Tianliang Zhou

Band gap calculation and photo catalytic activity of rare earths doped rutile TiO2

Abstract The density of states (DOS) of 17 kinds of rare earths (RE) doped rutile TiO2 was by using first-principles density functional theory (DFT) calculation. The band gap widths of RE doped rutile TiO2 were important factors for altering their absorbing wavelengths. The results show that RE ions could obviously reduce the band gap widths and form of energy of rutile TiO2 except Lu, Y, Yb and Sc, and the order of absorbing wavelengths of RE doped rutile TiO2 were the same as that of the results of calculation. The ratio of RE dopant was another important factor for the photo catalytic activity of RE doped rutile TiO2, and there was an optimal ratio of dopant. There was a constant for predigesting the calculation difficulty, respectively, which were 0.5mol.% and 100 mol−1 under supposition. The band gap widths of RE doped rutile TiO2 by DFT calculation were much larger than that by experiment. Finally, by transferring the calculation values to experiment values, it could be found and predicted that RE enlarged obviously the absorbing wavelengh of rutile TiO2. In addition, the degree of RE ions edging out the Ti atom using the parameters of RE elements was computed.

Surface ζ potential and photocatalytic activity of rare earths doped TiO2

The iso-electric point of different rare earths (La, Ce, Y) doped anatase TiO2 was set out, and three organisms with different sur- face electrical properties (methylene blue trihydrate-positive electricity, methyl orange-negative electricity, methyl red-neutral electricity) were selected as photodegradable models. The result showed that the photocatalytic activity of 0.5wt.%Y ions doped anatase TiO2 was better than those of the others. The relationship between Zeta (ζ) potential and the photocatalytic activity of different RE doped anatase TiO2 were also investigated. The Y-doped anatase TiO2 was found with the special two iso-electric points and three ζ potential values.

The Synthesis and Luminescence Properties of a Red Phosphor Material (Ca1−xEux)3Al2O6

(Ca 1―x Eu x ) 3 Al 2 O 6 , a red light-emitting phosphor with the excitation of purple-blue light, was prepared by traditional solid reaction method with reducing atmosphere at 1350°C for 4 h in a tube furnace. CaEuAlO 4 emerged as an impurity phase when the content of Eu, x, in (Ca 1―x Eu x ) 3 Al 2 O 6 exceeds 0.03. Furthermore, the content of CaEuAlO 4 rises with Eu concentration. A strong excitation band centering at 467 nm and a broad emission band centering at 650 nm have been discovered in this phosphor, making it possible to manufacture a bargain price white light LEDs with high CRI.

Synthesis and luminescence properties of europium activated Ca3Al2O6-Sr3Al2O6 system

Abstract Divalent europium activated tristrontium dialuminum hexaoxide phosphor, (Sr 1- x Eu x ) 3 Al 2 O 6 , was obtained by solid state reaction. Crystal structure and luminescence properties of synthesized (Sr 1- x Eu x ) 3 Al 2 O 6 were investigated. The major excitation band of (Sr 1- x Eu x ) 3 Al 2 O 6 located in blue light region, the photoluminescence spectrum showed red light emission peaked at 618 nm which could be attributed to the d-f transition of the Eu 2+ . The influence of Ca 2+ substitution for Sr 2+ on structural and luminescence properties of Eu 2+ doped Sr 3 Al 2 O 6 was also studied. The photoluminescence peak position of (Sr 1- y Ca y ) 2.94 Eu 0.06 Al 2 O 6 varied from 618 to 655 nm with increasing y value. The reason for redshift in the emission band of (Sr 1- y Ca y ) 2.94 Eu 0.06 Al 2 O 6 phosphor was also discussed.

Photo Catalytic Activity of Rare Earth La(Y)/Rutile TiO2

The rutile TiO2, La/rutile TiO2 and Y/rutile TiO2 were synthesized by one-step method, and the densities of states were investigated by ab initio method. Firstly, the result of ab initio calculation showed that the band gap of La/rutile TiO2 is less than that of Y/rutile TiO2 and rutile TiO2, and the crystal lattice energy of rare earths (La, Y)/rutile TiO2 are similar to each other. Secondly, the crystal structure and photocatalytic activity of La (Y)/rutile TiO2 are characterized by XRD, DRS, ζ potential and kinetics reaction of photocatalyzing methyl orange. In a word, the photocatalytic activity for degradation of methyl orange on 1.0wt% La/rutile TiO2 was better than those on Y/rutile TiO2 and rutile TiO2.