CO_2激光烧结合成负热膨胀材料Sc_2(MO_4)_3(M=W,Mo)及其拉曼光谱

用CO2激光烧结合成了负热膨胀材料Sc2(WO4)3和Sc2(MoO4)3.实验表明,激光合成负热膨胀材料Sc2(WO4)3和Sc2(MoO4)3属于快速合成技术,合成一个样品的时间仅需几秒到十几秒,具有快速凝固的特征;X射线衍射和拉曼光谱分析表明,所合成的材料为正交相结构,且具有较高的纯度;变温拉曼光谱分析表明,所合成的材料在室温以上没有相变,但可能有微弱的吸水性;在对Sc2O3,Mo O3,WO3,Sc2(MoO4)3和Sc2(WO4)3拉曼光谱分析的基础上,给出了激光光子能量及原料和合成产物的声子能级图,分析了激光烧结合成的机理.激光光子能量转化为激发声子的能量是光热转化的主要通道,原料在熔池中反应并快速凝固形成最终产物.     

Gd2(MoO4)3:Tb3+荧光粉的固相合成与光谱性质

以MoO3、Gd2O3及Tb4O7为原料,以NH4HF2为助溶剂,在碳粉还原条件下制备了不同Tb3+掺杂浓度的Gd2( MoO4)荧光粉样品.采用X射线衍射(XRD)对样品的晶体结构进行了表征,发现掺杂浓度的改变未对产物的晶体结构产生影响,产物均为单一正交相Gd2( MoO4)3.对样品的激发、发射光谱及荧光衰减特性进...     

GaN衬底材料LiGaO2晶体的温度梯度法生长及分析

以温度梯度法生产LiGaO2晶体，通过形貌观察、X射线衍射分析和X射线光电子能谱分析确认在样品的中部形成了单一相的LiGaO2晶体。但在生长过程中由于CO气体的存在，熔体表面形成了LiO-和金属态的Ga,钼坩埚被侵蚀形成Li2MoO4进入熔体，使样品上下两部分的结晶质量变差。     

亚微米级聚晶金刚石的高温高压合成

聚晶金刚石作为超硬材料具有很广泛的应用,常用于油气钻探、切削刀具、耐磨零件等领域。目前,工业上合成聚晶金刚石的内部晶粒尺寸一般都在微米量级以上,而合成微米级以下的聚晶金刚石则要面临很多困难。本工作使用熔渗法在高温高压的条件下合成了亚微米级聚晶金刚石,并对合成的样品进行了X射线衍射、扫描电子显微镜、电子背散射衍射、能谱、硬度等分析测试,结果表明:在5.5GPa、1 500℃、保温15min的情况下成功合成了维氏硬度高达57.0GPa的亚微米级聚晶金刚石;分层组装的方法可以使Co均匀地分散在聚晶金刚石样品中,呈现出圆孔状,从而保证样品具备均匀、优异的性能。同时,通过对烧结工艺的探索发现,温度和保温时间在亚微米级聚晶金刚石的合成过程中起着非常重要的作用。     

草酸铕颗粒微米层状颗粒的合成及其光学性能

在室温条件下, 以柠檬酸钠为辅助剂, 通过简单沉淀法合成了草酸铕Eu₂(C₂O₄)₃·10H₂O微米层状颗粒. 应用X射线衍射、X射线电子能谱、场发射扫描电子显微镜、光致发光光谱对Eu₂(C₂O₄)₃·10H₂O结构与性能进行了表征. 讨论了草酸铕微米层状颗粒可能的形成机理.     

水热法合成ZnS∶Au,Cu超细X射线发光粉

报道了水热法合成的高强度ZnS∶Au,Cu超细X射线发光粉及其光致发光(PL)和X射线激发发光(XEL)的光谱特性。200℃水热处理12h直接合成样品的纳米晶粒约15nm,尺寸分布窄,分散性好,具有纯立方相的类球形结构。氩气保护下1000℃焙烧1h后的样品存在一定的团聚,但团聚后尺寸为1～2μm,为超细X射线发光粉,此时样品为纯六角相的类球形为主的结构。所有样品的PL和XEL光谱均为宽带谱,水热法直接合成样品的XEL强度最强时,样品的Cu/Zn,Au/Cu比值分别为3×10-5和2。在此比值条件下,1000℃焙烧1h样品的XEL发光最强,此时其2个峰值分别位于445和513nm,且与未焙烧前相比强度增强了10倍左右。另外通过比较PL光谱与XEL光谱特性,讨论了PL和XEL光谱的发光机理和其不同的激发机制。     

水热法合成ZnS:Au,Cu超细X射线发光粉

报道了水热法合成的高强度ZnS:Au,Cu超细X射线发光粉及其光致发光(PL)和X射线激发发光(XEL)的光谱特性.200℃水热处理12 h直接合成样品的纳米晶粒约15 nm,尺寸分布窄,分散性好,具有纯立方相的类球形结构.氩气保护下1000℃焙烧1 h后的样品存在一定的团聚,但团聚后尺寸为1～2μm,为超细X射线发光粉,此时样品为纯六角相的类球形为主的结构.所有样品的PL和XEL光谱均为宽带谱,水热法直接合成样品的XEL强度最强时,样品的Cu/Zn,Au/Cu比值分别为3×10-5和2.在此比值条件下,1000℃焙烧1h样品的XEL发光最强,此时其2个峰值分别位于445和513 nm,且与未焙烧前相比强度增强了10倍左右.另外通过比较PL光谱与XEL光谱特性,讨论了PL和XEL光谱的发光机理和其不同的激发机制.     

La1．6（MoO4）3∶Eu3＋0．4纳米晶合成及发光特性

采用燃烧法合成了La1．6（MoO4）3∶Eu3＋0．4纳米晶末,研究了其声子-掺杂-晶格相互作用和发光性质。 X射线粉末衍射（XRD）分析表明,在500～900℃退火后,La1．6（MoO4）3∶Eu3＋0．4样品为单一晶相。对样品进行了光致发光（PL）测量,激发Mo6＋-O2－电荷迁移带,观察到Eu3＋的系列发光,表明Mo6＋-O2－带和Eu3＋间存在能量传递,中心波长分别在λ1＝469 nm和λ2＝426 nm处的两个one-phonon边带,相应的声子能量分别为767和1202 cm－1,分别对应于Mo O和Mo—O—Mo伸缩振动。同时,计算了两个局域模电子-声子耦合强度的黄昆因子分别为S1＝0.055和S2＝0.037,为揭示其三价离子高传导特性及其负热膨胀物理特性提供了实验基础。     

醇体系中合成CuGaS2纳米晶及其形貌演变

以CuCl2·2H2O,自制的GaCl3和(NH2)2CS为原料,在乙二醇体系中合成了花状结构的CuGaS2纳米晶．产物分别用X射线粉末衍射仪、透射电子显微镜、场发射扫描电子显微镜、高分辩透射电子显微镜和X射线光电子能谱仪进行了表征．实验结果表明,220℃反应24 h得到均匀的花状纳米结构CuGaS2,它是由厚度80-100 nm的片晶组成．同时,通过反应时间的控制,可以清楚的看到由纳米颗粒到纳米球以及花状纳米结构的演变过程．另外,研究了反应温度、反应时间、溶剂等对产物和形貌的影响．此外,对花状结构纳米晶的生长机理进行了初步的探讨．室温荧光光谱表明,随粒径的降低,发光位发生了部分蓝移．     

微柱电泳与紫外-可见分光光度法的在线联用

自制了紫外-可见分光光度计的微柱电泳高效分离附件, 介绍了X射线衍射法在电泳微柱制备中的应用以及微柱电泳与紫外-可见分光光度法的在线联用。使用水热法合成均匀石英微米晶粒,采用X射线衍射法表征和控制产物的晶相,并用扫描电子显微镜观察产物形貌。将合成的石英微米晶粒均匀填充在2 mm i.d.石英管中,制成电泳微柱。通过微柱电泳与紫外-可见分光光度法在线联用,对非衍生的色氨酸、苯丙氨酸和酪氨酸进行了分离检测。检出限分别为0.037, 0.20和0.20 μmol·L-1,色氨酸的分离效率为每米4.5×104,电泳微柱的样品容量达到35 μL。实验结果表明,填充石英微米晶粒的微柱电泳可抑制大柱径电泳热效应,增大样品容量,提高检测灵敏度。微柱电泳与常规紫外-可见分光光度法联用可简便地对混合物进行在线分离和测定,进一步拓宽了紫外-可见分光光度计在光谱重叠组分痕量分析中的应用。     

Ultrasonic-assisted synthesis of highly dispersed MoO3 nanospheres using 3-mercaptopropyltrimethoxysilane

With ultrasonic irradiation as assistance, highly dispersed MoO(3) nanospheres were synthesized using silane coupling agent 3-mercaptopropyltrimethoxysilane HS-(CH(2))(3)Si(OCH(3))(3) (MPTS) as figuration agent. The results of X-ray powder diffractometer (XRD) showed that the precursor was hexagonal molybdenum oxide hydrate (MoO(3).0.55H(2)O). It was converted into orthorhombic MoO(3) after annealed at 400 degrees C for 2h. Transmission electron microscopy (TEM) showed that MoO(3).0.55H(2)O and MoO(3) nanoparticles were spherical with particle-size distribution of ca. 30-80 nm and 25-75 nm, respectively. Results indicated that MPTS and ultrasonic irradiation played important role in formation of highly dispersed MoO(3) nanospheres. X-ray photoelectron spectroscopy (XPS) was also adopted to confirm the growth mechanism. The possible cause of formation was based on dispersion function of ultrasonic irradiation and figuration of MPTS.     

Solvothermal Synthesis of Molybdenum Disulfide Hollow Spheres Modified by Cyanex 301 in Water–Ethanol Medium

Hollow spherical molybdenum disulfide has been successfully synthesized via a solvothermal method using Cyanex 301 as sulfur source and modification agent. The hollow spheres are characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction and Energy-Dispersive X-ray analysis. The influences of reaction conditions are also discussed while a mechanism is proposed to explain the formation of the peculiar morphology.     

有序排列PMMA 模板法合成三维有序纳米孔道MgO

"利用由无乳化剂的乳液聚合法和水浮法联用技术合成得到的有序排列的聚甲基丙烯酸甲酯(PMMA)微球为硬模板,以硝酸镁为镁源,并采用硝酸镁-柠檬酸-乙醇混合溶液浸渍PMMA微球后经干燥以及先后在300 ℃恒温灼烧3 h和500 ℃恒温灼烧5 h,制备出具有有序纳米孔道结构的MgO粒子．应用X射线衍射、高分辨扫描电子显微镜、透射电子显微镜/选区电子衍射以及N2吸附-脱附法等技术表征了PMMA和MgO样品的物理化学性质．结果表明,所得PMMA微球颗粒较为均匀,粒径约为284 nm,且排列规整有序．由PMMA硬模板     

Magnetic composites based on hybrid spheres of aluminum oxide and superparamagnetic nanoparticles of iron oxides

Materials containing hybrid spheres of aluminum oxide and superparamagnetic nanoparticles of iron oxides were obtained from a chemical precursor prepared by admixing chitosan and iron and aluminum hydroxides. The oxides were first characterized with scanning electron microscopy, X-ray diffraction, and Mössbauer spectroscopy. Scanning electron microscopy micrographs showed the size distribution of the resulting spheres to be highly homogeneous. The occurrence of nano-composites containing aluminum oxides and iron oxides was confirmed from powder X-ray diffraction patterns; except for the sample with no aluminum, the superparamagnetic relaxation due to iron oxide particles were observed from Mössbauer spectra obtained at 298 and 110 K; the onset six line-spectrum collected at 20 K indicates a magnetic ordering related to the blocking relaxation effect for significant portion of small spheres in the sample with a molar ratio Al:Fe of 2:1.     

Template-free synthesis of ZnV2O4 hollow spheres and their application for organic dye removal

Hollow ZnV₂O₄ spheres with the shell aggregated by small nanoparticles were successfully synthesized through a facile one-pot template-free solvothermal method. The as-prepared product was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), and Brunauer-Emmett-Teller N₂ adsorption-desorption analyses. The formation of ZnV₂O₄ hollow spheres was based on flowerlike intermediate products supported reduction-dissolution-aggregation process at the expense of consumption of all the flowerlike products. The obtained ZnV₂O₄ hollow spheres showed a good adsorption capacity of methylene blue (MB) organic dye, which might be attributed to their special structural feature with large surface area. The adsorption kinetics and isotherm of MB on ZnV₂O₄ hollow spheres were also studied.     

Synthesis of porous hollow silica spheres using polystyrene-methyl acrylic acid latex template at different temperatures

Porous hollow silica spheres were prepared by using polystyrene-methyl acrylic acid latex as a template and cetyltrimethylammonium bromide as a wall structure-directing agent starting from tetraethoxysilane. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), FT-infrared spectroscopy (FT-IR) and nitrogen adsorption/desorption were used to characterize the hollow silica spheres. When silica-coated latex composites were prepared at room temperature, hollow silica spheres with micropores in the walls were formed after removing the latex templates by calcination. When silica-coated latex composites were aged at a higher temperature of 150 °C, intact mesoporous hollow silica spheres were formed after calcination treatment.     

Preparation of Manganese Oxide Hollow Spheres Using pH-responsive Microgels as Templates

以pH响应型微凝胶为模板制备出了二氧化锰空心球材料,并利用XRD、TGA、SEM、FT-IR和TEM等手段对其进行了表征. 结果表明,通过调节KMnO₄的用量可以有效控制二氧化锰空心球的球壳厚度. 对洗脱后上层清夜中的pH响应型微凝胶进一步研究发现,部分微凝胶呈现出非可逆的膨胀-收缩转变,这一现象主要是由于其内部的交联程度不高造成的. 在对表征结果进行分析后提出了空心球结构的形成机理.     

掺铕钼酸钆荧光粉的制备与发光性能分析

通过共沉淀法制备了红色荧光粉Gd_2-xEu_x(MoO₄)₃,并采用X射线衍射(XRD)、扫描电子显微镜(SEM)和荧光光谱对所制备的样品进行结构表征分析,讨论了不同掺杂量下合成的荧光材料的发光性质。研究结果表明:所制备的Gd_2-xEu_x(MoO₄)₃红色荧光粉的三处激发峰分别位于394,465,534 nm。发射光谱中在589 nm和613 nm处有很强的发射峰,其中最强发射峰位于613 nm左右,与Eu³⁺的⁵D₀→⁷F₂跃迁对应。随着Eu³⁺掺杂量的增加,所合成的荧光粉的发光强度逐渐增强。在三组实验结果中,Gd_1.4Eu_0.6(MoO₄)₃(x=0.6)的发光强度最强。     

A room-temperature approach to boron nitride hollow spheres

Boron nitride hollow spheres were synthesized by the reaction of BBr₃ and NaNH₂ at room temperature; X-ray powder diffraction pattern could be indexed as hexagonal BN with the lattice constants of a=2.482 and c=6.701 Å; high-resolution transmission electron microscopy image showed the hollow spheres consisted of BN nanoparticles, with diameter between 80 and 300 nm; a possible formation mechanism of BN hollow spheres was discussed.     

Morphology transformation of Cu<Subscript>2</Subscript>O by adding TEOA and their antibacterial activity

Cu₂O polyhedral particles and hollow spheres were successfully synthesized by adjusting the concentration of triethanolamine (TEOA). The as-prepared samples were structurally characterized by the scanning electron microscope (SEM), X-ray powder diffraction (XRD), and transmission electron microscopy (TEM). The results revealed that the solid polyhedral Cu₂O with sizes ranging from 70 to 150 nm was in good crystallization. The diameter of the hollow Cu₂O spheres increased to 350–450 nm. It was found that the sizes and morphologies of the products could be significantly affected by the concentration of TEOA. And the morphology of Cu₂O transformed from solid polyhedrons to hollow spheres with the further enrichment of TEOA concentration. A possible mechanism was proposed to explain the formation of the hollow Cu₂O spheres. In addition, we investigated the antibacterial activities of the samples. It was demonstrated that the hollow Cu₂O sphere exhibited better antibacterial activities for Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) compared with the solid polyhedral Cu₂O.