掺杂Ag纳米BaTiO3抑菌剂的制备及其性能

掺杂Ag纳米BaTiO3抑菌剂的制备及其性能;溶胶-凝胶;掺杂Ａｇ;ＢａＴｉＯ３;抑菌性能     

纳米晶钛酸钡的介电性能

采用硬脂酸凝胶法制备了纳米晶BaTiO3,用差热热重分析、红外光谱分析、X射线衍射分析等手段对产物的形成过程、晶型、粒径进行了分析.通过对材料介电性能的研究发现,纳米材料的静态介电常数远大于常规材料的介电常数,随着粒径的减小,纳米材料的介电常数先增大而后有所降低.随着环境湿度的升高,纳米晶材料的介电常数逐渐增大,在高湿度条件下,其介电常数与湿度成线性关系.     

锰掺杂Ba0.6Sr0.4TiO3-MgTiO3复相陶瓷的制备和介电性能

以分析纯的Ba(NO3)2、Sr(NO3)2、草酸和钛酸丁酯为原料, 采用草酸盐共沉淀法制备了钛酸锶钡（Ba0.6Sr0.4TiO3, BST）纳米粉体. XRD和SEM分析结果表明, 该方法制备出立方相的Ba0.6Sr0.4TiO3粉体, 平均粒径小于100 nm, 具有较高的烧结活性. 用传统固相法制备了锰掺杂钛酸锶钡-钛酸镁(Ba0.6Sr0.4TiO3-MgTiO3, BST-MT)复相陶瓷, 系统研究了掺杂0.1%-2.0%(x, 摩尔分数, 下同)锰对钛酸锶钡-钛酸镁复相陶瓷微观形貌和介电性能的影响机理. 结果表明, 当锰的掺杂量小于1.5%时, Mn作为受主掺杂取代占据钙钛矿ABO3的B位, 因此导致居里点略微向高温偏移和相变扩散的发生, 锰的掺杂导致晶格畸变, 促进了晶粒生长, 使晶界相比例下降, 因此介电损耗随着锰掺杂量的增大而减小; 当锰的掺杂量为1.5%时, 介电损耗达到最小值, 继续增大掺杂量, 介电常数下降, 介电损耗上升.     

锰掺杂Ba0.6Sr0．4TiO3-MgTiO3复相陶瓷的制备和介电性能

以分析纯的Ba(NO3)2、Sr(NO3)2、草酸和钛酸丁酯为原料,采用草酸盐共沉淀法制备了钛酸锶钡(Ba0.6Sr0.4tiO3,BST)纳米粉体.XRD和SEM分析结果表明,该方法制备出立方相的Ba0.6Sr0.4TiO3粉体,平均粒径小于100 nm,具有较高的烧结活性.用传统固相法制备了锰掺杂钛酸锶钡.钛酸镁(Ba0.6Sr0.4TiO3-MgTiO3,BST-MT)复相陶瓷,系统研究了掺杂0.1%-2.0%(x,摩尔分数,下同)锰对钛酸锶钡-钛酸镁复相陶瓷微观形貌和介电性能的影响机理.结果表明,当锰的掺杂量小于1.5%时,Mn作为受主掺杂取代占据钙钛矿ABO3的B位,因此导致居里点略微向高温偏移和相变扩散的发生,锰的掺杂导致晶格畸变,促进了晶粒生长,使晶界相比例下降,因此介电损耗随着锰掺杂量的增大而减小;当锰的掺杂量为1.5%时,介电损耗达到最小值,继续增大掺杂量,介电常数下降,介电损耗上升.     

FeCl3/共轭聚席夫碱复合材料的制备及介电性能

由戊二醛和对苯二胺通过缩合反应合成席夫碱聚合物,并将其与三聚氰胺交联构筑立体网状结构,再与氯化铁配位形成具有"海胆状"结构的FeCl_3/席夫碱复合材料,利用傅里叶红外光谱和扫描电镜对其进行表征。通过对比Fe~(3+)掺杂量分别为0.02、0.03、0.04 mol时复合材料半年前后的电导率、介电常数实部与虚部、介电损耗角正切值和科尔-科尔半圆的改变,发现静置后复合材料介电参数均大幅增长,介电弛豫从无到有,并且在刚合成时其介电常数虚部在3.664×10~6~1.000×10~7 Hz为负值,但经过静置后却转变为正值。其中,静置半年后,Fe~(3+)掺杂量为0.04 mol的席夫碱铁盐聚合物在102 Hz处的介电损耗角正切从0.02升至6.13,电导率从7.15×10~(-7)S·cm~(-1)升至2.19×10~(-5)S·cm~(-1),介电常数实部与虚部也大幅增加,介电损耗机理为二重介电驰豫。     

FeCl3/共轭聚席夫碱复合材料的制备及介电性能

由戊二醛和对苯二胺通过缩合反应合成席夫碱聚合物,并将其与三聚氰胺交联构筑立体网状结构,再与氯化铁配位形成具有"海胆状"结构的FeCl₃/席夫碱复合材料,利用傅里叶红外光谱和扫描电镜对其进行表征。通过对比Fe³⁺掺杂量分别为0.02、0.03、0.04 mol时复合材料半年前后的电导率、介电常数实部与虚部、介电损耗角正切值和科尔-科尔半圆的改变,发现静置后复合材料介电参数均大幅增长,介电弛豫从无到有,并且在刚合成时其介电常数虚部在3.664×10⁶~1.000×10⁷ Hz为负值,但经过静置后却转变为正值。其中,静置半年后,Fe³⁺掺杂量为0.04 mol的席夫碱铁盐聚合物在102 Hz处的介电损耗角正切从0.02升至6.13,电导率从7.15×10^-7 S·cm^-1升至2.19×10-5 S·cm^-1,介电常数实部与虚部也大幅增加,介电损耗机理为二重介电驰豫。     

室温固态反应制备纳米Ba1－xSrxTiO3固溶体及其结构与介电性能研究

采用室温固态反应合成了一系列Ba_1－xSr_xTiO₃固溶体纳米粉末(0≤x≤1.0). 经XRD物相分析和d-间距-组成图证明, 产品为立方晶系的完全互溶取代固溶体. TEM形貌观察, 粒子基本为球形, 平均粒径40 nm. 该方法具有产率高, 无需溶剂, 对环境无污染等优点. 通过制陶实验, 分别测定了该系列固溶体的室温介电常数、介电损失以及介电常数随温度的变化. 结果发现, 采用室温固态反应在BaTiO₃中掺入适量锶, 由于掺杂离子均匀进入母体晶格, 引起居里点降低, 室温介电常数达11000以上, 介电损耗由BaTiO₃纯相的0.03 (3%)降为0.008 (0.8%). 纳米粉体的烧结温度为1180 ℃, 比传统微米级粉体的烧结温度降低100～150 ℃.     

CaTiO3:Zn溶胶-凝胶法制备、结构及介电性能

采用溶胶-凝胶法制备了CaTiO3:Zn纳米粒子,透射电镜图显示平均粒径为25 nm.Zn的掺杂位置对于陶瓷相组成和烧结特性有很大影响.Ca1-xZnxTiO3和CaTiO3+zZnO样品的Zn以Zn2TiO4相形式存在;而CaZnyTi1-yO3-δy=0.01)样品中的Zn进入Ti位形成固溶体,无明显的降温效果,当Zn量增至0.05和0.1时,出现ZnO相.ZnO和Zn2TiO4第二相的存在均能明显促进陶瓷烧结.CaTiO3:Zn超细粉体可在较低温度下致密烧结(≤1 250 ℃).1 250℃烧结的CaZnyTi1-yO3-δ(y=0.01)陶瓷具有较好的介电性能:介电常数ε=157,品质因数Q×f=6 819 GHz,谐振频率温度系数(τ)f=7.51×10-4℃-1.     

室温固态反应制备纳米Ba1－xSrxTiO3固溶体及其结构与介电性能研究

采用室温固态反应合成了一系列Ba_1－xSr_xTiO₃固溶体纳米粉末(0≤x≤1.0). 经XRD物相分析和d-间距-组成图证明, 产品为立方晶系的完全互溶取代固溶体. TEM形貌观察, 粒子基本为球形, 平均粒径40 nm. 该方法具有产率高, 无需溶剂, 对环境无污染等优点. 通过制陶实验, 分别测定了该系列固溶体的室温介电常数、介电损失以及介电常数随温度的变化. 结果发现, 采用室温固态反应在BaTiO₃中掺入适量锶, 由于掺杂离子均匀进入母体晶格, 引起居里点降低, 室温介电常数达11000以上, 介电损耗由BaTiO₃纯相的0.03 (3%)降为0.008 (0.8%). 纳米粉体的烧结温度为1180 ℃, 比传统微米级粉体的烧结温度降低100～150 ℃.     

单分散钛酸钡纳米晶的制备

采用溶剂热法制备出表面包裹油酸的单分散立方相钛酸钡纳米晶, 晶粒平均尺寸为6.0 nm, 采用TEM和XRD对其微结构进行了表征; 研究了醇的链长度、油酸用量和热处理温度等对钛酸钡的相组成和形貌的影响规律. 研究结果表明, 产物粒径较小, 粒度分布较窄, 单分散性较好, 其表面为非极性, 可溶于非极性试剂; 由于纳米晶表面由亲油性的长链烷基所覆盖, 与周围的水性环境不相容, 产生一定的斥力; 在重力和该斥力的共同作用下, 纳米晶可以有效地从液相环境中分离出来.     

Low-Temperature Synthesis of Single-Phase Barium Strontium Titanate Thin Film with a nm-Seeding Technique and Its Dielectric Properties

Dielectric barium strontium titanate (Ba_0.5Sr_0.5TiO₃, BST) thin films containing crystalline seeds of BST nanoparticles were prepared on indium titanium oxide (ITO) glass electrodes with a complex alkoxide precursor method. BST precursor solution that dispersed the BST particles was spin-coated on the electrode and annealed at various temperatures. Thickness of the film was about 300 nm, and BST particle concentration in the film was varied from 0 to 17 mol%. An unseeded BST film was crystallized into a perovskite structure by annealing at 600C, while the seeding with the 17 mol%-BST particles promoted crystalline growth of BST perovskite and lowered crystallization temperature of the films to 525C. Measurement of dielectric properties at 1 kHz showed that the 4.9 mol% BST-seeded film annealed at 600C had a relative dielectric constant of 303, which was higher than that of the unseeded BST film.     

聚苯胺/钛酸钡纳米复合粒子的制备与表征

采用原位复合法制备出聚苯胺/钛酸钡复合粒子,借助TEM、XRD、FT-IR、 XPS、TG等分析手段研究了复合粒子的形貌、结构及其热性能.结果表明,复合粒子的粒径为1 μm左右,BaTiO3以40 nm左右的晶粒分散于聚苯胺基体之中,聚苯胺与钛酸钡之间存在化学键合作用,同时在一定程度上减少了纳米粒子的团聚.     

枝晶簇四方相钛酸钡的制备及其电场响应性能的研究

为了提高BaTiO3粒子在含水复合弹性体中的电场响应能力,本文采用简单的水热合成法,在不引入任何表面活性剂的情况下,仅通过对反应温度和溶液pH值的调控获得了新颖形貌的钛酸钡粒子。通过借助X射线衍射(XRD)、拉曼光谱(Raman)、扫描电子显微镜(SEM)及接触角(Contact Angle)测量等手段对粒子的微观结构和表面特性进行表征发现:该粒子为高纯四方相枝晶簇结构,具有良好的亲水性,而且在含水复合弹性体中对电场具有优良的响应能力。     

Preparation of Barium Titanate and Related Materials by the Alkoxide-Hydroxide Route

Formation of perovskites MTiO₃ (M = Ba, Sr) at low temperature (< 100°C) by heterogeneous reactions of M(OH)₂ aqueous solutions with hydrolysis products of Ti(OBu)₄ is discussed. Reaction products are characterized by means of chemical and X-ray analysis, and electron microscopy. Reaction rate is enhanced by hydroxide concentration and reaction temperature, and increases drastically when Sr(OH)₂ is used instead of Ba(OH)₂. Particles shape and size of the perovskites formed is independent of morphology of Ti(OBu)₄ hydrolysis product. The main factor of perovskites morphology regulation lies in the rate of M(OH)₂ absorption. Lowering the absorption rate allows us to prepare uniform perovskite powders which can be readily sintered to ceramic bodies with high dielectric permittivity.     

化学沉淀法制备BaTiO3纳米粉体的研究

以正钛酸(H₄TiO₄)、硝酸钡[Ba(NO₃)₂]为原料, 以双氧水、氨水为溶剂, 采用化学沉淀法制备出晶粒尺寸约20 nm的钛酸钡粉体. 研究了原料种类、煅烧温度、加料方式、反应温度对钛酸钡粉体性能的影响, 确定了最佳的制备条件. 结果表明: 当正钛酸(g)∶双氧水(mL)∶氨水(mL)＝1∶5∶3, 且采用正钛酸的双氧水-氨水溶液缓慢滴加到硝酸钡溶液中的加料方式时, 溶解完全, 制得的BaTiO₃粉体粒径小、纯度高. 用X射线衍射(XRD)和扫描电子显微镜(SEM)表征了颗粒的晶体结构、晶型转变机理以及颗粒的形貌|结果显示: 前驱体的起始晶型转变温度为500, 800 ℃煅烧获得的粒子晶型完整, 形貌呈规则的球形, 当煅烧温度升高到900 ℃时, 粉体晶体结构由立方相转变为四方相.     

简捷水热前驱物技术制备钛酸钡纳米棒与纳米球

A facile synthesis route has been developed to prepare barium titanate nanoparitcles via a low temperature (120 ℃) hydrothermal decomposition of single-source metal-organic precursor. A mixture of tetramethylammonium hydroxide (TMAH) and distilled water was used as reaction media, and Barium titanium ethyl-hexano- isoproxide [BaTi(O₂CC₇H₁₅)(OC₃H₇)₅] was used as precursor. The architecture of products can be selectively controlled from nanorods to nanospheres by adjusting the precursor′s concentration in the reaction system. Powder X-ray diffraction (XRD) analysis indicated that the products were in cubic phase. Transmission electronic microscopy (TEM) observation showed that the nanospheres were 30～50 nm in diameter, and the nanorods were 5～10 nm in diameter and 100～600 nm in length, respectively. Phase transformation behavior of the as-prepared products was also investigated.     

钛酸盐纳米管的制备及光电性能研究

采用水热法制备了钛酸盐纳米管, 并用TEM、XRD、XPS对其进行了表征. 纳米管管径在5~30 nm之间, 管长约为0.1~1 μm, 具有不同于锐钛矿型的钛酸盐结构, 分子组成可能是Na4－xHxTi2O5. 将钛酸盐纳米管制备成纳米管结构电极, 并进行了光电化学研究. 钛酸盐纳米管产生阳极光电流, 具有n型半导体特性.     

Preparation and Properties of Nb-Coated Barium Titanate Composite Particles by Surface Modification with Nb Alkoxide in Hydrophobic Solvent

Chemical processing for the preparation of Nb-coated barium titanate composite particles was investigated using surface modification technology, hydrolyzing Nb ethoxide on the surface of barium titanate particles dispersed in hydrophobic solvent.It was confirmed from the measurements of specific surface area and zeta potential as well as SEM, TEM and EDX observations of the resulting composite particles that the original barium titanate particles were coated uniformly with hydrolysis product of Nb ethoxide.Barium titanates coated with 1 wt% of Nb as oxide were well sintered at 1200–1300°C. The dielectric constants of the sintered barium titanates showed flattened temperature dependence, but it depended upon the average particle size of original barium titanate. The sintered bodies of Nb-coated barium titanate powders with average particle size of 0.2 m gave dielectric constants of 2000–3000 and those of barium titanate with average particle size of 0.5 m showed dielectric constants of 3000–4000 at room temperature.The microstructure of the sintered barium titanate coated with Nb oxide consisted of grains of about 1 m, smaller than those of sintered original barium titanate.