Piezoelectric ceramics single crystals

In contrast to piezoelectric single crystals, such as quartz, the piezoelectricity of PZT ceramics decays with time due to relaxation. Experimentally it is found that on a large time scale (for example, months and years), the aging process can be accurately described by a logarithmic law. For example, the coupling constant k varies with time f as... 

The piezoelectric coefficients are third rank tensors, hence the piezoelectric response is anisotropic. A two subscript matrix notation is also widely used. The number of non-zero coefficients is governed by crystal symmetry, as described by Nye [2], In most single crystals, the piezoelectric coefficients are defined in terms of the crystallographic axes in polycrystalline ceramics, by convention the poling axis is referred to as the 3 axis. 

Ferroelectric ceramics and single crystals have found wide applications in many electronic, acoustoptic and piezoelectric devices [1,2], Perovskites represent one of the most important classes of inorganic powders that are of great interest in functional ceramics used for electronic components among them BaTiOj is a typical and most frequently used representative. 

To understand why ceramics have particular structures and why certain defects form in these structures, it is really important to understand Pauling s rules. These rules require you to visualize a tetrahedron and an octahedron and to see how they fit together. To understand properties such as piezoelectricity or the mechanisms of phase transformations, you must be able to visualize the crystal structure of the material. This is particularly important when we want to predict the properties of single crystals. We summarize the features of crystallography that we use throughout the text and give references to more specialized resources for rigorous proof of theorems and more detailed discussion. 

Ferroelectrics are the prime material for piezoelectric applications in ceramic form, due to the discovery of the electrical poling process that aligns the internal polarization of the crystallites within the ceramic, and causes the ceramic to act in similar fashion to a piezoelectric single crystal. Three categories of applications have... 

Damjanovic, D. 2005. Contributions to the piezoelectric effect in ferroelectric single crystals and ceramics. Journal of the American Ceramic Society 88 [10] 2663-2676. 

Many routes for obtaining template particles are known using molten salt synthesis, hydrothermal synthesis, sol—gel processing, as well as hybrid, multistep methods. The TGG method has been widely used for the development and texturing of piezoelectric ceramics [44]. One of the reasons for this widespread use is the cost consideration, since TGG enables the relatively inexpensive fabrication of textured ceramics with single crystal-Uke properties. However, our present discussion pivots around the mechanical properties. 

Although piezoelectric ceramics are widely used for a large number of applications, single-crystal materials retain their utility, being essential for applications... 

---