Definitions & Terminology

Definitions and Terminology
In piezoelectric ceramics, material characteristics depend on the direction of the applied field, displacement, stress and strain. Hence superscripts and subscripts indicating the direction are added to the symbols. The direction of polarization is generally designated as the z-axis of an orthogonal crystallographic system. The axes x, y and z are respectively represented as 1, 2 and 3 directions and the shear about these axes are represented as 4, 5 and 6. This is shown schematically on the Symbols and Terminology Chart. The various piezoelectric material constants are generally expressed with subscripts using this notation. In addition to the above, planar modes are sometimes expressed with a subscript 'p'. Superscripts indicate a constant mechanical or electrical boundary condition. The table below gives a general description of the superscripts.