CoxR1-xAl2O4(R=Zn,Mg)钴蓝颜料反射性能的研究

采用化学共沉淀法成功地制备出适用于彩电显象管内荧光体着色的ＣｏｘＲ１－ｘＡＩ２Ｏ４）Ｒ＝Ｚｎ,Ｍｇ,ｘ＝０．８～１．０）钴蓝颜料,４５０ｎｍ波长处反射率最大提高１８．２％,６００ｎｍ处反射率最大了和低５％,通过对该颜料反射率的影响因素,如掺杂离子类型、掺杂浓度和Ｃｏ＾２＋浓度的探讨,结论如下,Ｚｎ＾２、Ｍｇ＾２＋改变钴蓝颜料反射性能的作用机理为晶格畸变引起Ｃｏ＾２＋３ｄ轨道是 级分裂程度的变化,对     

LiNiO2热分解反应动力学研究

用ＤＴＡ和ＸＲＤ研究了ＬｉＮｉＯ_２在空气中的热分解过程为：ＬｉＮｉＯ_２（ｓ）→(６５０～７２０℃)Ｌｉ_２Ｎｉ_８Ｏ_{１０（ｓ）}＋４Ｌｉ_２Ｏ_（ｓ）＋Ｏ_２（ｇ）→(８５０～９５０℃)Ｌｉ_２Ｏ_（ｓ）＋８ＮｉＯ_（ｓ）＋１／２Ｏ_２（ｇ） →(１０００～１１５０℃)ＮｉＯ（ｓ）＋Ｌｉ_２Ｏ_（ｇ）用 Ｄｏｙｌｅ－Ｏｚａｗａ法和 Ｋｉｓｓｉｎｇｅｒ法计算了各反应阶段的表观活化能分别为 ７４７．１８±１．０ ｋＪ·ｍｏｌ^－１、９３２．４６±１．０ ｋＪ·ｍｏｌ^－１和 １１２６．９７±１．０ ｋＪ·ｍｏｌ^－１．用 Ｋｉｓｓｉｎｇｅｒ法确定了反应级数和频率因子,确定了三个阶段的动力学方程分别为 ｄα／ｄt＝１．７３６ｘ１０３９ｅ^{－９００００／Ｔ}（１－α）^{１．０５７}; ｄα／ｄｔ＝１８０６×１０^３９ｅ^{－１１１５００／Ｔ}（１－α）^{０．８４４};ｄα／ｄｔ＝４．２６２×１０４２ｅ^{－１３５０００／Ｔ}（１－α）^{１．２７５}     

共沉淀法制备掺杂氧化锌压敏陶瓷粉料热力学分析

本文通过对Ｍｅ^ｎ＋（Ｚｎ^２＋;Ｃｒ_３^＋,Ｍｎ^２＋;Ｓｂ^３＋,Ｂｉ^３＋,Ｃｏ^２＋）－ＮＨ_３－ＣＯ_３^２－－Ｈ_２Ｏ体系进行热力学分析的基础上,获得了Ｍｅ－ＮＨ_３－ＣＯ_３^２－Ｈ_２Ｏ体系中的ｌｇ［Ｍ］_T－ｐＨ关系图,得到了用ＮＨ_４ＨＣＯ_３和ＮＨ_３·Ｈ_２Ｏ作沉淀剂,用共沉淀法制备掺杂氧化锌压敏陶瓷粉料时,最佳共沉淀ｐＨ为７．０左右．     

铋掺杂铌镁酸铅陶瓷的制备及其有序现象研究

采用二步固相合成法制备钙钛矿相的掺铋铌镁酸铅陶瓷,利用ＸＲＤ和ＴＥＭ选区电子衍射技术对Ｂ位离子非计量有序排列结构进行了表征．研究表明,当为施主掺杂而提高Ｍｇ^２＋、Ｎｂ^５＋离子比例时,铌酸镁前驱体中逐渐出现六方Ｍｇ_４Ｎｂ_９Ｏ_６相．施主Ｂｉ^３＋离子能够有效促进有序微区长大,提高系统有序度．利用Ｘ射线衍射线宽法对ＸＲＤ慢扫描谱进行处理,求得当掺入５％Ｂｉ^３＋离子时,有序微区平均尺寸由纯ＰＭＮ的５nｍ提高到２２ｎｍ．     

复合添加(Ca,Mg)-α-Sialon的晶胞参数研究

利用高分辨率的Ｇｕｉｎｉｅｒ－Ｈａｇｇ相机和计算机控制的底片扫描及数据处理程序系统,测定了复合添加,组份为（Ｃａ_０．５Ｍｇ_０．５）_xＳｉ_{１２－３ｘ}Al_3xＯ_ｘＮ１_６－ｘ（ｘ＝０．３、０．６、１．０和１．４）的α－Ｓｏａｌｏｎ的晶胞参数．材料由热压工艺制备而得．研究结果表明,当ｘ≥１．０时,材料的主晶相为α－Ｓｉａｌｏｎ和含Ｍｇ的ＡlＮ多型体．（Ｃａ,Ｍｇ）－α－Ｓｉａｌｏｎ的晶胞参数明显低于相同组份下的Ｃａ－α－Ｓｉａｌｏｎ的晶胞参数·ＥＤＡＸ的结果进一步给出固溶进入α－Ｓｉａｌｏｎ的包括名义组份中９０％的Ｃａ^＋＋和少量的Ｍｇ^＋＋,而大部分Ｍｇ^＋＋进入ＡlＮ多型体,这一结果为净化α－Ｓｉａｌｏｎ陶瓷的晶界提供了新的有效途径．     

Li2MnO3的柠檬酸盐溶胶-凝胶法合成及离子导电性

以Ｌｉ_２ＣＯ_３、ＭｎＣＯ_３为原料,用柠檬酸盐溶胶凝胶法合成了Ｌｉ_２ＭｎＯ_３超微粉．对合成的材料进行了ＤＴＡ、ＴＧ、ＸＲＤ和ＴＥＭ等表征,并应用交流阻抗谱技术测定了样品的电导率．结果表明,６５０。Ｃ以上生成Ｌｉ_２ＭｎＯ_３纯相超微粉,粒径在５０nｍ以下．在１８～４００℃温度范围内,产物烧结体的离子导电率为１０^－６～１０^－３Ｓ·ｃｍ^－１,其电导活化能为４４．８７ｋＪ·ｍｏｌ^－１．     

纳米相铁红粒子的液相制备

由０．２ｍｏｌ·Ｌ^－１Ｆｅ^３＋采用微波诱导加热制备了纳米尺寸的准立方形和纺锤形α－Ｆｅ_２Ｏ_３粒子,与常规加热方式比较微波加热制得的α－Ｆｅ_２Ｏ_３粒子粒径小且分布均匀,实验证明无机离子加 Ｈ^＋、ＯＨ^－和 Ｎａ^＋等的加入可明显加速反应速率．     

铬掺杂对PZT-PMN陶瓷材料性能的影响

采用ＴＥＭ、ＳＥＭ、ＥＳＲ（电子自旋共振）结合常规压电性能测试手段研究了Ｃｒ_２Ｏ_３掺杂对ＰＺＴ－ＰＭＮ陶瓷的压电性能、微结构及畴态的影响．压电性能测试结果表明,当Ｃｒ_２Ｏ_３含量低于０．０６Ｗｔ％时,可使Ｋ_ｐ和Ｑ_ｍ同时提高,这说明铬掺杂同时兼具“软掺杂”与“硬掺杂”的双重特性．此外,还发现随着烧结温度的提高,材料性能“硬化”明显．ＥＳＲ谱分析表明,Ｃｒ离子主要以Ｃｒ^３＋和 Ｃｒ^５＋的方式共存,随着烧结温度的提高,它有从高价态 Ｃｒ^５＋或Ｃｒ^６＋向低价态转变的趋势,这一价态变化被认为是材料性能随烧结温度提高而“变硬”的主要原因之一．ＴＥＭ图片显示,随着掺杂的Ｃｒ_２Ｏ_３的浓度的增大,由于氧空位或受主离子与氧空位构成的缺陷复合体对畴壁的钉扎,电畴将从正规带状畴向波纹状畴转变．     

配合物[Fe(bipy)2]3+修饰的MCM-41的合成与表征

以γ－氨丙基修饰介孔分子筛ＭＣＭ－４１内孔壁,将引入的γ－氨丙基与金属配位离子［Ｆｅ（ｂｉｐｙ）_２］^３＋通过配位键首次合成了金属配位化合物修饰的ＭＣＭ－４１（ＭＣＭ－ａｐ－Ｆｅ（ｂｉｐｙ）_２）．通过ＸＲＤ,７７Ｋ氮气吸附－脱附曲线,固体ＵＶ－ｖｉｓ漫反射光谱和循环伏安曲线表征了复合物ＭＣＭ－ａｐ－Ｆｅ（ｂｉｐｙ）_２。由于［Ｆｅ（ｂｉｐｙ）_２］^３＋的引入,使 ＭＣＭ－ａｐ－Ｆｅ（ｂｉｐｙ）_２的结晶度降低, ＢＥＴ比表面积、孔容和最可几孔径急剧下降．γ－氨丙基与Ｆｅ^３＋的配位而使其ＵＶ－ｖｉｓ漫反射吸收光谱与ＭＣＭ－Ｆｅ（ｂｉｐｙ）_２不同;循环伏安特性曲线表明ＭＣＭ－ａｐ－Ｆｅ（ｂｉｐｙ）_２在电化学上比浸渍法制备的ＭＣＭ－Ｆｅ（ｂｉｐｙ）_２稳定．     

Sol-Gel法制备ZnO压敏陶瓷及其电性

采用溶胶－凝胶（ｓｏｌ－ｇｅｌ）工艺制备ＺｎＯ电压敏陶瓷粉体．探讨其制备的最佳工艺条件：以 Ｚｎ（ＮＯ_３）_２与 ＮａＯＨ为反应前驱物制取胶体, Ｚｎ^２＋浓度控制在 ０．５ｍｏｌ·Ｌ^－１以上, ｐＨ值７．５左右,预烧温度３００℃,陶瓷烧结温度１２００℃;制得的压敏电阻的非线性系数α＝２８;研究了稀土Ｌａ_２Ｏ_３掺杂对该陶瓷电性的影响：低浓度掺杂时,可提高压敏电压,高浓度掺杂时;不呈现压敏特性;对粉体进行了Ｘ射线衍射和透射电镜分析,预烧后得到五元掺杂的ＺｎＯ粉体粒形呈球状,属六方晶系,粒径分布窄,约为４０～８０ｎｍ．     

掺杂Mg对纳米CoFe2O4/SiO2复合薄膜结构和磁性的影响

采用溶胶-凝胶旋涂法制备了纳米Co_1-xMg _xFe₂O₄/SiO₂(x = 0, 0.2, 0.4, 0.6, 0.8) 复合薄膜。利用XRD、SEM、原子力显微镜、振动样品磁强计对薄膜的结构、形貌和磁性进行了分析, 研究了Mg²⁺含量对样品结构和磁性的影响。结果表明, 样品中Co_1-xMg _xFe₂O₄具有尖晶石结构, 晶粒尺寸在38~46 nm之间。随着Mg²⁺含量的增加, Co_1-xMg _xFe₂O₄的晶格常数减小, 样品的饱和磁化强度减小, 矫顽力先增大后减小。样品Co_0.4Mg_0.6Fe₂O₄/SiO₂垂直和平行膜面的矫顽力分别为350.7 kA·m^-1和279.4 kA·m^-1, 剩磁比分别为67.2%和53.9%, Co_1-xMg _xFe₂O₄/SiO₂复合薄膜具有较明显的垂直磁各向异性。     

Effects of the inhomogenous co doping on the magnetoresistance of Zn1-xCo(x)O epitaxial films

A series of Zn1-xCo(x)O epitaxial films around 100 nm with nominal Co concentration from 5% to 15% was prepared by ultra high vacuum (UHV) magnetron reactive sputtering. The optical, magnetic and magneto-transport properties of this series of Zn1-xCo(x)O epitaxial films were investigated, respectively. Resonant Raman spectra indicate the high structural and crystalline quality of these Zn1-xCo(x)O (5 < or = x < or = 15%) films, and confirm a consistent correlation between the substituting Co ions content with the Co doping concentration as well. Paramagnetism, superparamagnetism and ferromagnetism with altered Curie temperature from low temperatures to above room temperatures have been observed in these films by SQUID magnetometry. The broad blocking temperature range indicates the presence of inhomogenous distribution of the magnetic nano-clusters in the superparamagnetic films. However, the magneto-transport behaviors do not strongly respond to the change of the magnetic properties from paramagnetism to ferromagnetism of these Zn1-xCo(x)O films. The lack of efficient coupling between the inhomogenous magnetic nanoclusters and the carrier system in ferromagnetic Zn1-xCo(x)O films highlights the absence of the intrinsic magnetic origins in high structural quality Zn1-xCo(x)O (5 < or = x < or = 15%) epitaxial films. On the other hand, the competition between the spin alignments and the inhomogenous local disorder effect by magnetic ions is suggested to be responsible for the carrier properties and the oberseved magnetoresistance in these Co doping Zn1-xCo(x)O (5 < or = x < or = 15%) epitaxial films.     

Eu2+、Dy3+、Li+共掺杂CaSi2O2N2荧光粉的发光性能

采用高温固相反应法制备了一系列白光LED用CaSi2O2N2:0.05Eu2+,xDy3+,xLi+(0≤x≤0.03)荧光粉.利用X射线衍射仪对样品的物相结构进行了分析,结果表明:Dy3+和Li+离子的掺入没有改变CaSi2O2N2:Eu2+荧光粉的主晶相.利用荧光光谱仪对样品的发光性能进行了测试,发现所有样品的激发光谱均覆盖了从近紫外到蓝光的较宽范围,400 nm激发下得到的发射光谱为宽波段的单峰,峰值位于545 nm左右,是Eu2+离子5d-4f电子跃迁引起的.Dy3+离子掺杂可以提高CaSi2O2N2:Eu2+荧光粉的发光强度,Dy3+与Li+共掺杂可进一步提高荧光粉的发光强度,当Dy3+和Li+的掺杂量为1mol%时,荧光粉的发光强度达到最大值,是单掺杂Eu2+的荧光粉发光强度的157%.     

Distribution of cations in nanosize and bulk Co-Zn ferrites

The structural and magnetic properties of Co(1-x)Zn(x)Fe2O4 ferrites (Co-Zn ferrites) are investigated in a narrow compositional range around x = 0.6, which is of interest because of applications in magnetic fluid hyperthermia. The study by x-ray and neutron diffraction, M?ssbauer spectroscopy and magnetization measurements is done on nanoparticles prepared by the coprecipitation method and bulk samples sintered at high temperatures. In spite of the known preference of Zn2+ for tetrahedral (A) sites and Co2+ for octahedral [B] sites, the cations are distributed nearly evenly over the two sites of spinel structure and there is also a variable number of [B] site vacancies (see text), making cobalt ions trivalent. In particular for x = 0.6, the cationic distribution is refined to [Formula: see text] and [Formula: see text] for the 13 nm particles (T(C) = 335 K) and bulk sample (T(C) = 351 K), respectively.     

尖晶石结构Ni掺杂ZnFe2O4纳米颗粒的性能表征

利用水热法成功合成了纯ZnFe2O4和不同含量Ni掺杂Zn1-xNixFe2O4纳米颗粒。采用X射线衍射(XRD)、高分辨透射电子显微镜(HRTEM)、选区电子衍射(SAED)、X射线能量色散分析(XEDS)、紫外可见吸收光谱(UV-Vis)、傅里叶变换红外光谱(FT-IR)和振动样品磁强计(VSM)等测试技术研究掺杂浓度对Zn1-xNixFe2O4(x=0,0.1,0.3,0.5)样品的晶体结构、形貌、光学性能和磁学性能的影响。结果表明:所制备的Zn1-xNixFe2O4纳米颗粒结晶良好,Ni2+以替代Zn2+的形式掺杂到ZnFe2O4晶格中,生成立方尖晶石结构ZnFe2O4。随着Ni含量的增加,晶粒尺寸增大,晶格常数发生收缩。样品的形貌呈不规则的椭球形,且颗粒大小比较均匀。红外光谱的吸收峰位置并没有随Ni掺杂浓度的增加而变化。Zn1-xNixFe2O4纳米晶的光学带隙随Ni掺杂浓度增加而增大,与相应块体相比发生蓝移。在室温下,纯ZnFe2O4纳米晶呈现超顺磁性,掺杂样品具有明显的铁磁性。     

A study of ZnGa2O4 phosphor prepared by the solid method

In this study, the mixtures of ZnO and Ga2O3 powder with addition of LiCl flux were fired, the raw material mixing ratio, doping with Mn2+ and firing atmosphere effects on phosphor characteristics were investigated. When fired at 1200 °C, its phosphor powder emits a broad-band spectrum range between 375 nm to 700 nm, with a peak at 470 nm. The optimal composition of phosphors is about ZnO/Ga2O5=47/53. Manganese-doped ZnGa2O4, fired in air, exhibits two new emission bands with peaks at 506 nm (Mn2+ emission centre) and 666 nm (Mn4+ emission centre). However, if fired under vacuum, the emission spectrum presents only the 506 nm peak with increased intensity. The 666 nm emission peak derived from a little Mn2 oxidized to Mn4+ which substituted Ga3+ to occupy the B sites of the spinel structure. The emission intensity of the 506 nm peak of Zn1-xMnxGa2O4 is strongest when [Mn2+] x=0.006 and decreases markedly as the concentration of Mn2+ exceeds x=0.01. Most of the substitutional Mn2+ doping species in spinel ZnGa2O4 occupy the zinc sites. The luminescent band was associated to the spin-forbidden transition, 4T1(4G)6A1 (6S). © 1998 Kluwer Academic Publishers     

Upconversion luminescence enhancement in Yb3+/Tm3+-codoped Lu2O3 nanocrystals induced by doping with Li+ ions

Lutetium oxide (Lu2O3) nanocrystals doped with 2%Yb3+, 0.5%Tm3+, and various doping concentrations of Li+ (0, 3, 5, 7, 10, 12, and 15 mol%) were prepared by the sol-gel method. The dependence on different doping concentrations of Li+ ions of the structure, morphology, and the upconversion emission intensity of the Lu2O3:2%Yb3+, 0.5%Tm3+ nanocrystals was investigated. The obtained Lu2O3 nanocrystals were systematically characterized by X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), Fourier transformed infrared (FT-IR) spectra, Raman spectra, and upconversion spectra measurements. It was found that all the nanocrystals can be readily indexed to pure cubic phase of Lu2O3, indicating good crystallinity. The experimental results show that Li+ doping in Lu2O3:2%Yb3+, 0.5%Tm3+ nanocrystals can greatly enhance the upconversion emission intensity. The strong blue (490 nm) and the weak red (653 nm) emissions from the prepared nanocrystals were observed under 980 nm laser excitation, and attributed to the 1G4 --> 3H6 and 1G4 --> 3F4 transitions of Tm3+ ions, respectively. An simple analysis based on steady-state rate equations and a power-dependent study both indicate that the 1G4 levels can be populated by three-step energy transfer (ET) processes. The enhancement of the upconversion luminescence was suggested to be the consequence of the modification of the local field symmetry around the Tm3+ ion, reduced number of OH- groups, and the enlarged nanocrystal size induced by the Li+ ions.     

溶胶-凝胶法制备MgxZn1-xO薄膜及性能研究

采用溶胶-凝胶法在石英玻璃片衬底上制备了Mg2+掺杂的ZnO(MgxZn1-xO)薄膜,研究了Mg2+掺杂对ZnO薄膜结构和紫外透过率的影响;在氧化物薄膜上真空蒸镀了Al叉指电极,制得紫外原型探测器件,测试了I-Ⅴ特性.结果表明,Mg2+掺杂后,MgxZn1-xO薄膜为纤锌矿结构,随着x值增加,晶格常数c逐渐减少,α逐渐增大,Mg2+掺杂抑制了(002)晶面的生长;紫外透过光谱表明,Mg2+掺杂后吸收边发生蓝移,可提高ZnO薄膜的禁带宽度;I-Ⅴ特性曲线表明,正向偏压下探测器的暗电流和光照电流随外加偏压呈线性增长,但光照电流与暗电流的差别较大.     

Zn_(1-x)Mn_xS稀磁半导体的合成与光学性能

通过水热法制备不同掺杂浓度的Zn_(1-x)Mn_xS(x=0.00,0.02,0.05,0.07)稀磁半导体材料,研究Mn~(2+)掺杂浓度对ZnS纳米棒微观结构和光学性能的影响。采用X射线衍射(XRD)、高分辨透射电子显微镜(HRTEM)、选区电子衍射(SAED)、X射线能量色散分析谱仪(XEDS)和紫外可见吸收光谱(UV-vis)对样品的晶体结构、形貌和光学性能进行表征。结果表明:制备的所有样品均具有结晶良好的纤锌矿结构,没有杂峰出现,生成纯相Zn_(1-x)Mn_xS纳米晶。样品形貌为纳米棒状结构,分散性良好。掺杂的Mn元素进入到ZnS纳米晶中,Mn~(2+)替代了Zn~(2+),而且随着Mn掺杂量的增加晶格常数减小。同时UV-vis光谱发现样品的光学带隙增大,发生了蓝移现象。     

Structural and electrical properties of Gd3+ ion substituted CoGdxFe(2-x)O4 nano-ferrites

Nano particles of CoGdxFe(2-x)O4, with x = 0.0, 0.1, 0.3, 0.5 have been prepared by chemical co-precipitation method. The as synthesized particles are annealed at 300 degrees C for two hours to improve crystallinity. The X-ray diffraction patterns reveal the single cobalt ferrite phase formation and the average crystallite size decreases to 7 nm in the Gd3+ ion doped sample (with x = 0.5) compared to 27 nm in case of un-doped cobalt ferrite sample. The electrical properties for the different compositions of Gd3+ ion substituted cobalt ferrite material were studied in the frequency range 100 Hz to 10 MHz at room temperature using WK impedance analyzer. It is found that the electrical conductivity of the samples increases with increasing Gd3+ ion concentration. The results of our investigations reveal a strong dependence of material properties on Gd3+ ion doping.