Two　alkali-metal　zinc　borates,　alpha-LiZnBO3　and　Li0.48Na0.52ZnBO3,　have　been　prepared　by　solid-state　reactions　below　850　degrees　C.　Single-crystal　XRD　analyses　showed　that　the　former　crystallizes　in　the　C2/c　group　with　a　=　8.746(2)　angstrom,　b　=　5.091　(1)　angstrom,　c　=　6.129(1)　angstrom,　beta　=　118.75(3)degrees,　Z　=　4　and　the　latter　in　the　group　P　(1)　over　bar　with　a　=　5.054(1)　angstrom,　b　=　6.113(1)　angstrom,　c　=　8.045(2)　angstrom,　alpha　=　75.73(2)degrees,　beta　=　89.87(3)degrees,　gamma　=　89.86(3)degrees,　Z　=　4.　The　crystal　structure　of　alpha-LiZnBO3　is　composed　of　tetrahedral　ZnO4　and　triangular　BO3　groups　that　are　arranged　into　a　three-dimensional　(3D)　network　by　sharing　O　vertices.　Li0.48Na0.52ZnBO3　is　also　characterized　by　a　3D　framework,　but　built　up　from　corner-sharing　ZnO4　tetratahedra,　ZnO5　trigonal　bipyramids,　and　BO3　triangles.　Both　structures　afford　open　channels　that　are　occupied　by　alkali-metal　cations.　The　IR　spectra　further　confirmed　the　presence　of　BO3　groups　and　UV-vis　diffuse　reflectance　spectra　showed　band　gaps　of　about　3.10　and　2.95　eV　for　the　Li　and　Li/Na　compounds,　respectively.　Band　structure　calculations　indicated　that　both　compounds　are　direct　semiconductors　with　the　calculated　band　gaps　close　to　the　observed　ones.　(C)　2009　Elsevier　Masson　SAS.　All　rights　reserved.