5 research outputs found
Charge-ice dynamics in the negative thermal expansion material Cd(CN)
We use variable-temperature (150--300\,K) single-crystal X-ray diffraction to
re-examine the interplay between structure and dynamics in the ambient phase of
the isotropic negative thermal expansion (NTE) material Cd(CN). We find
strong experimental evidence for the existence of low-energy vibrational modes
that involve off-centering of Cd ions. These modes have the effect of
increasing network packing density---suggesting a mechanism for NTE that is
different to the generally-accepted picture of correlated Cd(C/N) rotation
modes. Strong local correlations in the displacement directions of neighbouring
cadmium centres are evident in the existence of highly-structured diffuse
scattering in the experimental X-ray diffraction patterns. Monte Carlo
simulations suggest these patterns might be interpreted in terms of a basic set
of `ice-rules' that establish a mapping between the dynamics of Cd(CN) and
proton ordering in cubic ice VII.Comment: 5 pages, 5 figures, submitted to PR
Source rock potential and depositional environment of the Lower Oligocene Ä°hsaniye Formation in NW Turkey (Thrace, Karaburun)
Cow Cave, Chudleigh, Devon
The Cow Cave CC16 project was a rescue excavation and sampling project undertaken in response to ongoing damage to the site through natural and human causes. The project was funded by Historic England and managed by Devon County Council, with fieldwork carried out in 2016 and laboratory analysis over 2016 and early 2017. The cave preserves a nationally important long sequence of sediments dating from the late Middle Pleistocene to the Holocene