Fig. 4: Polarization vs electric field relationships.
From: Incipient ferroelectricity in methylammonium lead halide perovskites
The results for the crystals of MAPbCl3 (a), MAPbBr3 (b), and MAPbI3 (c), measured at different temperatures below Tmax (solid line) and above Tmax (dashed line) at the field frequency of 1 kHz.
