Optics and phase relationships of the optically anisotropic C 3A

Abstract

The birefringence (γ−β) of each optically anisotropic variety of C 3A has been measured as a function of temperature in monochromatic light of different wavelengths. The orthorhombic phase remains structurally unchanged up to the decomposition temperature, and the orientation of the optic axial plane and dispersion of 2V X change during heating. The optic orientation and dispersion type of the monoclinic phase above the transition point indicate that this phase transforms reversibly into the orthorhombic phase.