Piezoelectric Coefficients of mNA Organic Nonlinear Optical Material Using Synchrotron X-Ray Multiple Diffraction

Abstract

Distortions produced in the unit cell of a nonlinear organic crystal under the influence of an applied electric field $E$ are investigated by using synchrotron x-ray multiple diffraction (MD). A typical MD pattern shows numerous $(\mathrm{hkl})$ secondary peaks and the position of each one is basically a function of the unit cell lattice parameters. Thus small changes in any parameter due to a strain produced by $E$ give rise to a corresponding variation in the $(\mathrm{hkl})$ peak position. The method was applied to the meta-nitroaniline (mNA) crystal and we were able to determine three piezoelectric coefficients.