Refractive indices of (NH{sub 4}){sub 2}SO{sub 4} crystals under uniaxial pressure

Journal Article · Sun Mar 15 04:00:00 EDT 2009 · Crystallography Reports

DOI:https://doi.org/10.1134/S1063774509020229· OSTI ID:22050845

Romanyuk, M O ^[1]; Andrievskii, B V ^[2]; Tuzyak, N R ^[1]

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1. Franko National University of Lviv (Ukraine)
2. Koszalin University of Technology (Poland)

The effect of uniaxial pressure {sigma}{sub m} {<=} 200 bar on the spectral (300-800 nm) and temperature (300-77 K) dependences of the refractive indices of(NH{sub 4}){sub 2}SO{sub 4} crystals has been investigated. The baric dependences of the electronic polarizability, specific refraction, and parameters of the Sellmeier formula have been calculated. It is established that uniaxial pressure increases the refractive indices, mainly because of the narrowing of the band gap, increase in the oscillator density, and redshift of the UV absorption band maximum. The anomalies arising as a result of ferroelectric phase transition are related to the occurrence of spontaneous deformation and polarization (the latter is a superposition of two sublattice polarizations). The spectral and temperature dependences of the piezooptic constants are analyzed and the values of electro-optic coefficients are estimated.

• OSTI ID: 22050845
• Journal Information: Crystallography Reports, Journal Name: Crystallography Reports Journal Issue: 2 Vol. 54; ISSN CYSTE3; ISSN 1063-7745
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
AMMONIUM SULFATES
CRYSTALS
DEFORMATION
ENERGY ABSORPTION
FERROELECTRIC MATERIALS
OSCILLATORS
PHASE TRANSFORMATIONS
POLARIZABILITY
POLARIZATION
RED SHIFT
REFRACTION
REFRACTIVE INDEX
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K