草酸络合物沉淀法制备钛酸钡超细粉的研究

根据传统的草酸盐沉淀法合成超细BaTiO3粉末的条件不易控制的问题,提出了一种新的改进草酸盐沉淀法：先使Ti^4 与C2O4^2-形成TiO(C2O4)2^2 络离子,再使其与Ba^2 反应生成草酸氧钛钡前驱体,然后干燥、煅烧得超细BaTiO3粉末。草酸氧钛络合物的形成应控制在pH=2.5-3,前驱体的煅烧温度,以及反应时物料的混合对最终产物的粒度及分布有较大的影响。在反应物Ba/Ti比为1－1．01,煅烧温度800℃,时间为1h,反应物料充分混合的条件下,采用所提出的新工艺可制备出质量较理想的BaTiO3粉末。     

A Novel Process for Synthesis of Ultrafine BaTiO3 Powders

A novel process termed low-temperature combustion-synthesis(LCS)of Ba(ON3)2-TiO2-C6H8O7.H2O system was investigated at the initial temperature of 600℃ and ultrafine BiTiO3 powders with a particle size of 200-350nm were prepared.It was found that the molar ratio of NO3^-/citric acid and the homogeneity of combustion have remarkable effect on the characterstice of the powder,The reaction mechanism of LCS BaTiO3 powders was proposed on the basis of thermodynamic analysis.     

Preparation and densification of BaTiO3 nanopowder by sol—gel autoigniting synthesis

Autoigniting synthesis of gel from Ba(NO3)2,TiO(NO3)2 and C6H8O7.H2O aqueous solution was investigated at an initial temperature of 600℃ and tetragonal BaTiO3 nanopowder with particle size of 80nm was prepared.It is indicated that the specific surface area of the combustion product before and after calcination is 14.74m^2/g and 12.49m^2/g,respectively.The combustion wave is composed of solid phase reaction zone and gaseous phase flame reaction zone.The combustion flame temperature is 1123K derived from thermo couple measurement.The characteristics and densification behavior of the sol-gel autoigniting synthesized BaTiO3 nanopowder were in vestigated.     

钛酸锶钡(BST)薄膜SOL-GEL制备方法研究

利用碳酸盐代替部分醇盐，探讨了采用Sol-Gel技术制备Ba1-xSrxTiO3(BST)铁电薄膜的可行性。以醋酸钡[Ba(CH3COO)2]、碳酸锶[SrCO3]和钛酸四丁酯[Ti(OC4H9)4]作原料，运用一般的Sol-Gel工艺制备BST铁电薄膜，通过XRD分析物质结构，用SEM测定表面形貌，XPS及EDAX测定薄膜的组成。结果表明：采用碳酸锶原料和其他醇盐一起来制备BST铁电薄膜的方法是可行的。     

SYNTHESIS AND X-RAY POWDER STUDY OF A NEW COMPOUND:Ba_6Ti_7Nb_9O_(42)

A new compound Ba6Ti7Nb9O42 was prepared for the first time by solid state reaction in BaO-TiO2-Nb2O5, ternary system. The X-ray powder diffraction data of the title compound was determined. Ba6Ti7Nb9O42 crystallizes in the hexagonal system -with unit cell parameters a=9.0527(4) A,c=11.790(1) A,and space group P63/mcm(193),z=1. The calculated and measured densities are 5. 293 g/cm3 and 5.285 g/cm3, respectively.     

Synthesis mechanism of Pr doped BaTi4O9 powder by sol-gel process

Pr Doped BaTi4O9 gel was prepared by sol-gel method using Ti(OC4H9)4, Ba(CH3COO)2, CH3COOH and CH3OCH2CH2OH as raw materials. Through analyzing dry gel thermal treated at different temperatures, the possible synthesis mechanism of Pr doped BaTi4O9 powder was discussed. At first, Ti(OC4H9)4 hydrolyzes and three dimensional networks form, in which Ba2 and CH3COO- are mostly in the form of ions; organic solvent is gradually volatilized through calefaction at 700 ℃, then the offspring is turned into BaTi5O11. With the temperature increasing to 850 ℃, BaTi5O11 begins resolving partly and forming BaTi4O9, and at 1000℃ Ba4Ti13O22 forms partly, but BaTi4O9 is the main crystal phase. BaTi5O11 and Ba4Ti13O30 decomposes completely at 1200℃ and forms single-phase BaTi4O9. The infrared (IR) analysis also shows that the absorbing peak of Ti-O bond is not in the characteristic absorption range of Ti-O-Ti (700-900 cm-1), but slightly shifted to the higher end (908 cm-1). It is probably because that doping Pr enters into the crystal lattice and causes the abnormal absorption of Ti-O bond.     

溶胶-凝胶法制备BaTiO3纳米粉体

阐述了用溶胶－凝胶工艺的半醇盐法制备BaTiO3纳米粉体的基本原理和工艺流程，讨论了溶剂、pH值、Ti/Ba摩尔比以及热处理工艺对BaTiO3纳米粉体性能的影响，并分析了目前以该法制备BaTiO3纳米粉体存在的问题。     

Electric characteristics of Nd_2O_3 doped BaTiO_3 ceramics

0　INTRODUCTIONBaTiO3hasbeenextensivelystudiedandwidelyuti lizedasaceramicmaterialforelectronicapplications .TheuseofadditivespermitsvaryingoftheCurietemperatureandpresentsapeculiarvariationoftheresistancewithtemperature[1,2 ] .Commonadditivesaredopantionssuchasyttrium ,whichsubstituteforbariumandpromotean typesemiconductivity .Therare earthelementsinBa TiO3ceramicscouldlowertheresistivitiy ,improvethedi electriccharacteristicsanddecreasethesinteringtempera turenoticeably[3,4 ] ,sotheim…     

Ab Initio Study of Doping Mechanisms in Ba TiO_3-BiYO_3

A density functional plane-wave pseudopotential method is used to study the doping mechanisms of impurity defects(Bi_(Ba),Y_(Ti)) in BaTi O_3-BiYO_3. Single Bi_(Ba) and Y_(Ti) impurities have little structure distortion. Bi forms ionic bond with nearby O atom in single Bi impurity, Y formed [YO_6] octahedral in single Y impurity. However, in the co-doped Bi_(Ba) and Y_(Ti) structure, Bi formed three valence bonds with nearby O atom, which causes the large structure distortion. The doped ion makes the mobile of Ti~(4+) difficult and loss local ferroelectricity, which will broaden the dielectric constant temperature curve and increase the temperature stability of BaTiO_3 ceramic matrix.     

Dy在BaTiO_3中的位占据研究

应用冷压陶瓷技术制备Dy分别掺杂在BaTiO3中的Ba位、Ti位和Ba/Ti位的陶瓷.采用X射线衍射(XRD)、拉曼光谱(RS)和电子顺磁共振(EPR)测试技术调查了Dy在BaTiO3中的位占据倾向.结果表明:Dy倾向于占据Ba位优于Ti位;无论在Ba位还是Ti位占据的名义配比下,Dy都以少量Dy3+形式不可避免地进入BaTiO3中的另一位.x=0.01时,(Ba1-xDyx)TiO3和(Ba1-xDyx)Ti1-x/4O3陶瓷出现很强的g=1.974的Ba空位缺陷信号.Ba(Ti1-xDyx)O3陶瓷在x=0.01时有第二相Ba12Dy4.67Ti8O35析出并且出现一个较弱的g=2.002的Ti空位缺陷信号.(Ba1-xDyx)(Ti1-xDyx)O3陶瓷的固溶度大于x=0.03,在825 cm-1处有较强的拉曼电荷效应.     

水热处理对固相合成的钛酸钡粉体的影响

以采用固相法合成的BaTiO3粉体为前驱物，研究了3种不同配料方式的水热条件进行水热处理后粉体的化学组成、颗粒形貌以及粒度分布的变化。结果表明，经过BaTiO3＋HzO＋NaOH＋BaCl2水热处理，原始粉体中的大颗粒发生裂解，小颗粒发生溶解，外加的Ba^2＋与颗粒表面的Ti（OH）6^2-发生水热反应而生成新的BaTiO2晶粒，使粉体的粒度变小，粒度分布范围变窄，颗粒形貌变得规则，粉体化学组成更符合化学计量，实现了高温高压下水热反应的“整形”作用。     

微波水热法制备含氟钛酸铋系光催化剂及光催化性能研究

以Bi(NO3)3·5H2O和(NH4)2TiF6为原料,采用微波水热法在120℃~220℃反应1h得到了具有不同形貌的粉体.借助XRD、FE-SEM和EDS等分析手段对粉体的组成和形貌进行了表征,并以罗丹明B溶液为目标降解物,研究了200℃下所得粉体的光催化性能.结果表明:所得粉体是一种新型的F掺杂钛酸铋粉体,其中Bi、Ti、O、F的原子比例约为6∶11∶27∶8;随着反应温度的升高,粉体形貌从球形向六棱短柱状转变;紫外光照射下粉体具有较好的降解罗丹明B溶液的能力.     

溶胶-凝胶法合成锂离子电池负极材料及其性能

取0.2 mol/L的Li4Ti5(OEt)19(acac)5[acac-为乙酰丙酮基]为前驱体,经溶胶-凝胶后在600℃加热2 h制得纳米Li4Ti5O12粉体,产物通过X射线衍射(XRD)、粒度分布仪、拉曼光谱(Raman)与差热-热重进行表征。实验表明,前驱体中含有acac-基团,它可以阻止团聚现象;以获得的纳米Li4Ti5O12粉体(粒径为15~20 nm)作为锂电池负极材料,实际循环容量约为164 mAh/g,电池循环性能稳定,使用寿命长。     

含二硫代甲酸酯配体铁硫簇合物的合成与表征

报道通过2–呋喃甲硫醇/十二羰基三铁/三乙胺体系所形成的中间物[（μ-2-SCH2C4H3O）（μ-CO）Fe2（CO）6]Et3NH同CS2作用生成络阴离子[（μ-2-SCH2C4H3O）（μ-S C—S—）Fe2（CO）6]后,同卤代物原位反应,合成了3个新颖的含μ–二硫代甲酸酯配体的铁硫簇合物（μ-2-SCH2C4H3O）（μ-RS—C S）Fe2（CO）6（R=CH3、CH2Ph、CH2COOC2H5）.这3个新颖配合物均通过核磁共振氢谱、红外光谱和元素分析表征了其结构.     

拉曼光谱在Ba(Ti_(1-x)Fe_x)O_(3-δ)陶瓷中的“电荷效应”湮灭

采用冷压陶瓷技术制备具有六方钙钛矿结构的Ba(Ti1-xFex)O3-δ(x=0.05,0.08)陶瓷.由拉曼光谱(RS)技术研究Ba(Ti1-xFex)O3-δ陶瓷在840 cm-1处的"电荷效应".实验观察到代表电荷效应的840 cm-1带消失,其原因最可能是:Fe3+相对于Ti4+具有更小的离子半径、Fe3+-Vo-Fe3+缺陷复合体的形成以及具有低对称性晶格点阵的六方畸变导致电荷效应湮灭.     

Synthesis and Characterization of Vanadium Substituted Dawson-Type Heteropoly Acid （Mo, As）

SubstitutedDawson typepolyoxometalateshave beencalledinorganicmetalloprophyrinbecauseof analogousstructureofmetalloprophyrinandstronger antioxidantthanmetalloprophyrin.Theywerealso usedaseffectivenovelcatalystsofalkeneepoxyring reactions[1].Becausevanadiu…     

水热法制备Sb_2Se_3纳米晶

以酒石酸锑钾(K(SbO)C4H4O6.1/2H2O)和硒粉作为锑源和硒源,自制的2-十一烷基-1-二硫脲乙基咪唑啉季铵盐(SUDEI)为表面活性剂,150℃水热反应24 h,得到不同形貌的Sb2Se3纳米晶。通过透射电镜(TEM)、X射线衍射(XRD)、X射线光电子能谱仪(XPS)对Sb2Se3纳米晶进行了表征。讨论了反应条件对Sb2Se3纳米晶形貌的影响。     

均相沉淀法合成Gd2O2S:Dy3+荧光粉的光致发光

采用Gd2O3、Dy2O3、H2SO4和尿素为实验原料,通过均相沉淀法合成了Gd2O2S:Dy3+荧光粉。利用X射线衍射(XRD)、场发射扫描电子显微镜(FE-SEM)和光致发光(PL)光谱对合成的粉体进行了表征。XRD分析表明:前驱体在氢气气氛下900℃煅烧2h能转化成单相的Gd2O2S粉体。FE-SEM观察显示:Gd2O2S粉体形貌为近球形,平均粒度大小为300～500nm。PL光谱分析表明:在270nm紫外光激发下,Gd2O2S:Dy3+荧光粉的主次发射峰分别位于579和488nm,分别归属于Dy3+的4F9/2→6 H13/2和4F9/2→6 H15/2跃迁,这两个跃迁均具有e单指数衰减行为。Dy3+的猝灭摩尔分数是1%,(Gd0.99,Dy0.01)2O2S荧光粉的色坐标和色温分别为(0.308,0.379,0.313)和6 464K。     

气相中二氧化铬与乙烯反应机理的理论研究

用密度泛函B3LYP／6—311＋＋G（3df,3pd）//6—311G（2d,p）法研究了CrO2＋（2A1／^4A″）＋C2H4生成P1[Cr（OCH2）^＋（^2A″／^4A″）＋CH2O]和P2[CrO^＋（^2∑g/^4∑g）＋C2H2O]的气相反应,重点对影响反应机理和反应速率的势能面交叉现象进行了讨论,并运用Hammond假设和Yoshizawa等的内禀反应坐标单点垂直激发计算的方法大致确定了势能面交叉点（crossing point（CP））或势能面交叉缝（crossjng seam）的位置。研究结果表明,CrO2^＋活化乙烯C-C键是一个[2＋2]类型反应,整个反应经历了重排过程。     

片状钛酸钡颗粒的熔盐法制备及其形貌

为了得到有利于晶粒择优取向的片状钛酸钡形貌颗粒,采用合成出的片状模板原料,通过熔盐法制备了片状钛酸钡颗粒.首先,以碳酸钾、二氧化钛和钛酸锂为原料,在氯化钾熔盐中制备了具有类纤铁矿层状结构的钛酸盐（K0.8Ti1.73Li0.27O4）.经酸交换后,得到了片状钛酸（H1.07Ti1.73O4,HTO）颗粒.HTO是一种具有层间通道结构和良好的离子交换性的片状模板,以HTO和碳酸钡为原料,氯化钠和氯化钾为熔盐,在820℃保温5h得到纯相的钛酸钡,其颗粒形貌呈现为宽5～8μm、长10～15μm,厚度约1μm左右的片状形貌,而且这些片状颗粒是由1μm的小片状颗粒按特定晶向排列而成.结果表明以HTO为模板的原位反应机制起了主要作用,产生保持了片状HTO模板形状的片状钛酸钡颗粒.该方法有望为制备织构化陶瓷提供良好各向异性钛酸钡粉体.