Synthesis, structure characterization and optical properties of a new tripotassium cadmium pentaborate, K3CdB5O10

A new ternary borate oxide, K3CdB5O10, has been synthesized by solid-state reaction at 580 °C. The compound crystallizes in the monoclinic space group P21/n with a=7.6707 (7) Å, b=19.1765 (17) Å, c=7.8784 (6) Å, β=115.6083 (49)°, and Z=4. The crystal structure consists of a two-dimensional infinite [CdB5O10] layer, which forms by connecting isolated double ring [B5O10] groups and CdO4 tetrahedra. K atoms filling in the interlayer and intralayer link the layers together and balance charge. The IR spectrum has been studied and confirmed the presence of both BO3 and BO4 groups, and the UV–vis-IR diffuse reflectance spectrum exhibits a band gap of about 3.4 eV. The DSC analysis proves that K3CdB5O10 is a congruent melting compound.