High-energy x-ray diffraction study on phase transition asymmetry of plastic crystal neopentylglycol

As a prototype material of colossal barocaloric effects, neopentylglycol is investigated by combining high-precision differential scanning calorimetric measurement and high-energy x-ray diffraction measurement. The diffraction data at constant temperatures indicate a first-order phase transition with thermal hysteresis as well as the phase transition asymmetry,specifically, the phase transition is completed faster at cooling than at heating. The analysis of resulting pair distribution function confirms the intermolecular disorder in the high-temperature phase. The phase transition asymmetry is quantitatively characterized by time-resolved x-ray diffraction, which is in agreement with the thermal measurement. Also, such an asymmetry is observed to be suppressed at high pressures.

塑料晶体的庞压卡效应

制冷对现代社会至关重要,世界上25%到30%的电力用于制冷。例如,食品储存和空调的使用等都需要耗费大量的电力。目前的制冷技术主要还是以传统蒸汽压缩循环为主,但由于具有加剧全球变暖的潜力危险,人们一直尝试找到更好的替代方案。在这背景下,基于固态相变热效应的制冷技术作为一种很有前途的替代技术,在近几十年来一直是研究者们关注的重点。但是,由于其等温爛变化小,所需驱动动能大以及材料性能有限等种种劣势均限制了其应用推广。