Optical properties of amorphous thin film of Se-Te-Ag system prepared by using thermal evaporation technique

Zn_(0.95)Co_(0.05)O and Zn_(0.91)Co_(0.05)Cu_(0.04)O thin films were fabricated on Si(111) substrate by the reactive magnetron sputtering method at different O-Ar ratios.Detailed characterizations by X-ray diffractometry(XRD),X-ray photo-electronic spectrum(XPS), and electron paramagnetic resonance(EPR) indicate that the doped Cu ions substitute the Zn~(2+) ions in the ZnO lattice.The doped Cu ions are in Cu~+ and Cu~(2+) mixture valence states.The ferromagnetism of the Zn_(0.91)Co_(0.05)Cu_(0.04)O film ...     

Structure and transport studies on nanometer YBCO/PBCGO multilayers

We have fabricated M doped （M = Al, Co, Fe, Ga, Ni and Zn） PrBa2Cu3O7（PBCO）, i.e. PrBa2（CU1-xMx）3O7. The doping levels x are 0.05, 0.10, 0.15, and 0.20. X-ray data indicated no significant second phase for substituting Cu by Al, Co, Fe and Ga up to 20%. However impurity phases were detected for Ni and Zn substituted samples with doping levels equal to and higher than 15%. At 77 K the electrical resistivity of these compounds is orders in magnitude higher than that of PBCO. We also found that although the lattice parameters in the doped samples differ from PBCO, all samples remain orthorhombic. The lattice parameters of the doped sample are very close to those of YBa2CU3O7-δ （YBCO） and PBCO. For this reason these compounds are better materials to be used as the I-layer for YBCO SIS junctions. Results of structural and transport studies on 2000 A thick PrBa2[Cu0.80G0.2]3O7 （PBCGO） and YBCO/PBCGO multilayers are presented in this paper.     

La0.7Ca0.3Mn1-xCuxO3的电输运特性

通过固相反应法制备不同掺杂浓度的La_0.7Ca_0.3Mn_1-xCu_xO₃（x=0~0.15）样品, 在77~300 K温度范围内测量了铜掺杂后样品电阻随温度的变化关系. 结果表明, 在未引入铜杂质时, 低温铁磁相的电阻率满足T^2.5关系, 顺磁相符合小极化子近邻跳跃模型; 在低掺杂下, 铁磁区可用T^4.5关系解释; 随着掺杂浓度的增加, 在铁磁区和顺磁区, 任何单一模型均与实验不相符, 表明高掺杂样品的电输运性质存在未知模型.      

自旋梯状化合物Sr14(Cu1-xZnx)24O41的电输运及磁学性质

采用标准固相反应法制备了Sr14(Cu1-xZnx)24O41(x=0, 0. 01, 0. 02, 0. 03)系列多晶样品. X射线衍射谱表明所有样品均呈单相,且样品晶格常数大小随Zn掺杂量x的变化存在微弱波动. X射线光电子能谱表明Sr14Cu24O41中Cu离子以+2价形式存在,Zn掺杂对体系中Cu离子化合价不造成影响. 磁化率测量结果表明在10~300 K温度范围内Zn掺杂使体系磁化率降低,拟合结果表明随着Zn掺杂量x的增大,居里-外斯项对体系磁化率贡献逐渐减弱,二聚体耦合能JD 逐渐降低,每个分子中CuO2 自旋链内二聚体个数ND 与自由Cu2+离子自旋数NF 均逐渐减少,进一步分析显示替换二聚体内Cu2+离子的Zn2+离子数少于替换自由Cu2+离子的Zn2+离子数. 电阻率测量结果表明Sr14Cu24O41体系具有半导体特性,并且Zn掺杂会使体系电阻率降低,降低程度随掺杂量x增大而增大,但并未使体系发生金属- 绝缘体转变. 认为电阻率降低可能是由于Zn2+离子掺杂使体系内CuO2 自旋链中二聚体发生退耦,破坏了电荷有序超结构,从而使更多的空穴释放出来并转移到导电性好的Cu2O3自旋梯子中所致.     

Cu2+对UV-nTiO2光催化降解抗生素的影响研究

Cu~(2+)是环境中常见二价金属离子,但其对光催化降解抗生素废水的影响有待探明。为此,构建UV-nTiO_2体系并探究Cu~(2+)共存下三类抗生素(磺胺类抗生素、氯霉素类抗生素及四环素类抗生素)的光催化降解特性。结果表明,Cu~(2+)可显著影响抗生素光催化降解且呈"低浓度促进,高浓度抑制"效应。当Cu~(2+)浓度介于0.001～0.03mol/L时,抗生素降解半衰期(T_(0.5))可降低15%～90%;当浓度介于0.01～0.1mol/L时,T_(0.5)可增大1.5～4倍。结果也表明,Cu~(2+)浓度和T_(0.5)之间的关系可通过正弦函数进行表征(R~20.905),且Cu~(2+)对抗生素光催化降解效率的影响和抗生素的结构特征显著相关(P 0.05)。     

复合有序壳聚糖膜对Na+,Cu2+渗透性能的研究

 以壳聚糖微球为原料,硝化棉-醋酸纤维素微孔滤膜为支撑体,制得强度较高的复合有序壳聚糖膜.研究了该膜与普通壳聚糖交联膜对Cu²⁺,Na⁺2种金属离子的渗透行为.发现Na⁺在复合有序壳聚糖膜中的透过率明显大于Cu²⁺,即该膜可选择性地让Na+离子透过而截留大部分Cu²⁺离子.     

“微超酸”改性硅藻土对Pb~(2+),Cu~(2+),Cd~(2+)的吸附性能研究

以天然硅藻土为原料,通过微波、超声、酸化制备得到"微超酸"改性硅藻土.探讨了该改性硅藻土对水溶液中Pb~(2+)、Cu~(2+)、Cd~(2+)3种重金属离子的吸附效果及影响因素.实验结果表明,在一定范围内,提高溶液pH值、延长吸附时间、升高吸附温度、增加吸附剂的用量均可提高3种金属离子的吸附去除效果;"微超酸"改性硅藻土对3种金属离子的等温吸附符合Langmuir方程.     

Cu2+和Zn2+对模拟胃液中NDMA形成的影响

【目的】在模拟胃液条件下研究重金属Cu~(2+)和Zn~(2+)对内源致癌性N-二甲基亚硝胺(NDMA)形成的影响,并进一步探讨其作用机理。【方法】分别用气相色谱-质谱联用法(GC-MS)和离子色谱法(IC)来测定NDMA、二甲胺(DMA)和亚硝酸根(NO_2~-)含量。【结果】在模拟胃液条件下,Cu~(2+)和Zn~(2+)浓度高于50mg/L时,可以促进NDMA的形成,且当浓度由50mg/L增大到200mg/L时,Cu~(2+)促进率由1.16%增大到94.56%,Zn~(2+)促进率由21.32%增大到45.86%。在重金属浓度为符合或接近符合水质基准值1.0mg/L时,Cu~(2+)和Zn~(2+)对NDMA的形成也分别有16.88%和13.42%的促进率;而当重金属浓度为10mg/L时,两种离子却均抑制NDMA的形成。机理研究表明Cu~(2+)、Zn~(2+)促进NDMA的形成主要是由于其与DMA发生相互作用,进而导致NDMA形成。【结论】高浓度的Cu~(2+)和Zn~(2+)通过与DMA相互作用,形成活性中间体从而促进NDMA的生成。     

Co掺杂对Zn1-xCoxO稀磁半导体光学性质的影响

溶胶-凝胶法制备了Co掺杂的ZnO基稀磁半导体,研究其粉体和薄膜的结构和光学特性.X射线衍射结果表明Co2 随机替代Zn2 位置进入ZnO晶格,并引起晶格常数的变化.紫外-可见透射光谱表明样品的禁带宽度随着Co掺杂浓度的增大呈现非单调变化规律,低浓度掺杂样品的光学带隙随掺杂浓度增大而减小(红移),这是由于Co2 替代Zn2 ,局域d电子与能带电子之间的sp-d交换耦合引起的.     

烧结温度对Zn_(0.98)Cu_(0.01)Co_(0.01)O稀磁半导体性质的影响

本文以Zn(NO3)2·6H2O,Co(NO3)2·6H2O,Cu(NO3)2·3H2O为原料,与适量的柠檬酸配制成溶液,采用溶胶—凝胶法(sol-gel)合成前驱体,将前驱体在氩气气氛中选择不同温度进行烧结得到Zn0.98Cu0.01Co0.01O稀磁半导体样品,利用X射线衍射(XRD)、光致发光谱仪(PL)、振动样品磁强计(VSM)对所制备样品的结构、光学性能及磁性进行研究.实验结果表明:制备的样品为单一的纤锌矿结构,烧结温度改善了样品的光学性质及磁性.     

Structure and electrochemical properties of LiLaxMn2-xO4 cathode material by the ultrasonic-assisted sol-gel method

Powders of spinel LiLa_xMn_2—xO₄ were successfully synthesized by the ultrasonic-assisted sol-gel (UASG) method. The structure and properties of LiLa_xMn_2—xO₄ were examined by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electronic microscopy (SEM), galvanostatic charge-discharge test, and cyclic voltammetry (CV). XRD results show that the La³⁺ can partially replace Mn³⁺ in the spinel and the doped materials with La³⁺ have a larger lattice constant compared with pristine LiMn₂O₄. FT-IR indicates that the absorption peak of Mn³⁺−O and Mn⁴⁺− O bonds has a red and blue shift with the increase of doping lanthanum in LiLa_xMn_2—xO₄, respectively. The charge-discharge test exhibits that the initial discharge capacity of LiLa_xMn_2—xO₄ drops off, and the capacity retention increases gradually at C/5 discharge rate with the increase of doping lanthanum, and LiLa_0.01Mn_1.99O₄ has a higher discharge capacity and a better cycling performance at 1C discharge rate. CV reveals that the doping La³⁺ is beneficial to the reversible extraction and intercalation of Li⁺ ions.     

Luminescent Cu doped CdTe nanocrystals via cation exchange of Cu7Te5 nanocubes: From undoped to doped emission

In II-VI group, the doping in CdTe nanocrystals (NCs) is more difficult than other chalcogenides. In this communication, CdTe nanocrystals containing Cu impurities were carefully synthesized based on controlled reverse cation exchange process between as-prepared Cu₇Te₅ nanocubes and Cd²⁺ ions. By well-defined Cu₇Te₅ nanocubes, the obtained CdTe NCs kept the original morphology. The concentration of Cu impurities in CdTe NCs was controlled by the regulation such reverse cation exchange. Additionally, the regulation from band gap (BG) photoluminescence (PL) to the coexistence of the bandgap emission, dopant emission, and surface-state emission was realized. This tailoring from undoped to doped emission in the case of Cu impurities is helpful to study the Cu related doping in telluride NCs.     

Na0.54Bi0.46Ti0.96Al0.04O2.94氧离子导体制备与性能研究

采用传统的固相反应法合成Na0.54Bi0.46Ti0.96Al0.04O2.94氧离子导体,借助于交流阻抗谱和介电弛豫谱分别研究了钠和铝的双掺杂对Na0.5Bi0.5TiO3材料电学性能及氧离子扩散的影响。在400℃时,Na0.54Bi0.46Ti0.96Al0.04O2.94材料的晶粒电导率可以达到1.51×10-3 S/cm,是Na0.5Bi0.5TiO3材料电导率的5.5倍。在Na0.54Bi0.46Ti0.96Al0.04O2.94材料中观察到一个与氧离子弛豫相关的介电弛豫峰,弛豫参数为E= 0.80 eV和t0= 6.12×10-13 s,氧离子在Na0.54Bi0.46Ti0.96Al0.04O2.94材料中主要通过Na-Bi-Ti的路径进行扩散迁移的。结合结构参数容忍因子及自由体积的分析,钠和铝的双掺杂改善了氧离子在Na0.5Bi0.5TiO3材料中的扩散通道,但是铝的引入一定程度上提高了氧空位扩散的能量壁垒。     

Cu2+对好氧颗粒污泥理化特性的影响分析

以普通活性污泥为接种污泥,葡萄糖和乙酸钠为碳源,在SBR反应器中培养好氧颗粒污泥,考察不同质量浓度Cu2+(0 mg/L、1 mg/L、3 mg/L、5 mg/L和10 mg/L)冲击作用对好氧颗粒污泥理化特性的影响。结果表明,随着Cu2+质量浓度从0 mg/L上升至10 mg/L,好氧颗粒污泥的理化特性均受到不同程度的影响。质量浓度为1 mg/L和3 mg/L的Cu2+对COD和NH+4-N的去除率影响较小,而质量浓度为5 mg/L和10 mg/L的Cu2+对COD和NH+4-N的去除率影响较大。随着Cu2+质量浓度的增加,好氧颗粒污泥的丝状菌逐渐增多,污泥浓度不断下降,沉降性能急剧恶化;密实度降低,结构越来越松散,粒径出现两极分化的现象,而且在质量浓度为10 mg/L的Cu2+作用下颗粒污泥解体。     

甚高频片式电感用低温烧结平面六角软磁铁氧体的电磁性能

采用BPb玻璃为助烧剂，870℃烧结Y型平面六角结构软磁铁氧体，分析其烧结工艺、显微结构及起始磁导率和介电常数的频率特性。研究发现，含Co、Zn、Cu的Y型铁氧体材料(Ba2Me2Fe12O22，Me=Co、Zn、Cu)在甚高频段具有良好的磁性能，采用BPb玻璃为助烧剂可有效地实现此种材料的低温烧结，并大大改善其介电性能。     

Zn_(1-x)Co_xO稀磁半导体的XAFS研究

利用XAFS技术研究溶胶-凝胶法制备的Zn1-xCoxO稀磁半导体材料结构随Co含量(x)的变化.结果表明在低含量的Co掺杂ZnO(x=0.02,0.05)时Co2 离子完全进入ZnO晶格中,替代了Zn2 离子,并且造成了Co2 离子周围局域结构的膨胀.当Co的含量x增加到0.10或更高时,只有一部分的Co2 离子进入晶格,剩余的Co2 和Co3 析出晶格形成Co3O4相.     

Magnetism in Mn and Co doped ZnO bulk samples

Bulk samples with nominal composition Zn0.95Co0.05O and Zn0.92Co0.05Mn0.03O were fabricated by a solid-state reaction method at 600℃.X-ray diffraction experiment showed that the peaks of secondary phase Co3O4 with a cubic structure were visible in both samples,besides the main peaks of wurtzite structure as ZnO.Magnetization measurement indicated that doping Co alone can induce ferromag- netism in ZnO itself,while the introduction of Mn significantly enhances ferromagnetism.However, both samples showed different magnetic behavior at temperatures below 50 K.It was also noted that ferromagnetic coupling interaction was weakened due to the presence of antiferromagnetic Co3O4.     

柠檬酸溶胶凝胶法合成YBa_2Cu_3O_(7-δ)

采用溶胶 凝胶法制备了均匀的YBa2Cu3O7-δ超导细粉·讨论了凝胶的形成过程·配合剂柠檬酸与金属离子结合形成了可溶性的大分子化合物,除水后缩聚反应形成的聚合物长大为小粒子簇,相互连结成连续的三维网络·柠檬酸盐溶液的pH值控制在6 4～6 7之间可防止白色Ba(NO3)2沉淀·溶剂挥发温度宜控制在300℃,使凝胶的形成和自燃过程能在相同温度条件下连续进行·合成YBa2Cu3O7-δ的温度大约在880℃左右,其粉末粒度大约在0 2～1μm之间·     

红色荧光粉YAlO3:Eu3+Cu+的制备和发光特性

研究了化学沉淀法制备YAP:Eu3+Cu+荧光粉,得到适宜工艺参数.用XRD和PL谱分别表征前驱体的晶体结构和荧光粉的荧光特性.前驱体的焙烧温度为1 200℃,焙烧时间为2 h;Eu3+的适宜掺杂浓度为3%,而且在398 nm紫外光激发下荧光粉呈现红色光谱,这是由于Eu3+的4fn电子组态内5D0→7FJ(J=0～4)的跃迁发射,由5D0→7F2的发射特性和发射强度表明Eu3+主要处于非反演对称中心.Cu+增强了YAP:Eu3+的发光强度是因为Cu+→Eu3+之间的能量传递,Cu+对Eu3+有敏化作用.     

不同离子对氧化锌晶体形貌的影响

以不同Zn盐Zn(CH3COO)2.2H2O,ZnCl2,ZnSO4.7H2O,Zn(NO3)2.6H2O与不同碱NaOH,KOH为原料,制得Zn(OH)42-前驱溶液,使之在水热环境下分解,生成ZnO晶体.产物通过全自动X射线衍射仪(XRD)进行物相分析,扫描电子显微镜(SEM)观测ZnO晶体的形貌和大小.170℃,溶液中的阴离子CH3COO-,SO42-,NO3-,Cl-分别与Na+构成干扰离子对,伴随着晶体生长12 h,晶体成长为片球集状、极性生长明显的花状、极性生长不明显的花状、小尺寸花状ZnO晶体;140℃,溶液中阳离子Na+,K+分别与CH3COO-作为离子对,干扰晶体生长,12 ...