Fig. 1
From: Colossal barocaloric effects near room temperature in plastic crystals of neopentylglycol
Thermally driven phase transition in NPG at atmospheric pressure. a Measurements of dQ/|dT| after baseline subtraction, on heating (red) and cooling (blue) across the first-order cubic-monoclinic phase transition, revealing a large latent heat. The insets represent simplified plan views of the globular (CH3)2C(CH2OH)2 molecules (C = dark green spheres, H = grey spheres and O = light green spheres), which are configurationally ordered in the monoclinic ordered-crystal (OC) phase (left inset), and configurationally disordered in the cubic plastic-crystal (PC) phase (right inset). We assume only one molecule per unit cell for ease of representation. b Specific heat Cp either side of the transition on heating (red) and cooling (blue). c Entropy S′(T) = S(T)−S(250 \({\mathrm{K}}\)), evaluated via \({S\prime (T) = S(T) - S(250\,{\mathrm{K}}) = {\int}_{250\,{\mathrm{K}}}^{T} \left( {C_{p} + \left| {{\mathrm{d}}Q/{\mathrm{d}}T\prime } \right|} \right)/T\prime {\mathrm{d}}T\prime}\), revealing a large entropy change |ΔS0| for the transition. d Specific volume V(T) on heating, revealing a large volume change |ΔV0| for the transition. Symbols represent experimental data, lines are guides to the eye
