Yb3+共掺杂对Zn2GeO4∶Mn2+绿色长余辉发光性能增强研究

利用高温固相法合成了Zn2GeO4∶Mn2+以及Zn2GeO4∶Mn2+,Yb3+绿色发射长余辉发光材料,对样品进行了X射线衍射分析、荧光光谱分析、色坐标、热释发光以及发光寿命测量。分析结果表明,在1 050℃下烧结3 h的Zn2GeO4为单相产物,所得Zn2GeO4∶Mn2+发光材料具有良好的发光性能,在紫外灯激发下发出最强发射位于528 nm的宽带发射并具有优良的长余辉发光特性,其色坐标值分别为x=0.145,y=0.773。Yb3+共掺杂对其长余辉发光性能提高明显。余辉发光在暗场环境下肉眼可观察的持续时间超过2 h。通过热释光谱对陷阱进行了分析。对Yb3+共掺杂的长余辉发光增强机理进行了讨论。     

Die Verteilungkoeffizienten von TiO2+, Cr3+, Mn2+ und Fe3+

Ohne Zusammenfassung     

The hydration process of La2O3 studied by the electron spin resonance of Gd3+ and Mn2+ ions

The hydration of single-crystal La₂O₃ samples was studied following the evolution versus time of ESR spectra of Gd³⁺ and Mn²⁺ ions which enter the lattice substitutionally at lanthanum sites. Our results, which confirm those obtained previously on the macroscopic scale, permit a better understanding of the hydration process on the atomic scale.     

EPR and electronic absorption studies of Mn2+ ion in 3CdSO4 · 8H2O single crystals

EPR and electronic absorption spectra of the Mn²⁺ion in 3CdSO₄ · 8H₂O crystals have been studied at 300 K and 80 K. The EPR spectra have     

Cd3Al2Ge3O12: Mn2+磷光体的发光和长余辉性能

采用传统的高温固相法合成了Cd₃Al₂Ge₃O₁₂: Mn²⁺长余辉发光材料, 利用X射线粉末衍射仪、荧光光谱仪、热释光谱计量仪等手段对粉末样品进行了表征。研究了以Zr⁴⁺离子作为辅助激活剂离子, 对发光材料Cd₃Al₂Ge₃O₁₂: Mn²⁺余辉性能的影响。分析结果表明, 样品位于500~700 nm的黄光宽带发射峰源于Mn²⁺的⁴T₁(⁴G)→⁶A₁(⁶S)跃迁发射结果。并且观察到了由Cd₃Al₂Ge₃O₁₂基质向激活剂离子Mn²⁺的能量传递。共掺杂Zr⁴⁺离子后样品发射峰位没有明显变化, 但是余辉亮度衰减曲线表明适量的Zr⁴⁺离子掺杂可延长Cd₃Al₂Ge₃O₁₂: Mn²⁺的余辉时间。通过对热释光谱的分析, 解释了双掺杂荧光粉余辉性能增强的原因, Zr⁴⁺的掺杂在材料中引入了深度更为合适的缺陷陷阱, 可有效存储光能, 增强余辉的时间和强度。     

Cd3Al2Ge3O12:Mn2+磷光体的发光和长余辉性能

采用传统的高温固相法合成了Cd₃Al₂Ge₃O₁₂:Mn²⁺长余辉发光材料,利用X射线粉末衍射仪、荧光光谱仪、热释光谱计量仪等手段对粉末样品进行了表征。研究了以Zr⁴⁺离子作为辅助激活剂离子,对发光材料Cd₃Al₂Ge₃O₁₂:Mn²⁺余辉性能的影响。分析结果表明,样品位于500~700 nm的黄光宽带发射峰源于Mn²⁺的⁴T₁(⁴G)→⁶A₁(⁶S)跃迁发射结果。并且观察到了由Cd₃Al₂Ge₃O₁₂基质向激活剂离子Mn²⁺的能量传递。共掺杂Zr⁴⁺离子后样品发射峰位没有明显变化,但是余辉亮度衰减曲线表明适量的Zr⁴⁺离子掺杂可延长Cd₃Al₂Ge₃O₁₂:Mn²⁺的余辉时间。通过对热释光谱的分析,解释了双掺杂荧光粉余辉性能增强的原因,Zr⁴⁺的掺杂在材料中引入了深度更为合适的缺陷陷阱,可有效存储光能,增强余辉的时间和强度。     

Eu2+、Mn2+、Sr2+掺杂BaMgAl10O17的燃烧法合成及光致发光性能研究

在600℃温度下,采用液相燃烧法合成了Sr²⁺、Eu²⁺和Mn²⁺三掺的BaMgAl₁₀O₁₇（BAM）蓝绿荧光粉。用XRD、SEM和荧光光谱仪分别分析和表征该荧光粉的物相、形貌和光致发光性能。结果表明,液相燃烧法合成BAM的温度明显低于传统的高温固相合成法;合成的纳米棒均匀、无团聚现象;荧光光谱仪分析表明Eu²⁺、Mn²⁺离子间存在能量传递,且Sr²⁺能有效提高BAM的发光强度,约为固相法制备荧光强度的1.8倍。BAM：0.1Eu²⁺,0.04Mn²⁺,0.05Sr²⁺色坐标为（0.146,0.250）,属于蓝绿光。     

Investigation of the Mn2+-F− distance for Mn2+ in fluoride lattices with hexahedral coordination

The Mn²⁺-F^? distance for Mn²⁺-doped CaF₂, CdF₂, SrF₂ and BaF₂ is derived from the experimental isotropic superhyperfine constant A_s. The results obtained indicate the existence of inwards relaxation processes in all these cases, as well as values of the Mn²⁺-F^? distance which are ≈0.1 A larger than those found for systems with [MnF₆]^4? units. This allows one to explain the low 10D_q values recently found by Alonso an Alcalá in CdF₂: Mn²⁺.     

Li+掺杂对TeO2:Tm3+/Er3+/Yb3+纳米材料上转换发光的增强作用

采用水热法制备了发白光的Li+掺杂α-TeO2∶Tm3+/Er3+/Yb3+和β-TeO2∶Tm3+/Er3+/Yb3+纳米上转换发光材料。采用X射线衍射、透射电镜和上转换发光光谱对制备的TeO2∶Tm3+/Er3+/Yb3+/Li+纳米材料进行表征,结果显示:Li+的掺入基本不改变纳米材料的晶型和结构;在980 nm近红外光的激发下,纳米材料发射出中心波长476 nm的蓝光,525 nm及545 nm的绿光和659 nm及675nm的红光,分别对应于Tm3+的1G4→3H6能级跃迁,Er3+的2H11/2→4I15/2和4S3/2→4I15/2能级跃迁,Er3+的4F9/2→4I15/2能级跃迁和Tm3+的3F2→3H6能级跃迁;Li+的掺入能够增大白光体系的发光强度,基本不改变纳米材料的白光颜色。此外,探讨了纳米材料的上转换发光机理。     

Mn4+掺杂Co3O4纳米纤维的静电纺丝法制备及其电化学性能

通过静电纺丝法制备Mn⁴⁺掺杂的Co₃O₄复合纳米纤维,利用XRD、XPS、BET、SEM和电化学工作站等对材料的结构、成分、形貌和电化学性能进行表征与测试。研究发现,通过Mn⁴⁺掺杂,Co₃O₄复合纳米纤维的电化学性能得到明显改善。当n_Co∶n_Mn=20∶2时,相应的复合纤维具有较大比表面积68 m²·g^-1,而且该样品呈现出清晰的氧化还原峰,在1 A·g^-1的电流密度下,放电比电容量为585 F·g^-1,这比纯Co₃O₄纳米纤维的416 F·g^-1,有显著提高;循环500圈电容保持率达到82.6%,而纯Co₃O₄纳米纤维则是76.4%。     

Mechanism of ascorbic acid oxidation by molecular oxygen in aqueous pyridine catalyzed by CO2+, Ni2+, Mn2+ and Zn2+

Data on the radical non-chain mechanism of ascorbic acid oxidation by molecular oxygen catalyzed by Co²⁺, Ni²⁺, Mn²⁺ and Zn²⁺ ions are reported.

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Co²⁺, Ni²⁺, Mn²⁺ Zn²⁺.

     

EPR evidence of possible metastable regions in Mn2+ doped ferroelectric NaNO2

Of the various EPR spectra observed in the ferroelectric phase of NaNO₂, a spectrum designated as spectrum II is observed to have some peculiar properties like dependence of its intensity on growth conditions of the crystal, its disappearance below ≈60°C after heat treatment of the crystal, its reappearance by heating above ≈60°C and also by application of an external dc electric field at ≈30°C. These observations suggest the possible existence, around Mn²⁺-vacancy complex in the ferroelectric phase of NaNO₂, of a metastable structure intermediate to the paraelectric and ferroelectric phase structures.     

Coordinating sites in non-cyclic neutral ionophores determined by Mn2+ induced 13C-spin-lattice relaxation

¹³C-Spin-lattice relaxation times induced by Mn²⁺ were measured for some ionophores and interpreted in terms of the ion-ligand interaction and position of the metal ion relative to the carbon atoms.     

ESR spectra and magnetic constants of α-Al2O3:Co2+,H+ and α-Al2O3 :Co2+,X+

New anisotropic ESR spectra of Co²⁺ doped sapphire, different from hitherto known, are reported. The new spectra which are observed, beside the well-known spectra of α-Al₂O₃:Co²⁺, are shown to form two sets, each one consisting of six spectra (1–6) and (7–12). The spectra of both sets are proven to be interrelated by B_3a symmetry. g and A tensors for each set will be given. Evidence is given that the two sets are to be assigned to the defects α-Al₂O₃:Co²⁺,H⁺ and α-Al₂O₃:Co²⁺,X⁺. The former is concluded to consists of a Co²⁺ ion at the substitutional site (c) and a proton located in a potential minimum along a straight line between O^2- ions situated in O²⁺ triangles above and below the CO²⁺ ion. The potential function for the proton has been calculated by quantum-chemical calculations to clucidate the geometrical structure of the paramagnetic center. The α-Al₂O₃:Co²⁺,X⁺ could not be fully analyzed but some evidence is presented, that X⁺ might be alkali ions.     

EPR of Mn2+ in cobalt fluosilicate hexahydrate

The EPR of Mn²⁺ in cobalt fluosilicate hexahydrate has been studied at room temperature. An axial spin-hamiltornian explained the observed spectrum. The presence of a single Mn²⁺ site in an octahedral oxygen environment was confirmed. A phase transition at ?55°C was observed.     

Gd2O3:Yb3+,Nd3+,Tm3+/SiO2/Ag纳米复合材料的合成及上转换发光性质

通过多步骤的化学法合成了Gd₂O₃：Yb³⁺,Nd³⁺,Tm³⁺/SiO₂/Ag纳米复合材料。利用XRD,TEM,EDS,XPS,CLSM等方法对样品进行表征。实验结果表明,具有低声子能、稳定的化学性质的Gd₂O₃作为上转换发光的基质,当掺杂的敏化剂Nd³⁺离子浓度为1.0%（n/n）,激活剂离子Tm³⁺浓度为0.5%（n/n）时,上转换发光强度达到最大值。此外,表面吸附的Ag纳米颗粒,由于表面等离激元共振耦合作用,使得上转换发光蓝光波段的强度增强1.70倍。     

Optical transitions of Mn2+ in fluoride glasses

The optical properties of Mn²⁺ ions have been extensively investigated in numerous host materials. The 3d⁵ electrons associated with the manganese ion are sensitive to crystal field and the optical transitions yield valuable information on the local environment. Thus, the Mn²⁺ ion optical spectra in fluorozirconate and fluorohafnate glasses suggest that these ions are in positions of low crystal field. Most likely Mn²⁺ substitutes for Ba²⁺ ions in these glasses. As the glass undergoes devitrification the Mn²⁺ ion spectrum changes suggesting that optical methods can be used for studying the temperature dependence of glass transitions.     

Catalytic oxidation of ascorbic acid by molecular oxygen in aqueous pyridine in the presence of Co2+, Ni2+, Mn2+ and Zn2+ ions

In aqueous pyridine solutions, Co²⁺, Ni²⁺, Mn²⁺ and Zn²⁺ effectively catalyze the oxidation of ascorbic acid by molecular oxygen. A kinetic expression consistent with the experimental data is given and a possible mechanism proposed.

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On the mechanism of the ion-molecule reaction CH3+ + CH4 = C2H5+ + H2

Experimental evidence supporting the “direct” reaction model and the “intermediate complex” model for the reaction CH₃⁺(CH₄, H₂)C₂H₅⁺ are analysed. It is shown that the evidence for the former can equally well be interpreted in terms of a proposed model of persistent complex formation and decay. The plausibility of a “direct” mechanism is discussed and is found to be poor.     

The system ZrO2CaO studied by the electron spin resonance of Mn2+ ions

We have used the electron spin resonance of Mn²⁺ ions to study the zirconia-calcia system from 9 to 60 mole% CaO. With the exception of single crystals of calcia-stabilized zirconia (CSZ) with 15 and 20 mole% CaO, the experiments were carried out on polycrystalline samples. From the different values measured for the hyperfine coupling constant A with increasing amount of calcia, we have deduced that Mn²⁺ substitutes for Ca²⁺ in the three following host lattices: cubic CSZ, CaZrO₃, and CaO.