By utilizing the electrorheological effect, three-dimensional colloidal crystals can be produced, whose lattice struc-ture can be changed from the body-centered-tetragonal lattice to other lattices under the application of electric fields. This paper calculates photonic band structures of such crystals with lattice structure transformation, and demonstrates the existence of complete band gaps for some intermediate lattices. Thus, it becomes possible to use the electrorheo-logical effect to achieve photonic crystals with desired photonic gap properties resulting from tunable structures.
