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Optical Absorption of Ferroelectrical Copper and Chromium Boracites
Author(s) -
Nesterova N. N.,
Pisarev R. V.,
Andreeva G. T.
Publication year - 1974
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2220650108
Subject(s) - tetragonal crystal system , copper , analytical chemistry (journal) , absorption spectroscopy , absorption edge , absorption band , ion , absorption (acoustics) , oscillator strength , materials science , phase transition , chromium , crystal (programming language) , single crystal , spectral line , chemistry , crystal structure , crystallography , condensed matter physics , band gap , optics , physics , programming language , optoelectronics , organic chemistry , chromatography , astronomy , computer science , metallurgy , composite material
Optical absorption spectra of ferroelectrical boracites Cr 3 B 7 O 13 Cl, Cu 3 B 7 O 13 Cl, Cu 3 B 7 O 13 Cl, Cu 3 B 7 O 13 Br, and also borate CuB 2 O 4 were studied in the spectral range from 2000 to 30000 cm −1 in the temperature interval 77 to 450 °K. The interpretation of the spectra are given on the basis of the crystal field theory including tetragonal distortion of the local environment of 3d‐ions in the lattice. The temperature dependence of the oscillator strength of the absorption band and absorption coefficient at a fixed frequency were investigated around the temperature of the ferroelectric phase transition in the copper boracites. The results show that the absorption is very sensitive to the displacement of the ions in the crystal lattice at the phase transition. For CuCl boracite a change of the slope of the temperature dependence of the absorption near the fundamental absorption edge was observed.