共查询到20条相似文献,搜索用时 78 毫秒
1.
Pr^3+掺杂的Cd3M2Ge3O12(M=Al,Ga)石榴石的阴极射线发光特性 总被引:3,自引:0,他引:3
首次报道Pr^3+分别激活的Cd3Al2Ge3O12(CAGG)和Cd3Ga2Ge3O12(CGGG)锗酸盐石榴石的阴极射线发光光谱,Pr^3+的4f能级发射强度与Pr^3+浓度关系以及粉红色较长余辉特性。与CAGG相比,发现在CGGG中Pr^3+的所有4f-4f跃迁发射峰位置向短波移动,并分析造成这种光谱“蓝移”的原因。 相似文献
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朝阳产“机选3^#”高岭土合成洗用4A沸石的研究 总被引:1,自引:0,他引:1
研究了利用辽宁省明阳产含铝较低的低质“机选3^#”高岭土,通过液相补铝合成Ca^2+交换能力较高的洗涤剂助剂4A沸石的方法,经实验考察确定,在原始物料组成为硅铝比(SiO2/Al2O3)2.0,钠硅比(Na2O/SiO2)2.8,水钠比(H1O/Na2O)50,经35℃,2h胶化和850170,4h晶化的合成制备条件下,所得产品的Ca^2+交换能力为298.8mgCaCo3/g沸石,产率为83%。 相似文献
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硅酸盐水泥熟料是由多种矿物组成的集合体,它的颜色与各种矿物本身的颜色有着本质的联系。硅酸盐水泥熟料中的A矿(54CaO·16SiO2·Al2O3·MgO)是含有少量MgO、Al2O3的硅酸三钙固溶体,它常以单斜晶系、三方晶系、三斜晶系存在于熟料中,在单偏光镜下为无色透明的棱柱状。B矿(Ca2MxSi1-xO4-x/2,其中M=Al,Fe等)是含有Al、Fe、K、Na、Ti、Ba、V和Co等离子的硅酸二钙固溶体,它大部分为β型,属单斜晶系,在单偏光镜下为无色透明体。铝酸盐类矿物主要包括铝酸三钙、七… 相似文献
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液膜分离富集测定镓 总被引:1,自引:0,他引:1
用TOPO「(C8H17)3PO」为流动载体,N205为表面活性剂,液体石蜡为膜增强剂,正己烷为膜溶剂,H2C2O4作内相试剂的乳状液膜体系,迁移富集Ga^3+,研究了乳状液膜的稳定性、温度、Ga^3+的浓度、外相pH值、乳水比(Rew)、油内比(Roi)等因素对富集Ga^3+的影响。实验结果表明,在适宜的条件下,Ga^3+的富集率可达99.5%~100.5%,在相同条件下,常见共存的Cu^2+、Co^2+、Ni^2+、MnA^2+、Fe^3+、Al^3+、Cr^3+、Ti^4+、Zr^4+、Pb^2+、Zn^2+、碱金属离子、碱土金属离子等不被迁移富集;大量Cl^-、F^-、、NO3^-、SO4^2-、PO4^3-等都不影响Ca^3+的富集,高式样应预先用氯化氢除硅,以防止影响迁移富集Ga^3+,只a^3+可 相似文献
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近几年开发的国外农药新品种(5) 总被引:3,自引:0,他引:3
甲氧磺草胺(metosulam)NHSO2NNNNOCH3OCH3ClClCH3C14H13Cl2N5O4S4183中文通用名称甲氧磺草胺英文通用名称metosulam(BSI,ISO,ANSI)商品名称Eclipse;Pronto;Sansac;... 相似文献
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高效液膜分离富集镍基合金镀层中稀土总量 总被引:2,自引:0,他引:2
用TBP-TTA(协同流动载体)、SPAN80和煤油高效液膜体系,研究∑RE^3+迁移行为。在适宜条件下,10min内,∑RE^3+的迁移率达99.5%以上。在同样条件下,常见共存金属离子如Fe^3+、Al^3+、Ni^2+、Cr^3+、Mo^6+、Cu^2+、Co^2+、Zn^2+、Cd^2+等均不被迁移;大量碱金属、碱土金属、Cl、NO3、ClO4、F、SiO3^2-、SO4^2-等离子也不影 相似文献
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王新德 《陶瓷研究与职业教育》1994,(2)
在合成的(Ba0.65Pb0.35)TiO3中分别掺入了Al2O3,SiO2,La2O3,MnO2和TiO2.讨论了每种掺杂物与烧成气氛和升温制度对常温电阻率的影响,找出了PTC陶瓷的最佳组成;1mol(Ba0.65Pb0.35)TiO3,0.002molAl2O3,0.004molSiO2,0.01molTiO2,0.003molLa2O3,0.0002molMnO2.这种PTC陶瓷的表面温度为270℃,常温电阻率为5~8×103Ω·cm,时任性为240v/mm. 相似文献
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采用DFT中Dmol~3软件包对M(BH_4)_n(M=Ca,Mg,n=1,2,3)进行结构优化,应用Adsorption Locator软件包模拟M(BH_4)_n对氢的吸附,并对产生的能量变化进行计算。结果表明:M(BH_4)_n可以完成优化,最多在300步即可完成;Mg(BH_4)_2与Ca(BH_4)_2对氢的吸附存在差异,主要在吸附点及吸附能。Mg(BH_4)_2在0Ha处形成态密度的峰要比Ca(BH_4)_2尖锐,但是Ca(BH_4)_2形成态密度的峰较宽,说明Ca(BH_4)_2成键较强,电子离域性强。 相似文献
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M2WO3MoO4(M=Li,Na):Eu3+的发光特性 总被引:2,自引:0,他引:2
针对目前商用白光二极管普遍缺少红光部分辐射的问题,研究了M2WO3MoO4(M=Li,Na):Eu3 样品的结构和发光特性.M2WO3MoO4(M=Li,Na):Eu3 体系在长波紫外(400nm)附近有较强的吸收峰;在394nm光波长的激发下,594,617nm附近都有很强的发光峰.在电偶极子的作用下,617nm处的发光峰最强.由于阳离子半径大小的缘故,Li2(MoO4)比Na2(MoO4)发光要强;虽然W6 的离子半径比Mo6 的大,W含量的增加使Eu3 和O2-之间的距离增加,减少了离子互换的可能性,但W-O化学键对浓度淬灭的影响也随之增加并占主导作用,因此,Li2WO3MoO4比Li2(MoO4)的发光要强. 相似文献
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Summary Phenylacetylene could be polymerized by (mesitylene)W(CO)3 in CCl4 to give a polymer with
12,000 in ca. 80% yield. UV irradiation was unnecessary unlike the W(CO)6–CCl4-h catalyst. The present polymerization did not proceed in toluene. The (mesitylene)W(CO)3 catalyst afforded high molecular weight polymers
from phenylacetylenes bearing bulky substituents (e.g., Me3Si and CF3) at the ortho position. The Mo counterpart, (mesitylene)Mo(CO)3, catalyzed the polymerization of 1-chloro-2-phenylacetylene and 1-chloro-1-octyne to provide high molecular weight polymers
. Catalytic amounts of Lewis acids accelerated the polymerization of phenylacetylene by (mesitylene)W(CO)3, but decreased the polymer molecular weight; this polymerization proceeded not only in CCl4 but also in toluene. 相似文献
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This Account reports recent progress in the study of some approximately 20 heterometal derivatives of [Mo3S4(H2O)9]4+ with reference also to W and Se analogues. Single cubes (3:1) and corner-shared double cubes (6:1), as well as dimers of the 3:1 single cubes, are considered. A classification of the heterometals as subtypes A, B, and C is introduced. 相似文献
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《Journal of the European Ceramic Society》2005,25(1):49-54
A new (Ca,Y)Si4(N,C)7 phase has been characterised lying between the two end-members Y2Si4N6C and CaYSi4N7. This phase is similar to BaYbSi4N7, which is made up of a network of [N(SiN3)4] structural units linked together in a three-dimensional network, with the large cations located in the interstices, but (Ca,Y)Si4(N,C)7 is a disordered variant, with nitrogen atoms partially occupying two sets of equivalent sites related by the combined operations of rotation and tilt. The crystal of (Ca,Y)Si4(N,C)7 used for structure determination contained Ca and Y in the atomic ratio 2:3, the excess positive charge in the cation sites being balanced by the partial replacement of nitrogen by carbon in the central non-metal site of the [N(SiN3)4] unit. Powder diffraction data are listed for Ca0.8Y1.2Si4N6.8C0.2, which is hexagonal with a=5.9874(4), c=9.7849(8) Å at ambient temperature. The crystal structure has been determined from single crystal data; Z=2; S.G. P63mc (no. 186); Rint=0.0274, R1=0.0384, wR2=0.0993 for all data. 相似文献
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《Journal of the European Ceramic Society》2005,25(1):37-47
A series of new nitrides and carbonitrides has been identified with crystal structures similar to those of the hexagonal quaternary nitrides of the type (Ba,Sr,Eu)YbSi4N7. The large divalent cations in these structures can be replaced by trivalent cations such as Ln and/or Y, if valency balance is preserved by the simultaneous substitution of carbon for nitrogen in the unique [4]-coordinated anion site. This has been demonstrated by carbon-13 magic-angle spinning NMR spectra which for the yttrium member of this series shows a peak at 36.7 ppm corresponding to carbon atoms occupying the central non-metal atom site in the characteristic [C(NSi3)4] structural unit. The resulting compounds have compositions of the types La2Si4N6C, Y2Si4N6C or (La,Y)2Si4N6C; the crystal structure of a related mixed (Ca,Y) derivative of composition (Ca,Y)2Si4(N,C)7 is reported in Part II of this series. When the two large cations are different, the hexagonal symmetry characteristic of the (Ba,Sr,Eu)YbSi4N7 compounds is maintained; when both cations are the same, lower symmetries are observed. The powder diffraction pattern of La2Si4N6C indexes on an orthorhombic unit cell with a=6.0360(7), b=10.1246(9), c=10.5664(11) Å and the crystal structure has been determined. An alternative way of achieving valency balance without incorporation of carbon is to replace some of the silicon by aluminium; related derivatives of the type M2Si3AlN7, where M=La, Y or mixed La,Y have been prepared and their unit cell dimensions are reported. 相似文献
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《Ceramics International》2022,48(20):29770-29781
The substituted (Ca2+/Cu2+), and co-substituted (Cu2+/Zn2+), (Cu2+/Sr2+), and (Sr2+/Mn2+) β-tricalcium phosphate (β-TCP)-based Ca3-2x(MˊMˊˊ)x(PO4)2 (M = Zn2+, Cu2+, Mn2+ and Sr2+) solid solutions have been synthesized using solid-state route. The powder X-ray diffraction study shows the formation of β-TCP-type structure as the main phase in all solid solutions. The crystal structures and chemical compositions were approved using Fourier-transform infrared (FT-IR) absorption spectra and energy-dispersive X-ray spectrometry (EDX) data, respectively. The unit cell parameters and volume of as-synthesized samples directly depend on the radius of the incorporated ions. The limits of the single-phase solid solutions were found based on the possible occupation of the crystal sites in β-TCP structure. For the divalent ions with small radii, such as Cu2+ or Zn2+, the limit composition was found as Ca2.571Mˊ0.429–xMˊˊx(PO4)2 for Mˊ and Mˊˊ – Cu2+ and Zn2+. The enlargement of the unit cell by incorporation of Sr2+ allows to extend the limit of solid solutions up to Ca2.5Sr0.5–xMˊx(PO4)2 for Mˊ – Cu2+ or Mn2+. The antibacterial properties were studied on 4 bacteria (S. aureus, P. aeruginosa, E. coli and E. faecalis) and 1 fungus (C. albicans). It has been showed that co-doped Ca2.5Sr0.25Cu0.25(PO4)2 sample exhibits the highest antimicrobial activity resulting in 92%, 96% and 96% inhibition growth rate for S. aureus, P. aeruginosa and E. faecalis, respectively. The antimicrobial properties are strongly related to the occupation of the crystal sites in the β-TCP structure by doping ions. 相似文献