Growth and Characterization of Multiphased Mixed Crystals of NaBr and KBr

On the large temperature variation of the dielectric constant of Na0.4K0.6Br

“…In this study, Padma and Mahadevan [22] achieved the preparation of mixed crystals (Na x K 1-x Br) of NaBr and KBr from melts and their X-ray diffraction analysis indicated the existence of two phases in the mixed crystals.…”

“…In this paper we solely focus on the explanation of the variation of ε with temperature for which Padma and Mahadevan [22] offered the following qualitative remarks: This is generally attributed to the crystal expansion, the electronic and ionic polarizations and the presence of impurities and crystal defects. The variation at low temperatures is mainly due to the expansion and electronic and ionic polarizations.…”

“…The growth of the following five systems was reported [22]: Na 0.2 K 0.8 Br, Na 0.4 K 0.6 Br, Na 0.5 K 0.5 Br, Na 0.6 K 0.4 Br, Na 0.8 K 0.2 Br (the composition written is taken for crystallization, see their Table 1). Beyond the study of thermal parameters (Debye-Waller factor, mean square amplitude of vibration, Debye temperature and Debye frequency), Padma and Mahadevan performed electrical measurements in all these (polycrystalline) mixed systems in the temperature range 308 to 423 K. Namely, they measured the dc and ac conductivity (labeled dc σ and ac ) σ as well as the (real part of the) dielectric constant ( ) ε and the dielectric loss factor (tan ) δ .…”

“…Here, we deal with the most recent experimental study [22] that refers to multiphased mixed crystals of NaBr and KBr. In this study, Padma and Mahadevan [22] achieved the preparation of mixed crystals (Na x K 1-x Br) of NaBr and KBr from melts and their X-ray diffraction analysis indicated the existence of two phases in the mixed crystals.…”

“…This nonlinearity is found to increase with the increase in temperature in the dc , σ , ε tan δ and ac σ values. In particular, Padma and Mahadevan [22] plotted each of these parameters versus the composition x and a maximum was identified at x = 0.4 (see their Figs. [5][6][7][8].…”