过渡金属离子对碳酸铈与二氧化钛为基础的着色玻璃的影响

一前言氧化铈在玻璃中以Ce~(4+)Ce~(3+)的平衡状态而存在,并随着熔化气氛而变动。铈的着色离子为Ce~(4+)。单一的CeO_2着色很弱,只相当于CoO的1/50。Ce~(4+)在短波的吸收最远可延至550mμ。随着CeO_2含量的增加可使玻璃呈黄色至橙色。二氧化钛与二氧化铈的混合着色,使     

A fluorescent probe based on a spiropyran for sensitive detection of Ce~(3+) ion

A spiropyran-based probe was developed.It serves as a fluorescence turn-on probe for selective detection of Ce~(3+) in both ethanol and aqueous(water/ethanol,1:9 or 9:1,v/v) media.Ce~(3+) can induce photochromism of the probe though the probe exhibits negligible photochromic property by itself.The probe is sensitive to Ce~(3+) and the detection limit reaches 1.7 μmol/L.It exhibits a high selectivity for Ce~(3+)ion over other common metal cations including Li~+,Na~+,Ag~+,Sr~(2+),Ni~(2+),Co~(2+),Hg~(2+),Zn~(2+),Cr~(3+),Al~(3+),Fe~(3+) and Bi~(3+) and lanthanide ions Nd~(3+),Yb~(3+) and La~(3+).The probe may be used for quantitative determination of the concentration of Ce~(3+) ion in a range of 1-10 μmol/L and for application to environmental water samples.Sensing mechanism of the probe towards Ce~(3+) ion is proposed.     

Ce~(4+)掺杂对CaO-SiO_2-MgO-Al_2O_3系透辉石微晶玻璃析晶行为的影响

在采用熔融法制备含Ce~(4+)的CaO-SiO_2-MgO-Al_2O_3系透辉石微晶玻璃过程中,采用差示扫描量热法(DSC)、扫描电子显微镜(SEM)和X射线衍射(XRD)相结合的分析检测方法,研究了Ce~(4+)掺杂对基础玻璃结构的稳定性、热处理后晶体层的晶体形态及晶相组成的影响规律。研究结果表明,Ce~(4+)掺杂能显著提高基础玻璃的玻璃化转变温度,提高基础玻璃结构稳定性并抑制透辉石晶体长大,CeO_2不能作为CaO-SiO_2-MgO-Al_2O_3系微晶玻璃的有效晶核剂。Ce~(4+)掺杂对CaO-SiO_2-MgO-Al_2O_3系微晶玻璃的析晶矿物种类和数量均无明显影响。     

EDTA络合滴定法测量高炉渣中铁(Ⅲ)和铁(Ⅱ)

采用盐酸溶解样品,在保护气二氧化碳的保护下,控制溶液温度在(75±2)℃、pH值在1.5~2.0范围内,以磺基水杨酸为指示剂,用EDTA标准溶液滴定Fe~(3+);然后加入过硫酸铵氧化Fe~(2+),继续用EDTA标准溶液滴定氧化生成的Fe~(3+),再减去金属铁(MFe)即得到Fe~(2+)含量。试验讨论了溶液温度、酸度及环境保护措施的选择等条件对测定结果的影响。实验方法用于测定3个高炉渣样品中Fe~(3+)和Fe~(2+),结果的相对标准偏差(RSD,n=5)为0.76%~2.3%。按照实验方法测定3个高炉渣样品中Fe~(3+)和Fe~(2+),结果与邻二氮菲分光光度法测定结果相吻合。     

铈和铽氧化物酸分解过程热力学研究

通过热力学计算,建立了298.15K时Ce和Tb氧化物酸分解过程的φ-pH图。结果表明,CeO_2与TbO_2两种氧化物均难以被酸直接分解,但在还原性条件下采用酸分解可使其转化为Ce~(3+)和Tb~(3+);与CeO2和TbO2相比,Ce_2O_3和Tb_2O_3能在较高的pH值条件下被酸直接分解成Ce~(3+)和Tb~(3+),从而实现对Ce和Tb的提取。     

白云鄂博稀土尾矿催化CO还原NO实验研究

针对稀土尾矿催化CO还原NO进行实验研究。实验结果表明,稀土尾矿能有效催化还原NO,且脱硝率随着反应温度的升高和碳氮比的增加而增加。稀土尾矿在中高温段的脱硝率高于纯物质CeO_2、Fe_2O_3、Fe_2O_3/CeO_2和5Fe_2O_3/CeO_2;H_2-TPR测试表明,稀土尾矿在800℃以上出现的还原峰也高于这4种纯物质。XRD分析表明稀土尾矿的主要矿相在脱硝反应前后没有变化,但各矿相特征峰的强度下降,氟碳铈矿特征峰消失。SEM图像显示脱硝反应后稀土尾矿中出现裂缝和孔隙。EDS分析表明,稀土尾矿单一颗粒中存在多种金属元素的重叠区。XPS分析结果表明稀土尾矿脱硝后Fe~(3+)和Ce~(3+)的比例增加。当反应温度为900℃,碳氮比为4∶1时,稀土尾矿的脱硝率为98%。     

Tunable emission properties of tri-doped Ca_9LiY_(2/3)(PO_4)_7:Ce~(3+),Tb~(3+),Mn~(2+) phosphors with warm white emitting based on energy transfer

Tri-doped Ca_9 LiY_(2/3)(PO_4)_7:Ce~(3+),Tb~(3+),Mn~(2+)phosphors were prepared by a high-temperature solid state method.Under UV light excitation,Ca_9 LiY_(2/3)(PO_4)_7:Ce~(3+)samples exhibit a broad band ranging from 320 to 500 nm.At 77 K,the emission spectra of Ca_9 LiY_(2/3)(PO_4)7:Ce~(3+)samples present two obvious emission peaks,indicating that Ce~(3+)ions occupy two different kinds of lattice sites(Ca(1/2) and Ca(3)),As a good sensitizer for Tb~(3+),Ce~(3+)ions in Ca_9 LiY_(2/3)(PO_4)_7 lattice can effectively transfer part of energy to Tb~(3+),and the energy trans fer mechanism is determined to be dipole-dipole interaction.Consequently,the emitting color for Ce~(3+) and Tb~(3+) co-doped Ca_9 LiY_(2/3)(PO_4)_7 samples can be tuned from bluish violet to green.In order to further enlarge the emission gamut,Mn~(2+)ions as red emission components were added,forming tri-doped single-phase Ca_9 LiY_(2/3)(PO_4)_7:Ce~(3+),Tb~(3+),Mn~(2+)phosphors.The Ca_9 LiY_(2/3)(PO_4)_7:Ce~(3+),Tb~(3+),Mn~(2+)phosphors exhibit tunable emission properties through controlling the relative doping concentration of Ce~(3+),Tb~(3+)and Mn~(2+).Especially,Ca_9 LiY_(2/3)(PO_4)_7:0.09 Ce~(3+),0.12 Tb~(3+),0.30 Mn~(2+)can emit warm white light.The sample shows good thermal stability.At 150℃,the emission intensity for Ce~(3+)(360 nm),Tb~(3+)(545 nm) and Mn~(2+)(655 nm) decreases to 63%,69%,and 72% of its initial intensity,respectively.Moreover,the sample obtains good stability after 10 cycles between room temperature and150℃.     

废旧荧光粉中稀土元素浸出的电位-pH图

废旧稀土荧光粉经"酸浸-碱焙烧-水洗-酸浸"处理可浸出回收其中的Y, Eu, Tb, Ce等稀土。本文根据酸浸过程中的各组分的吉布斯自由能Δ_fG分别计算出各酸浸过程中各化学反应的吉布斯自由能Δ_rG,由能斯特公式计算出反应的电位与pH关系,进而绘制出两段酸浸过程中的电位-pH图,即不同活度的Al~(3+)与Y-Eu-H_2O系的电位-pH图和Tb-Ce-H_2O系电位-pH图,并分析了各组分的稳定区域。结果表明:废旧稀土荧光粉直接酸浸时,从25～100℃,在pH6的酸性条件下,红粉中的Y_2O_3, Eu_2O_3以Y~(3+), Eu~(3+)的形式稳定存在水溶液中, Al(OH)_3稳定区域在pH为4.8～8.3之间,为防止Al ~(3+)水解,酸浸出液终点pH值应控制在3.5～4.0之间;从25～100℃,在酸性条件下,经碱焙烧水洗除铝后得到的TbO_2, CeO_2很难被酸直接浸出,同时Tb~(4+), Ce~(4+)在水溶液中不能稳定存在,但通过加入适当的还原剂,可将Tb~(4+), Ce~(4+)还原成Tb~(3+), Ce~(3+),便可存在于水溶液中。     

气电纺丝法制备硅铝增强氧化铈纳微纤维

通过在聚乙烯吡咯烷酮/硝酸铈(PVP/Ce(NO_3)_3)纺丝液中添加一定比例硅铝溶胶,结合气电纺丝法和高温煅烧工艺成功制备出硅铝增强氧化铈(CeO_2)纳微纤维。采用SEM、XPS、XRD等手段研究了添加比例、电压、风压、煅烧温度等对纤维形貌与结构的影响。结果表明,适量硅铝溶胶的加入,有助于提高PVP/Ce(NO_3)_3纺丝液的粘度;当PVP/Ce(NO_3)_3纺丝液与硅铝溶胶比为6∶1(纺丝液粘度为2.85 Pa·s),纺丝电压为38 kV,风压0.08 MPa时,纺丝效果最佳,制得初生纤维连续、光滑,经高温煅烧后得到纤维材料蓬松、柔软,纤维直径约为1μm~2μm,长度可在10 mm以上;其晶型结构为CeO_2的立方晶系,Si/Al存在一定程度上抑制了CeO_2晶粒的生长,有利于改善纤维的柔韧性。     

阳离子对嗜酸氧化亚铁硫杆菌氧化活性的影响

以嗜酸氧化亚铁硫杆菌(Acidthiobacillus ferrooxidans,At.f,FN811931)为研究对象,研究了脉石矿物溶出阳离子(K~+,Mg~(2+),Ca~(2+)和Al~(3+))对At.f菌氧化活性的影响。研究结果表明:不同阳离子对At.f菌氧化活性的影响效应不同,其影响由大到小的顺序依次为Mg~(2+),Al~(3+),K+,Ca~(2+),当Mg~(2+),Al~(3+),K~+浓度分别超过1,5,10 g·L~(-1)时显著降低了At.f菌的氧化活性,而Ca~(2+)在所研究0~2 g·L~(-1)浓度范围内对At.f菌氧化活性影响不大。培养25 h时,低浓度条件下(0.5 g·L~(-1)),K+,Ca~(2+),Al~(3+),Mg~(2+)作用下的Fe~(2+)的氧化率分别为67.78%,68.76%,65.27%,61.28%,均高于不添加任何离子作用下的Fe~(2+)的氧化率(60.74%);高浓度条件下(15 g·L~(-1)),K+,Al~(3+),Mg~(2+)作用下的Fe~(2+)的氧化率分别为35.82%,25.25%,21.47%,均低于不添加任何离子作用下的Fe~(2+)的氧化率。阳离子Mg~(2+),Al~(3+),K~+随离子浓度的增加,Fe~(2+)的氧化率均呈现逐渐降低的趋势。     

Cu~(2+),Fe~(3+)对萤石浮选的活化作用机制

针对萤石选别流程复杂,浮选分离成本高以及浮选药剂对萤石的影响效果问题,本文通过单矿物浮选实验,采用溶液化学计算、Zeta电位测试和红外光谱分析的方法,研究了Cu~(2+),Fe~(3+)对萤石浮选过程的影响,并分析了Cu~(2+),Fe~(3+)对萤石浮选过程的活化机制,试验分析结果表明:油酸钠作为萤石捕收剂时,在p H=8~10范围内萤石的浮选回收率为83%;而采用Cu~(2+),Fe~(3+)作为活化剂对萤石进行活化后,萤石回收率分别达到96%和91%,提高了8%和13%,使萤石浮选效果显著提升,有明显的活化作用。溶液化学计算和XRD结果表明在p H=8~10范围内的萤石浮选溶液中,Cu~(2+)和Fe~(3+)主要以Fe(OH)3和Cu(OH)2沉淀的形式存在,进一步验证Fe~(3+),Cu~(2+)阳离子作用的有效组分是氢氧化物或者络合物沉淀;Zeta电位结果表明Fe~(3+)和Cu~(2+)两种金属离子都能使萤石的Zeta电位发生正移,而且Fe~(3+)使萤石的Zeta电位偏移幅度大于Cu~(2+)的偏移幅度,说明萤石表面的Fe~(3+)吸附量多于Cu~(2+);红外光谱分析结果表明油酸钠在分别经过Cu~(2+),Fe~(3+)活化后的萤石表面的作用方式主要为化学吸附。     

铁水预处理脱硫渣吸附稀土铈离子的研究

铁水预处理过程中所产生的脱硫渣具有较高的利用价值,目前已引起广大研究者密切关注。本文采用铁水预处理脱硫渣为吸附剂,研究脱硫渣吸附Ce~(3+)吸附性能和吸附机理,实验考察了Ce~(3+)浓度、脱硫渣加入量、吸附温度和吸附时间对Ce~(3+)吸附效果影响。结果表明,在室温,Ce~(3+)初始浓度为150 mg/L,脱硫渣加入量为0.05 g,吸附时间为2 h时,Ce~(3+)吸附率达96.84%,吸附温度对吸附效果影响不大。通过吸附动力学和吸附等温线实验得出,脱硫渣吸附Ce~(3+)的吸附曲线符合准二级动力学方程模型和Langmuir等温吸附模型,说明Ce~(3+)吸附是单分子层吸附且吸附过程是容易进行的。     

用配合还原反萃取法从P204有机相中去除Fe(Ⅲ)

P204萃取剂对Fe~(3+)选择性高,生成的萃合物稳定,但有机相中的Fe~(3+)难以反萃取。研究了采用配合还原反萃取法从P204有机相中反萃取Fe~(3+),考察了几种配合离子及还原剂对Fe~(3+)反萃取的影响。强酸性条件下,Cl-易与Fe~(3+)配位形成FeCl_4~-,硫代硫酸钠对Fe~(3+)的反萃取有明显促进作用,因此,探索了以盐酸为配合剂,硫代硫酸钠为还原剂,通过还原反萃取从P204有机相中去除Fe~(3+)。试验结果表明:在常温、相比Vo/Va=3/1、盐酸浓度5 mol/L、一次振荡时间4 min、硫代硫酸钠加入量为理论量的4倍、二次间歇振荡12min条件下,Fe~(3+)反萃取率达88.6%。该方法可有效去除P204有机相中的Fe~(3+),使有机相得到净化。     

Yb~(3+)共掺杂Sr_2MgSi_2O_7∶Eu~(2+),Dy~(3+)长余辉发光材料的制备与性能研究

通过高温固相法制备了Sr_2MgSi_2O_7∶Eu~(2+),Dy~(3+),Yb~(3+)长余辉发光材料。采用XRD、SEM、激发光谱、发射光谱和余辉衰减曲线对Sr_2MgSi_2O_7∶Eu~(2+),Dy~(3+),Yb~(3+)长余辉发光材料的微观结构以及光学性能进行了表征,研究结果表明Sr_2MgSi_2O_7∶Eu~(2+),Dy~(3+),Yb~(3+)长余辉发光材料的晶体结构和显微结构均未发生明显变化。Yb~(3+)的引入使得Sr_2MgSi_2O_7∶Eu~(2+),Dy~(3+)显示出更优良的荧光性能和余辉性能,不同Yb~(3+)掺量对长余辉发光材料的陷阱深度和电子传输速率有显著影响。实验表明,当Yb~(3+)掺杂量为0.03时,Sr_2MgSi_2O_7∶Eu~(2+),Dy~(3+),Yb~(3+)的荧光光谱相对强度最强,且表现出最佳的余辉衰减性能。     

红土镍矿回转窑焙烧预还原的工厂试验研究

在中试厂进行了红土镍矿焙烧预还原试验研究,试验结果显示,焙烧温度从800℃提高到900℃,Ni~(2+)到Ni的还原率提高9%,Fe~(3+)到Fe~(2+)的还原率提高35.7%,提高温度能够同时提高Ni~(2+)和Fe~(3+)的还原率,但相对于Fe~(3+),Ni~(2+)的还原率提高并不明显,850℃是回转窑焙烧预还原合理的温度。     

Photoluminescence properties and energy transfer of a single-phased white-emitting NaAlSiO_4:Ce~(3+),Sm~(3+) phosphor

A series of tunable phosphors NaAlSiO_4:Ce~(3+),Sm~(3+) were synthesized using a conventional high-temperature, solid-state method. Crystal structure, photoluminescence excitation, and emission spectra with fluorescence decay curves were investigated. Under UV excitation(325 nm), NaAlSiO_4:Ce~(3+),Sm~(3+) showed strong blue emission located at 444 nm and orange-reddish emission centered at 563, 601, 648 and 712 nm, stemming from the characteristic emission for 4f-5d transition of Ce~(3+) and ~4G_(5/2)→~6H_J(J=5/2, 7/2, 9/2, 11/2) transition of Sm~(3+), respectively. In addition, we studied the detailed energy transfer process between Ce~(3+) and Sm~(3+) and found that it belonged to dipole-dipole resonance energy transfer. Furthermore, we noted that the white light emitting from the Ce~(3+), Sm~(3+) co-doped phosphors with the color coordinate(x=0.313, y=0.283) could be observed under 325 nm excitation, which was close to the ideal white light(x=0.33, y=0.33). The results indicated that this phosphor has a potential application as a single-phased alumino-silicate phosphor for ultraviolet white light-emitting diodes(UV-WLEDs).     

Enhanced photoluminescence property of sulfate ions modified YAG:Ce~(3+) phosphor by co-precipitation method

The sulfate ions modified YAG:Ce~(3+) phosphors were prepared by co-precipitation method and characterized by X-ray diffraction,transmission electron microscopy,and photoluminescence.Effects of sulfate ions on the photoluminescence(PL) property of the as-prepared YAG:Ce~(3+) phosphors were studied,with sodium dodecyl sulfate(SDS) being added to R~(3+)(Ce~(3+),Y~(3+),Al~(3+)) ions.Results indicated that pure YAG:Ce~(3+) phosphors with different ratios of sulfate ions could be easily obtained by calcining the as-synthesized precursor at 950 ℃ for 2 h,the YAG:Ce~(3+) phosphors with an optimal mass ratio of 3.5 wt.%SDS had the highest emission intensity and the best dispersion behavior,and the fluorescence decay of the as-obtained YAG:Ce~(3+) phosphors was related to the lattice defect,reabsorption and cross correlation.Furthermore,thermal quenching properties of the YAG:Ce~(3+) phosphors and the YAG:Ce~(3+) phosphors with 3.5 wt.%SDS were also discussed,indicating that the YAG:Ce~(3+) with SDS phosphors could have potential applications in the daylight LEDs or warm white LEDs.     

从盐酸腐蚀废液中选择性沉淀除去铁离子

在印刷工厂的盐酸腐蚀废液中含有176g/L Fe~(3+),44g/L Fe~(2+),40g/L Ni,0.3g/L Co,0.8g/L Mn,稀释10倍后的pH=1.2。为从这种废液中回收Ni、Co、Mn,进行了以氢氧化铁形式选择性沉淀除去铁离子的研究。首先用组成为2.2g/L Fe~(3+)、0.4g/L Ni、3mg/L Co和8mg/L Mn的人工配制的腐蚀液研究了各种金属离子的沉淀特性,观测了加入氢氧化钠或氢氧化钙时,Ni、Mn、、Co与氢氧化铁共沉淀的性能。显然用碳酸钙使Fe~(3+)离子沉淀时,其它金属离子的共沉淀量比用氢氧化钠等中和沉淀时要少,这种现象可以用碳酸钙的低溶解性和不溶解二氧化碳的缓冲作用来解释。最后用真实腐蚀废液进行试验,将1:10比例稀释的盐酸腐蚀液用丹佛型浮选机通空气30min,然后加入50g/L碳酸钙选择性沉淀铁离子。此时过滤速度非常慢,当加入硫酸钠时可缩短过滤时间,增加滤液的体积。     

镧系元素—2—羧基喹啉二元配合物的表征及其光谱特性的研究

2-羧基喹啉(Qld)是属于喹啉类的衍生物,它可以与许多金属形成稳定的络合物,可以作为Cu~(2+),Zn~(2+),Cd~(2+)和UO_2~(2+)的重量测定和Fe~(2+)的比色分析试剂,近年来,2-羧基喹啉被开发用作溶剂萃取试剂。喹啉类也是一类常用的荧光试剂,已用于Al~(3+),Gd~(3+),In~(3+),Zn~(2+),Cd~(2+),Zr~(4+)等元素的测定中,但在稀土离子的荧光测定中尚未见报道。     

氧离子浓度对CaAlSiN_3:Eu~(2+)荧光材料温度特性的影响

采用高温固相法合成了氮化物荧光材料CaAlSiN_3:Eu~(2+),研究了不同氧含量时CaAlSiN_3:Eu~(2+)发光性能的变化。当氧含量为2.5%时,得到了最高的发光强度和最佳的温度猝灭性能。从CaAlSiN_3:Eu~(2+)结晶性能以及CaAlSiN_3基质能带结构的变化等方面分析了氧离子浓度变化引起CaAlSiN_3:Eu~(2+)发光性能改变的原因。