掺Bi的MgO-CaO-Al_2O_3-SiO_2玻璃的吸收和近红外发光特性

研究了4种不同Bi_2O_3掺杂量(0.5%,1%,2%和3%,摩尔分数)的23MgO-11CaO-15Al_2O_3-51SiO_2(摩尔比)玻璃的发光特性。测量了吸收光谱、荧光光谱和荧光寿命。通过电子顺磁共振图谱观察了玻璃受γ辐射前后结构的变化,探讨了玻璃颜色变化和近红外发光的机理。结果表明:在500nm激发下,随着Bi_2O_3掺杂量从1%到3%的逐渐增加,发光波长发生红移,荧光半高宽从312nm增加到352 nm;最优的Bi_2O_3掺杂量为1%,玻璃的受激发射截面和荧光寿命的乘积为3.10×10~(-24)cm~2·s;γ辐射后发光强度的增加和玻璃颜色加深的现象说明Bi掺杂玻璃的近红外发光中心可能是低价态的Bi离子或者Bi团簇。     

光学碱度与铋离子掺杂锗酸盐玻璃近红外发光性质之间的关系

制备了铋离子掺杂的碱金属和碱土金属锗酸盐玻璃,并研究了玻璃光学碱度与铋离子近红外发光性质之间的关系。结果表明:铋离子的宽带近红外发光的强度、峰位以及荧光半高宽可以通过锗酸盐玻璃的光学碱度进行调控:随着玻璃光学碱度的增加,红外发光强度下降,半高宽增大,同时发光峰红移;玻璃中Bi~(3+)/Bi~(2+)的摩尔比变化趋势与Duffy光学碱度理论相符。而铋离子近红外发光强度与光学碱度的依存关系表明,近红外宽带发光可能源于低价态铋离子。     

高硅氧发光玻璃的制备及其荧光性能

石英玻璃具有低膨胀、耐热冲击、高机械强度和高化学隐定性等优点,是稀土和过渡金属发光离子掺杂的优选的基质材料。但发光离子在石英玻璃中容易自发形成团簇,产生浓度淬灭效应,介绍一种用二氧化硅质量分数超过95%的纳米微孔玻璃来抑制发光离子团簇的自发形成的新方法,以制备高发光强度的石英破璃和激光玻璃。该方法是将发光离子浸入微孔玻璃中并在适当气氛中烧结,目前已经制得多种颜色、量子效率接近于1的强发光玻璃,真空紫外光激发发光玻璃,高铒离子掺杂的高硅氧玻璃,还获得了新颖的低膨胀、耐高温的掺钕高硅氧激光玻璃和掺铋红外宽带发光玻璃用这种方法还容易进行多种发光活性离子掺杂,实现不同离子间的能量转换,提高发光强度和改变激发光的波长范围。这种新方法有望扩大石英发光玻璃的应用范围。     

Bi3+激活的Sr2SiO4材料发光特性研究

采用溶胶-凝胶法制备了Sr2SiO4:Bi3+发光材料.X射线衍射谱显示其为纯相的Sr2SiO4晶体.测量了Sr2SiO4∶ Bi3+材料的激发与发射光谱,结果显示,材料的发射光谱为一单峰宽带,主峰位于441nm处;监测441nm发射峰,所得材料的激发光谱为一主峰位于376nm处的单峰宽带.研究了Bi3+掺杂浓度对Sr2SiO4∶ Bi3+材料发射光谱的影响,结果显示,随Bi3+掺杂浓度的增大,Sr2SiO4∶ Bi3+材料的发射光谱峰值强度表现出先增大后减小的趋势,在Bi3+掺杂物质的量浓度为3%时,可获得最大的峰值强度.加入电荷补偿剂Li+、Na+和K+,均提高了Sr2SiO4∶ Bi3+材料发射光谱峰值强度,其中以加入Li+的情况最明显.     

铋掺杂铝硅酸盐玻璃的超宽带近红外发光性质

采用高温熔融法制备了组分为50SiO_2-xAl_2O_3-(50-x)MgO-Bi_2O_3(x=5,10,15,20,摩尔比)的铋掺杂铝硅酸盐玻璃。研究了铋掺杂铝硅酸盐玻璃超宽带近红外发光性质,探讨了玻璃基质的光学碱度对铋离子宽带发光特性的影响。结果表明:在690nm和808nm的激发下,铋掺杂铝硅酸盐玻璃的红外荧光中心分别位于1106nm和1294nm;随光学碱度的增强,铋离子的红外发光强度减弱。并对铋离子超宽带发光的机理进行了探讨,认为其红外发光源于低价的Bi~+和Bi~(2+)。     

铝硅酸盐玻璃中基于局域过剩电荷模型的Bi近红外发光调控

玻璃中铋离子的超宽带近红外(NIR)发光应用前景广泛,但Bi近红外中心的稳定性问题限制了其实际应用.为此,本工作以铋掺杂钇铝硅酸盐玻璃为研究对象,对可有效调控铋近红外发光行为的局域过剩电荷模型进行了补充与拓展,通过调控玻璃网络中引入的网络修饰体(Y3+)和低于四价的可取代Si4+的网络形成体(Al3+),在铋离子周围建...     

不同惰性调控离子对钕掺杂氟磷酸锶透明陶瓷微观结构和光谱性能的影响

采用传统热压烧结法制备了不同惰性调控离子掺杂的Nd:Sr₅(PO₄)₃F (Nd:S-FAP)透明陶瓷,研究了陶瓷相组成对微观结构、光谱性能的影响规律。结果表明：所制备的S-FAP透明陶瓷为纯相,无杂相生成,晶格常数随着掺杂离子与Sr离子半径差异的增大而减小;所制备的样品在1μm处透过率为70%,在500 nm处为40%;掺入惰性调控离子后,Nd:S-FAP透明陶瓷的发射强度及荧光寿命存在增大的趋势,其中掺入Y离子后调控作用更为有效。通过共掺惰性离子,打破了钕离子在S-FAP基质材料中的团簇现象,提升了钕离子的发光性能。     

BaWO4:Eu3+/Tb3+荧光粉的制备及其发光性能的研究

采用共沉淀法制备了Eu3+、Tb3+单掺或双掺的BaWO4荧光粉,探究了Eu3+的掺杂浓度、退火温度及Eu3+和Tb3+掺杂摩尔比对荧光粉发光性能的影响.实验结果表明,当反应温度为500℃、退火时间为2h、Eu3+掺杂浓度为5 mol％时,荧光粉发光强度最强.XRD结果表明,样品为立方晶系的BaWO4相.在掺杂Eu3+...     

Mg-Co共掺杂对ZnO-TCO薄膜光学特性及微观结构的影响

研究了Sol-Gel法制备不同掺杂浓度的Mg-Co共掺杂对ZnO-TCO(transparent conductive oxide,TCO)薄膜的微观结构及光学特性的影响。样品的光学、成分结构及表面形貌特性表征分别利用荧光光谱仪、紫外-可见-近红外光谱仪、XPS、X射线衍射仪、扫描电子显微镜。结果发现:Mg、Co均以离子态对ZnO进行了替位掺杂,薄膜的生长特性均呈现(002)峰择优取向;掺杂前,ZnO薄膜晶粒尺寸较小,表面平整、颗粒疏松;共掺杂后,薄膜表面团簇增加。Mg-Co掺杂比例为2∶2时,薄膜的内部缺陷增多,结晶质量明显下降。由光透过率谱发现薄膜在可见-近红外区域的光透过率基本保持在95%左右,由于掺杂Co,薄膜的禁带宽度变窄,在波长500~650 nm之间出现了特征吸收峰,蓝色发光增强,并且紫外发光峰发生红移。     

掺铈YVO_4晶体的上转换发光及其机理

在YVO4晶体中分别掺入摩尔分数为2%的Ce2(CO3)3和CeO2,在中频感应加热炉中采用提拉法生长了掺Ce的Ce:YVO4晶体。用X射线衍射测试了这两种晶体的物相,发现两种样品都主要以YVO4相存在。X射线光电子能谱测试表明,在两种样品中铈离子都是以+3、+4混合价态的形式出现的。光谱测试表明,两种样品的光谱特性非常相似,同时发现,两种方式掺杂的Ce:YVO4晶体在620 nm的光激发下,均可发出以450 nm为中心的蓝色宽带荧光。分析认为,在Ce:YVO4晶体中由620nm引发的上转换发光的激发过程,不可能直接起源于Ce3+的基态2F5/2,它起源于由特殊的"Ce-O"构型形成的电荷迁移态的基态。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。