Charge separation during fracture

However, up to now, no fuUy clear mechanism by which TL occurs has been presented. Some works suggest that TL is a consequence of a recombination of charges separated during fracture of a crystal belonging to a non-centrosymmetric space group . On the other hand. Cotton and coworkers showed that centric compounds can exhibit TL, and they pointed to two non-centric compounds, at least, which show no TL at room temperature. However, TL in centrosymmetric compounds have been generally assigned to impurities or disorder of some atoms in the molecular structure . 

We have proposed a simpler model for systems involving charge separation during fracture. We have tested various aspects of this model on a number of materials.( 4,51,52) jhe basic features of this model as they relate to the fracture of materials in vacuum are the following ... 

The fracture of a brittle, electrically insulating material is often accompanied by the emission of electrons, photons, and/or ions. This fractoemission is probably due to microarc discharges resulting from charge separation during fracture. 

During crack propagation, charge separation occurs on the freshly created fracture surfaces. 

Fractoemission (adhesion) The emission of electrons during the fracture of a dielectric, brittle solid due to charge separation and arcing. Also called Exoemission. 

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