DIL L75 VS – Quarz – Thermal expansion – calculated DTA
Quarz Sample – Thermal expansion / quarz transformation / calculated DTA
The thermal expansion of α-SiO2 can be easily measured by L75 Dilatometer. However, quarz shows a change of expansion rate due to its quarz transformation that is not so easy to identify by pure expansion measurement. The additional calculated DTA feature of the Linseis L75 Dilatometer series enables an in-depth view of the thermal behavior of the material and easy detection of phase transitions. The calculated DTA measurement is a mathematical routine based on the sample temperature. Exo- and endothermic effects influence the change of the sample temperature during the dynamic heating or cooling cycle in comparison to the set heating profile.
The phase transition of SiO2 takes place at app. 575°C. The red temperature curve of the measurement shows a sudden increase at that range. Applying the DTA feature enables to determine the exact phase transition in case the expansion curve does not provide a definite onset point. The purple curve shows the baseline corrected difference between measured and set temperature and the blue curve shows the resulting calculated DTA peak.
The deviation of the measured temperature (575°C) from the literature value (574°C) can be used for a temperature calibration.