Fig. 5: Thermostability and overview of piezoelectric properties.

a DSC (black curve) and TGA (blue curve) results of the as-prepared films. The inset figure is the enlarged drawing of DSC curve between the temperature of 180 °C and 205 °C. b The in-situ variable temperature XRD patterns of the films. c The in-situ variable temperature Raman spectra. d The temperature-dependent relative permittivity for selected frequencies. e Dependence of d33 of the β-glycine nanocrystalline films on temperature. Error bar denotes the standard deviation. f PFM OOP amplitude mapping (left) and phase mapping (right) under 120 °C confirming the stable piezoelectric effect of the films under high temperature. The applied AC voltage is 2 V. Scale bar: 200 nm. g Comparison of longitudinal piezoelectric voltage coefficient g33 of most actively studied piezoelectric material systems with this work as a function of Curie temperature TC.