The current report describes the installation and the preliminary commissioning of the Material Science Powder Diffraction (MSPD) beamline at the Spanish synchrotron ALBA-CELLS. The beamline is fully dedicated to powder diffraction techniques and consists of two experimental stations positioned in series: a High Pressure/Microdiffraction station and a High Resolution/High Throughput powder diffraction station.
There is currently great interest in replacing the harmful volatile hydrofluorocarbon fluids used in refrigeration and air-conditioning with solid materials that display magnetocaloric, electrocaloric or mechanocaloric effects. However, the field-driven thermal changes in all of these caloric materials fall short with respect to their fluid counterparts. Here we show that plastic crystals of neopentylglycol (CH3)2C(CH2OH)2display extremely large pressure-driven thermal changes near room temperature due to molecular reconfiguration, that these changes outperform those observed in any type of caloric material, and that these changes are comparable with those exploited commercially in hydrofluorocarbons. Our discovery of colossal barocaloric effects in a plastic crystal should bring barocaloric materials to the forefront of research and development in order to achieve safe environmentally friendly cooling without compromising performance.
10 August 2015 in The European Physical Journal Plus
We have studied the barocaloric properties associated with the martensitic transition of a shape memory Heusler alloy which is composed of all--metal elements. The composition of the sample has been tailored to avoid long-range ferromagnetic order in both austenite and martensite. The lack of ferromagnetism results in a weak magnetic contribution to the total entropy change, thereby leading to a large transition entropy change. The combination of such a large entropy change and a relatively large volume change at the martensitic transition gives rise to giant barocaloric properties in this alloy. When compared to other shape memory Heusler alloys, our material exhibits values for adiabatic temperature and isothermal entropy changes significantly larger than values reported so far for this class of materials. Furthermore, our also compares favorably to the best state-of-the-art magnetic barocaloric materials.