Multicaloric effect in Pb(Mn1/3Nb2/3)O3-32PbTiO3 single crystals: Modes of measurement

First paper reported the experimental measurement of various caloric effects in Pb(Mn1/3Nb2/3)O3-32PbTiO3 (PMN-PT) single crystals (Chauhan et al., 2015). This study expands upon the former one by discussing various modes for quantifying caloric effects in ferroelectric single crystals, based on different forms of Maxwell’s relations. Based on suitable combination between the dependent and driving factors, four types of caloric responses can be classified. This allows one to study previously unexplored components of the actual or net caloric behavior in a ferroelectric material. It is observed that quantification of entropy and temperature change in a ferroelectric material is highly dependent on the mode of measurement used and the nature of variables employed. A peak ΔTEC of −0.267 K is observed for applied electric field of 0–1.5 MV m−1 at 313 K, while a maximum ΔTeC of 0.27 K is predicted for applied stress of 0–14 MPa (313 K). Correspondingly a largest ΔTPC of −0.11 K is observed at 333 K (0–14 MPa) under electric field biasing of 1.5 MV m−1 while maximum cooling obtained through ΔTiPC is observed to be −1.01 K (323 K) for 0–1.5 MV m−1 electric field strength. Additionally it was observed that complimentary caloric effects are competing in nature and could act to oppose one another. This raises the concern towards selection of dependent and driving variables for suitable prediction of actual caloric response in a ferroelectric. Experimental verification is sought for corroboration of proposed theories. The results also hint at the large unexplored potential of bulk ferroelectric materials for solid-state refrigeration.

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