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1.
Mn2+作为激活剂加入一些基质中,发光比较弱。因此常常选择使用合适的敏化剂来提高Mn2+的发光效率,本文的研究目就是验证Eu2+是Mn2+的良好的敏化剂。采用高温固相法合成了Eu2+,Mn2+掺杂激活的CaZn2(PO4)2荧光粉,并对其发光性质进行了研究。单掺杂Eu2+时呈现发射峰位于504nm的带谱,属于Eu2+离子的5d-4f能级跃迁辐射,激发峰位于380nm,属于Eu2+的f-d跃迁特征激发谱带。单掺Mn2+时CaZn2(PO4)2不发光。当Eu2+和Mn2+共掺时,出现Mn2+的673nm发射峰,样品发红光,表明Eu2+对Mn2+的发光有很强的敏化作用。研究了Eu2+和Mn2+掺杂浓度对激发光谱和发射光谱的影响,证明在CaZn2(PO4)2:Eu2+,Mn2+中Eu2+对Mn2+的能量传递属于共振能量传递。 相似文献
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半导体级,纯度妇8.7%物理I性质分子量蒸汽压(ZoOC)沸点(1大气压)冰点(1大气压)无色1 01。OO。63巴(表压)8。2“C一122“C液态密度(20OC)1.261克/毫升气态密度(沸点,1大气压)4.94克/升在空气中燃烧界限4.1一98.8体积%气态比重(空气=1)3.93有刺激性和窒息性气味安全 警告:易燃、有毒和腐蚀物质。 危害性 八小时工作时间内空气中最大允许含量值未定气但毒性类似于四氯化硅。在空气中易燃,可燃范围极宽。在钢瓶中蒸汽压力约为0.6巴(表压)时呈液态。蒸汽比空气重得多。即使与少量卤素和其它氧化剂接触也会发生激烈反应,与水能发生激烈反应。… 相似文献
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研究了Ti(acac)2Cl2/AlEt2Cl催化丙烯腈聚合反应,分析了加入第三组分ZnCl2对聚合反应的影响,用^13C—NMR对聚合产物进行了表征,并探讨了聚合反应机理。结果表明,随着聚合温度的提高和聚合反应时间的增加,单体转化率增大,聚丙烯腈的分子量提高。当体系中n(AN)/n(Cat)超过一定量时,则得不到高聚物。体系中加入ZnCl2能明显提高单体转化率和产物分子量,并且产物的三单元规整结构含量明显增加。 相似文献
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G. T. Harrison M. C. Spadaro C. L. Pang D. C. Grinter C. M. Yim P. Luches 《Materials Science & Technology》2016,32(3):203-208
Ultrathin films of TiO2 were grown on a W(100)–O(2?×?1) substrate and characterised with a combination of scanning tunneling microscopy (STM) and low energy electron diffraction. In addition to islands of rutile TiO2(110) with (1?×?1) termination that were reported previously, we also observed rutile TiO2(110) islands with a (1?×?2) film termination. A lepidocrocite-like TiO2 nanosheet was also observed on the W(100) surface. High resolution STM images show that the nanosheet grows in the principal orthogonal directions of the W(100) substrate and forms a commensurate (1?×?7) coincident cell. 相似文献
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多氨基改性蔗渣对水溶液中Pb~(2+)、Zn~(2+)、Cd~(2+)、Cu~(2+)吸附性能的研究 总被引:2,自引:0,他引:2
蔗渣经多氨基改性处理后,得到多氨基改性蔗渣吸附剂。考察了多氨基改性蔗渣吸附剂对模拟废水中Pb2+、Zn2+、Cd2+、Cu2+的吸附性能,主要包括吸附时间、溶液pH值和温度对吸附量的影响以及吸附等温式的研究。研究表明,在实验范围内,Pb2+的吸附平衡时间为12h,适宜吸附Pb2+的pH值范围在4~5,Pb2+的最大吸附量为34.96mg/g;Zn2+的吸附平衡时间为20h,适宜吸附Zn2+的pH值在6.2左右,Zn2+的最大吸附容量为2.24mg/g;Cd2+的吸附平衡时间为20h,适宜吸附Cd2+的pH值在5.0左右,Cd2+的最大吸附容量为10.40mg/g;Cu2+的吸附平衡时间为20h;适宜吸附Cu2+的pH值在5.0左右;Cu2+在不同温度下的最大吸附容量为2.60mg/g。多氨基改性蔗渣对Pb2+、Zn2+、Cd2+、Cu2+的吸附均可用Freundlich方程和Langmuir方程描述。 相似文献
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The crystal structure of (NpO2)2(OOC)2C6H4·4H2O [rhombic cell: a = 15.937(3), b = 26.922(5), c = 8.020(2) Å, space group Pbcn, Z = 8, V = 3441.0(12) Å3, d
calc = 2.988 g cm-
3, CAD4, MoK
, graphite monochromator, 2934 independent reflections; R
1 = 0.0352, wR
2 = 0.0951] was studied. The structure consists of NpO2
+ cations, H4C6(COO)2
2
- anions, and molecules of coordinated and crystallization water. The crystal lattice involves neutral layers [(NpO2)2(OOC)2C6H4(H2O)3]
n
parallel to the {101} plane. The dioxocations in these layers are bonded to each other to form cationic networks [the Np···Np distance is 3.911(1)-4.202(1) Å]. The coordination polyhedra of Np(1) and Np(2) are pentagonal bipyramids (CN 7). The point group of the neptunyl(V) groups is close to D
h. These groups are bidentate ligands in the cation-cation interaction. The Np = O bond lengths are 1.852(6) [Np(1)-O(1)], 1.849(7) [Np(1)-O(2)], 1.845(7) [Np(2)-O(3)], and 1.841(7) Å [Np(2)-O(4)]; the O = Np = O bond angles are 178.6(3)° [O(2)-Np(1)-O(1)] and 177.4(3)° [O(3)-Np(2)-O(4)]. The equatorial plane of the Np(1) bipyramid consists of two oxygen atoms of adjacent Np(2)O2
+ dioxocations, two water molecules, and a single oxygen atom of the phthalate anion. The equatorial plane of the Np(2) bipyramid consists of two oxygen atoms of adjacent Np(1)O2
+ dioxocations, two oxygen atom of the phthalate anion, and a single water molecule. The bond lengths in the equatorial plane of the bipyramid lie in the following ranges: Np-Oyl 2.373(7)-2.437(7) Å (average 2.397 Å) , Np-Ophth 2.360(7)-2.474(7) Å (average 2.431 Å), and Np-Owater 2.534(8)-2.558(9) Å (average 2.544 Å). The phthalate anions are tridentate bridging ligands binding neptunium atoms only within a single cationic network. 相似文献
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介绍大块的、致密的、用作介电材料的非化学计量比化合物(“掺杂材料“)的合成及其应用。介质阻挡放电(DBD)是指在两金属电极之间插入一层绝缘材料的等离子放电装置。从放电物理学角度来讲,这层材料的介电常数越高,所产生的等离子能量就越高,这样,如果应用到等离子化学领域,就会提高化学反应能力。目前商业化生产的高介电常数材料的强度都较低,如BaTiO_3,在等离子发生的瞬间就会被击穿。所以要在DBD中使用高介电常数的材料,就必须进行新型介电材料的研发。介绍了高强度、高密度、高介电常数的非化学计量比化合物[(Ca_(1-x)Sr_x)_(2-2y)](Ti_(2-2y)Li_(2y))Si_(2y)O_(6-y)的合成理论、工艺方法及其在CO_2减排、资源化利用方面的应用。 相似文献
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主要讨论了矩形区域在II—型三角剖分下,一类具有C2连续的二元五次多项式插值逼近问题,并证明了它的存在性、唯一性,给出了它的逼近度。 相似文献
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《化工新型材料》2017,(7)
采用络合剂协助均相沉淀法和传统均相沉淀法分别制备了镍铁类水滑石材料(Ni~(2+)-Fe~(3+)-CO_3~(2-)-LDHs)和镍铝类水滑石材料(Ni~(2+)-Al~(3+)-CO_3~(2-)-LDHs)光催化材料。对光催化剂材料的结构和光催化活性进行了研究。研究结果表明,Ni~(2+)-Fe~(3+)-CO_3~(2-)-LDHs和Ni~(2+)-Al~(3+)-CO_3~(2-)-LDHs均为六边形新貌的层状结构,层间距分别为0.768nm和0.770nm。光催化降解甲基蓝的动力学研究表明二者均为一级反应。光催化性能研究表明,Ni~(2+)-Fe~(3+)-CO_3~(2-)-LDHs光催化活性优于Ni~(2+)-Al~(3+)-CO_3~(2-)-LDHs光催化剂。相比铝基LDHs,铁基LDHs(Ni~(2+)-Fe~(3+)-LDHs)具有较低禁带宽度(2.36eV),是理想的废水染料降解光催化剂。 相似文献
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Complexation of An(VI) (An = U, Np, Pu), and Np(V) with 2,3-pyridinedicarboxylic (quinolinic, H2Quin) acid in aqueous solutions was studied. Np(V) can form 1: 1 and 1: 2 complexes, and An(VI), also 1: 3 complexes (at pH ? 6 and [H2Quin] ? 0.1 M). Quinolinate ion can coordinate to actinide(VI) and (V) ions in solutions in different modes. The apparent stability constants of the complexes in a wide pH range and the concentration stability constants of the An(VI) complexes were measured. In the series from Pu(VI) to U(VI), the stability of the complexes slightly increases. Crystalline complexes [UO2(HQuin)2], [(NpO2)2(HQuin)2(HL)2]·2H2O (HL is N-protonated 2-hydroxypyridine-3-carboxylic acid anion), and [PuO2Quin(H2O)] were synthesized, and their structures were determined by single crystal X-ray diffraction. Different types of coordination of quinolinate ions to actinide ions are also observed in the crystalline complexes. 相似文献
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研究了La3+掺杂对BaSi2O2N2∶Eu2+发光性能的影响。通过高温固相反应制备了纯相的Ba0.94-Si2O2N2∶0.06Eu2+荧光粉。在此基础上进行La3+的掺杂,并对少量La3+掺杂的LaxBa0.94-1.5xSi2O2N2∶0.06Eu2+荧光粉的结构和光学性能进行了研究。XRD图谱表明粉体在低掺杂时保持了基质BaSi2O2N2的晶格结构。通过共掺x=0.035的La3+可使荧光粉的发光效率提高到157%,原因是La3+部分取代Ba2+产生了阳离子缺陷,其可以吸收光源能量并将能量传递给Eu2+。最终这些能量通过Eu2+的4f65d→4f7跃迁以光辐射的形式释放出来。 相似文献