The Eu-doped SiO2-B2O3-NaF glass was prepared by sol-gel process, using tetraethoxy Silicane, boric acid and sodium fluoride as starting materials, 0.10 mol·L-1 EuCl3 solution as the dopant. The luminescent prope...The Eu-doped SiO2-B2O3-NaF glass was prepared by sol-gel process, using tetraethoxy Silicane, boric acid and sodium fluoride as starting materials, 0.10 mol·L-1 EuCl3 solution as the dopant. The luminescent properties of Eu3+ doped SiO2-B2O3-NaF phosphors were investigated. The phosphors showed prominent luminescence in pink, the strong emission of Eu3+ comes from electronic transition of 5D0-7F1(591 nm)and 5D0-7F2(615 nm),which derived from two transition modes of magnetic-dipole and electric-dipole .The peak intensity of 591nm in SiO2-B2O3-NaF matrix is much stronger than it in the other matrixes, it means that SiO2-B2O3-NaF has sensitization on the transition of 5D0-7F1 (Eu3+). If there are broad bonds in the range of 275~380 nm in the excitation spectrum of Eu3+ -doped SiO2-B2O3-NaF glass, the emission peak intensity should be intensified. It is because the electron migration CT band of O2--Eu3+. For all Eu3+ concentrations used, the investigation found that when the mass of fraction got to 29.19×10-3, the luminescence intensity reached the summit. And there is a phenomenon of concentration quenching. Investigation with the same concentration of Eu3+ at different annealed temperature, we found that the sample annealed at 400 ℃, the luminescence intensity achieved its maximum value, and Eu3+ in this matrix had a phenomenon of temperature quenching. The structural characterization of these luminescent materials was carried by used XRD and TEM. The result showed that the phosphor was in amorphous phase.展开更多
ZrO2-mullite nano-ceramics were fabricated by in-situ controlled crystallizing from SiO2-Al2O3-ZrO2 amorphous bulk. The thermal transformation sequences of the SiO2-Al2O3-ZrO2 amorphous bulk were investigated by X-ray...ZrO2-mullite nano-ceramics were fabricated by in-situ controlled crystallizing from SiO2-Al2O3-ZrO2 amorphous bulk. The thermal transformation sequences of the SiO2-Al2O3-ZrO2 amorphous bulk were investigated by X-ray diffraction, infrared spectrum, scanning electron microscope and differential scanning calorimetric. And the mechanical properties of the nano-ceramics were studied. The results show that the bulks are still in amorphous state at 900 ℃ and the t-ZrO2 forms at about 950 ℃ with a faint spinel-like phase which changes into mullite on further heating. ZrO2 and mullite become major phases at 1 100 ℃ and an amount of m-ZrO2 occur at the same time. The sample heated at 950 ℃ for 2 h and then at 1 100 ℃ for 1 h shows very dense and homogenous microstructure with ball-like grains in size of 20-50 nm. With the increase of crystallization temperature up to 1 350 ℃, the grains grow quickly and some grow into lath-shaped grains with major diameter of 5 μm. After two-step treatment the highest micro-hardness, flexural strength and fracture toughness of the samples are 13.72 GPa, 520 MPa and 5.13 MPa·m1/2, respectively.展开更多
摘要The Eu-doped SiO2-B2O3-NaF glass was prepared by sol-gel process, using tetraethoxy Silicane, boric acid and sodium fluoride as starting materials, 0.10 mol·L-1 EuCl3 solution as the dopant. The luminescent properties of Eu3+ doped SiO2-B2O3-NaF phosphors were investigated. The phosphors showed prominent luminescence in pink, the strong emission of Eu3+ comes from electronic transition of 5D0-7F1(591 nm)and 5D0-7F2(615 nm),which derived from two transition modes of magnetic-dipole and electric-dipole .The peak intensity of 591nm in SiO2-B2O3-NaF matrix is much stronger than it in the other matrixes, it means that SiO2-B2O3-NaF has sensitization on the transition of 5D0-7F1 (Eu3+). If there are broad bonds in the range of 275~380 nm in the excitation spectrum of Eu3+ -doped SiO2-B2O3-NaF glass, the emission peak intensity should be intensified. It is because the electron migration CT band of O2--Eu3+. For all Eu3+ concentrations used, the investigation found that when the mass of fraction got to 29.19×10-3, the luminescence intensity reached the summit. And there is a phenomenon of concentration quenching. Investigation with the same concentration of Eu3+ at different annealed temperature, we found that the sample annealed at 400 ℃, the luminescence intensity achieved its maximum value, and Eu3+ in this matrix had a phenomenon of temperature quenching. The structural characterization of these luminescent materials was carried by used XRD and TEM. The result showed that the phosphor was in amorphous phase.
基金Project(2003AA332040) supported by the National High Technology Research and Development Program of China
摘要ZrO2-mullite nano-ceramics were fabricated by in-situ controlled crystallizing from SiO2-Al2O3-ZrO2 amorphous bulk. The thermal transformation sequences of the SiO2-Al2O3-ZrO2 amorphous bulk were investigated by X-ray diffraction, infrared spectrum, scanning electron microscope and differential scanning calorimetric. And the mechanical properties of the nano-ceramics were studied. The results show that the bulks are still in amorphous state at 900 ℃ and the t-ZrO2 forms at about 950 ℃ with a faint spinel-like phase which changes into mullite on further heating. ZrO2 and mullite become major phases at 1 100 ℃ and an amount of m-ZrO2 occur at the same time. The sample heated at 950 ℃ for 2 h and then at 1 100 ℃ for 1 h shows very dense and homogenous microstructure with ball-like grains in size of 20-50 nm. With the increase of crystallization temperature up to 1 350 ℃, the grains grow quickly and some grow into lath-shaped grains with major diameter of 5 μm. After two-step treatment the highest micro-hardness, flexural strength and fracture toughness of the samples are 13.72 GPa, 520 MPa and 5.13 MPa·m1/2, respectively.