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A solid-state green-light-emitting upconversion coherent random laser was realized by pumping macroporous erbium-doped lithium niobate with a 980 nm laser. The lasing threshold was determined to be about 40 k W∕cm~2.Above the threshold, the emission intensity increased sharply with the increasing pump intensity. Moreover, a narrow multi-peaks structure was observed in the green-light-emission band, and the positions of lasing lines were various at different angles. The results were the direct evidences of coherent random lasing emission from macroporous erbium-doped lithium niobate. These phenomena were attributed to the coexistence of upconversion emission and a multiple scattering feedback mechanism. 相似文献
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以超临界CO2为聚合介质, 硫代苯甲酰基特丁基硫酯(TTBT)为链转移剂, 通过可逆加成-断裂链转移(RAFT)聚合制备了聚丙烯酰胺多面体低聚倍半硅氧烷(PAMPOSS)均聚物及其与甲基丙烯酸甲酯(PMMA)的嵌段共聚物(PAMPOSS-b-PMMA). 对产物结构组成和分子量及其分布进行表征. 结果表明, 在TTBT的控制下, POSS的均聚物和嵌段共聚物具有高分子量及窄分子量分布. 含POSS单体在超临界CO2中为均相聚合, POSS聚合物的结晶性在一定程度上影响其在超临界CO2中溶解性. 相似文献
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采用PEG溶胶-凝胶法合成了纳米晶LaCoxFe1-xO3, 并用DTA-TGA、XRD以及SEM对样品进行表征. 结果表明, 所有样品的原粉在600 ℃焙烧下都形成了稳定的钙钛矿纳米晶, Co含量对形成纳米晶的固相反应和纳米晶的平均粒子尺寸都有明显的影响. 此外, 还研究了纳米晶LaCoxFe1-xO3的湿敏特性, 发现在所有的样品中, LaCo0.3Fe0.7O3表现出比其它样品好的湿敏特性, 但是此材料只在相对湿度(RH)大于54%时对湿度的变化有较高的灵敏度, 掺杂适量的Na2CO3可以改善此材料的湿敏特性, 使它在全程湿度范围(RH 11%-95%)内对湿度变化都有很好的响应. 相似文献
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在保持原有"层-柱"MOF[Zn4(bpta)2(dipytz)2(H2O)2]·4DMF·H2O (1)(H4bpta=2,2'',6,6''-联苯四羧酸,dipytz=3,6-二(4-吡啶基)-1,2,4,5-四嗪)主体结构不变的情况下,通过dipytz配体中四嗪环的原位水解反应将极性的二芳酰基联氨基团引入框架,成功构筑出配合物[Zn4(bpta)2(dipytzhydr)2(H2O)2]·solvent (2)(dipytzhydr=1,2-二异烟酰基肼)。对配合物2的系统表征和气体吸附性质研究结果证实了功能化目标的实现:配合物2相比于配合物1展现出更高的二氧化碳吸附热(由28.8 kJ·mol-1升高至30.3 kJ·mol-1)和CO2/CH4吸附选择性。以上结果表明基于配体中四嗪基团的原位水解后修饰能够有效提高相关MOFs材料的CO2吸附性能。 相似文献
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Threaded aluminum nitride(AlN) whiskers are grown by a physical vapor transport method in a radio-frequency induction heating furnace. The resultant whiskers are characterized by X-ray diffraction, Raman scattering, scanning electron microscopy, transmission electron microscopy and photoluminescence. The analysis shows that the whiskers are single-crystalline, wurtzite AlN. The threaded AlN whiskers are 0.5 μm~100 μm in diameter and several millimeters in length in the fiber direction, and have lots of tiny sawteeth on the surface. The morphology of this threaded AlN whisker is beneficial for bonding when the whisker is used in composite. The growth of the whiskers is dominated by the vapor–solid(VS) mechanism, and the particular morphology might result from an oscillating condition produced in the radio-frequency induction heating furnace. 相似文献
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在热壁LPCVD系统中利用间隔生长法在6H-SiC衬底上淀积Si薄膜,采用XRD、SEM、激光共聚焦显微镜和拉曼光谱对Si薄膜的表面形貌和结构进行表征.结果表明:相比于连续生长法,用间隔法制备Si薄膜的速率有所降低,但表面粗糙度有所减小,同时晶粒尺寸也增大.XRD测试结果表明:间隔法可以控制薄膜生长的择优取向.Raman光谱测试结果表明:采用间隔法且断源时间控制在30 s时,生长温度900℃,H2∶ SiH4 =400∶20 sccm时生长Si薄膜的Raman半峰宽最小. 相似文献
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