玻璃网络结构对CsPbI3钙钛矿量子点玻璃光学性质的影响

采用高温熔融-热处理技术,以Cs₂O、PbI₂和NaI为CsPbI₃量子点前驱体,制备了CsPbI₃量子点掺杂硼硅酸盐玻璃。X射线衍射和透射电镜观察表明,在玻璃内部析出了CsPbI₃量子点。随热处理温度上升或B₂O₃含量的增加,发光峰和吸收边出现红移,荧光强度和量子产率先增大后减小,量子点的荧光衰减寿命逐渐增长。进一步分析表明,随着B₂O₃含量增大,玻璃中二维（2D）网络结构增多,Cs⁺、Pb²⁺和I^-移动能力增强,有利于CsPbI₃量子点析出和表面缺陷钝化。CsPbI₃量子点掺杂硼硅酸盐玻璃的可调谐红光发射,在可见波段激光器和白光LED等领域具有潜在应用。     

Cu2+和Mn2+改性铈掺杂铥铁石榴石铁氧体的合成及磁性能研究

铥铁石榴石型铁氧体材料具有优异的电磁性能,在信息通信和电子领域具有潜在的应用价值。采用溶胶-凝胶法,成功制备了Ce_0.1Tm_2.9M_xFe₍(5-x))O₁₂(M=Cu²⁺或Mn²⁺;x=0.15,0.25,0.35)铥铁石榴石铁氧体材料。通过X射线衍射测试分析发现,Cu²⁺或Mn²⁺均被成功合成到铈掺杂Tm₃Fe₅O₁₂(Ce:Tm IG)结构中;同时,拉曼图谱中也印证了掺杂TmIG石榴石铁氧体的特征信号峰。Cu²⁺和Mn²⁺掺杂改性后,其饱和磁化强度Ms均有所增加,推测其与Cu²⁺和Mn²⁺占据八面体位置后,增强了Fe³⁺形成离子之间的强偶和作用的有效磁矩有关,掺杂改性后的铥铁石榴石铁氧体具备了进一步器件化应用的潜...     

离子掺杂磷酸铋的制备及其光催化性能研究

利用水热法制备Cu²⁺及Cu²⁺、Zn²⁺共掺杂的磷酸铋基复合光催化材料。采用X-射线衍射(XRD)、电子扫描显微镜(SEM)、傅里叶变换红外光谱仪(FT-IR)等进行表征。以亚甲基蓝为目标降解物,研究Cu^2+-掺杂及Cu²⁺、Zn²⁺共掺杂BiPO₄的复合催化剂光催化活性。结果表明,掺杂改性后的催化剂催化降解率明显增高：其中Cu²⁺掺杂降解率为90%, Cu²⁺、Zn²⁺掺杂降解率为95%。     

Sm3+掺杂双钙钛矿结构Sr3Sn2O7的应力发光特性

Sr₃Sn₂O₇:Sm³⁺是一种被广泛研究的应力法光材料,但关于Sm³⁺掺杂量的研究仍然存在缺失。本工作采用高温固相法制备Sr_3–xSn₂O₇:x Sm³⁺。在Sr₃Sn₂O₇中掺入少量Sm³⁺后,样品仍然保持着非中心对称的双钙钛矿结构。样品在受到紫外灯激励或应力施加之后,能展现出稳定的光致发光、长余辉和应力发光性能,且这三者的光谱显示出一致性。应力发光来源于Sm³⁺的⁴G_5/2激发态向⁶H_J (J=5/2,7/2,9/2)基态的电子跃迁。通过调控x值对其发光性能进行优化,在x=0.020时性能最好。Sm³⁺掺杂量的变化对应力发光性能的影响,既对现有的相关工作进行了补充,同时...     

锡掺杂溴铅铯钙钛矿纳米晶的合成、结构及发光性能

为了降低CsPbBr₃钙钛矿纳米晶的Pb²⁺毒性，同时优化Sn²⁺掺杂CsPbBr₃纳米晶的发光性能，采用热注入法合成了Sn²⁺掺杂的Cs Pb_1-xSn_x Br₃纳米晶(x=0.1、0.2、0.3、0.4和0.5)，使用X射线衍射仪(XRD)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)和荧光光谱仪(PL)对所合成纳米晶的物相结构、微观形貌及发光性能进行表征。结果表明，纳米晶中掺杂的Sn元素以Sn²⁺和Sn⁴⁺形式存在，且含有Pb²⁺阳离子空位，当x=0.3时，Sn元素实际掺杂物质的量分数高达43.91%。x=0.1～0.4时，纳米晶为纯单斜相钙钛矿结构，尺寸约16～20 nm，立方块形貌较均匀。Sn²⁺掺杂调控了Cs Pb_1-xSn_x Br₃纳米晶的...     

Cu/SSZ-13催化剂脱硝活性中心与催化性能构效关系的研究

NH₃选择性催化还原NO_x（NH₃-SCR）是目前最有应用前景的柴油车尾气净化技术,该技术的核心是开发具备优异催化性能的催化剂。以具有菱沸石（chabazite,CHA）结构的小孔分子筛SSZ-13为载体制备的Cu/SSZ-13催化剂,因具有优异的催化性能和水热稳定性能而受到广泛关注。制备了系列Cu_x/SSZ-13催化剂,并通过CO原位漫反射红外光谱（DRIFT）和H₂-TPR等方法能够确定具有高催化活性的铜离子在SSZ-13分子筛上的落位和存在状态。CO红外吸附实验发现,采用Cu(NO₃)₂水溶液离子交换法制备的Cu/SSZ-13催化剂上存在多种落位的Cu⁺活性中心。在较低的Cu⁺交换度条件下,Cu⁺优先落位于SSZ-13分子筛的八元环位置,随着交换度的提高,Cu⁺开始落位于SSZ-13分子筛双六元环的位置。H₂-TPR结果表明Cu_x/SSZ-13催化剂上也存在大量落位在八元环位置不稳定的Cu²⁺,这些Cu²⁺很容易被还原为Cu⁺。Cu_x/SSZ-13催化剂经800℃水蒸气连续老化16 h,分子筛骨架崩塌程度随着Cu含量的增加而提高,骨架铝的脱除,导致Cu物种发生团聚,而第二金属Ce元素的引入能够在一定程度上提高Cu/SSZ-13的水热稳定性。催化剂构效关系研究表明,具有一定量稳定存在的Cu⁺,并且拥有大量不稳定存在Cu²⁺的催化剂具有较宽温度范围的脱硝性能。     

氧化铈-二氧化硅介孔材料制备及对铜离子的吸附性能

采用共沉淀法和沉淀浸渍法制备了纳米氧化铈-二氧化硅（CeO₂-SiO₂）介孔材料吸附剂,主要考察了其对水中铜离子（Cu²⁺）的吸附行为。通过X射线衍射（XRD）、扫描电镜（SEM）和氮吸附（BET）等手段对合成的介孔材料进行了性能表征,并通过静态吸附实验分析了溶液pH、溶液初始金属离子质量浓度、吸附剂用量、吸附时间等条件对介孔材料吸附Cu²⁺性能的影响。结果表明：共沉淀法制备的纳米CeO₂-SiO₂介孔材料对Cu²⁺的去除效果较沉淀浸渍法要好;当溶液pH=7.0时CeO₂-SiO₂介孔材料对Cu²⁺的吸附效果最好,20 min时基本达到吸附平衡;溶液初始Cu²⁺浓度增大Cu²⁺去除率降低,Cu²⁺累计吸附量增大;随着吸附剂用量增加Cu²⁺去除率增大,当CeO₂-SiO₂吸附剂用量为0.15 g/L时对Cu²⁺的去除率趋于稳定;CeO₂-SiO₂吸附剂对不同金属离子吸附性能由大到小的顺序为Cu²⁺、Fe²⁺、Mn²⁺,该吸附过程均符合准二级动力学模型。     

Ba2+、MoO42-掺杂对NaCaPO4：Eu3+荧光粉发光性能的影响研究

为提高红色荧光粉的发光强度和色纯度,以硝酸钙、硝酸钠、硝酸铕、磷酸二氢铵、钼酸铵、硝酸钡为原料,采用高温固相法合成了NaCa_1-xPO₄：xEu³⁺、NaCa_1-x（PO₄）_1-y（MoO₄）_y：xEu³⁺、NaCa_1-x-zPO₄：xEu³⁺,zBa²⁺系列红色荧光粉。探讨了Eu³⁺单掺杂和Eu³⁺/MoO₄^2-、Eu³⁺/Ba²⁺共掺杂对荧光粉发光性能的影响。用X射线衍射（XRD）、荧光分光光度计、色坐标等对荧光粉的结构进行表征。研究结果表明：掺杂Eu³⁺、MoO₄^2-、Ba²⁺后NaCaPO₄晶系没有发生变化,但是晶胞参数发生了变化,说明Eu³⁺、MoO₄^2-、Ba²⁺进入NaCaPO₄晶格中。在393 nm紫外光激发下,荧光粉发射光谱图出现两个Eu³⁺比较强的特征发射峰,分别属于Eu³⁺的⁵D₀→⁷F₁和⁵D₀→⁷F₂跃迁。与单掺杂16%Eu³⁺荧光粉相比,共掺杂16%Eu³⁺/3%MoO₄^2-或16%Eu³⁺/6%Ba²⁺荧光粉的发射光谱中⁵D₀→⁷F₂跃迁产生的发射峰强度均高于单掺杂16%Eu³⁺荧光粉的发射峰强度,其⁵D₀→⁷F₂与⁵D₀→⁷F₁发射光强度之比（R）分别为1.76（R_Mo）和1.28（R_Ba）,都大于单掺杂16%Eu³⁺荧光粉的R_Eu（0.99）,共掺杂Eu³⁺/MoO₄^2-荧光粉的色纯度比单掺杂Eu³⁺和共掺杂Eu³⁺/Ba²⁺荧光粉的色纯度更好。     

无机杂化钙钛矿团簇材料：介尺度钙钛矿材料发光性质研究

近年来,介尺度钙钛矿材料体系中钙钛矿魔幻尺寸团簇（PMSCs）材料因具有优异的半导体特性而在新兴光电器件领域极具潜力。然而,介尺度PMSCs容易在合成过程中生成尺寸较大的介尺度钙钛矿量子点（PQDs）,难以满足实际应用的需求。本研究采用配体辅助再沉淀（LAPR）方法,通过调节戊酸（VA）和油胺（OAm）配体比例制备了不同发光性质的无机杂化介尺度钙钛矿材料CsPbBr₃ PMSCs、CsPbBr₃ PMSCs/CsPbBr₃ PQDs混合物和CsPbBr₃ PQDs,研究并分析了PQDs和PMSCs的光学性质、形貌结构、稳定性和介尺度结构演变机理。研究发现,表面协同钝化配体VA和OAm的比例是反应能否生成介尺度纯相CsPbBr₃ PMSCs的关键。而且,当VA和OAm配体的表面钝化效果越佳越易生成发光性质优异的纯相CsPbBr₃ PMSCs。     

Eu3+掺杂Ba2LaZrO5.5基荧光粉的制备及发光研究

以溶胶凝胶法制备了Ba₂LaZrO_5.5:Eu³⁺荧光粉，探讨溶液的pH值、焙烧温度和掺杂Eu³⁺的量对荧光粉的结构和发光的影响。证实了当pH=3、焙烧温度为800℃时Ba₂LaZrO_5.5:21%Eu³⁺荧光粉为立方体钙钛矿结构；在280nm激发下基质Ba₂LaZrO_5.5在468nm处有较强的蓝光发射，而Ba2LaZrO_5.5:21%Eu³⁺荧光粉在612nm处有Eu³⁺的红光发射峰最强。     

Cu2+掺杂MnO2作为水系锌离子电池正极材料的合成与电化学性能

采用简单的一步电沉积方法制备了Cu²⁺掺杂的MnO₂材料。通过XRD、SEM、TEM等方法对材料进行了表征,结果表明其具有蓬松多孔的纳米结构,作为电池正极材料时有利于Zn²⁺的存储,具有较高的电池容量。与未掺杂样品相比Cu²⁺掺杂的MnO₂材料有更好的电化学性能,在电流密度为200 mA/g时,比容量达到235 mAh/g,增加了47.8%,阻抗也由997.3 Ω降到了564.3 Ω。     

Role of Si in the Luminescence of AlN:Eu,Si Phosphors

The luminescence properties of Si,Eu-codoped AlN phosphors were investigated by means of cathodoluminescence. The concentration of Eu was kept constant, while that of Si was varied from 0 to 9.0 at.% using two different Si-source starting powders, Si₃N₄ and SiC. The luminescence of Eu²⁺ in AlN is only observed for samples doped with Si. On the other hand, a concentration quenching is observed for samples doped with high amount of Si from Si₃N₄ while not for those doped from SiC. These results show the importance of Si in the luminescence properties of Eu²⁺-doped AlN.     

Strong Suppression and Enhancement of Photoluminescence in Zn2SiO4:Mn2+ Inverse Opal Photonic Crystals

Inverse opal photonic crystals based on a luminescent matrix of Mn²⁺-doped Zn₂SiO₄ were synthesized, and their photoluminescence was investigated using a fluorescence microscope and spectrometer. Strong suppression of the luminescence from the Zn₂SiO₄:Mn²⁺ matrix in certain directions was observed directly due to the overlap of the pseudo-photonic bandgap (PPBG) and the emission band. As a result, the luminescence in other orientations (outer of the PPBG) was enhanced significantly. This cost-effective, non-lithographic method to produce luminescent inverse opals is expected to be useful for the fabrication of anisotropic photonic crystal light sources for display applications.     

One-electron reducibility of isolated copper oxide on alumina for selective NO–CO reaction

The H₂-TPR (temperature-programmed reduction) study was performed for supported copper oxide catalysts with low loading (0.5 wt% as copper). Among the various kinds of support materials (γ-Al₂O₃, TiO₂, ZrO₂, SiO₂, ZSM-5), alumina-supported copper oxide indicated a one-electron reduction behavior of Cu²⁺ into Cu⁺ ions in the presence of H₂. The reduction of the isolated Cu²⁺ species in a tetragonally distorted octahedral symmetry into the low coordinated Cu⁺ ions was identified by means of X-ray absorption spectroscopy (XANES and EXAFS). The isolated Cu⁺ ions hosted by γ-Al₂O₃ surface were prevented from further reduction into metallic Cu⁰ state under reducing condition with H₂ at 773 K. Less dispersed supported copper oxide species were easily reduced to Cu⁰ metal particles with H₂ at 573 K regardless of the kinds of support materials. It is suggested that the one-electron redox behavior of the isolated copper oxide species over γ-Al₂O₃ promotes the catalytic reduction of NO with CO in the presence of oxygen on the basis of redox-type mechanism between Cu²⁺ and Cu⁺ in atomically dispersed state.     

Eu2+-Doped Glass Ceramics Containing BaF2 Nanocrystals as a Potential Blue Phosphor for UV-LED

The Eu²⁺-doped glass ceramics containing BaF₂ nanocrystals were prepared and their luminescence properties were investigated. The excitation spectra of Eu²⁺-doped glass ceramics showed an excellent overlap with the main emission region of an ultraviolet light-emitting diode (UV-LED) centered at 380 nm. The 450 nm emission of Eu²⁺ in glass ceramics under the 385 nm excitation was much stronger than that in glass. The Eu²⁺-doped glass ceramics containing BaF₂ nanocrystals may be used as a potential blue-emitting phosphor for UV-LED.     

A new insight in the unusual adsorption properties of Cu cations in Cu-ZSM-5 zeolite

ZSM-5 zeolites modified with Cu⁺ ions were prepared either by the high-temperature chemical reaction of hydrogen form with CuCl vapour or by the wet ion exchange with subsequent reduction of the modified samples in CO at 873 K. Adsorption of H₂, N₂ or C₂H₆ by Cu⁺ ions was studied by DRIFTS and by volumetric technique. The conclusions about the structure of adsorption complexes were supported by the DFT cluster quantum chemical calculations. The obtained results indicated that in addition to the previously reported strong adsorption of nitrogen, the univalent copper also unusually strongly adsorbs molecular hydrogen and ethane. Adsorption of hydrogen is the most amazing since the observed low-frequency shifts of the HH stretching vibrations were as high as about 1000 cm⁻¹. This is quite different from much weaker H₂ perturbation by Cu²⁺ cations. Adsorption of ethane by Cu⁺ ions also resulted in the low-frequency shifts of some of CH IR stretching bands up to 400 cm⁻¹. The DFT cluster modelling indicated that both adsorption of hydrogen and ethane could be explained by interaction with the isolated Cu⁺ ions localized at the sites of the ZSM-5 framework. Quantum chemical calculations indicated the important role in the bonding of adsorbed hydrogen and ethane of electron back donation from d_π-orbitals of Cu⁺ ions to the σ^*HH or CH orbitals. The overall yield of Cu⁺ sites of the strong H₂ or N₂ adsorption is about twice lower than the total copper content.     

Facile synthesis and enhanced visible-light photocatalytic activity of Ti3+-doped TiO2 sheets with tunable phase composition? ?

Ti³⁺-doped TiO₂ nanosheets with tunable phase composition (doped TiO₂ (A/R)) were synthesized via a hydrothermal method with high surface area anatase TiO₂ nanosheets TiO₂ (A) as a substrate, structure directing agent, and inhibitor; the activity was evaluated using a probe reaction-photocatalytic CO₂ conversion to methane under visible light irradiation with H₂ as an electron donor and hydrogen source. High-resolution transmission electron microscope (HRTEM), field emission scanning electron microscope, UV-Vis diffuse reflectance spectra, and X-ray diffraction (XRD) etc., were used to characterize the photocatalysts. XRD and HRTEM measurements confirmed the existence of anatase-rutile phase junction, while Ti³⁺ and single-electron-trapped oxygen vacancy in the doped TiO₂ (A/R) photocatalyst were revealed byelectron paramagnetic resonance (EPR) measurements. Effects of hydrothermal synthesis temperature and the amount of added anatase TiO₂ on the photocatalytic activity were elucidated. Significantly enhanced photocatalytic activity of doped TiO₂ (A/R) was observed; under the optimized synthesis conditions, CH₄ generation rate of doped TiO₂ (A/R) was 2.3 times that of Ti³⁺-doped rutile TiO₂.     

Active sites of Cu-ZSM-5 for the decomposition of acrylonitrile

The catalytic decomposition of acrylonitrile (AN) over Cu-ZSM-5 prepared with various Cu loadings was investigated. AN conversion, during which the nitrogen atoms in AN were mainly converted to N₂, increased as Cu loading increased. N₂ selectivities as high as 90–95% were attained. X-ray diffraction measurements (XRD) and temperature-programmed reduction by H₂ (H₂-TPR) showed the existence of bulk CuO in Cu-ZSM-5 with a Cu loading of 6.4 wt% and the existence of highly dispersed CuO in Cu-ZSM-5 with a Cu loading of 3.3 wt%. Electron spin resonance measurements revealed that Cu-ZSM-5 contains three forms of isolated Cu²⁺ ions (square-planar, square-pyramidal, and distorted square-pyramidal). The H₂-TPR results suggested that in Cu-ZSM-5 with a Cu loading of 2.9 wt% and below, Cu⁺ existed even after oxidizing pretreatment. The activity of AN decomposition over Cu/SiO₂ suggested that CuO could form N₂, but, independent of the CuO dispersion, nitrogen oxides (NO_x) were formed above 350 °C. Cu⁺ and the square-pyramidal and distorted square-pyramidal forms of Cu²⁺ showed low activity for AN decomposition. Temperature-programmed desorption of NH₃ suggested that N₂ formation from NH₃ proceeded on Cu²⁺, resulting in the formation of Cu⁺. The Cu⁺ ions were oxidized to Cu²⁺ at around 300 °C. Thus, high N₂ selectivity over Cu-ZSM-5 with a wide range of temperature was probably attained by the reaction over the square-planar Cu²⁺, which can be reversibly reduced and oxidized.     

Energy Transfer Enables 1.53 μm Photoluminescence from Erbium-Doped TiO2 Semiconductor Nanocrystals Synthesized by Ar/O2 Radio-Frequency Thermal Plasma

Highly crystalline, highly luminescent nanopowders of Er³⁺-doped TiO₂ have been successfully synthesized via one-step Ar/O₂ radio-frequency thermal plasma processing. Energy transfer from the TiO₂ host to Er³⁺ activators has been confirmed by combined means of UV-vis, excitation, and photoluminescence spectroscopies. As a consequence, bright photoluminescence at ∼1.53 μm was observed from the nanopowders either by directly exciting the Er³⁺ activator or by exciting the TiO₂ host lattice. A comparative study shows that the nanopowder of the same system made via coprecipitation lacks the energy transfer. The plasma-generated nanopowders may thus find applications in optoelectronic devices.