Protection of BN for MgB2 Films Against Degradation in Water

MgB
₂
films and MgB
₂
/BN bilayer films have been fabricated in the same reactor. The MgB
₂
films and the bottom MgB
₂
layers of the MgB
₂
/BN bilayer films were synthesized by hybrid physical-chemical vapor deposition. Furthermore, the BN layers were synthesized by chemical vapor deposition. The degradation of MgB
₂
films and MgB
₂
/BN bilayer films that are submerged into deionized water at room temperature has been studied. To clarify the protection of BN for MgB
₂
films against degradation in water, we analyzed the physical and magnetic properties, including the superconducting critical temperature T
_c
, the critical current density J
_c
, and the residual resistivity ratio. In addition, scanning electron microscopy and X-ray diffraction measurements were taken. The results indicate that the BN films can protect MgB
₂
films from degradation in water, which would be beneficial for the device application of MgB
₂
films.