X-ray multiple diffraction as a probe to determine all the piezoelectric coefficients of a crystal: Rochelle salt case

The x-ray multiple diffraction method, which allows us to determine the piezoelectric coefficients of a single crystal under an external electric field (E), was applied to Rochelle salt (dos Santos et al 2001 J. Phys.: Condens. Matter 13 10497) for E parallel to the piezoelectric Y direction. In this work, the theory was extended to consider an observed monoclinic–triclinic distortion under E application into the other two piezoelectric X and Z directions. Renninger scans carried out using the chosen (060) primary reflection have provided the four remaining coefficients through the measurement of the properly chosen secondary peaks. so that all eight piezoelectric coefficients (d₁₄, d₁₆, d₂₁, d₂₂, d₂₃, d₂₅, d₃₄ and d₃₆) for Rochelle salt were determined.