Sintering Study in the Partially Vitreous As‐S‐Se System

A study of sintering of vitreous As‐S‐Se spheres has indicated relations concerning the viscous flow mechanism. Sphere‐sphere geometric models are proposed to relate surface area to the sintering rate; one such model accurately describes the relation observed. In sphere‐sphere sintering, the slope of the logarithm of the ratio of neck radius to the initial radius plotted against the logarithm of time is compositionally dependent Three types of internal structure are suggested in order of increasing arsenic content: ( a ) a system of chains and rings with arsenic “pinning points,” ( b ) trigonal As(S,Se) 3 elements bound together by Se‐Se, Se‐S, and/or S‐S linkages, and ( c ) a dense network of entirely As‐S and/or As‐Se linkages. When the ratio of surface area to final equilibrium surface area was plotted against time of sintering, the relation was linear. This indicates a constant dissipation of internal energy by a flow process. Deviation from this linear relation exists for structures involving ring and long chain configurations at viscosities above approximately 10 7.5 poises, suggesting the presence of non‐viscous properties. A linear shrinkage equation was obtained for compositions where slopes of logarithm of the ratio of neck radius to the initial radius plotted against the logarithm of time of sintering were greater than 0.5.