A　novel　quaternary　borate,　dipotassium　sodium　zinc　pentaborate.　K2NaZnB5O10,　has　been　prepared　by　high-temperature　solution　reaction　at　temperature　below　780　C.　Single-crystal　XRD　analyses　showed　that　it　crystallizes　in　the　monoclinic　C2/c　group　with　a　=　7.9244　(16)　angstrom,　b　=　12.805　(3)　angstrom,　c　=　18.962　(4)　angstrom,　beta　=　99.39　(3)degrees,　z　=　8.　The　crystal　structure　is　composed　of　double　ring　[B5O10](5-)　and　tetrahedral　ZnO4　groups　that　are　linked　to　form　a　two-dimensional　(2)infinity　[ZnB5O10](3-)　layer　by　sharing　O　vertices.　The　layers　are　stacked　along　the　c-axis,　with　the　interlayer　void　spaces　filled　by　K+　and　intralayer　open　channels　occupied　by　Na+　cations　to　balance　charge.　The　IR　spectrum　further　confirmed　the　presence　of　both　BO3　and　BO4　groups,　UV-vis　diffuse　reflectance　spectrum　showed　a　band　gap　of　about　3.1　eV.　Solid-state　fluorescence　spectrum　was　also　investigated　exhibiting　the　maximum　emission　peak　at　around　387.4　nm.　Band　structure　calculations　indicated　that　the　compound　is　an　indirect　semiconductor　with　the　calculated　band　gap　close　to　the　observed　one.　(C)　2009　Elsevier　B.V.　All　rights　reserved.