Residual Stress in Siliceous Glass Between Mullite Crystals

A birefringence of siliceous glass, which is coexisting with mullite crystals, was studied by an optical polarizing microscope. The cause of the birefringence was assumed to be the residual stress induced by a large contraction difference between the mullite and glass on cooling. The stress has been evaluated to be as high as—0.3 GPa, and to correspond to the elastic one which began to develop at the glass transition point.     

Preparation and Characterization of Superconducting B1-Type Mo1-xNbxN Thin Films

Solid-solution thin films, Mo_1−xNb_xN, with B1 (NaCl) structure have been deposited on substrates at 450°C by reactive sputtering of composite targets with Mo and Nb metals in an equimolar Ar and N₂ gas mixture. The lattice parameter of the solid solution increased linearly with an increase of Nb content, x . The superconducting transition temperature, T _c, of the Mo-rich films ( x ≦ 0.12) was around 6 K, which was lower than that expected from theoretical prediction. The residual resistivity ratio, r =ρ(300 K)/ρ(20 K), of the films varied with x , and a minimum value of r was observed in the vicinity of x = 0.5.