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采用高温固相法制备R2MgSi2O7:Eu(R=Ca,Sr,Ba)荧光粉,并对其发光性能及封装应用进行研究。详细讨论碱土元素的种类及锶/钙的比例对激发与发射光谱的影响,同时考察激活剂Eu^2+浓度对发光强度的影响,也考察了将Ba2MgSi2O7:Eu0.005荧光粉封装于紫光芯片中的发光特性。结果表明,荧光粉基质中碱土元素的种类及碱土元素锶钙的含量对其发射及激发光谱有较大影响,随着碱土离子Ca。’含量的增加,发射光谱逐渐红移,发光强度逐渐减弱。本文对这一变化机理进行了初步分析。当激活剂Eu^2+摩尔浓度为0.005时,荧光粉具有较好的发光强度,并且当荧光粉的质量浓度达到19%时,LED具有较好的光效。 相似文献
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采用溶胶-凝胶法制备了钙钛矿结构的MSnO3(M=Ca,Sr,Ba)晶体.将其作为锂离子电池负极材料的活性物质,利用恒电流电池测试仪研究其电化学性能.结果表明CaSnO3、SrSnO3和BaSnO3的首次放电容量分别为894.3
mAh/g、703.8 mAh/g和673.6 mAh/g,首次充电容量分别为418.3 mAh/g、257.8 mAh/g和224.8
mAh/g,不可逆容量损失分别达53.2%、63.3%和66.6%. 相似文献
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《照明工程学报》2017,(1)
通过常压合成工艺成功制备了一系列高亮度的(Sr,Ca)AlSiN_3:Eu~(2+) 氮化物荧光粉,比较了常压合成和高压合成工艺对荧光粉晶体结构、光谱特性和晶体形貌的影响。荧光光谱分析表明,常压合成工艺制备的(Sr,Ca)AlSiN_3:Eu~(2+)荧光材料表现出优异的荧光强度,其发射波长位于615 nm~640 nm的红光范围,实现了一定范围内的光谱调控。X射线衍射结果表明,该氮化物红色荧光材料具有正交晶系的CaAlSiN_3晶体结构,且产物中不存在杂质相。峰值波长位于615 nm和625 nm的样品能够作为光谱中的有效红色组成部分用以制备高显色性的白光LED光源。通过LED封装的优化实验,所获得的白光LED光源具有86.8 lm/W的流明效率,并具有良好的显色指数(Ra=85)。进而,通过改变氮化物红粉的组成和比例能够制备具有不同色温(4 000 K~6 000 K)的白光LED光源。 相似文献
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利用机械活化辅助的燃烧合成方法制备了稀土元素Eu掺杂的(Ca,Y)-α-SiAlON陶瓷荧光粉。采用X射线衍射仪(XRD)。扫描电子显微镜(SEM)和光致荧光光谱仪(PL)对合成产物进行了分析,结果表明,合成出的产物由平均粒度小于5μm的a—SiAlON粉末颗粒组成。该粉末在日光下呈黄绿色。在蓝光和近紫外光波段有宽的激发峰,对应的发射峰中心位于绿光至黄光波段,从而可以配合蓝光或近紫外光LED使用。制成白光LED光源。 相似文献
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A2FeNbO6 (A?=?Ba, Sr, and Ca, abbreviated as AFN) ceramics were synthesized by a wolframite method with monoclinic FeNbO4 precursor. X-ray diffraction studies revealed that Sr2FeNbO6 and Ca2FeNbO6 had a orthorhombic structure, while Ba2FeNbO6 had a cubic symmetry. Dielectric properties of the AFN ceramics were characterized in a broad frequency range (1 Hz–10 MHz) at a temperature ranged from ?120 to 300 °C. Two dielectric relaxations were observed to follow the Arrhenius law at both low and high temperatures for all samples. Polaron relaxation was proposed to explain the low temperature dielectric relaxations in AFN. The high temperature dielectric relaxations in AFN were a competitive phenomenon between the dielectric relaxation and the electrical conduction of the relaxing species. 相似文献
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Ca(Eu1-xLax)4Si3O13红色荧光粉的研究及其在三基色白光LED上的应用 总被引:4,自引:0,他引:4
研发了更适合应用于三基色白光LED的Ca(Eu1-xLax)4Si3O13红色荧光粉,它在395nm峰值的近紫外光的激励下能放射出峰值为613nm的红色光.当x=0.5时,此红色荧光粉的转换效率能达到最大值0.14.用外部量子效率为0.40的近紫外LED与Ca(Eu1-xLax)4Si3O13红色荧光粉和绿色、蓝色荧光粉共同组合的三基色白光LED,白光的光效和平均显色指数分别达到了21.61m/W和83.9. 相似文献
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首先介绍了W型铁氧体的化学组成、晶体结构、晶格参数,并与M型铁氧体作了比较,进而具体介绍最新研究成果,说明它具有永磁材料的潜力.但它的工艺操作要求更为严格,矫顽力还不够高,有待进一步努力,才可推广到大规模生产中去. 相似文献
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用XRD和传统直流四极探针电导测试法研究了烧结制度和不同掺杂元素对固相反应所合成的La_2Ni_(0.5)M_(0.5)O_(4 δ)(M=Co,Cu)材料结构和电性能的影响。实验结果发现:固相反应可以合成出类钙钛矿结构La_2Ni_(0.5)M_(0.5)O_(4 δ)(M=Co,Cu)材料。随着烧结温度的提高和保温时间的延长,该类材料的晶型更加趋于完整,晶粒尺寸也在不断长大;同时该类材料在1300 ℃、5 h情况下形成的样品,其电导率在空气中于100~800 ℃条件下也在增加,但保温时间对电导率的影响要大于烧结温度对其影响,因此确定该类材料固相反应法合成的烧结温度为1 400 ℃保温时间14 h。掺杂Co、Cu后的材料La_2NiO_(4 δ),其电导率均有增加,但掺杂Co后材料电导率要大于掺杂Cu的电导率。 相似文献
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The electrical and microstructural properties of (Ba x Sr 1 m x )Ti 1+y O 3+z (BST) thin films prepared by RF magnetron sputtering were investigated as a function of deposition temperature over the range of 100 C to 650 C. Films deposited above approximately 350 C on Pt/TiO 2 /SiO 2 /Si substrates were polycrystalline with relative permittivites of 100 nm thick BST thin films varying from 100 at 350 C to 600 at 650 C. For deposition temperatures below approximately 350 C, the electrical properties were strongly influenced by the presence of a less crystalline BST layer. Films deposited at 250 C were comprised of a multilayer polycrystalline/less crystalline BST structure. The less crystalline BST layer strongly affected both measured dielectric permittivity and leakage properties. Leakage characteristics of Pt/BST(250C)/Pt capacitors exhibited a power law dependence on voltage or an exponential dependence on square root of the applied voltage depending on whether the top Pt electrode adjacent ot the polycrystalline BST layer was biased at a high or low electric potential, respectively. Mechanisms for the observed leakage behavior are discussed. 相似文献
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V.V. Kharton A.A. Yaremchenko A.P. Viskup G.C. Mather E.N. Naumovich F.M.B. Marques 《Journal of Electroceramics》2001,7(1):57-66
Partial electronic and ionic conductivities, crystal structure, thermal expansion and infrared absorption spectra of the perovskite-type series, LaGa0.40Mg0.20M0.40O3– (M = Cr, Mn, Fe, and Co), have been studied. The rhombohedral distortion of the perovskite lattice decreases and the unit cell volume increases in the sequence Co < Cr < Mn < Fe. The p-type electronic conduction increases with atomic number of the transition metal cation; the activation energy varies in air from 15.9 to 32.1 kJ/mol. The oxygen ionic conductivity of the M-doped phases at temperatures below 1200 K is significantly lower than that of LaGa(Mg)O3. The highest ionic conductivity was found for the Fe- and Co-containing phases. The ion transference numbers of La(Ga,Mg,M)O3– at 970–1270 K were determined to vary in a wide range, from 2 × 10–5 to 3 × 10–2. Thermal expansion coefficients, calculated from the dilatometric data collected in the temperature range 300–1100 K, lie in the range (7.2–15.5) × 10–6 K–1. 相似文献