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...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, Mr = 719.46, Dc = 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]n4n- 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.展开更多
Green-photoluminescence material Zn4B6O13: Ce3+, Tb3+ was first synthesized by spread method of high temperature and solid state reaction, which is cubic crystal system with lattice parameters: a(0) = 0.7472 nm, V = 0...Green-photoluminescence material Zn4B6O13: Ce3+, Tb3+ was first synthesized by spread method of high temperature and solid state reaction, which is cubic crystal system with lattice parameters: a(0) = 0.7472 nm, V = 0.4172 nm(3), and structural properties are investigated by XRD. The excitation and emission band of Ce3+ ion single-doped in Zn4B6O13 transfer longer spectra 2.38 similar to 4.94 kk than in other matrices. Emission band of Ce3+ ion better overlaps with the F-7(6)-->(5)G(2),D-5(1),H-5(7) absorption band of Tb3+. It shows that emission of Tb3+ ion is sensitized by Ce3+. In Zn4B6O13:Ce3+, Tb3+, it is due to the energy transfer mechanism, resonance transfer of electric multipolar interaction of the dipole-dipole between Ce3+-->Ce3+ and Ce3+-->Tb3+. The color coordinates of Zn4B6O13: X 0.281, gamma = 0.619. The mean diameter of the particles is 0.23 mum.展开更多
The hydrostatic-pressure-dependent mechanical stability and optoelectronic behavior of Zn_4B_6O_（13）（ZBO） are calculated using the exchange-correlation functional Perdew–Burke–Ernzerhof generalized gradient appr...The hydrostatic-pressure-dependent mechanical stability and optoelectronic behavior of Zn_4B_6O_（13）（ZBO） are calculated using the exchange-correlation functional Perdew–Burke–Ernzerhof generalized gradient approximation and the hybrid functional PBE0 based on density functional theory. The calculated and experimental unit cell volumes and Vickers hardness of ZBO at zero pressure agree well. ZBO is mechanically stable under the critical pressure of 52.98 GPa according to the generalized stability criteria. Furthermore, Young＇s modulus and Vickers hardness decrease with increasing hydrostatic pressure. The strength and type of ZBO bonds are investigated by population and electron density difference. The electronic structure at zero pressure reveals that ZBO is an indirect band gap semiconductor, and the calculated 5.62-e V bandgap coincides well with the 5.73-e V experimental value, highlighting the success of the hybrid functional PBE0 calculations of electronic properties. The band gap almost increases as a second-order polynomial of pressure, and the indirect nature does not change with the applied external pressure. The optical reflectivity and absorption coefficient show that ZBO is an excellent ultraviolet photodetector. Our calculation results suggest that the elastic and optical properties of ZBO are highly stable over a wide pressure range.展开更多
基金Supported by the National Natural Science Foundation of China(No.20871012)
文摘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, Mr = 719.46, Dc = 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]n4n- 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.
文摘Green-photoluminescence material Zn4B6O13: Ce3+, Tb3+ was first synthesized by spread method of high temperature and solid state reaction, which is cubic crystal system with lattice parameters: a(0) = 0.7472 nm, V = 0.4172 nm(3), and structural properties are investigated by XRD. The excitation and emission band of Ce3+ ion single-doped in Zn4B6O13 transfer longer spectra 2.38 similar to 4.94 kk than in other matrices. Emission band of Ce3+ ion better overlaps with the F-7(6)-->(5)G(2),D-5(1),H-5(7) absorption band of Tb3+. It shows that emission of Tb3+ ion is sensitized by Ce3+. In Zn4B6O13:Ce3+, Tb3+, it is due to the energy transfer mechanism, resonance transfer of electric multipolar interaction of the dipole-dipole between Ce3+-->Ce3+ and Ce3+-->Tb3+. The color coordinates of Zn4B6O13: X 0.281, gamma = 0.619. The mean diameter of the particles is 0.23 mum.
基金Project supported by the National Natural Science Foundation of China(Grant No.51171156)
文摘The hydrostatic-pressure-dependent mechanical stability and optoelectronic behavior of Zn_4B_6O_（13）（ZBO） are calculated using the exchange-correlation functional Perdew–Burke–Ernzerhof generalized gradient approximation and the hybrid functional PBE0 based on density functional theory. The calculated and experimental unit cell volumes and Vickers hardness of ZBO at zero pressure agree well. ZBO is mechanically stable under the critical pressure of 52.98 GPa according to the generalized stability criteria. Furthermore, Young＇s modulus and Vickers hardness decrease with increasing hydrostatic pressure. The strength and type of ZBO bonds are investigated by population and electron density difference. The electronic structure at zero pressure reveals that ZBO is an indirect band gap semiconductor, and the calculated 5.62-e V bandgap coincides well with the 5.73-e V experimental value, highlighting the success of the hybrid functional PBE0 calculations of electronic properties. The band gap almost increases as a second-order polynomial of pressure, and the indirect nature does not change with the applied external pressure. The optical reflectivity and absorption coefficient show that ZBO is an excellent ultraviolet photodetector. Our calculation results suggest that the elastic and optical properties of ZBO are highly stable over a wide pressure range.
