A novel monoclinic phase of impurity-doped CaGa(2)S(4) as a phosphor with high emission intensity.

In the solid-state synthesis of impurity-doped CaGa(2)S(4), calcium tetra-thio-digallate(III), a novel phosphor material (denominated as the X-phase), with monoclinic symmetry in the space group P2(1)/a, has been discovered. Its emission intensity is higher than that of the known ortho-rhom-bic polymorph of CaGa(2)S(4) crystallizing in the space group Fddd. The asymmetric unit of the monoclinic phase consists of two Ca, four Ga and eight S sites.