As an unique and important kind of HTS material,the superiorities of Magnesium diboride( MgB_2) in superconducting characters cover high superconducting transition temperature,long coherence length,high critical current and critical field,thus the application of MgB_2 is very potential in the superconducting electronics fields. The preparation of MgB_2 superconducting devices is thought as the master key of the large-scale applications. In the CVD prepatation of MgB_2 superconducting thin film,we found the ...