Al~(3+)-Ce~(3+)共掺杂纳米SiO_2的发光性能

采用溶胶-凝胶技术制备了Al3+-Ce3+共掺杂的纳米SiO2,并对其进行H2气氛中700～800℃的热处理.采用透射电子显微镜(transmission electron microscope,TEM)、Fourier红外光谱仪(Fourier transform infrared spectroscopy,FTIR)、紫外-可见分光光度计(ultraviolet-visible spectrophotometry,UV-Vis)及荧光光谱仪观察并测试掺杂改性纳米SiO2的形貌及光学性能.结果表明,掺杂纳米SiO2中存在两个起源小同的383nm发光带:一个为由245nm激发产生的383nm和402nm双峰结构的发光带.该发光起源于纳米SiO2的本征缺陷中心;另一个为由314nm激发产生的383nm宽带发光,该发光带起源于掺杂的Ce3+;并且研究了该发光带强度与Al3+的掺杂浓度以及热处理温度的关系.     

阴极电沉积制备铝掺杂ZnO薄膜及其光催化性能

以不锈钢为基体,采用阴极电沉积法,从Zn(NO3)2和Zn(NO3)2+Al(NO3)3水溶液中制备了纯ZnO薄膜和铝掺杂ZnO薄膜.用X射线衍射、 扫描电镜和紫外-可见光漫反射光谱研究了铝掺杂对ZnO薄膜相变和光催化活性的影响.结果表明:在铝掺杂ZnO薄膜中,部分Al3+进入ZnO的晶 格,形成固溶体:铝掺杂使ZnO的吸收阈值蓝移大约50nm.和纯ZnO薄膜相比,铝掺杂ZnO薄膜在紫外光和可见光区均呈现出更高的催化活性, 反应60min后.甲基橙的降解率分别提高了45%和30%.探讨了铝掺杂ZnO薄膜光催化活性提高的原因.     

ZnO一维纳米材料的热蒸发法制备及光学性能研究

以Zn粉为原料,在1050℃空气气氛中采用热蒸发法成功制备了ZnO一维纳米材料.探讨了覆盖瓷舟对ZnO纳米晶的形成及其形貌和光学性能的影响.X射线衍射(XRD)分析表明,产物是纯六方纤锌矿结构的ZnO;扫描电子显微镜(SEM)形貌观察显示,产物为ZnO纳米线、微纳米棒和四角针状ZnO;光致发光谱(PL)表明ZnO一维纳米材料主要有3个蓝光发光带;紫外-可见光光谱(UV-vis)显示ZnO一维纳米材料能有效的催化降解次甲基蓝溶液.     

水热法制备In掺杂ZnO薄膜的表面形貌及其光学性质

采用水热法在ZnO籽晶层上制备了不同In掺杂量的ZnO薄膜,用X射线衍射仪(XRD)、原子力显微镜(AFM)、紫外可见分光光度计和荧光光谱仪等测试分析薄膜的微结构、表面形貌、透射谱和室温光致发光谱.结果表明,In离子的掺入未改变薄膜的晶相结构,但抑制了ZnO晶粒的生长,使得ZnO的结晶度明显下降.随着In含量的增加,薄膜表面rms粗糙度和平均颗粒尺寸均逐渐减小,光学带隙Eg先增大后减小.所有薄膜的PL谱中均观察到405 nm左右的紫光发光带,研究了In掺杂量对紫光发光带的强度和峰位的影响,并对其紫光发射机理进行了探讨.     

掺N纳米ZnO的制备及光催化活性

采用溶胶-凝胶法合成纳米ZnO,用碳酸铵溶液浸渍的方法对其进行N掺杂。利用X射线衍射仪,透射电子显微镜,X射线能谱仪,Fourier红外光谱仪,X射线光电子能谱仪,紫外-可见光谱仪对产物结构进行了表征,通过可见光催化降解甲基橙对N-ZnO的光催化活性进行了考察。结果表明:合成的ZnO颗粒大小在20～30 nm,N的掺杂没有改变ZnO的晶型,N在ZnO晶格中形成N—Zn—O键;N掺杂拓宽了ZnO的可见光吸收范围。N-ZnO作为光催化剂在可见光作用下能有效降解甲基橙,表现出较高的可见光催化活性。当(NH4)2CO3和ZnO的摩尔比为0.20时,N-ZnO的光催化性能最好。     

氧化锌晶体的低温热释光光谱

测量了在25K下经剂量为5Gy的X射线辐照的两组氧化锌(ZnO)晶体在25～280K范围内的热释光发光光谱。结果表明:ZnO晶体的低温热释光光谱的发光带的中心波长分别为600,670nm和727nm,其中,中心波长为727nm的发光带同其他2个发光带发光谱线在150K左右峰温约有20K的差别,反映了晶体内部缺陷的转型过程。两组ZnO晶体的热释光谱差异表明,晶体的热释光对样品的生长条件及样品后续处理的条件非常敏感。     

Synthesis and Photocatalytic Activity of N-doped ZnO

采用溶胶–凝胶法合成纳米 ZnO，用碳酸铵溶液浸渍的方法对其进行 N 掺杂。利用 X 射线衍射仪，透射电子显微镜，X 射线能谱仪，Fourier红外光谱仪，X 射线光电子能谱仪，紫外–可见光谱仪对产物结构进行了表征，通过可见光催化降解甲基橙对 N-ZnO 的光催化活性进行了考察。结果表明：合成的 ZnO 颗粒大小在 20～30 nm，N 的掺杂没有改变 ZnO 的晶型，N 在 ZnO 晶格中形成 N—Zn—O 键；N 掺杂拓宽了 ZnO 的可见光吸收范围。N-ZnO 作为光催化剂在可见光作用下能有效降解甲基橙，表现出较高的可见光催化活性。当（NH4）2CO3和 ZnO 的摩尔比为 0.20 时，N-ZnO 的光催化性能最好。     

稀土掺杂ZnO纳米材料的制备与表征

采用超声化学法，以六水合硝酸锌、六水合硝酸铕和三乙醇胺为原料，在加入聚乙二醇20000的水中进行反应，制备了呈球状的纳米ZnO:Dy³⁺。采用微波水热法制备ZnO:Eu³⁺纳米材料。采用X射线衍射(XRD)、场致发射扫描电镜(SEM)、紫外-可见光谱(UV-Vis)、光致发光谱(PL)等技术对所制备的样品进行了系列表征。结果表明：掺杂后并未改变纳米颗粒的晶型结构，紫外-可见吸收光谱显示其在紫外、可见光区域的吸收能力均有所增强；荧光光谱显示在紫外、可见光区存在多个发光峰，掺杂后发光强度增强。     

Eu~(3+)掺杂ZnO纳米材料的制备与表征

采用超声化学法,以六水合硝酸锌、六水合硝酸铕和三乙醇胺为原料,在加入聚乙二醇20000的水中进行反应,制备了呈球状的纳米ZnO:Eu~(3+)。采用X射线衍射(XRD)、场致发射扫描电镜(SEM)、紫外-可见光谱(UVVis)、光致发光谱(PL)等技术对所制备的样品进行了系列表征。结果表明,掺杂后并未改变纳米颗粒的晶型结构,紫外-可见吸收光谱显示其在紫外、可见光区域的吸收能力均有所增强;荧光光谱显示在紫外、可见光区存在多个发光峰,掺杂后发光强度增强。     

Eu~(3+)掺杂ZnO纳米材料的制备与表征

采用超声化学法,以六水合硝酸锌、六水合硝酸铕和三乙醇胺为原料,在加入聚乙二醇20000的水中进行反应,制备了呈球状的纳米ZnO:Eu⁽³⁺⁾。采用X射线衍射(XRD)、场致发射扫描电镜(SEM)、紫外-可见光谱(UVVis)、光致发光谱(PL)等技术对所制备的样品进行了系列表征。结果表明,掺杂后并未改变纳米颗粒的晶型结构,紫外-可见吸收光谱显示其在紫外、可见光区域的吸收能力均有所增强;荧光光谱显示在紫外、可见光区存在多个发光峰,掺杂后发光强度增强。     

Growth and characterization of the Al-doped and Al–Sn co-doped ZnO nanostructures

In the present work, well-dispersed structures of spherical-like pure ZnO, Al doped ZnO (AZO) and Al, Sn co-doped ZnO (ATZO) nanocrystals were successfully synthesized by using zinc acetate dihydrate as the starting material and also the low temperature hydrothermal process without any additional surfactant or catalytic agent. The ZnO structures were characterized by X-ray diffraction (XRD), and transmission electron microscopy (TEM). The XRD results revealed that ZnO powders have a hexagonal crystal structure and the TEM indicated that the nanoparticles self-aggregate. An X-ray photoelectron spectroscopy (XPS) study confirmed the substitution of Zn²⁺ by Sn and Al ions. Optical properties of the ZnO structures were investigated by Raman spectroscopy and room-temperature photoluminescence (PL) spectroscopy. The Raman spectroscopy results demonstrated that the doped ZnO nanoparticles had a higher crystalline quality than that of pure ZnO. Room-temperature PL spectra of these structures showed a strong UV emission peak and a relative weak green emission peak, and the UV peak of the doped ZnO nanoparticles was blue-shifted with respect to that of the undoped ZnO nanoparticles.     

Analysis of structural,optical and magnetic properties of Fe/Co co-doped ZnO nanocrystals

In this paper, the structural, optical and magnetic properties of pure ZnO and Fe/Co co-doped ZnO nanoparticles are presented. Rietveld refinement of XRD pattern revealed the single phase wurtzite structure for prepared samples. FTIR study confirmed the formation of tetrahedral coordination between zinc and oxygen ions. SEM and TEM techniques were used to examine the morphology of samples. The absorption spectra showed the decrease in optical energy band gap with Fe/Co co-doping in ZnO. PL spectra demonstrated five peaks correspond to the ultraviolet region, violet, violet-blue, blue-green and green in the visible region. Emission peak in the UV region is attributed to near band-edge excitonic emission. Other four emission peaks in PL spectra are related to different defect states. M-H curve showed room temperature ferromagnetic (RTFM) behaviour of doped ZnO sample. This paper enhances the understanding of structural, optical and magnetic properties of Fe/Co co-doped ZnO nanocrystals for application in spintronics, solar cells, and ceramics.     

Effects of aluminium doping on structural and photoluminescence properties of ZnO nanoparticles

Structural and optical properties of Al doped ZnO nanoparticles prepared by the thermal decomposition method are presented. X-ray diffraction studies confirmed the substitution of Al on Zn sites without changing the hexagonal structure of ZnO. Also, lattice parameters, the crystallite size and other physical parameters such as strain, stress and energy density were calculated from various modified forms of W–H equation and their variation with the doping of Al is discussed. A blue shift in the energy band gap attributed to increase in carrier concentration (Burstein Moss Effect) is observed by absorption spectra. Photoluminescence studies show a strong and dominant peak corresponding to the near band edge emission in ultraviolet range and a broad band in the range 420–520 nm corresponding to defects and oxygen vacancies. Phonon modes were studied by FTIR measurements. The tunability of the band gap of ZnO nanoparticles could eventually be useful for potential optoelectronic applications.     

Structural,optical and photocatalytic properties of hafnium doped zinc oxide nanophotocatalyst

A series of novel hafnium (Hf) doped ZnO nanophotocatalyst were synthesized using a simple sol–gel method with a doping content of up to 6 mol%. The structure, morphology and optical characteristics of the photocatalysts were characterized by XRD, SEM, TEM, FTIR, XPS, DRS and PL spectroscopy. The successful synthesis and chemical composition of pure and doped ZnO photocatalysts were confirmed by XRD and XPS. DRS confirmed that the spectral responses of the photocatalysts were shifted towards the visible light region and showed a reduction in band gap energy from 3.26 to 3.17 eV. Fluorescence emission spectra indicated that doped ZnO samples possess better charge separation capability than pure ZnO. The photocatalytic activity of Hf-doped ZnO was evaluated by the methylene blue (MB) degradation in aqueous solution under sunlight irradiation. Parameters such as irradiation time and doping content were found effective on the photoactivity of pure ZnO and Hf-doped ZnO. The photocatalysis experiments demonstrated that 2 mol% Hf-ZnO exhibited higher photocatalytic activity as compared to ZnO, ZnO commercial and other hafnium doped ZnO photocatalysts and also revealed that MB was effectively degraded by more than 85% within 120 min. The enhanced photoactivity might be attributed to effective charge separation and enhanced visible light absorption. It was concluded that the presence of hafnium within ZnO lattice could enhance the photocatalytic oxidation over pure ZnO.     

Photoluminescence properties of praseodymium doped cerium oxide nanocrystals

The structure and photoluminescence (PL) properties of CeO₂ nanocrystals synthesized by the microwave-assisted hydrothermal (MAH) method with different praseodymium (Pr³⁺) ions contents were performed. X-ray diffraction (XRD), transmission electron microscopy (TEM), diffuse reflectance ultraviolet-visible (UV-vis), Fourier transform Raman (FT-Raman) spectroscopies and PL measurements at room temperature were employed. XRD patterns indicated that the nanocrystals are free of secondary phases and crystallize in the cubic structure while FT-Raman revealed a typical scattering mode of fluorite type. The UV-vis spectra suggested the presence of intermediate energy levels in the band gap of these nanocrystals. The most intense PL emission was obtained for CeO₂ nanocrystals doped with 1.6% of Pr³⁺ ions and smaller particle size.     

Al,Ni掺杂ZnO的电子结构与光学性质

利用基于密度泛函理论的第一性原理方法计算了纯ZnO和分别掺摩尔分数均为6.25%Al,Ni的ZnO的能带结构、电子态密度分布及光学性质。计算结果表明:ZnO掺杂Al,Ni后,其Fermi面均上移并进入导带;Zn0.9375Ni0.0625O的能带结构在导带底附近出现了4条杂质带。纯ZnO,Zn0.9375Al0.0625O和Zn0.9375Ni0.0625O的光学性质在低能处有较大的差异,其中Zn0.9375Al0.0625O在可见光区的吸收系数和反射率较之另外两种材料都相对较低,但三者的光学性质在高能处却非常相似。Zn0.9375Al0.0625O的吸收边有蓝移的趋势,而Zn0.9375Ni0.0625O的吸收边红移。掺杂Ni对ZnO的吸收系数等光学性质的改变更为明显。     

超声辅助均匀沉淀法由前躯体ZnS制备ZnO纳米颗粒及其表征

前躯体ZnS在超声辅助60℃的低温条件下,采用醋酸锌为锌源、硫代乙酰胺为硫源来制备,然后采用在空气中热处理前躯体ZnS的方法制备了直径约为20~40 nm的ZnO纳米颗粒。所得产物分别采用红外光谱(FTIR)、热重-差热分析(TGA-DTA)、X射线衍射(XRD)、场发射扫描电镜(FE-SEM)、透射电镜(TEM)、电子能谱(EDS)和荧光光谱(PL)进行表征。实验结果表明,所得产物ZnO为六方纤锌矿结构,且结晶性很好,并且随着超声时间的延长其粒径有所降低。室温PL光谱表明,样品在400~550 nm内有3个较强的荧光发射峰。     

In3+离子在多孔SiO2干凝胶中的发光

采用常规的Sol-gel工艺合成了In^3 掺杂的多孔SiO2干凝胶，In^3 离子作为间隙离子存在于SiO2网络中，展示了一种新颖的发光现象，改变了多孔SiO2干凝胶的发射光谱。这种掺杂的多孔SiO2干凝胶的激发和发射光谱均由2个带组成，短波长的发光峰在440nm(λex=380nm），其相对荧光强度约是未掺杂的多孔SiO2干凝胶的4倍；长波长的发光峰（In^3 离子在多孔SiO2干凝胶的特征发射）在600nm(λex=476nm），其相对荧光强度约是In^3 掺杂ZnS纳米晶的10倍。由此可以看出：掺杂的多孔SiO2干凝胶是一种高效的发光材料。     

Optoelectronic performances on different structures of Al‐doped ZnO

ZnO films and Al‐doped ZnO (AZO) films were deposited on p‐Si substrate by magnetron sputtering to investigate its chemical composition, structural and photoelectric properties. XRD and FTIR show that Al ions can enter into the substitutional and interstitial site of ZnO crystal, and O atoms in AZO films are more abundant. Three different structures of Al‐doped ZnO (substitutional Al, interstitial Al, and O‐rich Al‐doped ZnO) were built using first‐principles method based on experimental results, charge density difference, and density of States (DOS) illustrate that there are strong ionic interactions between Al and O atoms in substitutional Al‐doped ZnO, moreover, substitutional and interstitial Al doping both are beneficial to N type, but oxygen‐enriched ZnO is not conducive to N type. Furthermore, the optical properties of 3 different Al‐doped ZnO structures were investigated respectively. Compared with pure ZnO, the real and imaginary part of dielectric function of O‐rich and interstitial Al have a significant increase and move to lower energy (red shift), the reflectivity of O‐rich is 3 times of pure ZnO and substitutional Al‐doped ZnO. The results are hoped to be helpful to study AZO thin film and predict the properties of Al‐doped ZnO.     

微乳液法制备纳米球形YAG:Ce3+荧光粉及其发光性能

采用反相微乳液法,以水/曲拉通X-100/正己醇/(环己烷 正己烷)为微乳体系,铝(Al)、钇(Y)和(Ce)的硝酸盐和氯化物作为起始反应物,氨水作为沉淀剂,成功制备了纳米球形铈掺杂钇铝石榴石(cerium doped yttrium aluminum garnet,YAG:Ce3 )荧光粉.实验表明:单相YAG可以在800℃合成,比周相反应法合成温度(1 500℃)大幅度降低.用失重-差热分析仪、Fourier变换红外光谱仪、X射线衍射仪、透射电镜、荧光分光光度计等对粉体特性进行了表征.结果表明:粉体颗粒粒径约为50nm,粒度分布均匀,球形度好,分散性好,粉体的激发光谱为双峰结构,主激发波长为469nm,发射波长为532nm,适用于白光发光二极管.