HA:RE(RE=Eu3+、Tb3+)纳米棒的制备与细胞毒性研究

采用EDTA为模板,以CaCO3、NH4H2PO4、Eu2O3、Tb7O4、HNO3为原料,用NH3 H2O调节pH值,成功制备了掺铕羟基磷灰石(HA:Eu3+)及掺铽羟基磷灰石(HA:Tb3+)纳米棒,并采用XRD、场发射环境扫描电子显微镜、荧光光谱、酶联监测仪等对其荧光及细胞毒性进行了研究。结果表明:制备的HA:Eu3+纳米棒最强发射峰位于617 nm处,发射出明亮的红光;制备的HA:Tb3+纳米棒最强发射峰位于544 nm处,发射出明亮的绿光;细胞毒性研究表明HA:RE(RE=Eu3+、Tb3+)纳米棒是一种良好的生物示踪材料。     

Zn2(OH)3VO3∶Eu3+纳米晶的水热合成及发光性能

以NaVO3、Zn(NO3)2·6H2O为原料,采用水热法合成了铕离子掺杂Zn2(OH)3VO3纳米晶体。运用X射线粉末衍射、扫描电子显微镜、荧光测试仪对纳米晶进行了表征,研究了水乙醇体系不同pH值对产物晶相、微观形貌及荧光性能的影响。在溶剂体系pH值为7~10时,得到片状的Zn2(OH)3VO3,而在pH值为4~6和11~12时得到Zn3(OH)2V2O7·2H2O,表明强酸性和强碱性的溶剂体系都不太适合Zn2(OH)3VO3的合成,而最佳的合成体系为中性偏碱性;荧光测试表明在pH=10的水乙醇体系下合成的Zn2(OH)3VO3∶8%Eu3+纳米片的荧光性能最好,其中发射主峰位于612nm处。     

Ba3V2O8∶Eu3+纳米花的制备及光致发光性能研究

采用复合氢氧化物媒介法制备了Ba3V2O8∶Eu3+纳米花。利用SEM-EDS、XRD、TEM和XPS对晶体的形貌和尺寸、结构和化学组成进行了表征。结果表明产物是由厚度约20nm的纳米片组成的花状Ba3V2O8∶Eu3+纳米晶体。荧光光谱测定发现Ba3V2O8∶Eu3+晶体在紫外光和蓝光激发下都能产生591和612nm 2个强发射峰,表明其具有将紫外光和蓝光转换成红光的能力,可以进一步应用于光转换和光发射领域。探讨了Ba3V2O8∶Eu3+纳米花的发光机理。     

含水量对Bi2Te3纳米片合成的影响

本文采用溶剂热法制备热电纳米材料Bi2Te3,研究了不同含水量对所得产物组成与形貌的影响。利用X射线衍射(XRD)、能谱仪(EDS)、冷场发射扫描电子显微镜(FESEM)和透射电子显微镜(TEM)等对产物进行了详细表征分析。结果表明,反应体系无水,也可以获得标准的六角形Bi2Te3纳米片。随着含水量增加,产物出现团聚现象;含水量大于一定值时,开始出现Te和Bi2TeO5杂相。     

高能球磨合成纳米碳包覆α-Al2O3复合粉体

以膨胀石墨和α-Al2O3微粉为原料,采用高能球磨制备了纳米碳包覆的α-Al2O3复合粉体,研究了高能球磨时间和球磨速率对复合粉体物相及形貌的影响。采用X射线衍射仪、场发射扫描电子显微镜和透射电子显微镜对复合粉体的物相、形貌和微观结构进行了表征。结果表明:按膨胀石墨与α-Al2O3质量百分比为1:2,球磨速率为600 r/min,球磨5 h可得到被粒度为20～50 nm碳颗粒包覆的α-Al2O3复合粉体;随着球磨时间延长,石墨(002)晶面特征峰逐渐消失,膨胀石墨中纳米片层会随球磨时间延长不断剥离脱落,并逐渐龟裂成纳米碳颗粒;相同球磨时间下,提高球磨速率可以促进纳米碳颗粒形成,但超过一定速率后纳米碳颗粒粒度不再减少;480 r/min速率球磨5 h未形成纳米碳颗粒包覆复合粉体,600和700 r/min速率球磨5 h后复合粉体形貌基本一致。     

球形Mn2O3晶体的制备及其光催化性能

在乙二醇体系中,以MnCl2.4H2O和NaAc为主要原料溶剂热制备锰氧前驱物.该前驱物经600℃煅烧5h得到球形Mn2O3晶体.利用X射线粉末衍射(XRD)、透射电子显微镜(TEM)和扫描电子显微镜(SEM)等手段对产物进行了表征,对其形成机理进行了初步的分析,并对其光催化性能进行了初步探讨.实验结果表明,产物为球形Mn2O3晶体,其平均直径约为7μm,且由多层纳米片组成,而纳米片则是由细小的纳米颗粒构成.产物Mn2O3晶体的特殊形貌结构对光催化H2O2氧化分解亚甲基蓝有较好的催化性能.     

Y2O3:Eu3+纳米晶的制备及其光学性能研究

以NaOH,Y(NO3)3.6H2O和Eu(NO3)3.6H2O为前驱体,通过添加络合剂PEG-2000,采用水热法,成功地合成了Y2O3∶Eu3+纳米棒和纳米管,并采用先进的测试手段对其结构和性能进行了表征与测试。探讨了Y2O3∶Eu3+纳米棒和纳米管的生长机制,同时研究了Y2O3:Eu3+纳米晶的光致发光性能。研究结果表明,水热温度、反应时间、NaOH的添加量和PEG-2000对产物形貌有着非常重要的影响,所制备的材料具有Eu3+的特征红光发射,并在Eu3+的掺杂量为5%(摩尔分数)时样品发光最好。     

Y2O3∶Eu$1纳米晶的尺寸调控与发光性能研究

以尿素为沉淀剂,柠檬酸为表面活性剂,通过水热法得到了非晶态的水合硝酸氧钇前驱体,进一步烧结处理后生成了立方相Y2 O3纳米晶．利用X－射线衍射（ XRD）、扫描电镜（ SEM）、透射电镜（ TEM）、红外光谱（ FTIR）和荧光光谱（ PL）分别对所得样品的相结构、形貌粒度、表面结构以及发光性能进行研究．结果表明：当烧结温度从600℃升高到900℃,Y2 O3∶Eu3＋纳米颗粒的结晶性增强,并实现了粒径调控,由13．0 nm增加至27．9 nm．随着Y2 O3∶Eu3＋纳米颗粒尺寸的增加,比表面积减小会导致发光离子附近的表面晶格缺陷降低,同时纳米晶表面吸附水、硝酸根以及柠檬酸根等杂质离子逐渐被去除,减少了荧光猝灭中心,从而有利于增强荧光发射强度以及延长荧光寿命．     

水相沉淀法制备纳米片状钼铜矿（Cu3（MoO4）2（OH）2）（英文）

以硝酸铜、钼酸钠及氢氧化钠为原料,采用简单的水相沉淀法,在60℃下合成出钼铜矿(Cu3(MoO4)2(OH)2).通过X射线衍射、扫描电镜、透射电镜、热重与差热分析、红外光谱及荧光光谱等测试手段对材料的微观结构、形貌、热稳定性及谱学特性进行表征分析.结果显示,制备的产物为结晶性良好的、至少一维是纳米的片状结构材料,属于单斜型(晶胞参数a=0.53863 nm,b=1.40006 nm,c=0.56003 nm),其元素摩尔含量比约为3:2:10,与推测的分子式完全吻合.热重与差热分析数据表明Cu3(MoO4)2(OH)2纳米晶具有很好的热稳定性且起始分解温度为320℃.通过软件测得的d(021)面与d(ī21)面的晶间面距分别为0.435 nm与0.358 nm,与理论值基本相符.经测量,Cu3(MoO4)2(OH)2纳米晶具有强的荧光性质,在激发波长369 nm的作用下在530 nm表现为强发射峰.此外,还探讨了Cu3(MoO4)2(OH)2纳米晶的形成机理.     

Ce3+、Mn2+掺杂Zn3（BO3）2的制备及其发光性能

采用共沉淀法在700℃和较短的烧结时间下制备了Zn3(BO3)2和不同浓度的Ce3+、Mn2+离子掺杂的Zn3(BO3)2纳米晶粉末,对合成产物的发光性质及发光机理进行了研究。利用荧光分光光度计、X射线粉末衍射仪以及透射电镜对其光学性能和纳米晶形貌进行了表征。结果表明Ce3+离子掺杂的Zn3(BO3)2样品在340～400nm之间有强的荧光发射,其最高发射峰峰位为365nm,在Ce3+掺量为0.5%(摩尔分数,下同)时发光强度达到最高值。Ce3+取代Zn2+离子作为发光中心,Mn2+离子作为激活剂加入,并不影响荧光发射峰的位置,但能够有效增强其发光强度。当Mn2+离子掺量为0.7%(摩尔分数)时,Ce3+、Mn2+共掺杂的Zn3(BO3)2纳米晶发光强度达到最高值。     

Room temperature synthesis and characterization of different morphological TbF3 nano/microcrystals

At room temperature, a simple solution-based procedure employing NaBF₄ as the fluoride source has been developed to selectively prepare different morphological TbF₃ nano/microcrystals (disks, peanuts and spindles) with an orthorhombic structure. The crystal structure, morphology and photoluminescence properties of the as-prepared TbF₃ crystals were investigated by x-ray powder diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectrophotometer. The results revealed that large-scale and uniform disks with a mean thickness of 20 nm can be easily synthesized, and the spindle-like and peanut-like TbF₃ crystals were assembled from nanodisks. The effects of synthesis parameters such as NaBF₄, reaction time and molar ratio of the reactants were systematically investigated. The room temperature PL properties of these different morphological TbF₃ microcrystals were measured.     

第一性原理对CaTiO3和CaCu3Ti4O12的对比研究

通过Ca替换CaCu_3Ti_4O_(12)晶胞中的所有Cu,建立了包含TiO6八面体扭转的CaTiO3;通过Cu替换CaTiO32×2×2超胞中3/4的Ca,建立了不包含CuO_4正方形的CaCu_3Ti_4O_(12)。采用Materials Studio软件的CASTEP模块,对比了上述晶体和标准晶体成键状况、能带结构、态密度及介电函数,分析了TiO6八面体扭转和CuO_4正方形的影响,发现了Cu-O键或CuO_4正方形对CaCu_3Ti_4O_(12)光频介电常数的关键性作用。研究结果提供了通过内禀机制优化CaCu_3Ti_4O_(12)材料介电性能的新途径。     

Time-resolved spectroscopy of intrinsic luminescence of Y3Ga5O12 and (LaLu)3Lu2Ga3O12 single crystals

The nature of intrinsic luminescence of Y₃Ga₅O₁₂ (YGG) and (LaLu)₃Lu₂Ga₃O₁₂ (LLGG) single crystals grown from a melt was determined. In the case of a YGG single crystal containing Y_Ga antisite defects with a concentration of 0.25–0.275 at.% the intrinsic luminescence was considered as a superposition of luminescence of self-trapped excitons (STE), luminescence of excitons localized near antisite defects (LE(AD) centers) and luminescence caused by a recombination of an electron with a hole captured at Y_Ga antisite defects. Due to a large (2–3%) concentration of Lu_La antisite defects in LLGG single crystals the intrinsic luminescence was a superposition mainly of the LE(AD) center emission and the recombination luminescence of Lu_La antisite defects. The energy structure of the mentioned centers in YGG and LGGG hosts was determined from the excitation spectra of their luminescence under excitation by synchrotron radiation in the range of the fundamental absorption edge of these garnets.     

Synthesis and characterization of novel nanorod superstructures and twin octahedral morphologies of WO3 by hydrothermal treatment

Controlled WO₃ morphologies, such as nanorods and octahedral structures, were synthesized by the hydrothermal technique using sulfate salts based structure directing agents (SDAs). The role of the sulfate salts’ cation in controlling the shape, size and phase of WO₃ nanomaterials was investigated by choosing sulfate salts whose cations are from d-bloc elements (FeSO₄, (NH₄)₂Fe(SO₄)₂, CoSO₄, CuSO₄, ZnSO₄), an alkaline earth metal (MgSO₄) and a non-metal ((NH₄)₂SO₄). In addition chloride (MnCl₂) and acetate (Zn(CH₃CO₂)₂) anion based SDAs were also used in order to clarify the role of sulfate ions in the growth of WO₃ nanostructures. We controlled the pH of the reaction medium with oxalic acid. The obtained WO₃ samples were investigated by SEM, micro-Raman, and XRD. At pH = 1, the WO₃ samples exhibit novel superstructures consisting of aligned hexagonal nanorods, whereas at pH = 5.25, novel twin octahedral morphology with a cubic structure is obtained. The results demonstrate that the phase and morphology change is influenced by the pH and both the anion and the cation of the SDA. A growth mechanism for the obtained novel WO₃ morphologies is presented.     

Scintillation and optical properties of Pb-doped YCa4O(BO3)3 crystals

This communication reports optical properties and radiation responses of Pb²⁺ 0.5 and 1.0 mol%-doped YCa₄O(BO₃)₃ (YCOB) single crystals grown by the micro-pulling-down (μ-PD) method for neutron scintillator applications. The crystals had no impurity phases according to the results of X-ray powder diffraction. These Pb²⁺-doped crystals demonstrated blue-light luminescence at 330 nm because of Pb²⁺¹S₀-³P_0,1 transition in the photoluminescence spectra. The main emission decay component was determined to be about 250-260 ns under 260 nm excitation wavelength. When irradiated by a ²⁵²Cf source, the relative light yield of 0.5% Pb²⁺-doped crystal was about 300 ph/n that was determined using the light yield of a reference Li-glass scintillator.     

Structure and property changes of ZrO2/Al2O3/ZrO2 laminate induced by low-temperature NH3 annealing applicable to metal-insulator-metal capacitor

Phase transformation and morphology evolution of ZrO₂/Al₂O₃/ZrO₂ laminate induced by the post-deposition NH₃ annealing at 480 °C were studied and the effect on the electrical property of the TiN/ZrO₂/Al₂O₃/ZrO₂/TiN capacitor module was evaluated in dynamic random access memory cell. Experimental results indicated N could indeed be incorporated into the dielectric laminate by the low-temperature NH₃ annealing, resulting in tetragonal-to-cubic phase transformation and small crystallites in the ZrO₂ layers. The C residue and Cl impurity in the ZrO₂/Al₂O₃/ZrO₂ laminate, which derived from the dielectric film formation and capping TiN layer deposition, respectively, could also be reduced by the nitridation process. As a result of the better surface morphology and less impurity content, lower dielectric leakage current and longer reliability lifetime were observed for the nitrided ZrO₂/Al₂O₃/ZrO₂ capacitor. This study demonstrates the low-temperature NH₃ annealing on ZrO₂/Al₂O₃/ZrO₂ dielectric can be applicable to the metal-insulator-metal capacitor structure with nitride-based electrode, which brings advantages over mass production-wise property improvements and extends the practical applicability of the ZrO₂/Al₂O₃/ZrO₂ dielectric.     

Ammonia gas sensor based on PPy/ZnSnO3 nanocomposites

In this paper, Zinc stannate (ZnSnO₃) nanoparticles were synthesized by a sol-gel method. Then, polypyrrole (PPy)/ZnSnO₃ nanocomposites were prepared by a simple in situ chemical polymerization method. By means of X-ray diffraction, Fourier transform infrared and scanning electron microscopy, the microstructure of PPy/ZnSnO₃ nanocomposites was characterized. The XRD patterns indicate that ZnSnO₃ nanoparticles have a perovskite phase with an orthorhombic structure, and incorporation of PPy did not change the crystalline structure of ZnSnO₃. The PPy was evenly dispersed on the surface of ZnSnO₃ particles, which was endorsed by FTIR spectral analyses. SEM images indicate that the PPy was evenly dispersed on the surface of ZnSnO₃ particles without apparent agglomeration. We found that the nanocomposites exhibited a higher response to NH₃ gas.     

Polarized spectral properties of Tm:K5Bi(MoO4)4 crystal

Trivalent thulium-doped K₅Bi(MoO₄)₄ single crystals were grown by the Czochralski method. Its polarized absorption and fluorescence spectra and fluorescence decay curves were recorded at room temperature. On the basis of the Judd-Ofelt theory, the spectral parameters of the Tm³⁺:K₅Bi(MoO₄)₄ crystal were calculated. The cross relaxations between Tm³⁺ ions were analyzed. The emission cross sections of the ³F₄ → ³H₆ transition were obtained by the Fuchtbauer-Ladenburg formula and then the gain cross sections around 1.9 μm were calculated. The peak emission cross section and width of emission band around 1.9 μm are comparable to those for Tm³⁺:YAG and the tunable range is about 280 nm for the potential ∼1.9 μm laser operation via the ³F₄ → ³H₆ transition.     

Synthesis of micro-sized Sb2O3 hierarchical structures by carbothermal reduction method

Micro-sized Sb₂O₃ hierarchical structures were prepared by carbothermal reduction method, using antimony doped tin oxide (ATO) nanoparticles and graphite powder as source materials. The products were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and field-emission scanning electron microscopy (FE-SEM). Furthermore, the possible growth mechanism of the as-synthesized samples was discussed. The room-temperature photoluminescence (PL) measurement exhibited one relatively strong violet emission peak at about 420 nm under the 325 nm excitation wavelength and another violet emission peak, about three times stronger in intensity than the former, at about 435 nm under the 365 nm excitation wavelength. In addition, the optimal excitation wavelength of 363 nm was obtained and the luminescence causes were speculated.     

Structural,optical and photoluminescence properties of hybrid metal–organic halide perovskite thin films prepared by a single step solution method

We report an inexpensive single step solution method to produce hybrid organic–inorganic lead iodide perovskite thin films for their application to photovoltaic devices. Using PbI₂ and CH₃NH₃Cl (MACl) as precursors for this single step solution method, CH₃NH₃PbI₃ (MAPbI₃) mixed with a small amount of CH₃NH₃PbCl₃ (MAPbCl₃) can be obtained after an annealing process at temperatures around 100 °C for 2 h. The synthesis of the obtained hybrid halide perovskites yields uniform films with reproducible properties. The films were characterized by X-ray diffraction (XRD), Raman spectroscopy, UV–Vis spectroscopy and photoluminescence (PL). The XRD measurements confirm the presence of cubic CH₃NH₃PbCl₃ perovskite crystallites mixed with tetragonal perovskite crystallites of CH₃NH₃PbI₃ in the films with crystallite sizes for the latter around 34.8 nm. Texture analysis indicates that these crystallites have a preferential orientation at the (002) plane. Raman characterization shows the presence of PbI₂ and MAPbI₃ vibrational modes. Photoluminescence at room temperature shows an intense emission peak at 1.61 eV associated to the excitonic transition energy of the hybrid lead iodide perovskites. From optical transmittance measurements we notice that the absorption edge is around 1.61 eV, in good agreement with the photoluminescence results. This effective band gap energy is associated with a small amount of CH₃NH₃PbCl₃ (around 6%) mixed with CH₃NH₃PbI₃ crystallites. We are in the process of optimizing the photoelectronic and structural properties of the films for their application as inexpensive absorbing layers in solar cells.