Speaker
Description
Heating and cooling currently accounts for 50% of global final energy consumption and is responsible for more than 40% of energy related CO$_2$ emissions. As the planet warms, the demand for cooling increases, and without new environmentally friendly cooling devices, we risk runaway global warming. The most promising solid state replacement technology is based on barocalorics, where pressure drives an adiabatic temperature change at phase transitions with a large change in entropy.
Over the last 10 years, a huge range of barocalorics have been identified, but to engineer optimised materials for applications it is vital to understand what generates the large entropy changes. In addition to using diffraction to explore the configurational entropy, QENS and INS provide essential information about the dynamics, where vibrational entropy can sometimes be the dominant contribution.
We have used QENS and INS to explore ammonium sulfate and adamantane under hydrostatic pressure, but these used different samples since INS measurements require them to be perdeuterated. In the future we look forward to using polarised LET to enable us to extract the QENS and phonon scattering separately from the same sample measurement, even in samples where deuteration would be prohibitive. Since the lowest energy dynamics contribute most significantly to the calculated entropy, being able to cleanly separate the QENS and phonon signals will significantly impact the interpretation.
We had hoped to present our first pLET data, but unfortunately our experiments had to be cancelled due to instrument problems. Nevertheless, we are very excited to learn more about polarsiation analysed QENS, the instrumentation, the modelling and the data analysis, and are looking forward to discussions at the meeting.
