EXPERIMENTAL EVALUATION OF THE TEMPERATURE ACCURACY OF THE OXFORD PHENIX CRYOSTAT

Martijn Fransen and John Vasterink

PANalytical, Almelo, The Netherlands

Recently, Oxford Cryosystems has introduced a closed-circle cryostat for X-ray powder diffraction applications. The absence of the need for continuous supply of new liquid Helium, makes X-ray powder diffraction experiments possible also for users having limited experience with cryogenic techniques.

Ease of use of a non-ambient device with a powder diffractometer is of course nice, but much more important is the accuracy of the temperature readouts. Modern non-ambient chambers perform quite well in this respect and we were curious to see whether this was also the case for a cryostat.

There are two basic methods for determining the temperature accuracy:

· measure diffractograms over a large temperature range and calculate the lattice parameter change as a function of temperature,

· find material(s) with phase transition(s) at known temperature(s).

Both of these were used to test this non-ambient chamber.