水热合成NaYF_4:Tb~(3+)/Ce~(3+)或Bi~(3+)体系中Ce~(3+)和Bi~(3+)对Tb~(3+)离子发光的增强作用

利用水热法合成六方相NaYF4:Tb3+/Ce3+或Bi3+体系,用X射线粉末衍射仪以及荧光分光光度计对所合成样品的物相结构以及荧光性能进行表征。在紫外光激发下,Ce3+能有效吸收紫外光并传递给Tb3+离子,Tb3+离子的绿色发光得到增强,Bi3+离子对Tb3+离子的荧光性能也有一定的敏化作用。水热合成NaYF4:Tb3+/Ce3+或Bi3+体系中Ce3+和Bi3+对Tb3+离子的荧光性能具有增强作用。     

对叔丁基杯[4]芳烃乙酸萃取Cr~(3+)的反应研究

报道了以对叔丁基杯[4]芳烃乙酸(简称杯[4]水解)为萃取剂,从硝酸体系中萃取Cr3+的反应机理及反应热力学性质。通过考察溶液pH值对萃取分配比的影响,确认杯[4]水解萃取Cr3+的机理,并得到了萃取反应的表观平衡常数K=1.815×103;通过考察反应温度对分配比的影响,求得萃取热焓ΔH=69.89 kJ/mol;由ΔH和表观平衡常数K计算了自由能ΔG=-18.601 kJ/mol和熵变ΔS=294.97 J/(mol-1.K-1)。杯[4]水解萃取Cr3+的反应是一个吸热反应。     

硫酸介质中P507萃取Fe~(3+)的实验研究

本文以硫酸铁为料液,用2-乙基-己基膦酸-单2-乙基己基酯(P507)萃取剂在硫酸介质中萃取Fe3+。研究了温度、时间、P507的浓度、初始酸度、相比等因素对Fe3+萃取率的影响,以及有机相的反萃工艺。研究结果表明:温度为25℃,平衡时间为35min,初始氢离子浓度为0.4 mol/L,相比A/O=2/1,P507的体积分数为35%的条件下,水相经过四级逆流萃取,Fe3+的萃取率可达99.66%;反萃酸度为4 mol/LHCl,相比A/O=1/2,反萃时间为7min,经三级逆流反萃,反萃率可达到99.90%,有机相可以循环使用。     

Fe~(2+)/Fe~(3+)对SBBR工艺处理腈纶废水效果比较

通过平行对比试验,考察了分别外加Fe2+和Fe3+的SBBR反应器对实际腈纶废水的处理效果。结果表明:外加Fe2+/Fe3+对腈纶废水处理效果较好,COD去除率在60%左右,氨氮去除率高达90%以上,氨氮出水可达国家一级B标准。在水质波动阶段,外加Fe2+比Fe3+对腈纶废水中COD的处理效果更好。Fe2+对亚硝化反应具有促进作用,外加Fe2+的SBBR反应器对氨氮的降解速率较Fe3+更快。     

Fe~(3+)掺杂对硝酸羟胺热稳定性的影响及其机理

为研究Fe~(3+)掺杂对硝酸羟胺(HAN)热稳定性的影响,在升温速率分别为3、4、5K/min下对无Fe~(3+)以及Fe~(3+)掺杂的HAN水溶液进行热分析。借助非等温DSC曲线的参数值,应用Kissinger和Ozaw方法分别计算热分解反应动力学参数。采用密度泛函方法对影响机理进行研究,优化得到NH2OH及其与Fe~(3+)形成配位化合物Fe(NH2OH)3+6的稳定构型,计算了N-H和O-H键的键长、Wiberg键级以及分子的前线轨道分布。结果表明,Fe~(3+)掺杂使得硝酸羟胺的热稳定性降低,使HAN的起始分解温度平均降低约16℃,表观活化能略有升高,指前因子大幅增加,热分解反应速率提高;NH2OH与Fe~(3+)形成配位化合物Fe(NH2OH)3+6后,N-H和O-H键的键长增加,伸缩振动频率减弱,Wiberg键级减小,键周围的电子云密度减小,键的强度减弱,加快了HAN的热分解。     

茶叶质铁的吸附性能及动力学研究

研究了改性茶叶对Fe3+的吸附性能及吸附动力学。探讨了溶液的初始浓度、pH值、时间和温度对吸附性能的影响,并采用Langmuir等温吸附方程和准二级动力学吸附速率方程探讨了等温吸附过程和吸附动力学过程。结果表明:改性茶叶对Fe3+吸附时,溶液最佳pH为0.8~0.9之间,Fe3+初始浓度大于1.40 mol/L,吸附温度范围为50~60℃,吸附60 min基本达到饱和;改性茶叶吸附Fe3+的吸附规律符合Langmuir等温吸附方程,在不同初始浓度下,改性茶叶吸附Fe3+的吸附过程符合准二级动力学吸附速率方程,活化能为Ea=12.73 kJ/mol,该吸附行为是一个吸热过程。     

负载钛催化丁烯-1扩大溶液聚合反应过程

采用TiCl4/MgCl2-Al(i-Bu)3催化体系在10L聚合釜中用溶液法研究了丁烯-1聚合反应过程。结果表明,在反应温度为20℃条件下,聚合的速率方程为-d[Bt]/dt=41[Ti][Bt][PH2]0.4;在10～30℃,聚合的表观活化能为16kJ/mol;提高催化剂浓度、聚合温度、氢气压力能明显提高单体转化率、加快反应速率。     

基于蒽酰亚胺基团的新型Fe~(3+)和Hg~(2+)化学敏感器

含蒽酰亚胺基团的化合物N-(2-(6-氨基吡啶))-9-蒽酰亚胺(L1)对Fe3+表现出灵敏的荧光增强响应.L1的衍生物N,N-′(2,6-吡啶基)-二(9-蒽酰亚胺)(L2)对Hg2+在紫外-可见吸收光谱和荧光光谱上显示了良好的识别性.即使在其它金属阳离子存在下,L1和L2分别对于Fe3+和Hg2+仍然表现出较好的选择性.     

乳状液膜法提取Cr3+内相界面反应的研究

文章对乳状液膜法提取Cr3+内相界面的反萃取反应进行了研究。选择NaOH为反萃剂,H2O2为氧化剂,研究了内水相pH值、反应温度、搅拌速率、原料配比对反萃反应的影响,同时研究了反萃反应的反应方程式、反应的热力学性质。实验表明,反萃反应达平衡时的分配比随内相水溶液pH值及搅拌速度的升高而降低,随反应温度的升高而升高,随NaOH与[CrHn-mL(O)]2+摩尔比的增加先降低后升高;通过斜率法确定反萃反应为氧化-还原反应,并得到了反应的表观平衡常数k;计算了反萃反应的热焓ΔH,自由能ΔG和熵变ΔS。     

O3/Fe2+均相催化体系及其效能强化综述

针对O3/Fe2+催化氧化体系Fe2+消耗量大、适用的pH范围狭窄等问题,综述了O3/Fe2+催化氧化体系的研究现状.分析了O3/Fe2+氧化反应机理和pH、Fe2+投加量、O3投加量及投加方式、反应温度等因素对O3/Fe2+催化氧化效果的影响,以及UV辐照、H2 O2、螯合剂等效能强化手段的机理和效果,并类比了羟胺(HA)强化Fenton反应的机理、应用和效果,提出利用HA构建Fe3+/Fe2+循环,可能是强化O3/Fe2+均相催化体系的一种新方法.     

Photoluminescence analysis of Sm3+ and DY3+ doped PVA films

A couple of Poly vinyl alcohol (PVA) films with Sm³⁺ and Dy³⁺ ions have been prepared by a conventional solution cast technique. For these Sm³⁺ and Dy³⁺ doped PVA films, Fourier transform infrared and also absorption spectral measurements have been carried out. Excitation and emission spectra and decay curves have been recorded to understand emission performance of the polymers namely Sm³⁺: PVA film with λ_exci = 400 nm and Dy³⁺: PVA film with λ_exci = 349 nm. Emission performances of these films have been explained in terms of relevant energy level schemes. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Photodarkening mechanisms of Pr3+ singly doped and Pr3+/Ce3+ co-doped silicate glasses and fibers

In this work, we revealed the possible mechanisms of the photodarkening in Pr³⁺ ions singly doped and Pr³⁺/Ce³⁺ co-doped silicate glasses and fibers induced by X-ray and 488-nm laser radiations and studied the role of Ce³⁺ in increasing radiation resistance in Pr³⁺-doped silicate glasses and fibers. The absorption, emission, electron paramagnetic resonance (EPR), radiation induced attenuation spectra, and X-ray photoelectron spectroscopy (XPS) of Pr³⁺ singly doped and Pr³⁺/Ce³⁺ co-doped silicate glasses before and after X-ray radiation were measured and analyzed. The fluorescence intensity and photoinduced attenuation of Pr³⁺ singly doped and Pr³⁺/Ce³⁺ co-doped silicate fibers at visible wavelengths pumped by 488-nm laser were measured and analyzed. The influence of Ce³⁺ ions co-doping on the spectroscopic properties of Pr³⁺ ions as well as the radiation-induced defects in silicate glasses was studied. Results demonstrate that both X-ray and 488-nm laser radiations will induce photodamage in Pr³⁺ ions-doped silicate glasses and fibers. Co-doping Ce³⁺ (by up to 1 mol%) is efficient to suppress the darkening induced by both X-ray and 488-nm laser radiations without influence on the luminescence behavior of Pr³⁺ ions in silicate glasses and fibers. Our studies demonstrate the promising potential of Pr³⁺/Ce³⁺ co-doped silicate glasses for visible lasing applications.     

纳米粉体Y_2O_3:Ti~(3+),Pr~(3+)的光谱性能

采用共沉淀法在氮氢气氛中制备出Y2O3:Ti3+,Pr3+纳米粉体,通过XRD、TEM方法确认了它的晶相与晶粒尺寸,测量了它的激发与发射谱,并与Y2O3:Ti3+纳米粉体的光谱进行了比较。结果显示:共掺Pr3+仅在281nm处产生了激发峰,而在蓝绿光区没有产生激发峰,以致365～480nm的光激发不出Pr3+的特征红荧光。表明:共掺Pr3+的Y2O3:Ti3+用作白光LED荧光粉,难以改善发光性能。     

活性炭对不锈钢酸洗废水中Cr3+和Fe3+的吸附特性

对颗粒活性炭吸附不锈钢酸洗废水中的Cr3+和Fe3+进行了研究. 结果表明,活性炭对Cr3+的饱和吸附量为4.546 mg/g,对Fe3+的饱和吸附量为40.76 mg/g,吸附平衡时间分别为90和60 min. 对吸附过程进行准一级、准二级动力学模型拟合,发现准二级模型拟合较好. 活性炭对Cr3+的吸附基本符合Langmuir和Freundlich等温吸附模型,而对Fe3+的吸附与BET吸附模型拟合较好,吸附Cr3+, Fe3+的活化能Ea分别为37.19和51.01 kJ/mol. 活性炭对Cr3+的吸附以化学吸附为主,而物理吸附则主导对Fe3+的吸附.     

针铁矿法分离铬铁矿硫酸浸出液中Cr3+与Fe3+

采用针铁矿法分离铬铁矿硫酸浸出溶液中的Cr3+与Fe3+. 结果表明,以Fe2(SO4)3溶液中加入适量KOH后生成的Fe(OH)3为前驱体,在120℃的水热条件下保温8 h后可制备出晶体发育良好的针铁矿晶种. 将铬铁矿硫酸浸出液的Fe3+浓度稀释至1 g/L以下并加入针铁矿晶种,在pH=2.5、温度90℃条件下保温4 h后,Fe3+以针铁矿晶体沉淀析出,能实现铁与铬的分离,除铁率为97%,铬损失率为33%.     

YVO4:Eu3+,Bi3+荧光粉的制备及荧光性能研究

用溶胶凝胶法在较低温度下制备了YVO4:Eu3+,Bi3+荧光粉,采用X射线衍射仪(XRD),扫描电子显微镜(SEM)及荧光分光光度计测试,研究了合成产物的结构、表面形貌,分析了在Eu3+含量一定的情况下掺杂Bi3+的浓度的变化对发光性能的影响.结果表明,溶胶凝胶法合成的YVO4:Eu3+,Bi3荧光粉为单相结构、粒径在1 μm左右、无团聚现象;Bi3+对Eu3+离子有敏化作用,在一定浓度下使荧光粉的发射强度增加.     

高显色白光LED用YAG：Ce^3＋，Ln^3＋荧光粉的研究进展

综述了YAG：Ce荧光粉的制备方法,着重介绍了高显色白光LED用YAG：Ce^3＋,Ln^3＋（Ln=Sm,Pr,Gd,Tb）荧光粉的最新研究进展和发光性能。YAG：Ce^3＋,Ln^3＋荧光粉的发射谱带发生红移,或在红光区增加尖锐的红光发射峰,从而提高了白光LED的显色性能。     

Bi3+/Mn4+ co-doped dual-emission phosphors for potential plant lighting

Developing environment-friendly dual-emission phosphors of both blue–cyan and deep-red lights is desirable for the utilized indoor plant lighting research. Notably, the naked 6s and 6p Bi³⁺ ions are sensitive to the lattice sites, which emit from Ultraviolet (UV) to red lights in various crystal compounds. Meanwhile, the ²E → ⁴A_2g transition of Mn⁴⁺ ions promises its deep-red light emissions, which satisfies the demand for specific wavelength lights for plants growth. Hence, a Bi³⁺/Mn⁴⁺ co-doped Sr₂LaGaO₅: Bi³⁺, Mn⁴⁺ (SLGO:Bi³⁺:Mn⁴⁺) phosphor was finally synthesized. The phase, micromorphology and luminescent properties were systematically evaluated. Upon excitation at 350 nm light, dual emissions of both blue–cyan (470 nm) and deep-red (718 nm) lights were observed. Besides, due to the pronounced photoluminescence (PL) spectral overlap between Bi³⁺ and Mn⁴⁺ ions, a potential energy transfer process from Bi³⁺ to Mn⁴⁺ ions was confirmed. The relative PL intensities between Bi³⁺ and Mn⁴⁺ ions can be tuned just by adjusting the Mn⁴⁺ ion concentration. Besides, Li⁺ co-doping has been evidenced to improve the deep-red emissions (718 nm) of SLGO:0.005Mn⁴⁺ due to charge compensation and rationally designed lattice distortion, together with the improved thermal stability. Finally, the emissions of SLGO:Bi³⁺, Mn⁴⁺, Li⁺ phosphor suit properly with the absorption of the four fundamental pigments for plant growth, indicating that the prepared phosphorescent materials may have a prospect in plant light-emitting diodes lighting.     

Tb3+激活硅酸盐发光玻璃的研究进展

简要介绍了研究发光玻璃的必要性,发光玻璃的要求及分类,综合评述了Tb3+激活硅酸盐发光玻璃的研究现状,并对研究中存在的问题和研究方向做了进一步探讨.     

Toward temperature-dependent Bi3+-related tunable emission in the YVO4:Bi3+ phosphor

Up until now, many previous works have indicated us that the photoluminescence (PL) properties of phosphors sometimes can be changed with the change in the external temperature, resulting in the anomalous PL phenomena and correlated new applications that are difficult to achieve at room temperature. In this work, we report the temperature-dependent Bi³⁺-related PL properties in the YVO₄:Bi³⁺ phosphor. Our findings show that increasing the temperature from 10 to 300 K enables manipulating the energy interaction from groups to Bi³⁺, thereby leading to the temperature-induced color tuning from blue (0.183, 0.212) to yellow (0.418, 0.490). Upon this heating process, we further reveal that the dynamic Bi³⁺ luminescence has experienced a regular transition from double-exponential to single-exponential decay, which results in the decrease in the average Bi³⁺ lifetime from 122.606 to 0.376 μs. Discussions on the PL results imply that the tunable PL observations are due to the interplay of temperature-dependent energy transfer from groups to Bi³⁺ and redistribution of the excited ³P₀ and ³P₁ states of Bi³⁺ upon the thermal stimulation. This work not only presents the temperature-triggered Bi³⁺ tunable properties in the well-studied YVO₄ host lattice but also can provide new insights into revealing Bi³⁺-related PL mechanism in other Bi³⁺-doped photonic materials in the future and, in the meanwhile, gives some directive ideas for us to explore previously unnoticed applications for rare-earth (RE; eg, Eu³⁺, Pr³⁺, Tb³⁺, Eu²⁺, Er³⁺, etc) and other non-RE (eg, Bi³⁺, Mn⁴⁺, Mn²⁺, Cr³⁺, etc) doped phosphors.