Edge-sharing T2 supertetrahedra in Li _11.2(1) Ba ₂ Al _3.6(1) O ₁₃ , Li _10.0(1) Ba ₂ Al _4.0(1) O ₁₃ , and Li _7.9(1) Ba ₂ Al _4.7(1)

Abstract The structurally related compounds with the empirical formulæ Li 11.2(1) Ba 2 Al 3.6(1) O 13 ( 1 ), Li 10.0(1) Ba 2 Al 4.0(1) O 13 ( 2 ), and Li 7.9(1) Ba 2 Al 4.7(1) O 13 ( 3 ) have been synthesized by conventional solid-state synthesis. The crystal structures were solved and refined in the trigonal space group P 3‾ m 1 (no. 164) with the chemical compositions derived from single-crystal X-ray diffraction data. The lattice parameters have been refined to a = 6.0399(1) Å, c = 10.1264(4) Å, V = 319.92(2) Å 3 for 1 , a = 6.0505(2) Å, c = 10.1272(4) Å, V = 321.07(2) Å 3 for 2 , and a = 6.0436(1) Å, c = 10.1762(3) Å, V = 321.89(2) Å 3 for 3 . A common structure with a three-dimensional tetrahedron substructure is constructed from (Li/Al)O 4 and AlO 4 tetrahedra, coined by edge-sharing T2 supertetrahedra and sechser -rings. Upon blue-light excitation ( λ exc = 448 nm), broad-band emissions are observed for the Eu 2+ -activated compounds with a peak wavelength of λ em ∼ 563 nm and a full width at half maximum of FWHM ∼ 141 nm (0.56 eV, 4,534 cm −1 ) for 1 , λ em ∼ 526 nm with a FWHM ∼ 98 nm (0.45 eV, 3,637 cm −1 ) for 2 , and λ em ∼ 549 nm with a FWHM ∼ 151 nm (0.63 eV, 5,052 cm −1 ) for 3 .