Space symmetry of effective physical constants for biaxial crystals

In eight quadrants, the positive and negative signs of tensor components describing physical properties of biaxial crystals have been given. The distributions of the physical properties described with different order tensors and their space symmetries have been discussed. These results show that the distributions of effective physical constants are symmetrical in the eight quadrants for the orthorhombic system, but there are two and four kinds of distributions for monoclinic and triclinic systems respectively. Thence, to avoid ambiguities and difficulties in characterizing and applying properties of biaxial crystals, we suggest that the really positive directions of the coordinate axes should be defined before the measurements of their physical properties and their device applications.