Absolute calibration of the latent heat of transition using differential thermal analysis

TL;DR

This paper introduces a simple differential thermal analysis method for accurately measuring the latent heat of phase transitions in solids, with a novel calibration technique that does not require a reference sample.

Contribution

A new numerical calibration method for differential thermal analysis that enables absolute latent heat measurements without reference samples.

Findings

Latent heat measurements agree with literature values within error margins.

The method accurately tracks latent heat changes during non-equilibrium hysteresis.

The technique also measures temperature-dependent specific heat.

Abstract

We describe a simple and accurate differential thermal analysis set up to measure the latent heat of solid state materials undergoing abrupt phase transitions in the temperature range from 77 K to above room temperature. We report a numerical technique for the absolute calibration of the latent heat of the transition, without the need of a reference sample. The technique is applied to three different samples -- vanadium sesquioxide undergoing the Mott transition, bismuth barium ruthenate undergoing a magnetoelastic transition, and an intermetallic Heusler compound. In each case, the inferred latent heat value agrees with the literature value to within its error margins. To further demonstrate the importance of absolute calibration, we show that the changes in the latent heat of the Mott transition in vanadium sesquioxide (V$_2$O$_3$) stays constant to within 2% even as the depth of supersaturation changes by about 10 K, in non-equilibrium dynamic hysteresis measurements. We also apply this technique for the measurement of the temperature-dependent specific heat.