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处在六配位八面体晶体场的过渡金属镍离子(Ni2+)具有超宽带近红外发光特性,其荧光半高宽是传统稀土离子(如Pr3+、Er3+)的6~8倍。Ni2+激活的近红外增益材料有望应用于宽带光放大器和可调谐激光器,引发了中国内外广泛关注。Ni2+掺杂晶体具有极高的发光效率,但晶体存在制备工艺复杂、机械加工困难和难以成纤等问题,限制了此类材料在光纤放大器和激光器领域的应用。玻璃具有易加工和成纤的优点,但Ni2+在玻璃中缺少合适的晶体场(配位场)环境,无法产生高效近红外发光。通过对玻璃进行热处理,可以在玻璃内部原位生成出不同类型的纳米晶体,即获得纳米晶体复合的微晶玻璃,可以为Ni2+提供必需的晶体场。同时,控制玻璃内部生长的晶粒尺寸,使其远小于可见光波长(如小于30nm),可有效减弱瑞利散射,使微晶玻璃具有较低的光学损耗,满足光子器件实际应用要求。讨论了Ni2+激活微晶玻璃的发光机理以及Ni2+激活晶体、... 相似文献
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采用高铝高炉渣高温水淬法制备了Tb^(3+)单掺及Tb^(3+)/Ce^(3+)共掺的硅铝酸盐发光玻璃,研究了基体结构和共掺对玻璃发光性能的影响.结果表明:经过1000℃保温4 h后,玻璃晶化为Ca_(2)(Mg_(0.5)Al_(0.5))(Si_(1.5)Al_(0.5)O_(7)),发光性能急剧下降,4%(摩尔分数)Tb^(3+)掺杂的发光玻璃发光强度最高约是晶化后的12倍.Ce^(3+)和Tb^(3+)之间通过多极相互作用传递能量,Tb^(3+)/Ce^(3+)共掺的发光玻璃发光强度最高达到Tb^(3+)单掺的约6倍.4%Tb^(3+)/1%Ce^(3+)共掺的发光玻璃在150℃时具有良好的发光热稳定性,可以作为近紫外LED激发的绿光固体发光材料. 相似文献
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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。 相似文献
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采用传统的高温熔融法制备了80GeO2–20RO (R=Ca, Sr, Ba)掺铋锗酸盐玻璃。研究了铋掺杂锗酸盐玻璃超宽带近红外发光性质,探讨了铋离子掺杂玻璃超宽带发光机理。结果表明:在808 nm激光激发下,铋掺杂锗酸盐玻璃随着碱土金属离子半径增加,中心波长为1300 nm的发射强度逐渐降低;在690 nm激光激发下,铋掺杂锗酸盐玻璃的近红外发射覆盖从900 nm到2000 nm波段但不呈现正态分布,荧光半高宽达428 nm。随着碱土金属离子半径的增加,其近红外发射中心位置逐渐向长波方向移动,推测近红外发光可能源于两种不同形式铋的发光中心。铋掺杂的锗酸盐玻璃具有良好的光学性能,较宽的荧光半高宽,将成为未来超宽带光纤放大器的增益介质。 相似文献
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掺铒碲酸盐玻璃的制备和光谱性能 总被引:2,自引:0,他引:2
制备了掺铒碲酸盐玻璃80TeO2-10La2O3-10RmOn(RmOn=BaO,Na2O,Li2O),用差热分析方法研究了碲酸盐玻璃的热力学稳定性。应用MeCumber理论计算了Er3 在碲酸盐玻璃中的受激发射截面σemi=9.51×10-21 cm2。利用所测玻璃的吸收光谱,应用Jadd-Ofelt理论计算出碲酸盐玻璃的J-O强度参数,Er3 在玻璃中的自发辐射机率,荧光分支比及跃迁振子强度等光谱参数。从玻璃的荧光光镨测得掺Er3 碲酸盐玻璃的荧光半高峰为75 nm。作为光放大器介质的掺Er3 碲酸盐玻璃的荧光峰半高宽与受激发射截面积值分别为铝硅酸盐玻璃的2.8倍和4.3倍,是一种更为理想的宽带光纤放大器用基质材料。 相似文献
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硼硅酸锌玻璃的制备及其发光特性 总被引:1,自引:0,他引:1
由于发光玻璃独特的透明性,在激光、光学放大器、光通讯、储能和显示等光电子领域有着广泛的应用.本文利用高温固相法制备出了新型硼硅酸锌:铕掺杂的硼硅酸锌玻璃,讨论了掺杂离子浓度对玻璃发光特性的影响.结果表明Eu2+掺杂的硼硅酸锌玻璃在250~400 nm波长范围可以被很好地激发,有很宽的激发波长范围,发射谱为一个宽带峰,位于450 nm.掺杂不同浓度的Eu2+的硼硅酸锌发光玻璃的激发光谱有所不同,随着掺杂Eu2+浓度的增加,荧光强度增强,但发射光谱峰位置基本没有变化.另外,Eu2+掺杂硼硅酸锌玻璃较易合成,是一种很好的蓝色发光材料,具有较大的应用价值. 相似文献
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一种新的微型激光器材料--稀土掺杂玻璃 总被引:5,自引:0,他引:5
制得了具有双包层结构的掺Nd^3 和Yb^3 单模磷酸盐玻璃光纤,用中心波长为800nm的半导体激光器件钕光纤的光泵源,在室温下获得了波长为1.053um,输出功率为8.36mW的连续激光输出,用930nm的钛宝石激光泵浦掺镱光纤,也获得了1.067um的激光,研究了Nd^3 ,Yb^3 ,Er^3 离子掺杂四磷酸盐玻璃和氟化物玻璃的发光性能与浓度的关系,以及Yb^3 /Er^3 双掺杂玻璃的发光性能,得到了掺钕四磷酸盐玻璃,Yb^3 /Er^3 双掺四磷酸盐玻璃和掺氟铝酸盐玻璃等几种在微片激光器有应用前景的材料。 相似文献
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M. S. J. Simmonds W. M. Blaney F. Delle Monache M. Marquina Mac-Quhae G. B. Marini Bettolo 《Journal of chemical ecology》1985,11(12):1593-1599
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. 相似文献
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Cheng-Le Zhao Shane Porzio Alan Smith Haiyan Ge H. T. Davis L. E. Scriven 《Journal of Coatings Technology and Research》2006,3(2):109-115
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. 相似文献
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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. 相似文献
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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. 相似文献
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中蓝晨光化工研究院有限公司《塑料工业》编辑部 《塑料工业》2009,37(3)
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. 相似文献
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中蓝晨光化工研究院《塑料工业》编辑部 《塑料工业》2007,35(3):1-25,67
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。 相似文献