Концентраційні залежності діелектричних параметрів домішкових кристалів K2SO4

• Дата: 2022
• Автори: Stadnyk, V.Yo., Shchepanskyi, P.A., Rudysh, M.Ya., Matviiv, R.B., Brezvin, R.S.
• Формат: Стаття
• Мова: English; Ukrainian
• Опубліковано: Publishing house "Academperiodika" 2022
• Теми: кристал; домiшка; показник заломлення; двопроменезаломлення; елементарна комiрка; зонно-енергетична структура; заборонена зона
• Онлайн доступ: https://ujp.bitp.kiev.ua/index.php/ujp/article/view/2022242
• Назва журналу: Ukrainian Journal of Physics

The influence of a copper impurity with various concentrations on the unit cell parameters, band-energy structure, and refractive characteristics of potassium sulfate crystals has been studied. The unit-cell parameters and volume of impurity-doped crystals are found to increase almost linearly with the growth of the impurity content. At the same time, the refractive indices ni (i = x, y, z) of doped crystals slightly decrease (by about 2.5 × 10−3), but the relations nz > nx > ny and dnz /dλ > dnx/dλ > dny /dλ between them remain unchanged. The energy band structure of crystals with a copper content of 1.7% is calculated. It is found that the forbidden gap decreases, as the impurity concentration increases. Five localized levels corresponding to d-electron states of Cu2+ impurity ions are identified in the band gap. It is established that the top of the valence band is formed by the oxygen p-states, and the bottom of the conduction band by the 3s- and 4s-states of the sulfur and potassium atoms. The localized 4s-states of copper atoms are located at the bottom of the conduction band. The concentration dependences of the density and ionic radius are analyzed.