A　new　barium　potassium　zincoborate,　Ba4K2Zn5(B3O6)(3)(B9O19),　has　been　synthesized　by　high-temperature　solution　reaction　at　750　degrees　C.　Its　crystal　structure　was　established　by　single-crystal　X-ray　diffraction.　The　compound　crystallizes　in　the　monoclinic　space　group　P2(1)/n　(No.　14)　with　cell　parameters　of　a　=　7.1620(14)　angstrom,　b　=　38.772(8)　angstrom,　c　=　12.360(3)　angstrom,　beta　=　90.26(3)degrees,　V　=　3432.2(12)　angstrom(3),　and　Z　=　4.　It　has　a　new　structure　type　that　features　two-dimensional　(2)(infinity)[Zn-5(B3O6)(3)(B9O19)](10-)　anionic　layers　composed　of　ZnO4　tetrahedra,　[B3O6](3-)　rings　with　notation　of　3[3　Delta],　and　[B9O19](11-)　groups　with　notation　of　3　[2　Delta　+　1T]　+　3　Delta　+　3[2　Delta　+　1T],　where　Delta　and　T　represent　BO3　triangles　and　BO4　tetrahedra,　respectively.　The　zinc　borate　anionic　layers　stack　along　b-axis,　with　the　intralayer　open　channels　and　interlayer　void　spaces　filled　by　Ba2+,　K+,　or　Ba2+/K+　cations　to　compensate　the　negative　charges　of　the　layers.　Infrared　spectrum　was　measured,　which　confirms　the　presence　of　both　BO3　and　BO4　groups.　The　optical　properties　were　investigated　in　terms　of　diffuse　reflectance　and　fluorescence　spectra,　which　reveal　an　optical　band　gap　of　3.18　eV　as　well　as　a　broad　emission　band　at　around　515.8　nm　upon　laser　excitation　at　325　nm.　(C)　2013　Elsevier　Masson　SAS.　All　rights　reserved.