Calibration of CryojetHT and Cobra Plus Cryosystems used in X-ray diffraction studies

CryoJetHT (Oxford Instruments) and Cobra Plus (Oxford Cryosystems) cryosystems, which are used for sample cooling in X-ray diffraction experiments, have been calibrated. It is shown that the real temperature in the vicinity of the sample differs significantly (the deviation is as high as 8-10 K at low temperatures) from the temperature recorded by authorized sensors of these systems. The calibration results are confirmed by measurements of the unit-cell parameters of GdFe3(BO3)(4) single crystal in the temperature range of its phase transition. It is shown that, to determine the real temperature of a sample, one must perform an independent calibration of cryosystems rather than rely on their ratings.