The electroluminescence of ZnS-Cu,Mn

The brightness waves of ZnS-Cu, Mn phosphor were investigated and it was found that their shape changes from that characteristic for copper-activated phosphors to that characteristic for manganese-activated phosphors as a function of the magnitude of the voltage applied, the length of the pulses and the temperature. In order to explain the results it is assumed that simultaneously with the mechanism of electroluminescence, accepted for ZnS-Cu (ionization of activators; recombination and radiation delayed in phase compared with voltage), there exists an immediate recombination of the Cu activators in the barriers, which is accompanied by radiation in phase with the voltage.

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ZnS-Cu, Mn

ZnS-Cu, Mn. , , , , , , , , . , , ZnS-Cu ( ; , ), : Cu , , .

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In conclusion, the authors thank Dr. M. Trlifaj for valuable discussions and M. Skala for supplying the electroluminescent phosphor of ZnS-Cu, Mn.     

The electro-optic kerr effect in noncentrosymmetric KH2PO4 and KD2PO4 monocrystals

Experimental and theoretical results of the determination of the quadratic electro-optic coefficients in noncentrosymmetric KH₂PO₄(KDP) and KD₂PO₄(DKDP) monocrystals are presented. The coefficientR _c=R ₁₁₂₂-R ₁₁₁₁ for the X-cut crystals has been measured by a dynamic method in the a.c. electric field. The theoretical value of the coefficient has been calculated by the Kurtz-Robinson model. It has been found that the coefficientR _c was less than 10×10^–20m²V^–2.     

On the photo-electroluminescence of ZnS-Cu

The influence of weak ultra-violet irradiation on the brightness waves of electroluminescence is investigated for two types of ZnS-Cuphosphors. The observed effects (increase in brightness in the primary peak and its phase shift, the disappearance of the secondary peak) are explained on the basis of present-day conceptions on electroluminescence.

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ZnS-Cu

ZnS-Cu. ( , ) .

     

The kinetics of barium precipitation at dislocations in NaCl monocrystals

The kinetics of barium precipitation at dislocations in NaCl monocrystals has been studied in thermally and mechanically treated NaCl + 4 ppm BaCl₂ samples by investigating the isothermic variation of ionic conductivity as a function of time. The course of precipitation which takes place at dislocations located at grain boundaries can be divided into three time regions characterized by diffusion of impurities to dislocation cores at grain boundaries, nucleation, formation of new grain boundaries, etc. At higher number of dislocations an interruption of the precipitation appears due to a local free energy of nucleation minimum at radiusr ₀=6·92×10^–8 cm.     

Thermally stimulated and photo-stimulated conductivity in ZnS-Cu single crystals

The development of thermally stimulated and photo-stimulated conductivity in zinc-sulfide phosphors has been studied. The sign of the charge carriers in the single crystal samples inspected has been determined. The effect of infrared light in the region 1–3.5 m upon previously excited crystals has been investigated and the temperature dependence of the photostimulated conductivity established.In conclusion, the authors express their deep gratitude to E. S. Bespalovaya for the samples and also to K. Arun for his help in measuring the Hall constant.     

The third-order electric susceptibilities of NaCl and KCl monocrystals

The dispersion of the third-order electric susceptibilities(; , , –) and(; , 0, 0) of NaCl and KCl monocrystals has been calculated by means of experimental data on the electro-optic Kerr effect. The result has been obtained by using semi-classical models of anharmonic oscillators. An ionic contribution to the electro-optic coefficients has been presented. From the result obtained it follows that the third-order electric susceptibilities are of the order of 10^–22 m² V^–2.     

On avalanche processes in electroluminescence of single ZnS-Cu crystals

The electrical, photoelectrical and luminescent properties of single crystals (30 to 50 microns in size) of commercial ZnS-Cu electroluminophore with green emission have been investigated. The dependencies of dark current, photocurrent and luminescence brightness on the applied voltage have been found to reveal a greater complexity than those obtained for polycrystal samples.When the d.c. voltage applied to the crystal rose above 4 volts the dark and photo electrons were observed to multiply, this being accompanied by emission. The observed dependence of the multiplication coefficient on the applied voltage resembles in shape the curves obtained for other substances (Ge, Si, ZnO).