The Effect Of Pore Size On The Growth Morphology And Performance Of Single-domain SmBCO Superconducting Bulk Materials

Since the discovery of high-temperature superconducting materials of REBCO series in the 1980s,it has played a positive role in promoting the upgrading of energy,transportation,magnets and related high-tech industries due to its high critical current density,large trapped field ability,large magnetic levitation force and large size.REBCO high-temperature bulk superconductor have been widely used,and the SmBCO bulk superconductor,which have high critical transition temperature,critical current density and strong trapped field,making SmBCO bulk superconductor one of the most potential REBCO bulk superconductor.Therefore,the research on single domain REBCO bulk superconductor is not only of great scientific significance,but also of great practical value.In this laboratory,the improved RE+011 TSIG method was used to prepare the properties of SmBCO bulk superconductor.However,when RE+011 TSIG method was used in this paper to prepare SmBCO bulk superconductor,both the SmBCO bulk superconductor and the NdBCO seed used in this paper had a high melting temperature,which often made the NdBCO seed melt and lose its original lattice structure,thus failing to induce the crystal growth of SmBCO bulk superconductor.Therefore,in this paper RE+011 TSIG method(1)was used to systematically investigate the influence of solid phase pellet holing on the melting and growth of SmBCO bulk superconductor;(2)the influence of MgO doping on the melting temperature of NdBCO seed was systematically investigated,and the melting temperature of NdBCO seed was increased.The melting problem of NdBCO seed in the preparation of SmBCO bulk superconductor was successfully solved,and the independent separation of solid and liquid phase was found in the preparation of NdBCO seed by RE+011 TSIG method,and a preliminary exploration was made.The main conclusions of this paper are as follows:(1)RE+011 TSIG method was used to systematically investigate the influence of drilling holes in SmBCO bulk superconductor solid phase pellet on the melting and growth of seeded crystals.The results showed that:the melting problem of NdBCO seed is effectively solved by using hole drilling,when the diameter of the small holes is less than 3 mm,the small holes will not affect the growth direction of single-domain SmBCO bulk superconductor,when the hole diameter is larger than 3 mm,SmBCO bulk superconductor grow along the tangent line of the pore,and then gradually grow together,forming a subdomain boundary;the magnetic levitation force of SmBCO bulk superconductor decreases with the increase of the number or aperture of holes;Jc tends to increase gradually from the middle to the periphery and decrease gradually from the top down,its critical current density is better at the edge of the block or the edge of the hole;Sm211 particles are spherical or ellipsoidal,and the particle size is mainly between 400nm-5?m,and from center to edge,the size of 211 particles decreases gradually,and the distribution is regular,uniform and the more the number is,and from top to bottom,the size of 211 particles increases gradually,and the more irregular and uneven the distribution is,the less the number is,and at the edge of the block,the size of 211 particles decreases gradually,and the distribution is regular,uniform and the more the number is;the growth simulation illustration of SmBCO bulk superconductor prepared by RE+O11 TSIG method and the simulation diagram of the influence of drilling on the growth of SmBCO bulk superconductor,grain boundary orientation and subdomain distribution were further simulated.(2)RE+011 TSIG method was used to systematically explore the influence of MgO doping on the melting temperature of NdBCO seed.The results showed that:with the increase of MgO style doping amount,the XRD diffraction pattern of the higher peak strength of MgO style phase,and MgO style powder doped into the NdBCO crystals in the form of Mg2+ ions,the doping amount of 16 wt%,the maximum,when the doping amount higher than 16 wt%,although with more MgO style,but more in the basement of MgO style particles in the Nd123 phase,not in the form of Mg 2+ ions into the lattice of Nd123 phase,the melting temperature of NdBCO crystal is not working,instead makes the melting temperature;the melting temperature of NdBCO superconducting block is greatly increased by MgO doping,which proved,each in two ways when doped with 16 wt%of MgO style is to NdBCO bulk superconductor is one of the most significant effect of the melting temperature of ascension;the globular gray-white particles were MgO particles with a size between 500 nm-5?m,and the substrate was Nd123 layers.As the doping amount of MgO gradually increases,the number of microscopic particles gradually increases,and the particle size is uniform and the distribution is more uniform,which is very helpful for the improvement of the melting temperature of NdBCO samples(3)It was found that when RE+011 TSIG method was used to prepare NdBCO seed,the phenomenon of independent separation of solid and liquid phases occurred.Using SEM measurement its related components of solid liquid phase,show that NdBCO samples is all about Y related composition in the liquid phase,including Y211 particle concentration distribution in the liquid phase residual block center position,while the Y123 and 035 part mainly scattered in liquid residue blocks around the edges,with the solid phase under the surface of the component is distinct distribution,this may also be helpful for the separation of the two parts.Of course,the follow up and other related issues remain to be further studied.