NMR STUDIES OF PHASE TRANSITIONS,
Abstract
NaSH is one of a group of compounds M(QR) whose high temperature crystalline form might be called pseudo-NaCl cubic, but which crystallize in less symmetrical lattices at low temperatures. In the high temperature form the SH(-)ion is located at the Cl(-) site of the NaCl lattice. There have been two models proposed in the past to account for the obviously linear ion QR(-) replacing a spherical ion. Pauling proposed a model in which the QR(-) ion is tumbling spherically very rapidly and thus presents an outward spherical form to the surrounding ions. Frenkel proposed a model in which the QR(-) ions are static, and point along the cube body diagonals (<111> directions), each QR(-) ion thus having eight possible static orientations. In this model a random distribu tion of QR(-) orientations among the eight possibilities leads to long-range cubic sym metry. Previous attempts, based on X-ray dif fraction experiments, to decide between these models have been unsuccessful. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 28, 1963
- Accession Number
- AD0413937
Entities
People
- C.k. Coogan
- Herbert S. Gutowsky
Organizations
- University of Illinois Urbana–Champaign