复合掺杂VO_2(M)的实验设计及光电特性研究

以V2O5、钨酸铵、钼酸铵和草酸为原料,采用高温热解前驱体的方法制备了复合掺杂W6+和Mo6+的M型VO2粉体。采用均匀设计U7(72)考察了钨酸铵和钼酸铵的加入量与产物的相变温度之间的关系,建立了数学模型并进行了回归分析。结果表明钼和钨全部以离子形式进入了VO2的晶格,热分解产物具有良好的光电开关性能。     

二氧化钒粉体研究的新进展

VO2具有B、M和R等晶相,VO2(B)是亚稳态的单斜金红石结构,VO2(M)是单斜金红石结构,VO2(R)是四方金红石结构。VO2具有特殊的光学和电学性质,是一种具有广泛应用前景的功能材料。本文综述了VO2(B)纳米粉的合成方法、合成温度及所用试剂,分析了VO2(B)的性质与用途,讨论了VO2(M)粉体合成中的关键问题与研究现状,评述了M与R相之间转变的类型和诱导因素、相变温度影响因素、相变机理研究手段,总结了2007年以来VO2粉体研究的新进展,指出深入研究相变机理是控制VO2相变性质的前提,是研究发展的趋势。     

二氧化钒及其掺W粉末的制备及表征

二氧化钒(VO2)是一种热敏材料,在341 K可以发生从半导体单斜晶相VO2(M)到金属导体相VO2(R)的可逆转变,这种相变伴随着VO2的电、磁和光学性质发生突变,由于其相变的特性,使VO2被广泛应用。文章采用水淬-水热法,制备了VO2(B)粉体及其W掺杂粉体,经过热处理VO2(B)可以转变为具有相变特性的VO2(M),利用SEM、XRD、DSC等手段对VO2(B)和VO2(M)及其W掺杂粉体进行了表征。     

Sb掺杂SnO_2表面富集光电子能谱研究

采用化学共沉淀法,以SnCl4.5H2O和SbCl3为原料,成功地制备了5～20 nm左右、四方金红石Sb掺杂SnO2（ATO）微晶粉体。电阻率,XRD、XPS综合测试分析表明：Sb掺杂量、煅烧温度对Sb在SnO2晶粒中的分布、Sb价态的存在形式、电阻率的变化有较大的影响。掺杂到SnO2粉体中的Sb含量,不会改变SnO2的四方金红石结构,一部分Sb原子固溶到SnO2晶格中,剩余的Sb原子向SnO2粉体表面富集,并取代SnO2表面的Sn原子,形成Sb富集层,相当于一层＂栅栏＂,阻碍心部Sb原子向表面扩散,抑止掺杂SnO2（ATO）晶粒的长大。     

掺钨VO_2纳米粉体的制备及其热致相变特能的研究

以偏钒酸铵(NH_4VO_3)和偏钨酸铵((NH_4)_6H_2W_(12)O_(40).XH_2O)为分别为钒源和掺杂剂,采用水热法进行掺杂钨(W)离子的二氧化钒(VO_2)粉体的制备,在通有氩气气氛的管式炉中600℃热处理6 h后得到纯净的掺杂W二氧化钒粉体,通过XRD、SEM及XPS分析所制备的掺钨二氧化钒的晶体结构、表面形貌以及组分价态的变化。利用DSC及FTIR检测其相变温度点以及相变前后的红外透过率。结果表明:制备出的掺杂W的VO_2粉末为M型纳米片状粉体,钨元素以W~(6+)形式掺入VO_2晶体,取代晶格中部分V原子。随着W离子的摩尔比的增加,VO_2的相变点明显下降,当掺量为2%时,其相变点降低为43℃,相变前后的红外透过率也发生了显著地下降,最大下降量达到40%。     

Cu2+掺杂氧化钛凝胶的相变研究

本文采用溶胶-凝胶法制备不同含量Cu2+掺杂的纳米氧化钛粉体,利用差热-热重、X衍射仪研究了氧化钛凝胶的相变过程,分析了产物的晶体结构、金红石转变量和锐钛矿晶粒尺度.结果表明,Cu2+的掺杂抑制了锐钛矿相变,促进锐钛矿向金红石相转变,阻碍锐钛矿晶粒的长大,Cu2+掺杂量大于2%(物质的量含量,下同)时,在600 ℃烧结可获得小于40 nm的锐钛矿晶体.     

Eu~(3+)和Gd~(3+)共掺杂TiO_2粉体的制备及催化活性

采用溶胶-凝胶法制备纯TiO2和Gd3+/Eu3+共掺杂TiO2复合粉体,采用X射线衍射、漫反射光谱和扫描电镜等技术对样品进行表征,以亚甲基蓝(methyleneblue,MB)的光催化降解为目标反应评价其光催化活性,探讨Gd3+/Eu3+共掺杂对TiO2粉体光催化的影响机制。结果表明:Gd3+/Eu3+共掺杂可以显著提高TiO2粉体光催化活性。Gd3+/Eu3+共掺杂在TiO2粉体中产生协同作用,可以抑制TiO2由锐钛矿向金红石相转变,使TiO2的粒径减小。Gd3+/Eu3+共掺杂增大了TiO2粉体的晶格畸变,使TiO2粉体吸收带边蓝移。当Gd3+和Eu3+的质量掺量分别为0.05%和0.4%时,TiO2粉体光催化活性最高,降解率达到95.31%。     

窄带半导体敏化TiO_2光催化材料的制备及性能研究

本实验采用水热法在450℃温度下,以钛酸四丁酯作为前驱体制备了复合Ti O2粉体,XRD显示所有样品大都为锐钛矿型,部分呈金红石型,铜掺杂改变了Ti和O的结合能峰位,掺杂Cu2+进入了Ti O2晶格网络,说明水热法可以有效地掺杂Cu2+部分进入到Ti O2的晶格。SEM显示铜掺杂的Ti O2粉末的粒径更小,表明Cu2+掺杂Ti O2可以抑制纳米晶体的生长。IR-Vis图谱显示Cu2+掺杂纳米Ti O2的吸收边带位置上出现红移现象。复合的Ti O2粉体,催化实验显示荧光强度较小时,电子-空穴的复合率也会随之降低,从而明显地提高了光催化剂的催化活性。     

溶胶-凝胶法制备B掺杂TiO2纳米粉体及其光催化性能研究

本研究采用溶胶-凝胶法制备了B掺杂TiO2纳米粉体.采用X射线衍射(XRD)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)、紫外可见漫反射光谱(UV-Vis)等测试手段对其进行了表征,以亚甲基蓝为模拟污染物,评价了不同热处理条件下的粉体在可见光下的光催化活性.结果表明:B掺杂对TiO2表面形貌没有明显影响,但抑制了TiO2晶粒的长大和TiO2由锐钛矿型向金红石型的转变;部分B以B2O3的形式存在,部分B掺入到TiO2晶格间隙形成B-O-Ti键;B掺杂未改变TiO2的吸收边带,且使得TiO2对可见光的吸收有所减弱;B掺杂能有效促进TiO2表面活性基团Ti-OH的生成,该基团能够有效捕获空穴,从而提高光催化活性;B掺杂TiO2粉体在650℃煅烧的催化活性最高,对亚甲基蓝的2h降解率比未掺杂TiO2提高16.51％.     

柠檬酸络合法制备BiVO4的光催化性能研究

以柠檬酸为络合剂,五水钒酸铋Bi(NO3)3.5H2O和偏钒酸铵NH4VO3为原料,采用柠檬酸络合法制备新型可见光响应型光催化剂BiVO4。借助X射线衍射仪、傅里叶变换红外光谱仪和透射电子显微镜等手段对粉体进行了表征;探索比较了掺杂Cu2+和Ni2+对光催化活性的影响。结果表明:Cu2+的最佳掺入量为0.3%,Ni2+的最佳掺入量为1%;掺杂Ni2+所制得的复合光催化剂具有更高的光催化活性。     

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。