溶液法制备MgB_2超导膜研究

Deposition of MgB_2 Superconducting Thick Films in Sol-Gel Method

介绍了利用溶液法制备Mg(BH4)2前驱体,进而在衬底上涂抹粘稠的Mg(BH4)2乙醚溶胶(Mg(BH4)2.Et2O)制备MgB2厚膜的方法,也可称为溶胶凝胶法制备MgB2。运用此种方法制备出了10μm级厚度、转变温度达到37 K的MgB2超导厚膜。这种方法设备简单、制膜所需温度低、原料便宜,并且无毒无污染。更为重要的是,这种方法克服了困扰工业上因为硼(B)在采购、运输和存储过程中易于氧化的缺点,可以通过将Mg(BH4)2.Et2O溶胶直接在衬底上均匀甩胶,进而大规模制备MgB2带材。可见溶液法制备MgB2是一种有着很大应用潜力的方法。

The superconducting MgB2 thick films were deposited in sol-gel method on SiC and Al2O3 substrates.The viscous precursor solution,Mg（BH4）2·Et2O,of the MgB2,was first prepared via chemical route.Next,the precursor sol,painted on the substrates,was annealed at a high temperature.Repetition of the painting procedure increased the film thickness,from 200 nm to 1 μm.Finally,the MgB2 thick films were obtained by carefully annealing the precursor coatings in the reactor,filled with low pressure hydrogen,mixed with a small amount of Mg vapor generated by evaporation of Mg ingot.The impacts of the solution processing and annealing conditions on the microstructures and properties of the MgB2 thick films were evaluated.The MgB2 thick films were characterized with X-ray diffraction,and canning electron microscopy.The transition temperature of the 10 μm thick MgB2 coating was found to be 37 K.The possible means to reduce the surface pore and defect densities,and the feasibility of scaling up the MgB2 deposition in sol-get method were also tentatively discussed.