K2O·CaO·4B2O3·12H2O∶Nd3+的合成及发光性能

以CaCl2、K2B4O7和Nd2O3为原料,采用易于工业化、无污染的水溶液法反应合成碱-碱土金属硼酸盐K2O·CaO·4B2O3·12H2O∶Nd3+晶体,利用X射线衍射、红外光谱、扫描电镜、荧光分光度计等现代分析测试手段,对所合成晶体进行了分析和表征.结果表明,所制备的K2O·CaO·4B2O3·12H2O∶Nd3...     

K2O·CaO·4B2O3·12H2O∶Nd3+的合成及发光性能

以CaCl2、K2B4O7和Nd2O3为原料,采用易于工业化、无污染的水溶液法反应合成碱-碱土金属硼酸盐K2O·CaO·4B2O3·12H2O∶Nd3+晶体,利用X射线衍射、红外光谱、扫描电镜、荧光分光度计等现代分析测试手段,对所合成晶体进行了分析和表征.结果表明,所制备的K2O·CaO·4B2O3·12H2O∶Nd3+晶型发育良好、形貌规整.基质本身具有上转换发光特性,K2O·CaO·4B2O3·12H2O∶Nd3+的发光强度较基质弱.当激发源为828 nm时,材料呈橙红色光.     

Eu3+掺杂2ZnO·2.2B2O3·3H2O红色荧光粉的发光性能

采用水热法合成2ZnO.2.2B2O3·3H2O:Eu3+红色荧光粉.其形貌、结构和光学性能分别用扫描电镜、X射线衍射和荧光光谱进行表征.扫描电镜图片显示样品的尺寸分布在0.1～1 μm范围内.随着Eu3+掺杂浓度的升高,样品向无定形的玻璃态转变.当激发波长为253 nm(属于Eu3+ -O2 -电荷迁移带吸收)时,样...     

Pr2O3,Sm2O3,Eu2O3及Dy2O3掺杂SrTiO3的发光光谱

SrTiO_3粉末分别用Pr_2O3、Sm_2O_3、Eu_2O_3以及Dy_2O_3掺杂处理后,以SrTiO_3能吸收的光波(≤387nm)激发后发出的荧光具有稀土离子的发光特征。     

Effect of Li2O on the structure,electrical and dielectric properties of xLi2O·(20−x)CaO·30P2O5·30V2O5·20Fe2O3 glasses

Glasses of the general formula xLi₂O·(20?x)CaO·30P₂O₅·30V₂O₅·20Fe₂O₃ with x=0, 5, 10, 15 and 20 mol% were prepared; IR, density, electrical and dielectric properties have been investigated. Lithia-containing glasses revealed more (P₂O₇)^4?, FeO₆, V–O^? and PO^? groups and mostly have lower densities than those of lithia-free ones. The electrical properties showed random behavior by replacing Li₂O for CaO, which has been assigned to the change of the glass structure. The results of activation energy and frequency-dependent conductivity indicate that the conduction proceeds via electronic and ionic mechanisms, the former being dominant. The mechanism responsible for the electronic conduction is mostly thermally activated hopping of electrons from Fe(II) ions to neighboring Fe(III) sites and/or from V⁴⁺ to V⁵⁺. The dielectric constant (ε′) showed values that depend on the structure of glass according to its content of Li₂O. The (ε′) values are ranging between 3 and 41 at room temperature for 1 kHz, yet at high temperatures, glass with 20 mol Li₂O exhibits values of 110 and 3600 when measurement was carried out in the range 0.1–1 kHz, and at 5 MHz, respectively.     

Na0.15(H3O)0.2CoO2·wH2O的超导电性

最近发现的水合钴氧化物超导体在某些方面具有与高温超导体十分相似的性质.本文报道含有高浓度的水合氢离子的钴氧化物超导体的超导电性磁测量结果.通过对样品的M(H,T)的测量,得到了大致的H～T相图.最后还讨论了系统中可能存在的2D～3D转变.     

Diffuse reflectance spectra of Pb(Zr0·60RTi0·40) O3 solid solutions doped with Fe2O3, Cr2O3 and MnO2

Measurements of diffuse reflectance spectra in the range of 400, 2500 nm were used for study of the effect of doping with iron oxide, chromium oxide and manganese oxide on the properties of polycrystalline Pb(Zr_0.60Ti_0.4) O₃ solid solution. On the basis of analysis of experimental results it is concluded that mentioned oxides in the amount of 2 at.% interact at 1000 °C with perovskite crystal lattice of studied solid solution, creating local level in its forbidden gap. The values of charge carrier excitation energy found from these levels are 2·48 eV in the case of iron oxide doping, 1·68 eV in the case of chromium oxide and 1·44 eV in the case of manganese doping.     

Investigation of a high-temperature phase of 3Bi2O3·2TeO2 binary oxide

The high-temperature phase of 3Bi₂O₃·2TeO₂ binary oxide is characterized by thermal analysis, X-ray powder diffraction, and¹²⁵Te Mössbauer spectroscopy. The phase, obtained by rapid quenching from 900 °C, is identified to be cubic Bi₆Te₂O₁₃ with an oxygen-deficient fluorite structure, which is isomorphous with -Bi₂O₃.     

Dielectric relaxation of α-cyclodextrin-polyiodide complexes (α-cyclodextrin)2 · BaI2 · I2 · 8H2O and (α-cyclodextrin)2 · KI3 · I2 · 8H2O

The frequency and temperature dependence of the real (ε′) and imaginary (ε″) parts of the dielectric constant of the polycrystalline complexes (α-CD)₂ · Bal₂ · I₂ · 8H₂O and (α-CD)₂ · KI₃ · I₂ · 8H₂O (α-CD = α-cyclodetrin) have been investigated over the frequency and temperature ranges 0–100 kHz and 120–300 K, respectively. The temperature dependences of ε′, ε″ and the phase shift φ show two steps, two peaks and two minima, respectively, revealing the existence of two kinds of water molecule, the tightly bound and the easily movable water molecules, in both complexes. The first peak of (T) or the first minimum of φ(T) presents the transformation of flip-flop hydrogen bonds to the normal state. The second ε″ (T) peak or φ(T) minimum corresponds to the easily movable water molecules or to a partial transformation of tightly bound to easily movable water molecules. For T > 270K both samples show semiconductive behaviour with energy gaps of 1.84eV for the (α-CD)₂ · BaI₂ · I₂ · 8H₂O complex and 1.36eV for the (α-CD)₂ · KI₃ · I₂ · 8H₂O complex. The conductivity at room temperature decreases in the order: (α-CD)₂ · BaI₂ · I₂ · 8H₂O > (α-CD)₂ · LiI₃ · I₂ · 8H₂O > (α-CD)₂ · KI₃ · I₂ · 8H₂O > (α-CD)₂ · Cd_0.5 · I₅ · 26H₂O. The relaxation time varies in a Λ-like curve (from 120 to 250 K) and rises rapidly for temperatures greater than 250 K, indicating the process of ionic movements. The activation energies around the transition temperature 0.98–1.09 k _B T _trans for (α-CD)₂ · BaI₂ · I₂ · 8H₂O and 1.06-1.55 k _B T _trans for (α-CD)₂ · KI₃ · I₂ · 8H₂O reveal the greater stability of the α-K complex against that of the α-Ba complex.     

配合物La（C5O3H3）3·C12H8N2·H2O的合成和表征

本以α－呋喃甲酸（Ｃ５Ｏ３Ｈ４）和邻菲罗啉（Ｃ１２Ｈ８Ｎ２）为配体,在乙醇８溶剂中与硝酸镧反应,合成了与稀土离子Ｌａ（Ⅲ）的三元混配配合物。经元素分析确定其配合物的组成为Ｌａ（Ｃ５Ｏ３Ｈ３）·Ｃ１２Ｈ８Ｎ２·Ｈ２Ｏ,同时还通过了ＩＲ、＾１ＨＮＭＲ、ＵＶ、ＴＧ－ＤＴＡ等谱光的测试与分析,表征了配合物的组成结构和性质。ＩＲ、＾１ＨＮＭＲ和ＵＶ谱的分析结果表明配体羧酸是以脱质子的酸根形式与中心稀土离子     

NdL3·2H2O配合物的合成与表征

本文合成了NdL3·2H2O(L＝3-甲氧基苯甲酸,邻氯苯氧乙酸)固体配合物.对所合成的配合物进行了元素分析、TG-DTA、IR、UV等测定与表征.初步研究了配合物的组成结构和性质.     

State of iron atoms in SiO2·xFe2O3 gels

Mössbauer studies are made of ⁵⁷Fe nuclei in dry SiO₂·xFe₂O₃ gels at low temperatures in external magnetic fields. It is shown that the state of the iron atoms in the gels depends significantly on their concentration. In dry gels with an iron content exceeding 0.01Fe₂O₃, the Fe atoms belong to finely dispersed particles of the oxide with maximum sizes of ～80 Å in a superparamagnetic state. For lower iron contents, the Fe atoms are in the form of a highly diluted paramagnetic impurity of trivalent ions in a diamagnetic matrix. It is assumed that clusters develop from a small number of iron and oxygen ions dispersed in the gel matrix. Here spin-lattice relaxation of the magnetic moments of the iron atoms is observed.     

Eu（C8H7O3）3·C12N2·H2O配合物的合成与表征

合成了新的Eu(C8H7O3)3·C12H8N2·H2O配合物.并经元素分析、摩尔电导、IR、UV、1H NMR等表征,初步确定配体3-甲氧基苯甲酸以桥式双齿形式和Eu(Ⅲ)配位.     

基于EuCl_3·6H_2O晶体的光存储

量子存储器是构建未来大规模量子网络的核心器件.由于具有超长的量子相干寿命,稀土掺杂晶体逐渐成为最有希望实现实用量子存储的材料之一.然而掺杂晶体中不可避免的晶格畸变限制了该类材料的吸收深度和存储效率.纯稀土化合物晶体则同时满足了低晶格畸变和高稀土离子密度的需求,有望实现高光存储效率. EuCl_3·6H_2O晶体是目前研究较多的一种纯稀土化合物晶体,已经实现了低于超精细能级间距的光学非均匀展宽,并且理论预测的自旋相干寿命可达1000 s,是一种颇具潜力的量子存储材料.目前光存储或量子存储功能仅仅在稀土掺杂晶体中实现过,尚无实验报道纯稀土化合物晶体中的光存储现象.本文报告了在EuCl_3·6H_2O晶体中实现了原子频率梳型光存储.通过降温法生长得到了EuCl_3·6H_2O单晶,实验测得其~7F_0→~5D_0跃迁相干时间为55.7μs,存储时间1μs时的存储效率为1.71%,展现了这种材料实现光量子存储的原理可行性.通过分析温度依赖的吸收线频率移动,指出在这一材料中实现高效率光存储的主要挑战在于高效率的光谱烧孔.     

Intrinsic excitons in 12CaO·7Al2O3

Unusual crystal structure of 12CaO·7Al₂O₃ is composed by a framework of positively charged nanocages, which enable accommodation of various negative ions (and even electrons) inside these cages. Different filling of cages leads to significant changes in electronic structure and as the result in luminescence properties, as well. Luminescence was studied using time-resolved spectroscopy in VUV in the temperature range from 6 to 300 K. Electron loaded samples exhibit UV luminescence band peaked at ～5 eV. The excitation spectrum of this emission has the onset at the energy gap value of 6.8 eV, and its decay is well described with the sum of two exponential functions with life-times of τ₁ = 3.7 ns and τ₂ = 29 ns, respectively. Its thermal quenching is well approximated by the sum of two Mott-Seitz type curves with the activation energies of 34 meV and 70 meV. Experimental results indicate that this luminescence is possibly due to radiative decay of two singlet self-trapped exciton states, which hole components are localized on two non-equivalent framework oxygens.     

Photoluminescence quenching in zinc oxide modified by Al2O3 and Al2O3 · CeO2 Nanopowders under proton irradiations

The photoluminescence spectra of initial ZnO powder and that modified by Al₂O₃, Al₂O₃ · CeO₂ nanopowders are investigated in the range 360–660 nm before and after 100-keV proton irradiation. It is found that the introduction of nanoparticles causes a decrease in the UV-band intensity and a change in the luminescence bands in the visual spectrum due to V _O ⁺ oxygen vacancies, O _int ^- interstitial oxygen, and V _Zn ^- zinc vacancies. Luminescence quenching in the UV and visible spectra occurs under the effect of protons. The decomposition of the spectra into elementary defects and analysis of changes in their integrated intensity during modification and irradiation of the powders are carried out.     

3Cu(IO_3)_2·2H_2O晶体的电子结构研究

本文测定了3Cu(IO_3)_2·2H_2O球晶的电子吸收光谱,吸收峰位于9140cm~(-1)和15250cm~(-1)。首次观察到了高达6110cm~(-1)的低对称晶场分裂。吸收曲线经Gauss分解可得到八个Gauss型吸收峰,分别位于8590,10690,10870,12190,13500,14510,15330和16500cm~(-1)。测量其EPR谱可得g=2.141±0.004。本文进而用配位场理论和非自由Cu(Ⅱ)的径向波函数定量地处理了实验结果,计算值与实验值相符,从而综合地解释了该化合物晶体的电子结构。     

Surface segregation during the uptake of NO3 on coatings composed of NaI · 2H2O/NaBr · 2H2O and MgBr2 · 6H2O/MgCl2 · 6H2O binary salts: Solubility or deliquescence?

The uptake of NO₃ radicals on the surface of coatings prepared from the individual salts of NaI and NaBr dehydrates, hexahydrates of MgBr₂, and MgCl₂ and NaI · 2H₂O/NaBr · 2H₂O and MgBr₂ · 6H₂O/MgCl₂ · 6H₂O binary salts at various mole fractions of the doping salts, NaI · 2H₂O and MgBr₂ · 6H₂O in the initial aqueous solution was measured in a flow reactor by kinetic mass spectrometry. The dependences of the rates of the consumption of the reactant and of the formation of the products on the mole fraction of the doping salt made it possible to determine a quantitative relationship between the surface density of the doping salt and its mole fraction in the initial solution. A joint analysis of these dependences and the previously obtained data led to the conclusion that the deliquescence of the studied individual salts produces the predominant effect on the ratio between their surface densities.     

准—维反铁磁体CsMnCl_3·2H_2O(2D_2O)的电子光谱研究

在室温下研究了CsMnCl_3·2H_2O(2D_2O)(CMC)的吸收光谱。在250～650nm波长范围内观察到7个明显的吸收峰。根据CMC晶体的实际结构,对CMC晶体巾Mn~(2+)离子所处的对称晶场采用O_h近似,利用配位场理论计算出了Mn~(2+)离子的电子能级,并确认了能级跃迁与各吸收峰的对应关系。理论计算与实验结果较符合。     

Ga2O3组分对Tm 3+掺杂GeO2-Ga2O3-Li2O-BaO-La2O3玻璃的光谱性能影响

制备了Tm3 (8.0mol%)掺杂(77-x)GeO2-xGa2O3-8Li2O-10BaO-5La2O3(x=4,8,12,16)系列玻璃.系统地研究了Ga2O3从4mol%变化到16mol%时,玻璃的光谱性质与热学性质的变化规律.差热分析表明,随着Ga2O3含量的增加,锗酸盐玻璃的热稳定性增加.运用Judd-Ofelt(J-O)理论计算得到了Tm3 在不同Ga203含量的GeO2-Ga2O3-Li2O-BaO-La2O3玻璃中的J-O强度参数(Ω2,Ω4,Ω6)及Tm3 各激发能级的自发跃迁概率、荧光分支比以及辐射寿命等光谱参量.在808nm激光二极管的激发下,测试并分析了Ga2O3对Tm3 荧光光谱特性的影响.随着Ga2O3从4t001%增加到16mol%,Tm3 在1.8μm处的荧光强度呈现先减弱后增强的特性.当Ga2O3含量大约在12mol%时,Tm3 在1.8μm处的荧光强度最弱,受激发射截面达到最小.还初步讨论了Ga2O3对玻璃结构与光谱参数的影响规律.