On Isotropic Points in K2SO4 Impurity Crystals

摘要

The temperature, spectral and baric dependences of birefringence Delta n(i) of potassium sulfate crystals doped with 1.7% of copper are studied. It is established that the impurity introduction changes an absolute value of Delta n(i) and leads to an increase of the temperature dependence Delta n(i)(T). It is shown that the isotropic points, which are shifted towards low temperatures by 5 and 11 K, respectively, compared to a pure crystal, appear in a doped potassium sulfate crystal. It is established that uniaxial stresses change the magnitude of absolute values of Delta n(i), as well as the domain of existence of the isotropic state. The generalized temperature-spectral-baric diagrams of the isotropic state of a doped potassium sulfate crystal are plotted, which make it possible to use them as a crystallooptic sensor.