Does addition of Ag (in small weight % such as 5% and 10%) in superconductors necessarily induce metallicity in them?

For instance there are reports on Ag added effects  in YBCO , but superconducting YBCO already  shows a decrease in resistivity before Tc. What about a superconductor which shows a semiconducting...

02 March 2015 9,591 13 View