Method for preparing large-sized high-temperature superconducting monocrystals

Abstract

The invention discloses a method for preparing large-sized high-temperature superconducting monocrystals, which comprises the steps of: (a) carrying out mixing, wet grinding and sintering on BaCO3 powder and CuO powder so as to obtain Ba-Cu-O powder; (b) adding the Ba-Cu-O powder into a RE2O3 crucible, heating the Ba-Cu-O powder to a first temperature, continuing to carry out heat preservation on the obtained object so as to obtain a RE-Ba-Cu-O solution, and cooling the RE-Ba-Cu-O solution to a second temperature; (c) taking a REBCO / MgO thin film as a seed crystal, carrying out heat-preserving growth on the RE-Ba-Cu-O solution at the second temperature for 10-20 hours by using a pulling method firstly, then setting the slow cooling speed of the solution at 0.2-2.0 DEG C / h, and continuing to grow an obtained REBCO monocrystal for 50-100 hours by using the pulling method. According to the invention, a slow cooling process for a growth temperature is introduced, so that the supersaturation degree of the solution is continuously increased, thereby facilitating the increase of the growth speed of monocrystals and the preparation of large-sized REBCO high-temperature superconducting monocrystals.

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