Nd^(3+)掺杂钙钛锆石(Ca_(1-x)Nd_(x)ZrTi_(2)O_(7+x/2))相变行为的研究

为研究钙钛锆石对放射性元素Am^(3+)的稳定固化作用,以Nd^(3+)为Am^(3+)的模拟元素,系统研究了高温固相法制备Ca_(1-x)Nd_(x)ZrTi_(2)O_(7+x/2)时,Nd^(3+)异价取代钙钛锆石晶格中Ca^(2+)位(0≤x≤1.0)所导致的相态演变行为。合成Ca_(1-x)Nd_(x)ZrTi_(2)O_(7+x/2)的XRD、Raman、BSE和EDS测试结果表明:钙钛锆石(Zirconolite)晶格对Nd^(3+)离子的固溶量可达70%(x=0.7),可有效实现对Am^(3+)模拟元素Nd^(3+)离子的固化。但随着Nd^(3+)掺杂量(x≤0.3)增加,Zirconolite-2M晶格中O^(2-)和Nd^(3+)的无序化程度逐渐增加、(Ca/Nd)-O键长逐渐变小,直至(x=0.4)引起Zr^(2+)、Ti^(4+)附近的O^(2-)配位数发生改变(ZrO7→ZrO8、TiO5→TiO6),Zirconolite-2M晶格结构开始向Zirconolite-4M转变。x=0.5时,陶瓷体完全转变为Zirconolite-4M晶格且O^(2-)和Nd^(3+)有序度重新变高、Ti—O键长增加;直至x=0.6、x=0.7时,陶瓷体仍为单一Zirconolite-4M结构,但晶格中O^(2-)和Nd^(3+)的有序度又逐渐降低,以至于在x=0.7陶瓷体亚晶格中微量Ca^(2+)、Zr^(4+)、Nd^(3+)离子占位转变为烧绿石(Pyrochlore)结构。而在0.8≤x≤0.9范围内,Zirconolite-4M结构完全消失,陶瓷体为多相共存状态(Pyrochlore、ZrTiO_(4)和Nd2(TiZr)_(4)O_(11)物相)。Nd^(3+)完全取代Ca^(2+)位(x=1.0)时,陶瓷体变为单一Nd2(TiZr)_(4)O_(11)固溶体相。陶瓷体晶粒的BSE和EDS分析证实了这种相变规律。

g-C_(3)N_(4)-Nd的制备及其光催化性能

通过热聚合法成功制备了g-C_(3)N_(4)-Nd复合催化剂,利用SEM、XRD、FT-IR和紫外-可见漫反射光谱仪等分析方法探究了其微观形貌、晶体结构和光催化特性。结果显示,g-C_(3)N_(4)-Nd复合催化剂展现出优异的光催化性能,当Nd负载质量分数为1.5%时,光催化降解效果最佳,其对盐酸四环素(TCH)的降解率从51.1%提升至68.5%。经过3次连续的降解试验验证,g-C_(3)N_(4)-Nd复合光催化剂具备优异的重复利用性能。

Effects of Mg Doping Concentration on Resistive Switching Behavior and Properties of SrTi1-yMgyO3 Films

SrTi1-yMgyO3 films were synthesized through sol-gel method on p^+-Si substrates. The effects of Mg doping concentration on the microstructure, switching behavior and properties of SrTi1-yMgyO3 films were investigated. All SrTi1-yMgyO3 films are polycrystalline, but the grain becomes coarser, and the number of holes is reduced when the Mg doping content increases from 0.04 to 0.16. SrTi1-yMgyO3 films with different Mg doping concentrations all show bipolar resistive switching behaviors but display some differences in switching properties. When y=0.08, the SrTi1-yMgyO3 films show the largest RHRS/RLRS of 105 and better fatigue endurance after 103 cycles. When y≥0.08, the distribution of Vset and Vreset is narrow, indicating good stability of writing and erasing data for a resistive random access memory. At high-resistance state, the dominant conduction mechanism of SrTi1-yMgyO3 films is the Schottky emission mechanism. However, at low-resistance state, the dominant conduction mechanisms are the filamentary conduction and changes to space charge limited current when y=0.16.

F4-TCNQ concentration dependence of the current voltage characteristics in the Au/P3HT:PCBM:F4-TCNQ/n-Si(MPS) Schottky barrier diode

In this study, we investigate some main electrical parameters of the gold/poly（3-hexylthiophene）：[6,6]-phenyl C61 bu- tyric acid methyl ester：2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane/n-type silicon （Au/P3HT：PCBM：F4-TCNQ/n- Si） metal-polymer-semiconductor （MPS） Schottky barrier diode （SBD） in terms of the effects of F4-TCNQ concentration （0%, 1%, and 2%）. F4-TCNQ-doped P3HT：PCBM is fabricated to figure out the p-type doping effect on the device per- formance. The main electrical parameters, such as ideality factor （n）, barrier height （ФB0）, series resistance （Rs）, shunt resistance （Rsh）, and density of interface states （Nss） are determined from the forward and reverse bias current-voltage （l-V） characteristics in the dark and at room temperature. The values of n, Rs, ФB0, and Nss are significantly reduced by using the 1% F4-TCNQ doping in P3HT：PCBM：F4-TCNQ organic blend layer, additionally, the carrier mobility and current are increased by the soft （1%） doping. The most ideal values of electrical parameters are obtained for 1% F4-TCNQ used diode. On the other hand, the carrier mobility and current for the hard doping （2%） become far away from the ideal diode values due to the unbalanced generation of holes/electrons and doping-induced disproportion when compared with 1% F4-TCNQ doping. These results show that the electrical properties of MPS SBDs strongly depend on the F4-TCNQ doping and doping concentration of interfacial P3HT：PCBM：F4-TCNQ organic layer. Moreover, the soft F4-TCNQ dop- ing concentration （1%） in P3HT：PCBM：F4-TCNQ organic layer significantly improves the electrical characteristics of the Au/P3HT：PCBM：F4-TCNQ/n-Si （MPS） SBDs which enables the fabricating of high-quality electronic and optoelectronic devices.

Tm^(3+)高掺杂的NaYF_(4)纳米颗粒制备与发光性能研究

为了研究Tm^(3+)高掺杂浓度下NaYF_(4)纳米颗粒的上转换发光性能,采用热分解法合成了六方相的NaYF_(4)∶Yb^(3+)/Tm^(3+)(20%/8%)纳米颗粒,并用X射线衍射对其结构进行了表征,用透射电子显微镜对其形貌和大小进行了表征.通过搭建上转换光谱测试系统,研究了在980 nm激光激发下NaYF_(4)∶Yb^(3+)/Tm^(3+)纳米颗粒的上转换发光光谱,并分析了其发光机制.通过计算475,513,650,744,805 nm处发光强度与激发光功率间的依赖关系,证明了其上转换发光过程为双光子过程.

溶液燃烧法制备Nd^(3+)掺杂LaBO_(3)荧光粉

以La(NO_(3))_(3)·6H_(2)O、H_(3)BO_(3)为原料、C_(2)H_(5)NO_(2)为燃烧剂、Nd(NO_(3))_(3)·6H_(2)O为改性剂,通过溶液燃烧法合成Nd^(3+)掺杂LaBO_(3)荧光粉。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、紫外-可见漫反射光谱(UV-Vis DRS)以及荧光光谱(PL)对产物进行表征分析。结果表明,制备的粉体均为正交晶系硼酸镧,在煅烧温度875℃、Nd^(3+)掺杂量3%的优化条件下制备的硼酸镧荧光粉发光性能最好,且其在紫外光区和可见光区均表现出良好的光吸收性能,发蓝绿色光,可广泛应用于激光照明和LED照明等领域。

Nd^(3+)掺杂磷酸盐激光玻璃猝灭浓度的计算与预测

通过研究稀土离子在玻璃中激发态布居数与掺杂浓度之间的关系,建立了一种半定量的激光玻璃发光猝灭浓度预测的研究方法。研究发现,在Nd^(3+)掺杂磷酸盐玻璃中,无辐射跃迁速率与浓度的线性相关性大于其与浓度的平方相关性,表明OH-对无辐射跃迁几率的影响大于稀土离子之间的能量传递过程。选择低浓度下的荧光寿命代替自发辐射跃迁寿命预测猝灭浓度,有效降低了多声子弛豫以及OH-的影响,预测发光猝灭浓度与实验值的绝对误差从0.82%降低到了0.16%。本文所提出的预测计算方法具有较高的准确性和普适性,这为理论预测激光玻璃的猝灭浓度提供了一定的指导意义,有助于新型激光玻璃的研究和探索。

Ba_((1-x))Nd_(x)Ti_((1-y))Mg_(y)O_(3)陶瓷及其介电性能研究

实验采用高能球磨-固相合成法,将Nd^(3+)/Mg^(2+)掺杂到反应物体系中,制备了具有钙钛矿结构的Ba_((1-x))Nd_(x)Ti_((1-y))Mg_(y)O_(3)(取x=0.005,y分别取0.005、0.01、0.015)陶瓷粉体。XRD晶相分析表明,所制备的粉体主晶相为四方相钙钛矿型晶体结构;SEM形貌分析表明,Nd^(3+)/Mg^(2+)共掺具有显著细化晶粒的作用,能够提高其耐压性能,并有效改善陶瓷的介电性能。电学性能分析结果表明,随着Mg^(2+)引入比例的提高,其介电常数(ε_(r))呈现先增大后减小的趋势,介电损耗(tanδ)呈现先减小后逐渐增大的趋势,绝缘电阻(R)和直流击穿强度呈一直增大趋势。当Nd^(3+)/Mg^(2+)摩尔比为1:2时,综合介电性能最佳。

Photocatalytic Activity of Nanosized TiO_2 Enhanced by co-doping with Fe^(3+) and Nd^(3+) Ions

In this study, nanosized TiO2 co-doped with Fe3+ and Nd3+ ions was synthesized via a sol-gel method. The metallic ion doped TiO2 was thoroughly characterized with XRD and UV-vis, and the photocatalytic activity was evaluated by degrading methylene blue (MB) solution. The results indicated that TiO2 crystalline size was reduced and phase transformation of anatase to rutile was suppressed as the content of doped Nd3+ ion increased in the co-doped TiO2. The UV-vis spectra of co-doped TiO2 seemed to simply overlay two spectra of single metal doped TiO2, and had significantly increased absorbance in the ranges of 400～500 nm, 565～600 nm and 730～765 nm as compared to pure TiO2. The photocatalytic activity of co-doped TiO2 was obviously enhanced, and raised about 30% compared to that of pure TiO2 as doped Nd3+ content was 0.15% and Fe3+ content was 0.05%, respectively. The enhanced catalytic activity was attributed to a synergistic effect of two doped ions, where doped Fe3+ ion inhibited the recombination of photogenerated electron and hole, and Nd3+ ion brought more surface carboxyl to promote the degradation reaction.

Spectroscopic Properties of Nd^(3+)-Doped Tellurite Glasses

The Nd^3＋-doped pared. The absorption and tellurite glasses were preemission spectra of Nd^3 ＋- doped tellurite glasses at room temperature were measured. The Judd-Ofelt parameters （Ω2, Ω4, Ω6） of the glasses were calculated from measured absorption spectra. The calculation results of luminescence properties （A, β, τrad, σ） of Nd^3＋ ions in the tellurite were glasses were given. Spectroscopic properties, concentration quenching in these kinds of the glasses were investigated. The results indicate that the tellurite glasses with composition of 70% TeO2, 20% ZnO, （ 10 - x ） % La2O3, x % Nd2O3 （ mol% ） show high emission cross section and low phonon energy. The fluorescent intensity and the emission cross section have a maxi- mum value at x = 0.5, namely, the optimum Nd^3 ＋ ion concentration in the tellurite glass is 0.5% （1.93 × 10^20 ions·cm^-3）. The fluorescence properties of Nd^3＋ measured are basically in accord with the calculated results.

掺Nd^(3+)碲酸盐玻璃光谱性质的研究

制备了Nd3+掺杂的碲酸盐玻璃,测量了试样的吸收光谱、发射光谱,计算了碲酸盐玻璃中Nd3+离子的强度参数(Ω2,Ω4,Ω6),给出了Nd3+离子的发光特性(A,β,τrad,σ)的计算结果,研究了其荧光特性、浓度淬灭及其机制。研究发现组分70TeO2-20ZnO-(10-x)La2O3-xNd2O3(%,摩尔分数)碲酸盐玻璃具有高的发射截面和低声子能的特性。当x为0.5时荧光强度和发射截面最大,即在碲酸盐玻璃中Nd3+的最佳掺杂浓度为0.5%(1.93×1020ions.cm-3)。碲酸盐玻璃中Nd3+离子实测荧光特性与计算结果基本一致。

提高Nd∶YAG晶体中Nd3+离子浓度分布均匀性的研究

本文通过对Ｎｄ∶ＹＡＧ晶体掺质理论的分析，提出了提高Ｎｄ∶ＹＡＧ晶体中Ｎｄ３＋离子浓度分布均匀性的技术途径，并对实验结果进行了讨论。实验结果表明，通过降低析晶率（由３４．７％降到１５．９％），晶体中的Ｎｄ３＋离子浓度梯度由１．８６×１０－４ａｔ／ｃｍ降到５．８１×１０－５ａｔ／ｃｍ。

掺Nd^(3+)光纤环形激光器及其对激光陀螺的可能应用

报道用Ar^+激光泵浦抛磨型掺Nd^(3+)光纤定向耦合器构成的环形腔、环形激光器的激光阀值、双端输出功率、光谱、偏振等光学特性,并讨论其对激光陀螺应用的可能性。

Nd^(3+)掺杂对LiFePO_4结构及电化学性能的改善

采用两步加热高温固相法合成了掺杂Nd3+的LiFe1-xNdxPO4/C复合材料(x=0,0.01,0.02,0.04,0.06,0.08)。用TG-DSC对前驱体进行分析和SQUID(超导量子干涉仪)对样品中Fe3+的磁性测定,优化了合成工艺条件;采用XRD、FE-SEM、EDS等方法分析了样品的结构并对其电化学性能进行了测试。结果表明:LiFe1-xNdxPO4/C复合材料具有橄榄石型结构;当Nd3+的掺杂量6%(物质的量分数)、煅烧温度700℃、煅烧时间16 h时,样品在0.2C(1C=170.0 mA.g-1)电流密度下的最大放电比容量可达165.2 mAh.g-1,循环100次后的容量保持率仍为92.8%,在1C、2C、5C下的最大放电比容量分别为146.8、125.7和114.8 mAh.g-1。通过测定样品在不同较低倍率下的放电比容量,采用外推法得出制备样品的实测理论比容量为168.7 mAh.g-1。

多相基质中Cr^(3+)→Nd^(3+)能量传递

根据分相成核原理 ,通过一步热处理过程 ,制备了双掺杂B2 O3 Al2 O3 SiO2 系统透明玻璃陶瓷。XRD分析确定主晶相为莫来石固溶体 ;分别测定了材料的吸收光谱、发射光谱和荧光寿命 ,分析讨论了铬和钕格位分布及光谱特点。在双掺杂铬和钕玻璃陶瓷中存在较强的Cr3 + →Nd3 + 的辐射能量传递和无辐射传递。Cr3 +主要位于晶相格位中 ,Nd3 + 则全部保留在剩余玻璃相中 ,Cr3 + 的格位分布对光谱性能有很大的影响。

水热法制备Nd^(3+)掺杂纳米三氧化钨材料及气敏性能研究

以柠檬酸为辅助剂,采用水热法合成纳米三氧化钨,并原位水热合成了Nd3+掺杂量为1.0%、3.0%、5.0%、10.0%的纳米三氧化钨材料。用XRD、TG-DTA和SEM等方法对合成的纳米三氧化钨材料进行了结构表征。结果显示,制得的纳米三氧化钨材料为正交晶相,纯纳米三氧化钨形貌为四方形纳米盘。Nd3+掺杂可以提高纳米三氧化钨对硫化氢的灵敏度,Nd3+掺杂量为1.0%的综合效果最好,工作电压可低至2.00 V,硫化氢体积分数为2×10-6时,灵敏度可达15.65。

Nd^(3+)掺杂PbWO_4晶体的光谱特征和浓度效应

钨酸铅晶体(PbWO4)是新型的闪烁晶体,针对其广阔的光电子应用,实验测试了Nd3+掺杂PbWO4晶体的吸收光谱,讨论了不同的Nd3+掺杂浓度对于吸收系数和PbWO4光学吸收边的影响。依据Judd-Ofelt理论计算了吸收截面积、强度参数、量子荧光效率、荧光分支比等。讨论了不同浓度Nd3+掺杂的PbWO4晶体的光致发光光谱;室温LD808nm泵浦下,1.06μm荧光发射的荧光强度、荧光寿命和发射截面积,论述了这些性能随Nd3+掺杂浓度的变化关系。

掺杂Cr^（3＋）和Nd^（3＋）玻璃陶瓷的光谱特性

根据分相成核原理，通过一步热处理过程，制备了双掺杂Ｂ＿２Ｏ＿３→Ａｌ＿２Ｏ＿３→ＳｉＯ＿２系统透明玻璃陶瓷。ＸＲＤ分析确定主晶相为莫来石固溶体；分别测定了材料的吸收光谱、发射光谱和荧光寿命，分析讨论了铬和钕格位分布及光谱特点。在双掺杂铬和钕玻璃陶瓷中存在较强的Ｃｒ￣（３＋）→Ｎｄ￣（３＋）的辐射能量传递和非辐射传递，同时也存在Ｃｒ￣（３＋）→Ｃｒ￣（３＋）的能量传递。Ｃｒ￣（３＋）主要位于晶相格位中，Ｎｄ￣（３＋）则全部保留在剩余玻璃相中，Ｃｒ￣（３＋）的格位分布对光谱性能有很大的影响。

La^(3+),Nd^(3+),Ti^(4+)掺杂对纳米MnZn铁氧体粉末结构的影响

研究了La3 + 、Nd3 + 和Ti4+ 分别掺杂和多元掺杂对水热法制备纳米MnZn铁氧体粉末粒度、形貌和结构的影响。结果表明 ,掺Ti4+ 质量分数 >1 0 %的粉末粒度明显增大 (>10 0nm) ;掺La3 + 、Nd3 + 对粉末粒度影响不大 ;但TEM照片上 ,掺La3 + 质量分数为 1 2 %的样品晶粒大小均匀 ,成六角片状 ,且均比其他样品晶粒大 ,此含量的La3 + 离子对MnZn铁氧体水热晶化过程产生严重影响 ,它改变了晶粒的生长方向并促进晶粒生长。样品的XRD分析结果表明 ,掺质量分数≤ 0 4 %的Ti4+ 无杂相 ,而掺质量分数为 0 4 %的La3 + 、Nd3 +均出现杂相 ,多元掺杂也无明显杂相 ;IR分析表明 ,掺杂的纳米MnZn铁氧体的尖晶石特征吸收峰与未掺杂的样品相比向低波数方向移动 ,表明掺杂离子进入MnZn铁氧体次晶格影响了原有的离子分布状态。

Nd^(3+)掺杂B_2O_3-Nb_2O_5-BaO-La_2O_3玻璃光谱性质的研究

用高温熔融法制备了Nd3+(物质的量分数2%)掺杂40B2O3-(15-χ)Nb2O5-45BaO-χLa2O3玻璃,测量了样品的吸收光谱、发射光谱和差热分析(DTA)曲线。根据Nd3+光学跃起矩阵的特点,应用Judd-Ofelt理论,从吸收光谱获得了Nd3+光学跃起的强度参数。并计算了Nd3+离子的自发辐射跃迁几率、总自发辐射几率、荧光分支比、辐射能级寿命和受激发射截面。结果表明:该体系玻璃中,随着Nb2O5含量的增加和La2O3含量的减少,强度参数Ω2增大,说明材料的对称性降低;而Ω6减小,说明Nd-O键的共价性和键强增强;受激发射截面减小。DTA实验表明,随着Nb2O5含量的增加,材料的热稳定性提高。