An X-ray diffractometric investigation of the Sn-Hg binary system within the 0-40% Hg interval.

By use of a precise x-ray diffractometric method and a computer program for parameter determinations (PIRUM), the delta phase of the tin-mercury system was identified. The delta phase appeared to be an orthorhombic structure, existing as a solid solution of mercury in tin in the 15 to at least 40 weight-percentage mercury interval. The diffraction pattern of this phase was almost identical with that of the gamma phase, which explains why its existence has been very difficult to demonstrate with most conventional x-ray diffractometric techniques. The difference between these two phases is mainly related to a slight deformation of the hexagonal structure, causing a small angular change at the corners of the hexagonal structure. This angular change, although small, transforms the hexagonal structure to a structure which should be described as a base-centered orthorhombic structure. Since the delta phase is closer than the gamma phase to the liquidus part of the tin-mercury system at room temperature, it is more likely to be formed when a conventional amalgam sets.