Co、Sn共掺杂ZnO晶体的制备及其磁性

采用6 mol/L KOH作为矿化剂,SnO2、CoCl2和ZnO按物质的量比为0.02∶0.5∶1的比例混合作为前驱物,填充度70;,温度430℃,时间24h,采用水热法制备出Co、Sn元素掺杂的ZnO晶体.Sn元素掺杂明显改变了晶体的极性生长特征,较大面积的显露正极面c｛0001｝面,还显露柱面m{l0l0｝、正锥面p{1011｝、负锥面｛1011｝和负极面｛0001｝以及正锥面{1012｝和负锥面{1012｝,晶体长度约为50 μm.经过EDS测量表征,发现制备的ZnO单晶中Co元素的含量达到10.89at;,生成物中出现少量Co氧化物,SQUID测量表明样品主要表现为顺磁性.     

水热法生长的Co、Sn共掺杂ZnO晶体厚膜的顺磁性

采用水热法,6 mol/L KOH作为矿化剂,按物质的量比0.02∶0.5∶1添加SnO2、CoCl2和ZnO作为前驱物,填充度70%,温度430℃,以常规水热法制备的纯ZnO晶片为籽晶([0002]方向),在ZnO籽晶片上制备出多元掺杂的ZnO厚膜。厚膜呈墨绿色,EDS测量显示Co和Zn元素的相对含量为7.47∶92.53。电学测量晶体膜层为n型导电类型,载流子浓度1.15×1020cm-3,电阻率1.94×10-3Ω.cm,迁移率27.8 cm2/V.s,SQUID测量表明厚膜为顺磁性。     

水热法合成Zn1-xCoxO室温稀磁半导体

本文采用水热法,在430℃,填充度为35;,3mol/L KOH作为矿化剂,反应时间为24h,合成了Zn1-xCoxO晶体.当在Zn(OH)2中添加一定量的CoCl2·6H2O为前驱物时,水热反应产物中,可以获得多晶体形态的掺杂Zn1-xCoxO晶体.电子探针测量表明,随着前驱物中CoCl2·6H2O添加量的增加,晶体中的Co实际掺入量也随着增加.采用超导量子干涉磁强仪测量材料的磁性,发现在室温以下,水热法合成的Zn1-xCoxO晶体的磁化强度随温度变化很小,在300K存在明显的磁饱和现象和磁滞回线,表明具有室温下铁磁性.     

常压化学气相输运法合成Zn1-xCoxO晶体

本文采用高温化学气相输运法,温度970℃,在蓝宝石和石英基片上制备Zn1-xCoxO晶体.电子扫描显微镜(SEM)观察发现,蓝宝石晶片上的晶体形貌较SiO2 晶片上的规整,晶体呈现六棱柱或六棱锥体,一般显露柱面m{101-0}、正锥面p{101-1}、负极面c{0001-}和正极面c{0001},晶体表面光滑.在石英基片上得到的Zn1-xCoxO晶体生长的棱面较模糊,基片的部分晶体非定向密集生长,连续形成薄膜结构.X衍射证实晶体为ZnO纤锌矿结构.X光能谱﹙EDS﹚测量表明 ZnO 晶体有钴离子的存在,且浓度随原料中的Co2O3:ZnO的比值增大而增加 .     

Mn、Cu共掺ZnO磁性的研究

本文采用水热法,分别以ZnO、Zn(OH)2为前驱物,添加一定量的MnCl4.4H2O和CuSO4.2H2O, 3mol/LKOH作矿化剂,温度430℃,填充度35%,反应24h,制备了Mn、Cu共掺ZnO晶体。当前驱物为Zn(OH)2时,所得晶体大部分为短柱状晶体,显露正负极面{0001}、{0001-}、负锥面-p{101-1-}和柱面m{1-010},长度约为30 ～50μm。少部分晶体为单锥六棱柱状,显露正锥面p{101-1},柱面m{1-010},负极面-c{0001-},晶体的长度约为100μm,长径比为5:1。当ZnO用作前驱物时,短柱状晶体长度大约为10 ～30μm,晶体的六棱对称性都出现较大的偏差。X射线荧光能谱分析表明,前驱物为ZnO、Zn(OH)2时,Mn离子含量在分别为3.19%和1.62%原子分数,没有检测到Cu离子。虽然Mn、Cu离子的掺入会明显影响晶体形态,磁性测量显示掺杂Mn、Cu的ZnO仍为反铁磁。     

两步化学法制备Co掺杂ZnO薄膜及其磁性研究

采用电化学和湿化学法结合的两步化学法制备了Co掺杂的ZnO薄膜.X射线衍射(XRD)结果表明Co掺杂没有改变ZnO薄膜的六角纤锌矿结构.扫描电镜(SEM)和透射电镜(TEN)结果表明薄膜是由ZnO单晶纳米棒组成.X射线光电子能谱(XPS)结果表明Co2替代了Zn2+,实现了有效的掺杂.磁性测量的结果表明,样品在室温下的磁性表现为顺磁性和铁磁性的结合.     

In和过渡金属离子共掺杂对ZnO晶体形貌的影响

采用水热法,KOH作矿化剂,在ZnO前驱物中添加适量的CoCl2·6H2O,FeCl2·4 H2O,NiCl2·6H2O,In2O3,其中Co:In:Zn,Fe:In:Zn,Ni:In:Zn 分别为5:1:100,5:1:100,3:1:100.3 mol/L KOH作矿化剂,温度430 ℃,填充度35;,反应24 h,制备了In和过渡族金属离子共掺的ZnO晶体.结果表明,掺杂In2O3时,所合成的过渡族金属离子掺杂的ZnO晶体均呈现六角片状晶体,晶体形貌规则,表面光滑,直径为5～10 μm.和未掺杂In的晶体相比,掺杂In后,晶体c轴极性生长速度得到明显的控制,a、b轴方向生长速度提高,大面积显露+c{0001}、负极面-c{0001}面,另外还显露正锥面+p{1011}、负锥面-p{101-1-}.     

ZnO掺杂对PVK∶Ir(ppy)3体系发光特性的影响

以无机纳米颗粒ZnO作为电子传输材料,并以不同质量比掺杂到PVK∶ Ir(ppy)3体系作为发光层制成一系列磷光器件,器件结构为:ITO/PVK∶ Ir(ppy)3∶ ZnO(100∶ 1∶ x)/ BCP/Alq3/Al, ZnO的掺杂浓度x分别为0;,1;,2;,5;,10;,研究了它们的电致发光特性.结果表明:合适比例ZnO掺杂可以改善器件的发光特性,ZnO的最佳掺杂量为1;,此时器件的相对发光强度是未掺杂的器件的4倍,器件的启亮电压也由未掺杂时的15.5 V降到了10.5 V.当掺杂浓度较大时,电子传输过多在电极另一侧形成漏电流,没有在发光层内进行电子与空穴有效复合,没有对发光起到作用,导致器件的发光性能下降.     

共沉淀法制备Co掺杂纳米ZnO及其表征

以ZnCl2、CoCl2和NaOH为原料,采用共沉淀法制备了纯ZnO和Co掺杂ZnO(ZnO: Co)纳米粉体.利用XRD、EDS和FESEM对样品的结构和形貌进行了表征,利用光致发光光谱(PL)研究了样品的发光性质.结果表明,控制退火温度600 ℃煅烧2 h能得到纯度较高的ZnO: Co纳米粉体,此粉体属于六方纤锌矿结构;部分Co2 +取代了Zn2 +进入ZnO的晶格,掺入量为2.2 at;;Co掺杂对产品的形貌影响不大,掺杂前后均为准球形颗粒,掺杂后颗粒粒径略有减小;Co掺杂使ZnO的禁带宽度变窄,紫外发光峰位产生显著红移.     

Co掺杂对ZnO晶体中光生电子瞬态过程的影响

采用气相反应制备了ZnO和ZnO∶Co微晶,并通过热释光研究了材料中的电子陷阱能级(施主能级),采用微波介电谱研究了材料的光生电子瞬态过程.发现纯ZnO热释光谱有两个峰,分别为-183 ℃和-127 ℃,说明存在两个电子陷阱能级;而ZnO∶Co中热释光信号很弱,只有纯ZnO的十分之一.微波介电谱研究表明,由于电子陷阱对导带电子的驰豫作用,纯ZnO材料导带光电子的衰减为一级指数过程,寿命为802 ns.ZnO∶Co微晶体的最大微波介电谱强度低于纯ZnO晶体的五分之一,电子陷阱密度较小,其光生电子快速衰减,过程仅为10～20 ns.结果说明Co掺杂具有明显的抑制电子陷阱能级生成的作用.     

Crystallographic,optical and magnetic properties of Co‐doped ZnO thin films synthesized by sol gel route

ZnO thin films with various Co doping levels (0%, 1%, 3%, 5%, 8%, respectively) have been synthesized by sol gel spin coating method on glass substrates. XRD and XPS studies of the films reveal that cobalt ions are successfully doped into ZnO crystal lattice without changing the hexagonal wurtzite structure. The morphologies are studied by SEM and AFM and show wrinkle network structures with uniform size distribution. With Co doping concentration increasing, the wrinkle network width decreases gradually. The transmittance spectra indicate that Co doping can effectively reduce the optical bandgap of ZnO thin films. Photoluminescence show that all samples have ultraviolet, violet and green emission. When Co doping concentration increases up to 5%, the intensity of violet emission is greatly increased and a strong deep blue emission centered at 439 nm appears. The ferromagnetism of all samples was observed at room temperature. The emission mechanisms and ferromagnetism origination are discussed in detail. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis of zinc oxide crystals with different shapes from zincate aqueous solutions stabilized with triethanolamine

ZnO crystals were synthesized from basic aqueous solutions including zincate ions stabilized with triethanolamine (N(C₂H₄OH)₃, teaH₃) by heating at 60°C. The influence of the basicity of the solutions on the morphology of the ZnO crystals was examined. The aqueous solutions were prepared using ZnSO₄·7H₂O, N(CH₃)₄OH (TMAOH), and teaH₃ as a zinc source, a base, and a stabilizer, respectively, at a zinc concentration of 0.2 M at a teaH₃ / Zn molar ratio of 4. Clear solutions were obtained at a molar ratio of TMAOH / Zn ≥ 3.0. When the clear solutions, in which glass or polyester substrates were placed, were heated at 60°C, agglomerates of ZnO crystals were deposited on the substrates in the TMAOH / Zn range from 3.0 to 3.6. With increasing the TMAOH / Zn ratio, the shape of the resulting ZnO crystals changed from a short asymmetric column with a hexagonal flat edge and a rounded one, through a rocket‐like shape formed by intergrowth, to a hexagonal rod. Although no films of ZnO were formed, ZnO crystals with different shapes were synthesized. When the glass substrates pre‐coated with a ZnO thin film by a sol‐gel method were used, highly oriented, dense ZnO films were formed. The films consisted of rod‐like crystals aligned normal to the substrate surface. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Li+掺杂ZnO基荧光粉的制备、性能研究及其表面包覆

采用草酸根沉淀法制备ZnO∶ Eu3+荧光粉,探讨了Li+对Eu3+的敏化作用,并研究了SiO2的表面包覆对ZnO∶Eu3,Li+荧光粉性能的影响.采用XRD、IR、SEM、PL等分析了样品的物相、形貌及发光性能.结果表明:K+的掺杂能有效的增强Eu3+与ZnO之间的能量传递,提高其发光性能.而表面包覆SiO2使ZnO∶ Eu3+,Li+荧光粉的晶粒间团聚减小,并对其激发光谱产生影响.     

Optical and magnetic properties of Nd‐doped ZnO nanoparticles

Nd‐doped ZnO nanoparticles with different concentration were synthesized by sol‐gel method. The structures, magnetic and optical properties of as‐synthesized nanorods were investigated. X‐ray diffraction (XRD) and x‐ray photoelectron spectroscopy (XPS) results demonstrated that Nd ions were incorporated into ZnO lattice; but Zn_1‐xNd_xO nanoparticles with Nd concentration of x = 0.05 showed Nd₂O₃ phase, so the saturation concentration of Nd in Zn_1‐xNd_xO is less than 5 at%. Vibrating sample magnetometer (VSM) measurements indicated that Nd doped ZnO possessed dilute ferromagnetis behaviour at room temperature. Photoluminescence spectroscopy (PL) showed that Nd ions doping induced a red slight shift and decrease in UV emission with increase of Nd concentration.     

溶胶-凝胶法制备高Mg含量Zn1-x MgxO薄膜

采用溶胶-凝胶法在石英玻璃基板上制备了ZB1-xMgxO薄膜,研究退火温度对高Mg含量Zn0.5Mg0.5O薄膜的相组成、相偏析及紫外-可见透过光谱中吸收边移动的影响,当退火温度≤500℃时,Zn0.5Mg0.5O薄膜未发生相偏析现象,且400℃退火处理制备的Zn0.5Mg0.5O薄膜的紫外-可见透过光谱中吸收边蓝移最大.因此,对于高Mg含量Zn0.5Mg0.5O薄膜,退火温度是影响Mg2+在ZnO中固溶度的关键因素,且400℃是其理想的退火温度.在此条件下研究了不同Mg含量对Zn1-xMgO(x=0～0.8)薄膜带隙调节的影响,随着Mg含量的增加,其紫外-可见透过光谱中紫外光区吸收边呈现规律性蓝移,光学带隙值Eg从纯ZnO的3.3 eV调节至4.2 eV.     

Influence of microscopic defects on optical damage resistance of Zn:Fe:LiNbO3 crystals

Influence of defect structure on the infrared transmission spectra of OH^‐ in Zn:Fe:LiNbO₃ crystals with various ZnO concentration and different Li/Nb ratios was investigated. It indicates that above the Zn concentration threshold the OH^‐ absorptions bands successively shift from 3482cm^‐1 to 3504cm^‐1 and 3529cm^‐1. The intensity of the 3504cm^‐1 band increases with ZnO concentration increasing. The optical damage resistance of the Zn:Fe:LiNbO₃ crystals increases rapidly when the ZnO concentration exceeds a threshold value. This result contributed to the site alteration from the Li sites to Nb sites due to Zn‐doping in crystal. © 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim     

稀土金属Ce3+掺杂ZnO材料的光催化机理

通过溶胶凝胶法制备了光催化活性更高的Ce∶ZnO复合粉体光催化材料,并采用X射线衍射(XRD)、电子顺磁共振(EPR)、紫外可见光谱(UV-Vis)技术对所制备的粉体样品的晶体种类及结构、自由基种类及含量、光催化效率进行表征分析。复合样品的X射线衍射测试结果显示,随着掺杂浓度的增加,先后检测到CeO₂的(111)和(200)晶面特征峰,且衍射峰强度逐渐增强。此外,适量的掺杂(c(Ce³⁺)=2%)可减小ZnO晶体的晶粒尺寸。电子顺磁共振测试结果显示,Ce∶ZnO复合光催化材料中存在三类自由基,分别是Zn-H络合物、正一价氧空位、CeO₂表面吸附的超氧根离子。紫外可见光谱测试表明,适量的掺杂可有效提高ZnO催化剂的光催化活性,综合分析显示,ZnO光催化活性提高的主要原因是Ce³⁺的掺入使得材料中电子数量增多,进而提高了活性自由基·O^-₂的数量。本文通过EPR技术和XRD衍射技术,成功表征了Ce³⁺掺杂对ZnO材料中自由基种类合成的影响过程,并结合UV-Vis技术,对Ce∶ZnO复合材料光催化降解甲基橙的过程中的电子转移过程作出了合理的解释。     

高掺锌/镁铌酸锂薄膜的光电性质

室温下采用射频磁控溅射(RFMS)技术在玻璃与硅基板上分别沉积了纯铌酸锂LN薄膜、高掺锌(6%,摩尔分数,下同)LN∶ZnO薄膜和高掺镁(5%)LN∶MgO薄膜,并在575 ℃条件下退火进一步提高薄膜的结晶度。通过原子力显微镜(AFM)、X射线衍射(XRD)、紫外可见吸收(UV-Vis)和椭偏仪等测试研究了三种铌酸锂薄膜的形貌、结构和光学性质。XRD分析表明掺杂铌酸锂薄膜和纯铌酸锂薄膜具有相同的生长取向,AFM、XRD、UV-Vis测试结果表明,掺杂将增大铌酸锂薄膜的晶粒尺寸,光学带隙的红移现象与晶粒尺寸相关,且掺Mg的影响大于掺Zn。此外利用霍尔效应测试仪研究了LN、LN∶ZnO和LN∶MgO薄膜的电学性质,测试结果表明三种薄膜均为n型半导体,其中LN∶MgO薄膜电导率的变化趋势不同于LN∶ZnO和LN薄膜,且发现温度在18~50 ℃范围内,随着温度的升高,LN∶MgO薄膜的电导率变化微小,而LN∶ZnO和LN薄膜的电导率逐渐增大。     

Growth,structure and optical characterization of Al‐doped ZnO nanoparticle thin films

Al‐doped ZnO nanoparticle thin films were prepared on glass substrate at the optimum temperature of (410±10) °C by spray pyrolysis technique using zinc nitrate as a precursor solution and aluminium chloride as a dopant. The dopant concentration (Al/Zn at%) was varied from 0 to 2 at%. Structural analysis of the films shows that all the films are of polycrystalline zinc oxide in nature, possessing hexagonal wurtzite structure. The films exhibit variation in peak intensities corresponding to (100), (002) and (101) reflection planes on Al‐doping. The crystallite size calculated by Scherrer formula has been found to be in the range of 35‐65 nm. The optical absorption study shows that the optical band gap in the Al‐doped films varies in the range of 3.11 – 3.22 eV. The width of localized states in the band gap estimated by the Urbach tail analysis has been found to be minimum in case of the 1 at% Al‐doped zinc oxide thin film. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)