Phase diagram of electron-beam codeposited Nb3Ge: The influence of oxygen and other gases

Oxygen, air, or chlorine gas present in the vacuum system during evaporation extend the Ge-rich boundary of the A15 phase towards the ideal 3:1 ratio. X-ray evidence indicates the presence of an amorphous component below 775°C which is detrimental to the superconductivity and which is accompanied by an abrupt increase in the A15 lattice constant. Preliminary Auger results indicate that the Nb:O ratio first decreases as the partial pressure of O2increases and then remains constant.