We describe a web-based tool (PASCal; Principal Axis Strain Calculator) aimed at simplifying the determination of principal coefficients of thermal expansion and compressibilities from variable-temperature and variable-pressure lattice parameter data. In a series of three case studies, we use PASCal to re-analyse previously-published lattice parameter data and show that additional scientific insight is obtainable in each case. First, the two-dimensional metal-organic framework Cu-SIP-3 is found to exhibit the strongest area-negative thermal expansion (NTE) effect yet observed; second, the widely-used explosive HMX exhibits much stronger mechanical anisotropy than had previously been anticipated, including uniaxial NTE driven by thermal changes in molecular conformation; and, third, the high-pressure form of the mineral malayaite is shown to exhibit a strong negative linear compressibility (NLC) effect that arises from correlated tilting of SnO6 and SiO4 coordination polyhedra.
@article{arxiv.1204.3007,
title = {PASCal: A principal-axis strain calculator for thermal expansion and compressibility determination},
author = {Matthew J. Cliffe and Andrew L. Goodwin},
journal= {arXiv preprint arXiv:1204.3007},
year = {2012}
}
Comments
31 pages, 8 figures, formatted as preprint for J. Appl. Cryst