Local structure around the flux pinning centers in superconducting niobium silicon oxynitride (Nb0.87Si0.09□0.04)(N0.87O0.13)

Potential energy scan of the Si atom in the most stable Si3□O3N cube around the vacancy in our preliminary simulation on niobium silicon oxynitride (Nb0.87Si0.09□0.04)(N0.87O0.13). A possible distortion of the Si atom was suggested from its octahedral towards tetrahedral position forming the local structure similar to that in amorphous SiO2.