Today’s blog post describes in detail the different equation forms and standards, with a focus on the particular case of quartz - the material that causes the most confusion. Confused yet? I was when I first started reading the literature! IEEE actually revised the 1978 standard in 1987, but this version of the standard contained a number of errors and was subsequently withdrawn. To complicate things further, there are two standards used in the literature: the IEEE 1978 Standard and the IRE 1949 standard, and the material properties take different forms within the two standards. Different sets of material properties are required for each of these equation forms. The relationship between the material polarization and its deformation can be defined in two ways: the strain-charge or the stress-charge form. Several material properties must be defined in order to fully characterize the piezoelectric effect within a given material. This effect, known as the direct piezoelectric effect, is always accompanied by the inverse piezoelectric effect, in which the solid becomes strained when placed in an electric field. In certain crystal structures, this combines to give an average macroscopic dipole moment and a corresponding net electric polarization. From a microscopic perspective, the displacement of charged atoms within the crystal unit cell (when the solid is deformed) produces a net electric dipole moment within the medium. Piezoelectric materials become electrically polarized when strained. Although the particular focus of this post is on quartz, the standards described apply for any piezoelectric material. This blog post explains the multiple standards used to describe piezoelectrics in literature.

This has happened in the case of the standards for piezoelectric materials, particularly for quartz. But standards committees are not omnipotent and sometimes revised standards are not universally adopted.

Standards form an integral part of the work we do as engineers, providing a common language for communicating complex information.

Piezo electric material