Piezoelectric materials can be natural or synthetic. Natural occurring crystals include quartz, topaz, silk, wood etc. While as synthetic are quartz like, ceramic polymers and composites. Out of 32 piezoelectric crystal structures these are further grouped into seven sub-classes triclinic, monoclinic, orthorhombic, tetragonal, trigonal, hexagonal and cubic. All of these are elastic in nature, triclinic is anisotropic, …show more content…
The other ten are non-polar that is to say polarization appears after applying a mechanical loading.
There are various types of man-made ceramics with crystal structure as perovskite viz Barium titanate BaTiO3,Lead titanate PbTiO3,Lead Zirconium Titanate Pb (ZrxTi1-x)O3) PZT.Its chemical structure is called ABO3 type.Wherin A is larger metal ion, usually Lead/Barium, B denotes smaller metal ion, usually Ti/Zr. Formation of piezoelectric ceramics require mixing of fine powders of constituent metal oxides in suitable ratio, the mixture is heated around 800-1000 degree Celsius to obtain consistency. Which is then mixed with an organic binder and shaped into structural elements with …show more content…
It is chemically inert and exhibits very high sensitivity that guarantees nothing more sophisticated than a charge amplifier to buffer the extremely high source. Impedance of this largely capacitive transducer. The sensing capability of a PZT patch is utilized in sensing conductance to monitor health of a structure. Key features include low cost, small size, dynamic performance, and fast response, long range of linearity, long term stability, and high energy conversion efficiency. PZT patches of any shape, size or thickness can be manufactured at a relatively low cost and it can be used over a wide range of pressures without serious non-linearity. Since it is characterised by a high elastic modulus. If heated above Curie temperature, the crystals lose their piezoelectric effect. Which varies from 150-350 degree Celsius. It can lose piezoelectricity when exposed to high electric fields above 12 kV/cm opposite to polling direction (depolling) and can lead to permanent change in the dimension of sample. PZT patches are great actuators owing to their high stiffness. Their use vary from single to multi-layered PZT systems e.g. deformable mirrors, mechanical micro positioners, biomorphic actuators. Their brittle character makes them prone to poor conformability to curved surfaces and bending and fluctuation of electrical properties with temperature is another