Incompensated charges lead to charged defects such as vacancies in the lattice of the compound, which produce new energy levels in the bandgap of the phosphor. These levels can participate in electronic transitions and cause diverse effects, such as introduction of new emitting levels (new peaks in the emission spectra), not characteristic for the particular activators, but also can assist quenching the emission from the levels of the activators.
Incompensated charges lead to charged defects such as vacancies in the lattice of the compound, which produce new energy levels in the bandgap of the phosphor. These levels can participate in electronic transitions and cause diverse effects, such as introduction of new emitting levels (new peaks in the emission spectra), not characteristic for the particular activators, but also can assist quenching the emission from the levels of the activators.
It is sometimes argued that the chemistry of crystal - it is inorganic and physical chemistry of the classes of compounds that are capable of luminescence. This ignores the fact that the nature of the phosphors as physical and chemical processes that lead to the ability to luminescence can be known only by studying the regularities of formation of defects of the crystal lattice.
At the same time, in the case of the same compounds for purposes not related to the use of structure-sensitive properties, it is important for the problem of crystal is not of interest and therefore not studied. Misunderstanding of what chemistry of phosphors - primarily chemistry section of crystals with defects, leading to a denial or disregard of the principle of compensation valence (charge), the association of oppositely charged lattice defects and dislocations in the region of interaction and inter-block surfaces. In other words - those concepts that lie at the very basis of physical chemistry of crystal, semiconductor and laser materials.
As for the need of compensation of a charge, it, first of all, is connected with stability of crystalline phosphors and, as a result, their luminescence bands.
Best Regards, Leonid.
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