纳米硒化锌制备中的条件控制与优化实验研究

采用Zn(Ac)_2、NaBH_4、Na_2S、NaOH、Na_2SeO_3,以及稳定剂N-乙酰-L-半胱氨酸等试剂,利用水相合成法制备了ZnSe纳米粒子.利用电镜、红外分析仪、紫外分光光度计对ZnSe产物进行表征,探讨了稳定剂、原料配比、老化时间的变化对制备ZnSe纳米粒子的影响,确定优化ZnSe纳米粒子的最佳制备条件.     

肼还原法制备镍纳米粒子及其机理

在乙二醇中用肼作还原剂还原Ni2 制备镍纳米粒子。用X射线衍射仪测定出产物的相结构,用扫描电子显微镜观察产物的微观结构。根据反应现象和产物的相结构,研究温度、pH值调节剂种类和pH值对镍纳米粒子形成的影响,并推断其形成机理。研究结果表明,用肼作还原剂还原Ni2 制备纳米Ni的最佳反应温度为60℃,用NaOH作pH值调节剂调pH值到10～11得到的镍纳米粒子为体心立方结构,平均粒径为25nm。在Ni纳米粒子的形成过程中,NaOH不仅起到调节pH值的作用,还起催化作用。     

纳米ZnO的制备及其对甲基红的光催化降解

本文以Zn(NO3)、NaOH为原料,液相合成ZnO纳米粒子.研究ZnO纳米粒子对甲基红的光催化降解.讨论了ZnO纳米粒子用量,以及光照时间对甲基红降解率的影响.结果表明,在ZnO纳米粒子用量为0.001g,光照时间为30min时,甲基红脱色率可达58.1%     

ZnO纳米片的水热合成及其光催化性能

目的以Zn(CH_3COO)_2·2H_2O和NaOH为原料,制备ZnO纳米粒子,并研究ZnO纳米材料的形貌对其光催化性能的影响。方法采用一步水热法合成ZnO片状纳米粒子,通过X-射线粉末衍射(XRD),场发射扫描电镜(FE-SEM)和拉曼光谱(Raman)等分析手段对合成产物的结构和形貌进行表征,探讨反应物摩尔比、水热温度和水热时间等合成条件对形成的ZnO纳米粒子形貌的影响,以及形貌演变机理。通过光催化分解水实验对所制备的ZnO纳米粒子的光催化性能进行测试。结果 Zn~(2+)/OH~-摩尔比为1∶4时,在100℃反应6h,可制得片状的纳米ZnO,其产氢量为313μmol·h~(-1)·g~(-1)。结论在本文制备的ZnO纳米材料中,ZnO纳米片的光催化性能优于短棒状和纤维状的ZnO粒子。     

添加纳米粒子对脂肪酶交联酶聚集体活性及结构的影响

将纳米TiO2、纳米MgO和纳米Cu分别引入假丝酵母脂肪酶（Candida sp. 1619）的交联酶聚集体（CLEAs）制备过程，获得相应的纳米粒子-CLEAs，采用傅里叶变换红外光谱仪(FTIR)、扫描电子显微镜(SEM)、激光粒度分析仪(SLP)等分析了纳米粒子对CLEAs活性和结构的影响。结果表明与未加纳米粒子的CLEAs相比，适量纳米TiO2的加入可提高CLEAs的酶活，最大增加15.2%；而不管添加浓度大小，纳米MgO、纳米Cu对CLEAs酶活均有抑制作用，酶活下降63.7%~97.9%。SEM、SLP分析结果表明，与未添加纳米粒子时相比，加入纳米TiO2的CLEAs粒径变小，粒度较均匀，孔道增加；而纳米MgO-CLEAs和纳米Cu-CLEAs则出现粒度不均匀性增加、粒径范围扩大、孔道减少的现象。FTIR分析结果表明，加入3种纳米粒子后CLEAs二级结构中有序结构（α-螺旋、β-折叠）/无序结构（β-转角、无规则卷曲）值显著提高，顺序为纳米TiO2-CLEAs（0.55）>纳米MgO-CLEAs（0.43）>纳米Cu-CLEAs（0.35）>CLEAs（0.28），这与纳米粒子-CLEAs酶活顺序不一致，表明纳米粒子可能还存在其他影响CLEAs酶活的途径。     

共沉淀法合成Mg-Al-类水滑石影响因素研究

混合共沉淀法制备类水滑石(HTlc)纳米粒子时,其粒径及粒径分布会受到多种因素的影响。本文采用正交设计法研究了Mg-Al-HTlc纳米粒子的合成,比较了胶溶时间、胶溶温度、碱用量及老化时间对晶胞参数、粒径及粒度分布的影响及作用。各因素对平均粒径影响顺序为:胶溶温度>老化时间>胶溶时间>碱用量。各因素对粒度分布影响顺序为:碱用量>胶溶温度>老化时间>胶溶时间。单分散HTlc纳米粒子最佳制备条件为:胶溶时间48 h,胶溶温度100℃,碱用量nNH3.H2O/(2n(Mg2+)+3n(Al3+))=1,老化时间45 min。     

基于植酸胶束制备纳米金及其SERS特性研究

在溶液中用替换法合成稳定的拉曼信号较强的金纳米粒子,即首先以植酸为稳定剂和控型剂,用柠檬酸三钠还原硝酸银合成银纳米粒子,再利用银纳米粒子还原氯金酸,在水溶液中制备金纳米粒子.采用紫外-可见(UV-Vis)吸收光谱、透射电子显微镜(TEM)、能量散射光谱(EDX)对金纳米粒子的光学性质及形貌结构进行了表征,实验表明合成的金纳米粒子结构均一、分散性好.以罗丹明6G为探针分子,研究了金纳米粒子作为基底的表面增强拉曼光谱(SERS)效应,结果表明:这种金纳米粒子具有SERS信号强、检测限低、稳定性强等优点.     

增强广谱吸收硅表面

为增强黑硅的广谱吸收性能,在氢氧化钠/异丙醇(NaOH/IPA)体系下对单晶硅进行金字塔表面织构的基础上,采用金纳米粒子辅助湿法化学方法做了进一步刻蚀.利用扫描电子显微镜(SEM)和紫外—可见—近红外分光光度计对表面形貌和反射光谱进行了表征与测量.结果表明:增强广谱吸收硅表面具有纳米/微米双尺寸陷光结构,在350~2 500nm波段平均反射率低于5.5%.     

受限在单壁碳纳米管中的Pd-Au-Pt三元金属纳米粒子相变机理的研究

利用分子动力学模拟(MD)方法对受限于扶手椅型单壁碳纳米管中的(Pd_(0.33)Au_(0.33)Pt_(0.33))_(1522)三元金属纳米粒子在加热和冷却过程的相变机理进行了研究.总能量、结构和径向密度分布用于分析(Pd_(0.33)Au_(0.33)Pt_(0.33))_(1522)纳米粒子在加热和冷却过程中的结构特征.结果表明,受限在碳纳米管中的(Pd_(0.33)Au_(0.33)Pt_(0.33))_(1522)具有多层圆筒状结构,不同于游离的纳米粒子的结构.受限的(Pd_(0.33)Au_(0.33)Pt_(0.33))_(1522)三元金属纳米粒子的密度分布揭示了熔化起始于内层,结晶起始于金属与碳管的界面.本文揭示了受限Pd-Au-Pt纳米粒子熔化转变的结构特征.     

PS/Ag纳米复合粒子的制备与表征

目的 制备PS/Ag纳米复合粒子.方法 以二硫代苯甲酸异丙苯酯(CDB)为链转移剂,用可逆加成断裂链转移聚合(RAFT)的方法将硫代羰基引入到聚苯乙烯(PS)高分子链中,采用透射电子显微镜(TEM)对其进行了表征.利用PS高分子链中的硫代羰基有保护和稳定Ag纳米粒子的作用,制备了PS/Ag纳米复合粒子.结果 Ag纳米粒子具有良好的单晶结构,且均匀分散于PS胶体粒子中.结论 PS/Ag纳米复合粒子的结构与AgNO_3溶液的加入量有关.     

Mechanical properties and kinetics of thermally aged Z3CN20.09M cast duplex stainless steel

Cast stainless steels used in nuclear power plants suffer from fracture toughness losses owing to thermal aging after long-term service at temperatures ranging from 280-320℃. To study the thermal aging embrittlement of Z3CN20.09M duplex stainless steel produced in China, accelerated thermal aging experiments were carried out at 350, 380, and 400℃ for up to 10000 h. Microhardness and Charpy impact energies were measured at different aging times. The microhardness of ferrite increased drastically over the initial aging time of 2000 h at 380 and 400℃ and then slowly reached HV_0.01 560. In contrast to this observed change in microhardness, Charpy impact energies sharply decreased after initial aging and then gradually reached a minimum value. Taking the microhardness of the ferrite phase as the parameter describing the thermal kinetics of the stainless steel samples, the activation energy of thermal aging was calculated to be 51 kJ/mol. Correlations between the thermal aging parameter, P, and ferrite microhardness and between P and Charpy impact energy were also analyzed. The results showed that the activation energy calculated from the ferrite microhardness is much more reasonable than that obtained using other parameters, such as chemical composition and impact energy.     

磁介质吸波剂/多孔金属材料吸波性能

为了研究磁介质吸波剂/多孔金属材料吸波性能,在泡沫铝合金表面涂覆了Ni-Zn铁氧体(CFe)、羰基镍粉(CNi)以及二者的复合粉,利用GJB 2038—94"雷达吸波材料反射率测试方法"中的雷达截面(RCS)法对该材料的微波反射率进行了测量.结果表明,在12～18GHz频段内,复合磁介质吸波剂/泡沫铝材料吸波性能介于单一吸波剂样品CFe与CNi之间;在26.5～40 GHz频段内,羰基镍质量分数为40%的泡沫铝复合材料吸波性能最好,当其质量分数大于40%时,材料吸波性能逐渐降低.因此,在泡沫铝合金表面涂覆适当比例的Ni-Zn铁氧体与羰基镍复合粉,可以进一步改善材料的吸波性能.     

纳米级Mn-Zn软磁铁氧体磁粉溶胶-凝胶法制备

目的提高超细粉合成反应活性,降低合成温度,改善超细粉烧结性能,从而提高锰锌铁氧体的性能。方法应用溶胶-凝胶法制备软磁Mn-Zn铁氧体磁粉。用X射线衍射(XRD)和透射电镜(TEM)对粉体材料进行分析表征,并用振动样品磁强计(VSM)测定样品的饱和磁化强度和矫顽力。结果所得样品为纳米级单相Mn-Zn铁氧体,其晶粒大小约为40 nm,M=0.14 552 EMU,HC=11 480 Oe,这表明该纳米级Mn-Zn铁氧体不具有超顺磁特性,而具有很好的活性。结论采用溶胶-凝胶法制备的纳米级Mn-Zn铁氧体磁粉,可以用来制备高性能的软磁Mn-Zn铁氧体材料。     

低温石墨化退火对低钼、低镍球墨铸铁组织和力学性能的影响

对含钼0.25%,含镍0.2%~0.8%的球墨铸铁进行低温石墨化退火,测试了其力学性能,并对显微组织和冲击断口进行观察和分析.结果表明:添加少量钼和镍后铸态球墨铸铁中铁素体含量增加,冲击韧度提高50%以上,强度和硬度下降;进行低温石墨化退火后球墨铸铁中珠光体逐渐转变成铁素体,与铸态相比冲击韧度有大幅度提高,冲击吸收功最多增加500%,冲击断口存在较多的撕裂岭和少量韧窝;此外,添加钼和镍后,不同的退火工艺下试样的力学性能参数比较稳定,波动小.     

双相不锈钢热老化前后拉伸变形行为的电子背散射衍射表征

通过电子背散射衍射实验分析方法,研究变形量和热老化因素对双相不锈钢的拉伸性能、相边界、局部应变分布、重位点阵特殊晶界和取向分布的影响。研究结果表明：热老化后,双相不锈钢的强度提高,韧性降低;在大变形条件下铁素体晶粒内小角度晶界的数量和密度略有增加;热老化材料的铁素体的塑性变形和局部应变能力下降,大变形破坏初始奥氏体和铁素体以及∑3孪晶边界的分布。     

Dechlorination of 2,4-dichlorophenol by nickel nanoparticles under the acidic conditions

Metal nanoparticles are effective for remediation of contamination with a range of compounds including chlorinated organics.However,the sorption process of the passivation oxide layers on the metal nanoparticle surfaces may result in incomplete degradation of contaminants.This phenomenon can be prevented by an acidic washing procedure or reaction in an acidic medium.In this paper,nickel nanoparticles manufactured via the carbonyl powder process were analyzed using scanning electron microscopy,transmission electron microscopy,X-ray diffraction and energy-dispersive X-ray spectroscopy.The sorption and degradation of 2,4-dichlorophenol (2,4-DCP) by nickel nanoparticles under acidic conditions was then investigated.Transmission electron microscopy and XRD results showed that the nickel nanoparticles range in size from 10 to 20 nm,and a thin passivation layer of NiO is present on the surface.This oxide layer can be removed by pretreatment washing with acidic solutions.It was indicated that dechlorination was the key reaction pathway for degradation of 2,4-DCP by nickel nanoparticles under acidic conditions.The main degradation products were 4-Chlorophenol,2-Chlorophenol,and Phenol,and among these,Phenol was dominant.The acidic medium promoted degradation by providing an appropriate pH,and H+ may be involved in the reaction.Dechlorination of 2,4-DCP by nickel nanoparticles under the acidic condition follows the second order kinetic model,and the rate constants at 298,306,316 K are 0.02,0.2 and 0.3 (g L h)-1,respectively.     

One-pot synthesis of PVP-coated Ni<Subscript>0.6</Subscript>Fe<Subscript>2.4</Subscript>O<Subscript>4</Subscript> nanocrystals

Novel poly(N-vinyl-2-pyrrolidone) (PVP)-coated nickel ferrite nanocrystals were prepared by simultaneously pyrolyzing nickel(II) acetylacetonate (Ni(acac)₂) and iron(III) acetylacetonate (Fe(acac)₃) in N-vinyl-2-pyrrolidone (NVP). The PVP coating was formed in situ through polymerization of NVP. The crystalline structure of the resultant nickel ferrite was analyzed by high-resolution transmission electron microscopy, electron diffraction patterns, and powder X-ray diffraction. In addition, the valence state of Ni and the metal contents of Ni and Fe in different valence states were analyzed by X-ray photoelectron spectroscopy (XPS), atomic absorption and the phenanthroline method. The surface coating layer of PVP and its binding states were characterized by Fourier transform infrared spectroscopy in combination with XPS. Colloidal stability experiments revealed that the nanocrystals could be dispersed well in both phosphate-buffered saline and Dulbecco’s Modified Eagle Medium.     

Abnormal growth of Ag3Sn intermetalUc compounds in Sn-Ag lead-free solder

The abnormal growth of Ag3Sn intermetallic compounds in eutectic Sn-3.5% Ag solder was investigated through high-temperature aging treatment. Microstructural evolutions of this solder before and after the aging treatment were observed by optical microscopy and scanning electron microscopy. Precise differential thermal analysis was made to study the changes in enthalpies of the solder under different conditions. The results reveal that the water-cooled solder is in metastable thermodynamic state due to the high free energy of Ag3Sn nanoparticles, which sporadically distribute in the matrix as second-phase. The second-phase Ag3Sn nanoparticles aggregate rapidly and grow to form bulk intermetallic compounds due to the migration of grain boundary between primary Sn-rich phase and the Ag3Sn nanoparticles during high temperature aging treatment.     

铁酸铋负载石墨烯复合材料的制备及应用

为了降解工业废水,制备了铁酸铋负载石墨烯复合材料,并将其应用于工业废水降解中。制备氧化石墨烯和铁酸铋,在水热反应釜中,通过水热法制备铁酸铋负载石墨烯复合材料。利用X射线衍射分析和透射电子显微镜分析对复合材料进行表征。发现铁酸铋负载石墨烯复合材料衍射峰强度和铁酸铋相比向低位移动,说明复合材料被还原;铁酸铋纳米颗粒较均匀地分布于石墨烯表面上,说明铁酸铋负载石墨烯复合材料可有效结合铁酸铋与石墨烯。将制备材料应用于工业废水降解中,结果表明:降解5个月后,复合材料表层出现孔穴;降解10个月后,复合材料孔穴增加,有粗大的纤维裸露;经铁酸铋负载石墨烯复合材料降解后,废水p H、COD值以及色度均明显降低;工业废水在400 nm处出现吸收峰,在光催化时间逐渐增加的情况下,吸收峰逐渐降低,反应150 min后,吸收峰基本消失,水样色度也显著降低;制备复合材料降解率和反应速率常数最高;铁酸铋负载石墨烯复合材料在经多次使用后仍可保持很高的降解率。可见制备复合材料有助于工业废水降解,有更高的光催化性能,稳定性很高,可承受长时间多次循环使用,可将其应用在工业废水降解环境中。     

Competing crystallite size and zinc concentration in silica coated cobalt ferrite nanoparticles

Silica coated(30 wt%) cobalt zinc ferrite(Co1 xZnxFe2O4, x?0, 0.2, 0.3, 0.4, 0.5 and 1) nanoparticles were synthesized by using sol–gel method. Silica acts as a spacer among the nanoparticles to avoid the agglomeration. X-ray diffraction(XRD) reveals the cubic spinel ferrite structure of nanoparticles with crystallite size in the range 37–45 nm. Fourier transform infrared(FTIR) spectroscopy confirmed the formation of spinel ferrite and SiO2. Scanning electron microscopy(SEM) images show that the nanoparticles are nearly spherical and non-agglomerated due to presence of non-magnetic SiO2 surface coating. All these measurements signify that the structural and magnetic properties of Co1 xZnxFe2O4 ferrite nanoparticles strongly depend on Zn concentration and nanoparticle average crystallite size in different Zn concentration regimes.& 2014 Chinese Materials Research Society. Production and hosting by Elsevier B.V. All rights reserved.