Charge-compensating defect

Ferroelectric materials in this family have the perovskite crystal structure, where Ti+4(Zr+4) is in the B site at the center of the unit cell within an octrahedral coordination of O-2, and Pb+2 (La+3) occupies the A site at cube corners. Considerable discussion and experimentation have occurred to decide what charge-compensating defects are created by the... 

Subsequent steps in trapping that are particularly important to the photographic process include the dynamic ionic stabilization of deep trapping centers by mobile charge-compensating defects [118] and/or non-radiative recombination at the defect center [119]. 

As with lead azide, impurities were found to alter photodecomposition rates in AgNa [237]. The addition of Pb " retarded the gas evolution rate while CO2 enhanced it. No explanation for the effect was given, but it may involve changes in stoichiometric charge-compensating defects. The authors claim that photolysis is not concentrated in disordered regions of the crystal as is observed for lead and thallous azides (see Section D). 

The MCI2 (M = Ca, Sr, and Ba) crystals are ideal candidates for studies of the spectroscopic properties of Tm " ions. First, no charge-compensation defects are required after thulium ions are introduced into these hosts. Second, there is reliable experimental information about the absorption/emission spectra of these materials [2-8]. Moreover, the earth-alkaline halides are also important from an application point of view because the laser action has been achieved in CaF2 Tm [9]. The spectra of Tm " were modeled in our earlier publication [10]. 

Whereas the ionic conductivity is always much lower than the electronic conductivity in pure reduced ceria, the situation is quite different in ceria doped with oxides of two- or three-valent metals due to the introduction of oxide ion vacancies as charge compensating defects, according to Eqs. (12.2) and (12.3). The electronic conductivity in air may be very low and under these conditions doped ceria is an excellent electrolyte. 

In the presence of water vapor, protons can be incorporated directly as charge-compensating defects during the synthesis according to this equation ... 

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