Figure 5
From: First experimental evidence of the piezoelectric nature of struvite
Temperature dependence of d33 coefficient measured for the a.c. electric field strength of 4 kV/cm and the frequency of 160 Hz. Experiment has been performed for the same crystal for which data at 300 K are presented in Fig. 4. Above 380 K the crystal is already of dittmarite structure (see further in the text). Since dittmarite structure is of orthorhombic symmetry, the piezoelectric effect was also observed. However, in this experiment we could not establish the crystallographic orientation of the crystal after being transformed to dittmarite at 380 K. Thus, above this temperature, the piezoelectric tensor might not be ascribed as d33.
