On Isotropic Points in Potassium Ammonium Sulphate Crystals

V. Yo. Stadnyk; P. A. Shchepanskyi; R. S. Brezvin; M. Ya. Rudysh; Z. A. Kohut; O. R. Onufriv; Ya. P. Kost

doi:10.1134/S1063774519050201

On Isotropic Points in Potassium Ammonium Sulphate Crystals

Authors: Stadnyk V.Y.¹, Shchepanskyi P.A.¹^,2, Brezvin R.S.¹, Rudysh M.Y.¹^,2, Kohut Z.A.³, Onufriv O.R.⁴, Kost Y.P.⁵
Affiliations:
1. Ivan Franko Lviv National University
2. Jan Dlugosz University in Czestochowa, 42-200
3. Lviv Polytechnic National University
4. Ukranian National Forestry University
5. Karpenko Physico–Mechanical Institute of the National Academy of Sciences of Ukraine
Issue: Vol 64, No 5 (2019)
Pages: 787-792
Section: Physical Properties of Crystals
URL: https://journals.rcsi.science/1063-7745/article/view/194223
DOI: https://doi.org/10.1134/S1063774519050201
ID: 194223

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Abstract
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Abstract

An effect of uniaxial pressure on the spectral and temperature dependences of birefringence of K_1.75[NH₄]_0.25SO₄ single crystals has been studied. Different changes in the birefringence are found for different compression directions. The possibility of the occurrence of isotropic points in the crystal under uniaxial compression is discussed. A decrease in the birefringence under crystal heating is established, and the positions of two isotropic points in the range of 290–630 K are determined. The partial isomorphic substitution of NH₄ ions for K ions was found to result in a shift of isotropic points to lower temperatures.

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On Isotropic Points in Potassium Ammonium Sulphate Crystals

Full Text

Abstract

About the authors

V. Yo. Stadnyk

P. A. Shchepanskyi

R. S. Brezvin

M. Ya. Rudysh

Z. A. Kohut

O. R. Onufriv

Ya. P. Kost

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