-temperature superconductors have attracted widespread attention since they were discovered. First, because the traditional BCS theory cannot fully explain the superconducting mechanism of REBCO high-temperature superconductors, physicists around the world need high-quality high-temperature superconducting single crystals to explore the reasons for high-temperature superconductivity; Magnetic properties, high critical current density, and high freezing magnetic field, REBCO superconductors have many potential applications in areas such as magnetic levitation forces, magnetic bearings, flywheel energy storage, and permanent magnets; third, due to...

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Problems solved by technology

[0005] In the prior art, for the first aspect, the following main problems arise from prolonged crystal growth: firstly, the amount of solution in the crucible will decrease due to a certain degree of wettability climbing out of the crucible, which will cause a drop in the liquid level. Second, the liquid surface will produce floats because it is in a supersaturated state for a long time and the solute cannot be consumed in time, which is likely to cause the occurrence of polycrystals; third, as the crystal size changes Large, the temperature field near the liquid surface will also change, thus affecting the liquid surface temperature of crystal growth

However, although Sm or Nd has higher solubility than Y in this method, the growth rate of SmBCO or NdBCO single crystal is faster than that of YBCO, but this does not solve the problem of rapid growth of YBCO single crystal; in addition, in Y-Ba-Cu-O The introduction of Sm or Nd elements into the solution can also increase the growth rate, but the obtained samples are doped with Sm or Nd elements, which will eventually affect the lattice structure of the YBCO single crystal