A Method for Polarizing More Number of Impurity-Vacancy Dipoles

Jai Prakash,Devendra Prasad

doi:10.4236/jamp.2016.42051

Abstract

Free rotating impurity-vacancy (IV) dipoles in an alkali halide matrix are polarized to the extent of 1/3 of the total number of IV dipoles. An experimental procedure is suggested in this article which will help in the polarization of IV dipoles to the extent of 2/3 of the total number of IV dipoles. In the suggested experimental procedure, the electric field will be applied at first in one direction and then will be applied in succession in opposite direction. Ionic thermocurrent technique is employed to ascertain the increase in polarization of IV dipoles.

Highlights

Whenever a divalent impurity ion is introduced in an alkali halide matrix, a vacancy is created in its neighborhood for the sake of charge compensation
In the presence of polarizing electric field EP, these 12 probable orientations of IV dipoles will group into 3 categories as (a) 4 orientations with the energy − pEP favouring preferred direction of orientation, (b) 4 orientations with zero energy lying perpendicular to the electric field EP and (c) 4 orientations with the energy
ionic thermocurrent (ITC) spectrum recorded corresponding to the polarization conditions up to point D of Figure 1 following a constant linear heating rate will look like curve 1 of Figure 4

Summary

Introduction

Whenever a divalent impurity ion is introduced in an alkali halide matrix, a vacancy is created in its neighborhood for the sake of charge compensation. At such a low temperature the electric field is switched off at the point D of Figure 1, leaving the IV dipoles in the polarized condition since the relaxation time being practically infinite at T0 .

Results

Conclusion