Browsing by Author "Chen, Kuei-Bo"

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Direct Synthesis of Zr-Doped Ceria Nanotubes
(2009-04-02)
Chen, Ying-Chen
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Chen, Kuei-Bo
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Lee, Chi-Shen
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Lin, M. C.
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應用化學系
Zr-doped ceria nanotuhes (Zr(x)Ce(1-x)O(2)) Were obtained in a high yield from a hydrothermal reaction in an aqueous solution of NaOH with Ce(NO(3))(3)center dot 6H(2)O and ZrO(2) powder in a small proportion. The morphology and crystalline structure were characterized with X-ray diffraction, a scanning electron microscope, and a transmission electron microscope. Mechanisms for the growth of Zr-doped ceria nanotubes are proposed based oil the Kirkendall effect, the formation of the tubular structure is strongly dependent oil the precursor. This is the first report of a direct synthesis of cerium-oxide nanotubes in high yield. The surface area of the nanotubes is 76 m/g and their average pore size is similar to 52.2 nm, Catalytic measurements show that the nanotubes as synthesized are active for an oxygen-storage capacity and for ethanol reforming.
Enhanced catalytic activity of Ce(1-x)M(x)O(2) (M = Ti, Zr, and Hf) solid solution with controlled morphologies
(2010-01-01)
Chen, Wei-Ta
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Chen, Kuei-Bo
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Wang, Ming-Fang
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Weng, Sheng-Feng
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Lee, Chi-Shen
Ce(1-x)M(x)O(2) (M = Ti, Zr, and Hf) nanomaterials with controlled morphology and composition were synthesized by a two-step route for the first time. These nanomaterials exhibit high activities for hydrogen reduction and ethanol reforming reactions, and therefore, they may be useful for applications in catalysis and solid oxide fuel cells.
Enhanced catalytic activity of Ce1-xMxO2 (M = Ti, Zr, and Hf) solid solution with controlled morphologies
(2010-01-01)
Chen, Wei-Ta
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Chen, Kuei-Bo
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Wang, Ming-Fang
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Weng, Sheng-Feng
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Lee, Chi-Shen
Ce1-xMxO2 (M = Ti, Zr, and Hf) nanomaterials with controlled morphology and composition were synthesized by a two-step route for the first time. These nanomaterials exhibit high activities for hydrogen reduction and ethanol reforming reactions, and therefore, they may be useful for applications in catalysis and solid oxide fuel cells.
Experimental and theoretical studies of Sn(3-delta)Pb(delta)Bi(2)Se(6) (delta=0.0-0.7)
(2010-04-01)
Chen, Kuei-Bo
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Lee, Chi-Shen
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應用化學系
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Department of Applied Chemistry
New ternary and quaternary chalcogenides, Sn(3-delta)Pb(delta)Bi(2)Se(5) (delta=0.0-0.7), were synthesized from pure elements using the solid-state method. Their crystal structures, determined using single crystal X-ray diffraction, belong to the orthorhombic space group Pnma (No. 62). The structure is related to Pb(3)Bi(2)S(6), which contains NaCl [311] layer units and zigzag arrays of metal atoms along the c-axis. A correlation between the Pb composition and the shifted position of a metal site was observed. Band structure calculations confirmed that the structure is stabilized when the position of the M5 site is farther from the mirror plane. Thermopower and conductivity measurements indicated that all of the compounds are n-type semiconductors with small band gaps. (C) 2010 Elsevier Inc. All rights reserved.
Experimental and theoretical studies of Sn3-delta Pb delta Bi2Se6 (delta=0.0-0.7)
(2010-04-01)
Chen, Kuei-Bo
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Lee, Chi-Shen
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應用化學系
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Department of Applied Chemistry
New ternary and quaternary chalcogenides, Sn3-delta Pb delta Bi2Se5 (delta=0.0-0.7), were synthesized from pure elements using the solid-state method. Their crystal structures, determined using single crystal X-ray diffraction, belong to the orthorhombic space group Pnma (No. 62). The structure is related to Pb3Bi2S6, which contains NaCl [311] layer units and zigzag arrays of metal atoms along the c-axis. A correlation between the Pb composition and the shifted position of a metal site was observed. Band structure calculations confirmed that the structure is stabilized when the position of the M5 site is farther from the mirror plane. Thermopower and conductivity measurements indicated that all of the compounds are n-type semiconductors with small band gaps. (C) 2010 Elsevier Inc. All rights reserved.
Synthesis and characterization of alkali-metal tin(II) phosphates: Na(10)Sn(31)(HPO(4))(6)(P(2)O(7))(6)(PO(4))(12) and K(2)SnP(2)O(7)
(2008-11-01)
Weng, Sheng-Feng
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Chen, Kuei-Bo
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Lee, Chi-Shen
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應用化學系
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應用化學系分子科學碩博班
Two new alkali-metal tin(II) phosphates - Na(10)Sn(31)(HPO(4))(6)(P(2)O(7))(6)(PO(4))(12) (1) and K(2)SnP(2)O(7) (2) - were synthesized by high-temperature reactions and structurally characterized by single-crystal X-ray diffraction. Na(10)Sn(31)(HPO(4))(6)(P(2)O(7))(6)(PO(4))(12) crystallized in the noncentrosymmetric space group P-62c (No. 190) with a = 9.6445(1) angstrom, b = 9.6445(1) angstrom, c = 34.059(6) angstrom, V = 2743.6(7) angstrom(3) and Z = 1. K(2)SnP(2)O(7) crystallized in the monoclinic space group P2(1)/n with a = 9.856(3) angstrom, b = 6.7244(1) angstrom, c = 12.225(3) angstrom, beta = 108.240(5)degrees, V = 769. 5(3) angstrom(3) and Z = 4. Both structures exhibit a novel open-framework structure. The crystal structure of 1 contains SnO(3) and SnO(4) polyhedra sharing comers with [HPO(4)](2-), [PO(4) ](3-) and [P(2)O(7)](4-) groups, which form tunnels of six rings filled with Na(+) cations and parallel to the c-axis, which are connected via O-Sn-O bridges to form a three-dimensional open framework. The crystal structure of 2 contains SnO(4) seesaw polyhedra sharing comers with diphosphate groups to form a three-dimensional [SnP(2)O(7)](2-) framework that exhibits a tunnel structure of 10- and 12- membered rings expanding along [011] and [100] with four arrays of K(+) cations located in channels of the framework. (c) 2008 Elsevier Masson SAS. All rights reserved.
Synthesis and characterization of quaternary selenides Sn(2)Pb(5)Bi(4)Se(13) and Sn(8.65)Pb(0.35)Bi(4)Se(15)
(2009-09-01)
Chen, Kuei-Bo
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Lee, Chi-Shen
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應用化學系
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Department of Applied Chemistry
Quaternary selenides Sn(2)Pb(5)Bi(4)Se(13) and Sn(8.65)Pb(0.35)Bi(4)Se(15) were synthesized from the elements in sealed silica tubes; their crystal structures were determined by single-crystal and powder X-ray diffraction. Both compounds crystallize in monoclinic space group C2/m (No.12), with lattice parameters of Sn(2)Pb(5)Bi(4)Se(13): a = 14.001(6) angstrom, b = 4.234(2) angstrom, c = 23.471(8) angstrom, V = 1376.2(1) angstrom(3), R(1)/wR(2) = 0.0584/0.1477, and GOF = 1.023; Sn(8.65)Pb(0.35)Bi(4)Se(15): a = 13.872(3) angstrom. b = 4.2021(8) (4) angstrom, c = 26.855(5) angstrom, V = 1557.1(5) angstrom(3), R(1)/wR(2) = 0.0506/0.1227, and GOF = 1.425. These compounds exhibit tropochemical cell-twinning of NaCl-type structures with lillianite homologous series L(4, 5) and L(4, 7) for Sn(2)Pb(5)Bi(4)Se(13) and Sn(8.65)Pb(0.35)Bi(4)Se(15), respectively. Measurements of electrical conductivity indicate that these materials are semiconductors with narrow band gaps; Sn(2)Pb(5)Bi(4)Se(13) is n-type, whereas Sn(8.65)Pb(0.35)Bi(4)Se(15) is a p-type semiconductor with Seebeck coefficients -80(5) and 178(7) mu V/K at 300 K, respectively. (C) 2009 Elsevier Masson SAS. All rights reserved.
Synthesis and characterization of quaternary selenides Sn2Pb5Bi4Se13 and Sn8.65Pb0.35Bi4Se15
(2009-09-01)
Chen, Kuei-Bo
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Lee, Chi-Shen
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應用化學系
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Department of Applied Chemistry
Quaternary selenides Sn2Pb5Bi4Se13 and Sn8.65Pb0.35Bi4Se15 were synthesized from the elements in sealed silica tubes; their crystal structures were determined by single-crystal and powder X-ray diffraction. Both compounds crystallize in monoclinic space group C2/m (No.12), with lattice parameters of Sn2Pb5Bi4Se13: a = 14.001(6) angstrom, b = 4.234(2) angstrom, c = 23.471(8) angstrom, V = 1376.2(1) angstrom(3), R-1/wR(2) = 0.0584/0.1477, and GOF = 1.023; Sn8.65Pb0.35Bi4Se15: a = 13.872(3) angstrom. b = 4.2021(8) (4) angstrom, c = 26.855(5) angstrom, V = 1557.1(5) angstrom(3), R-1/wR(2) = 0.0506/0.1227, and GOF = 1.425. These compounds exhibit tropochemical cell-twinning of NaCl-type structures with lillianite homologous series L(4, 5) and L(4, 7) for Sn2Pb5Bi4Se13 and Sn8.65Pb0.35Bi4Se15, respectively. Measurements of electrical conductivity indicate that these materials are semiconductors with narrow band gaps; Sn2Pb5Bi4Se13 is n-type, whereas Sn8.65Pb0.35Bi4Se15 is a p-type semiconductor with Seebeck coefficients -80(5) and 178(7) mu V/K at 300 K, respectively. (C) 2009 Elsevier Masson SAS. All rights reserved.
Synthesis and phase width of new quaternary selenides Pb(x)Sn(6-x)Bi(2)Se(9) (x=0-4.36)
(2010-11-01)
Chen, Kuei-Bo
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Lee, Chi-Shen
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應用化學系
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Department of Applied Chemistry
Quaternary chalcogenides Pb(x)Sn(6-x)Bi(2)Se(9) (x=0-4.36) were synthesized with solid-state methods; their structures were determined from the X-ray diffraction of single crystals. Pb(x)Sn(6-x)Bi(2)Se(9) crystallizes in an orthorhombic space group Cmcm (No. 63); the structure features a three-dimensional framework containing slabs of NaCl-(3 1 1) type that exhibits identical layers containing seven octahedra units, which expand along the direction [0 1 0]. Each slab contains fused rectangular units that are connected to each other with M-Se contacts in a distorted octahedral environment. Calculations of the band structure, measurements of Seebeck coefficient and electrical conductivity confirm that these compounds are n-type semiconductors with small band gaps and large electrical conductivities. (C) 2010 Elsevier Inc. All rights reserved.
Synthesis and phase width of new quaternary selenides PbxSn6-xBi2Se9 (x=0-4.36)
(2010-11-01)
Chen, Kuei-Bo
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Lee, Chi-Shen
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應用化學系
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Department of Applied Chemistry
Quaternary chalcogenides PbxSn6-xBi2Se9 (x=0-4.36) were synthesized with solid-state methods; their structures were determined from the X-ray diffraction of single crystals. PbxSn6-xBi2Se9 crystallizes in an orthorhombic space group Cmcm (No. 63); the structure features a three-dimensional framework containing slabs of NaCl-(3 1 1) type that exhibits identical layers containing seven octahedra units, which expand along the direction [0 1 0]. Each slab contains fused rectangular units that are connected to each other with M-Se contacts in a distorted octahedral environment. Calculations of the band structure, measurements of Seebeck coefficient and electrical conductivity confirm that these compounds are n-type semiconductors with small band gaps and large electrical conductivities. (C) 2010 Elsevier Inc. All rights reserved.
Synthesis and VUV photoluminescence characterization of (Y,Gd)(V,P)O-4 : Eu3+ as a potential red-emitting PDP phosphor
(2007-06-26)
Wu, Chia-Chin
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Chen, Kuei-Bo
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Lee, Chi-Sen
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Chen, Teng-Ming
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Cheng, Bing-Ming
YVO4:Eu3+-based phosphors in three series with compositions (Y1-xEux)(V1-zPz)O-4, (Y0.95-yGdyEu0.05)(V0.4P0.6)O-4 and (Y0.95-yEu0.05Gdy)(V1-zPz)O-4 were synthesized and investigated as potential red-emitting phosphors for a plasma display panel (PDP). The optimal substitution proportions of P for V and Gd for Y were determined to be 60 and 20 mol %, respectively, for (Y0.95-yGdy)(V1-zPz)O-4 doped with 5 mol % Eu3+. The vacuum ultraviolet PL and PLE spectra and chromaticity characteristics for the synthesized phosphors were measured and compared against those of a commercial red-emitting phosphor. Pumping the (Y,Gd)(P,V)O-4:Eu3+ phosphors at a wavelength of 172 nm is more efficient than that at 147 nm. For VUV excitation at 147 nm, the CIE chromaticity coordinates for our red-emitting (Y1-yGdy)(V0.4P0.6)O-4:Eu3+ are (0.6614,0.3286), as compared to (0.6443, 0.3613) for (Y,Gd)BO3:Eu3+ from Kasei Optonix Ltd. We suggest that the composition-optimized (Y0.75Gd0.20Eu0.05)(V0.4P0.6)O-4 can serve as an alternative phosphor to replace a widely used red-emitting commercial phosphor such as (Y,Gd)BO3: Eu3+ or Y2O3: Eu3+.