Synthesis and Characterization of a New Barium Aluminoborate, Ba₂Al₄B₆O₁₇

【摘要】 A new barium aluminoborate, Ba₂Al₄B₆O₁₇, has been synthesized by the hightemperature solution reaction at 780 ℃. The single-crystal XRD analysis shows that it crystallizes in triclinic space group P■ with a = 8.9601（5）, b = 9.1835（6）, c = 10.6574（7） ?, a = 95.050（6）°, b = 111.569（5）°, g = 90.280（6）°, V = 811.71（9） ?³, Z = 2, M_r = 719.46, D_c = 2.944 g/cm³, μ = 5.127 mm^-1, F（000） = 660, R = 0.0361 and wR = 0.0855 for 3846 observed reflections and 262 variables. This compound represents a new structure that features a three-dimensional [Al₄B₆O₁₇]_n^4n- framework constructed by AlO₄ tetrahedra, BO₃ triangles, and B₂O₅₄-groups composed of two corner-sharing BO₃ triangles, with intersecting open channels accommodating Ba²⁺ cations. It melts incongruently at 849 ℃. The existence of BO₃ groups is confirmed by FT-IR and Raman spectra. The insulating nature with an optical band gap of about 3.50 eV is revealed by UV-VIS diffuse reflectance spectrum. Band structure calculations indicate that it is an indirect band material.更多还原

【Abstract】 A new barium aluminoborate, Ba₂Al₄B₆O₁₇, has been synthesized by the hightemperature solution reaction at 780 ℃. The single-crystal XRD analysis shows that it crystallizes in triclinic space group P■ with a = 8.9601（5）, b = 9.1835（6）, c = 10.6574（7） ?, a = 95.050（6）°, b = 111.569（5）°, g = 90.280（6）°, V = 811.71（9） ?³, Z = 2, M_r = 719.46, D_c = 2.944 g/cm³, μ = 5.127 mm^-1, F（000） = 660, R = 0.0361 and wR = 0.0855 for 3846 observed reflections and 262 variables. This compound represents a new structure that features a three-dimensional [Al₄B₆O₁₇]_n^4n- framework constructed by AlO₄ tetrahedra, BO₃ triangles, and B₂O₅₄-groups composed of two corner-sharing BO₃ triangles, with intersecting open channels accommodating Ba²⁺ cations. It melts incongruently at 849 ℃. The existence of BO₃ groups is confirmed by FT-IR and Raman spectra. The insulating nature with an optical band gap of about 3.50 eV is revealed by UV-VIS diffuse reflectance spectrum. Band structure calculations indicate that it is an indirect band material.更多还原