Thermal expansion,pyroelectricity and linear optical properties of Li2SeO4·H2O and Li2SO4·H2O

Large single crystals of polar Li₂SeO₄·H₂O were grown at 343 K from aqueous solution. Temperature dependent thermal expansion coefficients of Li₂SeO₄·H₂O and Li₂SO₄·H₂O were determined within the temperature range 133 K–313 K and coefficients of the pyroelectric effect within the temperature range 183–343 K. Refractive indices between 365 nm and 1530 nm as well as unpolarized absorption spectra of Li₂SeO₄·H₂O and Li₂SO₄·H₂O were measured and phase‐matching curves for second harmonic generation were calculated. Both compounds allow type I and type II phase‐matching at wavelengths from about 650 nm to the near infrared region. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)