The polymorph transition kinetics of the changes vaterite to calcite and aragonite to calcite have been followed using a DTA technique. The method eliminates the grinding process present in other analytical techniques and so has certain advantages. For both transitions the kinetic equation describing the process is found to be:
Values of activation energy were found to be 452±19 KJ mole−1 and 208±8 KJ mole−1 for aragonite and vaterite transitions respectively using a procedure which enabled the calculation of kinetic parameters from a rising temperature experiment.
A preliminary result employing neutron activation tomography in the study of the diffusion of a preservative in a sample of Scots pine is presented. The ability to determine the spatial distribution of elements within the wood without recourse to destructive sectioning makes this a better technique than others currently available.
A method, based on the measurement of the -photopeak at 332 keV arising from a124Sn(n, )125mSn reaction, has been developed for the rapid measurement of Sn at concentrations of 20 g g–1, present as the cross-linking agent, in explosive charges. The method is comparative, and has a limit of detection of 0.6 g g–1 and a precision of 5% RSD. The method requires no sample preparation and is economical in effort.
Authors:E. Charsley, J. Davies, E. Glöggler, N. Hawkins, G. Höhne, T. Lever, K. Peters, M. Richardson, I. Rothemund, and A. Stegmayer
With some attention to temperature calibration but no other special precautions the temperatures of both solid-solid and melting
transitions can be determined to within a few tenths of a Kelvin of absolute values in a range of heat-flux and power-compensation
DSC instruments. Materials showing several solid-solid transitions are potentially useful multiple calibrants but require
some work to define appropriate thermal treatments that lead to reproducible behaviour.