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Journal of Physical Studies 7(3), 349–352 (2003)
DOI: https://doi.org/10.30970/jps.07.349 CRYSTAL OPTICAL STUDY OF INCOMMENSURATE PHASE IN LiRbSO4V. Yo. Stadnyk, M. O. Romanyuk, L. T. Karplyuk
Ivan Franko National University of Lviv,
Department for Experimental Physics |
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The temperature changes of the linear expansion $Δ l/l_i$, the refractive indices $n_c$ and the piezooptical constants $π_{ij}$ of $\rm LiRbSO_4$ (LRS) crystals are measured in the regions of the paraelectric-incommensurate-commensurate-ferroelectric-paraelectric phase transitions. Considerable anomalies of $Δ l/l_i(T)$, $n_c(T)$ and $π_{ij}(T)$ are revealed at those transitions. It is shown that the $n_i(T)$ changes in the incommensurate phase of LRS are associated with the order parameter and the spontaneous strain changes. Under lowering temperature within the commensurate phase, the contributions from the spontaneous quadratic electrooptical effect become overwhelming, while the contributions from the order parameter decrease to zero. The existence of a metastable chaotic state in the temperature region 475-468 K is assumed.
PACS number(s): 78.20.Ci, 78.20.Hp, 64.70.Kb, 64.70.Rh