钇、镉共掺杂氧化锌纳米粉体的合成及光学性能

为了研究能隙修改和发光强度之间的关系,通过化学共沉淀法制备钇、镉共掺杂的氧化锌纳米粉体。采用XRD、XPS及PL对样品的晶体结构和光学性能进行研究。通过对钇、镉离子对氧化锌光学性能影响的研究发现,钇的掺入能够有效地增强氧化锌的紫外发光,钇、镉共掺杂在增强发光的同时,还使得氧化锌的带隙窄化,使得紫外发光红移,从而使得样品的室温光致发光图谱呈现出增强的紫光发射。该材料有望应用在制备光电器件方面。     

氧化锌纳米棒束的制备、表征及性质研究

以水合醋酸锌和水合肼为反应物,在不使用任何表面活性剂的条件下,采用一种简单温和的液相法制备了氧化锌纳米棒束.利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和高分辨透射电子显微镜(HRTEM)对所得产物的结构和形貌进行了表征,利用荧光光谱仪对产物的室温发光性质进行了测试.测试结果证明所得产物为定向排列的纳米棒自组装而成的尺寸均匀、结晶良好的氧化锌纳米棒束,单根纳米棒的直径20～30 nm,其相结构为六方纤锌矿氧化锌.所得产物在紫外区381 nm处具有一个尖锐的发光峰,在400～600 nm的可见光区域的发光被显著减弱,显示了优良的发光性质.     

气相氧化法制备氧化锌的结晶形貌

研究了锌蒸气高温气相氧化条件对氧化锌结晶形貌的影响结果.结果表明:气相氧化法制备的氧化锌有无定形、颗粒状、单针状、四针状、多针状等5种典型的结晶形貌;这些结晶形貌与原料锌粉的粒度及表面状态没有直接联系,但都强烈地依赖于锌蒸气氧化时的物理化学环境;在不同的氧分压下,锌蒸气具有不同的氧化行为,由此导致了不同形貌的氧化锌结晶;通过改变制备条件可以有效地调控氧化锌的结晶形貌.     

溶胶-凝胶法在多孔氧化铝模板中生长纳米氧化锌

以醋酸锌为前驱体,乙醇为溶剂,二乙醇胺为稳定剂,采用溶胶-凝胶法在多孔氧化铝模板中制备纳米氧化锌.实验结果表明,氧化锌首先吸附在模板孔洞的边壁,形核生长,随着反应时间的延长,逐渐填充孔洞,形成密实的氧化锌纳米线.其发光光谱显示出较好的紫外区发光性能.     

铈掺杂氧化锌微球的形貌、光致发光和气敏性能（英文）

采用溶剂热法合成铈掺杂氧化锌微球。利用粉末X射线衍射仪、场发射扫描电子显微镜、透射电子显微镜、荧光光谱仪和气敏测试系统对样品的显微组织、形貌、发光和气敏性能进行表征。结果表明,铈掺杂氧化锌微球具有纤锌矿结构,由无数直径为70 nm的氧化锌棒组成。铈掺杂引起微球中棒状氧化锌由疏松排列向紧密排列结构演变。与纯氧化锌微球相比,铈掺杂氧化锌微球的紫外发光峰出现明显的红移,蓝色发光得到加强。在320℃测试条件下,铈掺杂氧化锌微球对乙醇气体的灵敏度和选择性显著高于纯氧化锌微球。6%Ce掺杂的氧化锌微球具有最高的灵敏度(约30),其对于50×10~(-6)的乙醇气体的响应和恢复时间分别为2s和16s。     

低碳钢IQ&P工艺下元素配分行为及对组织性能影响

采用双相区再加热-淬火-碳配分(IQP)工艺,研究了双相区不同等温时间下低碳钢中元素配分行为,并分析其对组织形貌、残余奥氏体及力学性能的影响。结果表明:在IQP工艺中,在750℃随等温时间的延长,Mn元素向逆转奥氏体内富集现象逐渐明显,等温时间超过300s后,C元素在两相之间的配分效果不随时间的延长而改变;在750℃等温处理过程中,原奥氏体晶界生成块状逆转奥氏体,马氏体板条界间生成针状逆转奥氏体;随等温时间的延长,钢的最终组织中针状铁素体体积分数不断减小,而块状及针状马氏体体积分数不断增大,同样残余奥氏体体积分数也不断增大;在C、Mn元素的综合作用下,钢的抗拉强度不断增大,断后伸长率先减小而后增大,等温1800s时,钢的强塑积达到最大值21GPa%。     

BCNO发光材料发光机理的研究

实验采用前驱体法合成了BCNO发光材料,该发光材料的发射光在蓝光到绿光之间可调,发光性能优良。通过对BCNO发光材料进行X射线衍射分析,发现BCNO发光材料主要成分是B_2O_3、BN和石墨化碳。通过对BCNO发光材料进行透射电镜分析,发现BCNO发光材料是纳米晶体结构,其晶格条纹间距为0.34nm。通过对BCNO发光材料进行光谱分析,发现BCNO发光材料发射波长随激发波长增大而红移。综合上述分析发现,BCNO材料发光很可能源自碳取代h-BN中B或者N的格位而聚集在一起形成碳量子点发光。     

氧化锌对MgO-Al2O3-SiO2系玻璃结构和性能的影响

采用熔融法制备不同氧化锌含量的MgO-Al2O3-SiO2系玻璃,采用差热分析法研究氧化锌含量对MgO-Al2O3-SiO2系玻璃转变温度和晶化峰值温度的影响,利用红外光谱技术研究氧化锌对玻璃结构的影响,并验证玻璃的差热分析结果,采用粉末X射线衍射分析对950℃烧结后的微晶玻璃样品进行晶相分析。结果表明:少量氧化锌的加入(w(ZnO)≤3%)能够促进玻璃粉体的烧结致密化,过多的氧化锌将阻止样品的烧结。样品的介电常数和膨胀系数随着氧化锌的增加而增加。样品的介电损耗随氧化锌的增加呈先降后升的变化,与密度的变化规律相反。     

KLa(MoO_4)_2:Sm~(3+),Eu~(3+)荧光粉中能量传递研究

采用高温固相法合成了KLa0.7-x(MoO4)2:0.3Eu3+,xSm3+系列红色发射荧光粉,利用XRD对样品的晶体结构进行了分析,发现所得到的样品均为纯相。采用荧光光谱手段对样品的发光性质及能量传递进行了研究。在低Sm3+掺杂浓度时采用277及394 nm激发样品,其发光强度几乎不随掺杂浓度变化,若利用404 nm激发样品发光随Sm3+浓度有明显增强;当Sm3+掺杂浓度较高时,利用277,394及404 nm激发观察到了Sm3+对Eu3+发光产生了猝灭作用。采用电多极相互作用模型及交换相互作用模型对Sm3+到Eu3+的能量传递过程的物理本质进行了探讨,确定了在低掺杂浓度下Sm3+到Eu3+的能量传递是基于交换相互作用的结果。通过对Eu3+的5D0能级荧光动力学过程的分析进一步证实了在低Sm3+掺杂浓度时Sm3+充当能量传递供体,而高掺杂浓度时Sm3+对Eu3+发光产生了猝灭作用。     

沉积温度对ZnO薄膜结构及发光性能的影响

利用Nd-YAG激光器(波长为1064nm,频率为10Hz)做光源,采用纯金属锌靶,以Si(111)为基体在有氧的气氛中通过激光烧蚀锌靶表面来制备氧化锌薄膜,研究基体温度对ZnO薄膜结构及发光性能的影响.通过XRD和AFM原子力显微镜来表征氧化锌薄膜的结构和表面形貌,其光学性质由光致发光谱来表征.结果表明:在450-550 ℃的条件下沉积的ZnO薄膜具有c-轴择优取向,500℃时c-轴取向最明显.具有c-轴取向的ZnO薄膜具有强的紫外光发射和弱的绿光发射,发光中心在518nm处的黄绿光发射主要归因于电子从导带底部到氧位错缺陷OZn能级之间的跃迁.     

Shape controlled synthesis and growth mechanism of one-dimensional zinc oxide nanomaterials

Some types of ZnO nanostructures with various shape and size, including tetrapod-like ZnO (T-ZnO) nanorods, nanowires and nanonbbons, have been obtained by controlled growth process. The nanostructures of ZnO have been investigated by means of field-emission scanning electron microscope, transmission electron microscopy and high-resolution transmission electron microscopy. The growth mechanisms of various ZnO nanostructures were proposed and discussed.     

Synthesis of ZnO whiskers via hydrothermal decomposition route

ZnO whiskers with a length of 30-40μm and a diameter of about 1μm were synthesized by co-precipitation of ZnSO 4 and Na2CO3 solution at room temperature followed by hydrothermal treatment of the as-prepared Zn5(CO3)2(OH)6 precursor at 160 ℃for 6 h.The increase of the initial solution pH promotes the hydrothermal conversion of the particulate Zn5(CO3)2(OH)6 to ZnO whiskers.The presence of minor amount of EDTA in the hydrothermal solution promotes the one dimensional growth of ZnO whiskers,leading to the formation of ZnO whiskers with a length of 50-60μm and a diameter of 1-2μm.     

PREPARATION OF NANOMETER ZINC OXIDE BY EVAPORATION METHOD

Nanometer ZnO particles were synthesized by evaporating of zinc powders of averageparticle size of 370μm studied by XRD, TEM and electron diffraction. The particleswere formed by the oxidation of evaporated zinc vapor in the air. It was found that the particles range from 70 to 100nmin average particle size. The effect of experimental parameters was investigated, the increase of the air flow-rates reduced the average particle size, while increasing the evaporation temperature and the amount of metal charged increased the average particle size. TEM of the particles collected showed that the crystal habits of particles have a tetrapod-like of wurtzite structure consists of four needle crystals. It was found by electron diffraction that all particles were single crystal.     

Synthesis of tetrapod-shaped ZnO whiskers and microrods in one crucible by thermal evaporation of Zn/C mixtures

Tetrapod-shaped ZnO whiskers and microrods were synthesized in one crucible by thermal evaporation of Zn/C mixtures at 930 ℃ in air without any catalyst. The digital camera, optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction techniques were used to study the morphologies and crystal structures of these tetrapod-shaped ZnO microcrystals. The results show that these two types of ZnO tetrapods are grown at different heights within the same crucible. The legs of these tetrapod-shaped ZnO crystals are hexagonally faceted. Some tetrapod-shaped ZnO whiskers show hierarchical structures. A short button-like hexagonal ZnO microcrystal is observed at the triple junctions of some tetrapod-shaped ZnO whiskers. The tetrapod-shaped ZnO microrods are capped by two sets of hexagonal pyramids with two different groups of crystal planes for the surfaces. These two types of tetrapod-shaped ZnO microcrystals have different side faces and aspect ratio, which are believed to be the result of their different growth behaviors. The octa-twin model was used to discuss the different growth behaviors of these two types of ZnO tetrapods. The crystal planes of the legs and the pyramids were determined.     

基于氧化钛纳米管模板电沉积氧化锌纳米棒

研究了氧化锌纳米棒在用二次阳极氧化法制备的二氧化钛纳米管模板表面的电沉积生长。与一次阳极氧化法对比,以二次阳极氧化法获得的氧化钛纳米管薄膜为模板,更有利于形貌均一、取向一致的ZnO纳米棒的电沉积生长,并且在电解质溶液中添加六次甲基四胺(HMT)、适当延长沉积时间均可提高ZnO纳米棒的结晶度和择优生长趋势。当沉积电压为1.0~1.5 V时,可获得形貌规则的ZnO纳米棒;而电压继续增大时,ZnO沿c轴择优生长趋势消失,电沉积产物氧化锌纳米棒由六边形氧化锌纳米片取代。     

Sn-9Zn/Cu无铅焊点ZnO须自发生长

研究了Sn-9Zn/Cu无铅焊点ZnO须自发生长行为.结果表明,在室温条件下Sn-9Zn/Cu无铅焊点因为富锌相的氧化,在富锌相表面自发生长出大量的ZnO须,ZnO须呈现针状、块状、花朵状等不同形态;对ZnO须进行FIB测试,发现在富锌相中出现明显的空洞,主要是因为Zn元素扩散导致的.另外,证实在Zn元素扩散与氧发生反应的过程中,富锌相发生体积收缩,诱使结构中出现明显的拉应力,拉应力为ZnO须生长提供驱动力.     

Zinc whisker growth from electroplated finishes – a review

Abstract

Electroplated zinc finishes have been associated with the electronics industry for many years as a result of their excellent corrosion resistance and relatively low cost. They are normally applied onto ferrous products to provide corrosion protection in a range of different environments. However, the formation of spontaneously grown whiskers on zinc-electroplated components, which are capable of resulting in electrical shorting or other damaging effects, can be highly problematic for the reliability of long life electrical and electronic equipment. The growth of zinc whiskers has been identified as the cause of some electrical and electronic failures in telecommunications and aerospace-based applications, with consequences ranging from mild inconvenience to complete system failures. Investigators have been striving to address the problems induced by whisker growth since 1940s. However, most research effort has been focused on tin whiskers, especially following European Union environmental legislation that restricted the use of lead (Pb), which when alloyed with tin (3–10% by weight) provided effective tin whisker mitigation. Compared with tin whisker research, much less attention has been paid to zinc whiskers. A number of mechanisms to explain zinc whisker growth have been proposed, but none of them are widely accepted and some are in conflict with each other. The aim of this paper is to review the available literature in regard to zinc whiskers, to discuss the reported growth mechanisms, to evaluate the effect of deposition parameters and to explore potential mitigation methods. This paper presents a chronologically ordered review of zinc whisker-related studies from 1946 to 2013. Some important early research, which investigated whisker growth in tin and cadmium, as well as zinc, has also been included.     

硼酸镁晶须增强6061铝基复合材料的干摩擦磨损行为(英文)

研究搅拌铸造工艺制备的硼酸镁晶须增强6061铝基复合材料在干滑动条件下的摩擦磨损性能。复合材料的体积分数为2%,根据增强体种类,材料分别记为:Al基体、Mg2B2O5w/6061Al、ZnO/Mg2B2O5w/6061Al和CuO/Mg2B2O5w/6061Al;讨论磨损速率和摩擦因数之间的关系。结果表明:在4种材料中,ZnO/Mg2B2O5w/6061Al复合材料的磨损率最低。随着载荷和滑动速度的增大,基体和复合材料的摩擦因数和磨损率降低,摩擦磨损机制由轻微磨损机制转向严重磨损机制。     

钾对羟基磷灰石晶须的形貌及热稳定性的影响

通过α-TCP水化法制备了HA晶须,并通过向原料中添加KOH的方法来提高所制备晶须的热稳定性。结果表明:K的引入对HA晶须形貌有较大影响,K添加量过大时会抑制晶须的生长;同时,K的引入可以有效提高所制备晶须的热稳定性,相对于不添加K的HA晶须,添加适量K的晶须在1000℃下热处理2h后依然能较好的保持晶须形貌,X射线衍射和热分析结果发现此时仅有少量HA发生分解生成β-TCP,主晶相仍为HA。     

Structure and photoluminescence properties of Ag-coated ZnO nano-needles

A large number of zinc oxide (ZnO) nano-needles were synthesized by thermal oxidation of pure zinc. The surfaces of ZnO nano-needles were coated with a layer of Ag by pulse electro-deposition technique. The uncoated and coated ZnO nano-needles were characterized by using the X-ray diffraction and the scanning electron microscope (SEM). The results showed that the uncoated samples were close-packed hexagonal structure, which showed needle-like morphology. Their average diameter is about 40 nm, lengths up to 5 μm. At the same time we observed that the prepared ZnO nano-needles have been coated with Ag successfully. The photoluminescence spectrums of ZnO nano-needles with Ag-coated and uncoated were analyzed, finding that the uncoated ZnO nano-needles have two fluorescence peaks at 388 nm and 470.8 nm, respectively, the relative intensity of 143.4 and 93.61; and the Ag-coated ZnO nano-needles showed a pair of strong peaks at 387.4 nm and 405.2 nm, the relative intensity of 1366 and 1305, respectively, indicating that the Ag-coated ZnO nano-needles can increase the absorption of UV light.