Ferroelectric Polarization Modulated Thermal Conductivity in Barium Titanate Ceramic

Abstract

Thermal conductivity k dominates in a heat transfer medium, and a field modulated k would facilitate delicate control in thermal management technology, yet it is hardly realized in a single solid material unless with changing temperature. Herein, in BaTiO 3 ceramic, a modulated k was discovered by adjusting ferroelectric polarization P, which was a conventional strategy in ferroelectric functional materials. Four different states (P1, P2, P3, P4) were obtained by controlling poling time and field strength, showing that k leaped from 2.704 ± 0.054 to 3.201 ± 0.070 W (m K) −1 with increased P. Moreover, the strong correlation between P and k was also verified by the thermal depolarization measurement from room temperature to Curie temperature. The underlying origin of P modulated k was attributed to the internal bias field, which is born in the oriented ferroelectric domains, tightening special phonon modes in BaTiO 3 ceramics. Raman spectrum, P−E loops, first-order reversible curve, XRD analysis, and PFM measurement were then employed to clarify how ferroelectric polarization structurally influences phonon transport and subsequent thermal conductivity. This work will pave a brand-new research route for conventional ferroelectric ceramic, also potentiating the idea of the electric field-controlled k component and active solid heat-transport device in the future.

Proton-controlled molecular ionic ferroelectrics

“…The ability of heat conductance in ImClO 4 increases with temperature and saturates near the ferroelectric-paraelectric transition, indicating the electron-phonon coupling effect 37 . A reduced thermal conductivity is observed when ImClO 4 is cooled from 400 K (above its Curie temperature), implying ferroelectric ordering induced polarizationcontrolled thermal conductivity 38 (Fig. 3c).…”

“…3c). The proton/phonon contribution from polarized cations and anions could be considerable, as electron/proton-phonon coupling influences heat conductance [37][38][39] . Such entanglement between ferroelectric order and heat conductance is reliably observed in both powder and thin-film forms of molecular ionic ferroelectric materials (e.g., guanidinium perchlorate, Fig.…”