掺杂对高磁导率锰锌铁氧体磁性能的影响

锰锌铁氧体作为现代社会中全面发展现代化的电子信息技术所必备的一种功能材料，随着当前社会通讯、计算机等信息产业的不断发展，对高性能的锰锌铁氧体的研究已经成为了有效开展对磁性材料研究的关键。因此，文章对目前国内外学者有关高磁导率锰锌铁氧体性能的研究状况进行概述，并在此基础上进一步介绍目前相关学者关于掺杂对高磁导率锰锌铁氧体性能的影响的研究现状。     

掺Ni锰锌铁氧体力学与磁学性能

为了提高锰锌铁氧体的密度和力学性能,研究了Ni取代Mn对Zn0.32Mn0.60-xNixFe2.08O4铁氧体力学和磁学性能的影响.用X射线衍射和电子显微镜分析和观察样品的组成和微观形貌,计算了样品的晶格常数,测试了样品的密度、Vickers硬度、抗弯强度以及磁性能.结果表明:在锰锌铁氧体中掺加NiO,能降低铁氧体的晶格常数,提高材料的密度,有利于锰锌铁氧体的晶粒减小以及气孔率的降低,进而改善Zn032Mn0.60-xNixFe2.08O4铁氧体的力学和磁学性能.     

共沉淀水热法制备锰锌铁氧体纳米晶及其表征

本研究采用成本低,污染少的共沉淀法制备锰锌铁氧体前驱体后再采用水热法制备出最终的纳米锰锌铁氧体粉末.利用X-射线衍射(XRD)、透射电镜(TEM)、复磁导率等测试手段对材料的形貌、粒径、和吸波性能进行了表征和分析.研究反应物的种类及配比对锰锌铁氧体吸波性能的影响,当反应物采用氯化锰、氯化锌、氯化铁,m(Mn)∶ m(Zn)∶ m(Fe) =4∶ 1∶10,得到Mn08Zn0.2Fe2O4粒子,透射电镜分析表明,其粒子呈球状,粒径在10 ～ 20 nm.网络矢量分析仪表明,当吸收厚度为2 mm时,锰锌铁氧体材料的吸波性能最佳.     

Nd^3＋、Sm^3＋惨杂对CuZnTi铁氧体热敏特性的影响

对CuZnTi铁氧体的热敏特性进行了研究，材料的磁导率在居里温度再附近变化很快，通过改变成份中Zn和Ti的含量可以改变材料的居里温度的大小。在掺入稀土离子Nd^3＋和Sm^3＋后材料的起始磁导率μi在Tc附近变化速度增加10倍最高达791／℃。可以作为用于高精度温控开关的热敏材料。     

Ni~(2+)掺杂对锰锌铁氧体结构和性能的影响

采用化学共沉淀法制备Ni~(2+)掺杂的锰锌铁氧体微粒,并利用FTIR、XRD、BET、VSM等技术对其进行表征,研究Ni~(2+)掺杂对样品结构、磁性能的影响,并以苯胺为目标化合物,评价样品的催化活性。结果表明,Ni~(2+)的加入没有改变锰锌铁氧体的晶型结构,并使锰锌铁氧体的饱和磁化强度提高了2.88 emu/g,晶粒尺寸减小了5.270 7 nm,比表面积增大了0.247 0 m2/g,在130℃时对20 mg/L的苯胺溶液2.0 h降解率达到79.40%,为锰锌铁氧体处理含苯胺废水提供实验基础。     

贫铁锰锌铁氧体材料电磁特性

用传统陶瓷工艺制备MnZn和NiZn铁氧体材料.在富铁MnZn铁氧体材料Curie温度经验公式的基础上,提出了贫铁MnZn铁氧体材料Curie温度的经验计算公式.比较研究了贫铁MnZn铁氧体、富铁MnZn铁氧体和NiZn铁氧体材料的起始磁导率和电阻率的频率特性.在低频区域,贫铁MnZn铁氧体的高起始磁导率与富铁MnZn铁氧体相当;在高频区域,贫铁MnZn铁氧体的高起始磁导率与NiZn铁氧体相当;贫铁MnZn铁氧体的电阻率高达103 Ω·m.贫铁MnZn铁氧体几乎兼具了富铁MnZn铁氧体的低频特性和NiZn铁氧体的高频特性,且Curie温度也不低,是一种很有应用潜力的软磁铁氧体材料.     

钴掺杂量对Mn-Zn铁氧体结构和磁性质的影响

采用化学共沉淀方法制备了钴掺杂的Mn–Zn铁氧体,研究了钴掺杂量对其结构和磁性质的影响。结果表明：饱和磁感应强度和起始磁导率与钴含量之间的关系表现出S形特征,当钴含量为0.02%（摩尔分数）时,饱和磁感应强度与起始磁导率均达到最大值,分别为373 mT与7 862。电感对温度的依赖关系表明,铁氧体的磁导率温度稳定性可以...     

多种添加物联合作用对Mn-Zn铁氧体性能的影响

采用高温燃烧合成法制备Mn～Zn铁氧体粉体,并对多种添加物,如CaO,Nb2O5,SnO2和Ta2O5对Mn—Zn铁氧体性能的影响进行了深入地研究。结果表明：4种掺杂离子对Mn～Zn铁氧体性能的影响各不相同。掺入的部分Nb^5 和Sn^4 可溶于Mn—Zn铁氧体的晶格内,改变其品格大小,并使初始磁导率μ．与温度θ曲线上第2峰的位置向低温方向移动,但Nb^5 和Sn^4 对晶粒的生长影响较小。由于Ta^5 离子只存在于晶界处,所以对晶格常数和第2峰位置的影响均很小,但Ta^5 的存在有利于晶粒的生长,随Ta^5 的掺入量增加,铁氧体的晶粒尺寸增大,气孔率降低。此外,4种掺杂离子对Mn—Zn铁氧体性能的影响是相互关联的,当添加物的质量分数为CaCO30．05％,Nb2O50．024％,SnO20．15％,Ta2O50．024％时,初始磁导率,μi达到最大,功耗Pv达到最小。     

Ni~(2+)掺杂对锰锌铁氧体结构和性能的影响

采用化学共沉淀法制备Ni⁽²⁺⁾掺杂的锰锌铁氧体微粒,并利用FTIR、XRD、BET、VSM等技术对其进行表征,研究Ni(2+)掺杂的锰锌铁氧体微粒,并利用FTIR、XRD、BET、VSM等技术对其进行表征,研究Ni⁽²⁺⁾掺杂对样品结构、磁性能的影响,并以苯胺为目标化合物,评价样品的催化活性。结果表明,Ni(2+)掺杂对样品结构、磁性能的影响,并以苯胺为目标化合物,评价样品的催化活性。结果表明,Ni⁽²⁺⁾的加入没有改变锰锌铁氧体的晶型结构,并使锰锌铁氧体的饱和磁化强度提高了2.88 emu/g,晶粒尺寸减小了5.270 7 nm,比表面积增大了0.247 0 m2/g,在130℃时对20 mg/L的苯胺溶液2.0 h降解率达到79.40%,为锰锌铁氧体处理含苯胺废水提供实验基础。     

高含锰人造金红石母液制备锰锌铁氧体的研究

经过一系列的除杂过程,从人造金红石母液中提取出纯度较高的氯化亚铁晶体,并采用共沉淀的方法制得了锰锌铁氧体。分析结果表明:在煅烧温度为900～950℃时,可以得到结晶度较高、磁导率较大的Mn_xZn_(1-x)Fe_2O_4。     

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。