PYROELECTRICITY IN NONCENTRAL CRYSTALS

Unit cell electric arrangement of piezoelectric crystals may be descri bed by various multipole/octupole/dipole electric moments which corres ponds to a three/two/one-dimensional intrinsic polarity respectively. Such a latent polar structure is totally self-compensated in piezoelec trics if they are mechanically free, but it is non-compensated in pyro electrics and ferroelectrics. Uniform but anisotropic partial clamping destroys a total self-compensation of non-central crystal intrinsic p olarity. This decompensation allows to observe a polar response that i s a ''dipole projection'' DELTAP(i) from, broken by clamping, spatial polar arrangement of piezoelectrics.