微通道连续沉淀法制备球形BaTiO3颗粒及其在医学检测干片上的应用

以BaCl₂、TiCl₄、NaOH为原料，采用微通道连续沉淀法制备纳米级球形形貌的BaTiO₃颗粒。考察了钡浓度、体积流量、反应温度及两分支物料流量比等因素对产物形貌及粒径大小的影响，并将其与间歇沉淀法得到的产物进行了比较。实验结果表明：钡浓度0.15 mol/L，碱浓度3 mol/L，两分支物料体积流量均为2 ml/min，反应温度90℃条件下可制备得到具有规整球形形貌、粒径分布均匀的纳米级BaTiO₃颗粒，其粒径为80～150 nm。最后，将所得BaTiO₃扩散层应用到肌酸激酶干片中，重复性较好，且浓度梯度明显，光反射率值与浓度的关系与之对应。结果具有较高的可信度，说明微通道连续沉淀法得到的BaTiO₃颗粒在医用干片上应用是可行的。     

类球形低硫磷酸铁的制备技术研究

磷酸铁（FePO₄）是锂电池正极材料磷酸铁锂（LiFePO₄）的核心前驱体,FePO₄形貌及硫含量对合成的LiFePO₄材料性能有重要影响。为得到类球形低硫FePO₄产品,在传统液相沉淀法技术基础上做了改进优化,添加十六烷基三甲基溴化铵（CTAB）作为形貌助剂提高产品球形度,添加氨水作为配体形成磷酸铁铵配合物改善结晶过程,降低产品硫含量。结果表明：所制备的FePO₄产品硫质量分数低,达到2.6×10 ^-5,形貌为均一的微米类球形颗粒,D₅₀=11.4 μm,振实密度达到1.22 g/cm ³,有望成为制备高压实密度LiFePO₄材料的核心前驱体。     

钛酸钡与铌酸钾钠无铅压电陶瓷研究进展

钛酸钡(BaTiO₃)和铌酸钾钠(K_0.5Na_0.5NbO₃)压电陶瓷因具有环境友好、电学性能良好、居里温度较好等优势而成为国际高新技术材料研究的前沿热点,有望替代部分铅基压电陶瓷应用于国防、航空航天、通信等领域的电子器件中。本文综述了BaTiO₃和K_0.5Na_0.5NbO₃压电陶瓷材料的最新研究进展,从构造相界调控压电性能、BaTiO₃基压电陶瓷的材料体系设计、K_0.5Na_0.5NbO₃基压电陶瓷的热稳定性及改善、压电陶瓷的新型成型及烧结工艺等方面进行客观分析和总结,并展望了两种材料的未来发展趋势,为开发高性能无铅压电陶瓷提供参考。     

纳米氧化铬的制备与应用研究进展

氧化铬(Cr₂O₃)是无机盐行业主要产品之一，广泛应用于化工、冶金、机械等领域，在国民经济中具有重要的作用。大量研究表明，当Cr₂O₃的粒度达到纳米尺度时，将拥有更多独特效应(如小尺寸效应、表面效应等)，为新材料的开发应用提供了新思路。结合近年来国内外在纳米Cr₂O₃研究与应用领域的最新进展，对纳米Cr₂O₃的制备方法进行了详细综述，主要包括气相法(化学气相沉积法、微波等离子体法、激光气相沉积法)、湿化学法(沉淀法、微乳液法、溶胶-凝胶法、水热/溶剂热法、模板法)和固相法(固相热分解法、高能球磨法)；介绍了纳米Cr₂O₃在除颜料、耐磨防腐蚀涂层、气敏传感器等传统应用场景以外，在高效催化、新能源材料等新兴领域的应用进展。通过总结对比，提出了将湿化学法与固相法结合规模化制备高稳定纳米Cr₂O₃有效路径的建议。指出“双碳”目标战略背...     

BaTiO3-TiO2复合光催化剂降解盐酸四环素及机理研究

以钛酸丁酯(TBOT)和钛酸钡(BaTiO₃)为原料,采用水热法制备了BaTiO₃-TiO₂复合光催化剂,研究了不同煅烧温度(400,500,600,700℃)对复合光催化剂结构、形貌及对盐酸四环素(TCH)光催化性能的影响。结果表明：煅烧温度的升高促进了部分TiO₂向BaTiO₃的转变,BaTiO₃的衍射峰增强,晶粒尺寸逐渐增大,球状颗粒的生长成型更为完全。BaTiO₃-TiO₂复合光催化剂的禁带宽度为3.03 eV,煅烧温度的变化没有改变BaTiO₃-TiO₂的吸收带边,复合光催化剂的吸收强度随煅烧温度的升高先增大后减小,600℃退火处理的BaTiO₃-TiO₂光催化剂吸收强度最高。在180 min时,600℃退火的BaTiO₃-TiO₂光催化剂对TCH的降解率最高可达92.80...     

表面活性剂在超细粉体制备和分散中的应用

综述了表面活性剂在超细粉体制备和使用分散过程中的应用;介绍了几种制备超细粉体的湿化学法,包括溶胶-凝胶法、化学沉淀法、微乳液法、水热合成法,并介绍了表面活性剂在其中的应用情况;简要说明了表面活性剂的分散机理及分散过程中存在的影响因素;随着超细粉体技术的不断发展,表面活性剂应用技术也在不断地发展,展望了表面活性剂在超细粉体材料领域的广阔应用前景。     

X8R型BaTiO3基细晶陶瓷的制备、结构和性能

由于在-55~150 ℃存在正交-四方和四方-立方相变,相变对应的尖锐介电峰使BaTiO₃陶瓷介电性能难以满足X8R温度稳定性要求。本文采用50 nm的纳米BaTiO₃粉体和少量堇青石(MgO-Al₂O₃-SiO₂, MAS)玻璃,制备了满足X8R介电温度特性的BaTiO₃基细晶陶瓷。结果表明,随着MAS玻璃的加入,BaTiO₃基陶瓷的室温晶体结构从四方相转变成赝立方相,平均晶粒尺寸从纯BaTiO₃陶瓷的1.904 μm显著降低到添加0.5%(质量分数)MAS玻璃的BaTiO₃基陶瓷的183 nm。与此同时,BaTiO₃基陶瓷虽然介电常数有所下降,但是介电损耗和介电性能的温度稳定性大幅度改善。其中添加0.5%MAS玻璃的BaTiO₃基细晶陶瓷介电性能为:在1 kHz时室温介电常数为984,介电损耗为0.006 5,满足X8R温度特性要求。     

BaTiO3改性对碳/碳复合材料力学性能的影响

以聚丙烯腈(PAN)基碳纤维无纬布和短切网胎纤维交互叠层针刺,在预制体制备过程中掺杂0%、5%、15%、25%和35%五种不同质量分数的BaTiO₃,制备得到纵向纤维排布环形碳纤维预制体,通过化学气相沉积(CVD)和液相浸渍相结合的方法,制备得到BaTiO₃改性碳/碳复合材料。对该复合材料进行垂直和平行两个方向的力学性能测试,并且观察断口处的组织结构及其形貌特征。结果表明,引入纳米BaTiO₃后,加快了热解碳形核与生长的过程,改变了热解碳的组织结构,由单一的光滑层组织结构转变为光滑层和粗糙层两种组织结构。随着BaTiO₃含量的增加,复合材料的垂直压缩强度先基本不变后逐渐增大,平行压缩强度先增大后减小。复合材料的垂直压缩断裂方式均为脆性断裂,平行压缩断裂方式也均为脆性断裂同时呈现层间断裂的特征。     

乙醇-水体系3D纳/微米球形磷酸铁的制备与表征

提出了一种在温和条件下制备高振实密度球形磷酸铁的简单方法。制备过程中无需引入碱性物质调节pH和添加其他模板剂,仅以九水合硝酸铁[Fe（NO₃）·9H₂O]和磷酸（H₃PO₄）为原料,在乙醇-水体系中即可制备3D纳/微米球形磷酸铁（记为FPE）。采用扫描电镜（SEM）、激光粒度仪、X射线衍射仪（XRD）、热重-差式扫描量热仪（TG-DSC）、比表面积测试仪（BET）等对制备的磷酸铁进行表征分析。结果显示,制备的磷酸铁具有3D纳/微米球形结构,平均一次粒径为27.2 nm,二次粒径D₅₀为3.75 μm。FPE的组成为二水合磷酸铁（FePO₄·2H₂O）,纯度较高,具有介孔结构,平均孔径为2.75 nm,比表面积为22.41 cm ²/g,同时具有较高的振实密度（1.34 g/cm ³）。3D纳/微米球形磷酸铁制备方法简单,性能优异,以其为前驱体制备的磷酸铁锂（LiFePO₄/C）具有较高的振实密度（1.46 g/cm ³）,在0.2C倍率下的放电比容量为157.9 mA·h/g。     

织构PNN-PZT陶瓷的光固化成型制备及其电学性能研究

为高效制备织构压电陶瓷,以球状Pb(Ni_1/3Nb_2/3)O₃-PbZrO₃-PbTiO₃ (PNN-PZT) 为基体粉体,片状BaTiO₃ （BT）为模板粉体,采用光固化成型技术代替传统流延技术制备织构压电陶瓷。研究了粉体形貌对打印浆料流动性的影响、浆料的光敏参数以及不同BT含量织构陶瓷的晶体结构和电学性能。结果表明,球状粉体浆料具有低黏度的特性,能够有效提高打印浆料的固含量,最大固含量可达86%（质量）。此时陶瓷浆料的临界曝光量与透射深度分别为127.5 mJ/cm²和21.1 μm。打印后的PNN-PZT-BT陶瓷沿[00l]_c方向生长,BT模板粉体含量从1%增长到5%,陶瓷的织构度由42%增到92%。当BT含量为3%时,样品具有最高的压电常数d₃₃=1047 pC/N。与传统的流延法相比,SLA技术的工艺优势在于制备周期短,稳定性高,能够有效降低织构陶瓷的制备难度。     

织构PNN-PZT陶瓷的光固化成型制备及其电学性能研究

为高效制备织构压电陶瓷,以球状Pb(Ni_1/3Nb_2/3)O₃-PbZrO₃-PbTiO₃ (PNN-PZT) 为基体粉体,片状BaTiO₃ （BT）为模板粉体,采用光固化成型技术代替传统流延技术制备织构压电陶瓷。研究了粉体形貌对打印浆料流动性的影响、浆料的光敏参数以及不同BT含量织构陶瓷的晶体结构和电学性能。结果表明,球状粉体浆料具有低黏度的特性,能够有效提高打印浆料的固含量,最大固含量可达86%（质量）。此时陶瓷浆料的临界曝光量与透射深度分别为127.5 mJ/cm²和21.1 μm。打印后的PNN-PZT-BT陶瓷沿[00l]_c方向生长,BT模板粉体含量从1%增长到5%,陶瓷的织构度由42%增到92%。当BT含量为3%时,样品具有最高的压电常数d₃₃=1047 pC/N。与传统的流延法相比,SLA技术的工艺优势在于制备周期短,稳定性高,能够有效降低织构陶瓷的制备难度。     

Synthesis of Ultrafine and Spherical Barium Titanate Powders Using a Titania Nano-Sol

A novel synthetic method for the preparation of spherical, homogeneous, and ultrafine barium titanate (BaTiO₃) powders is described. An aqueous titania nano-sol was prepared by peptizing coarse aggregate of hydrous titania with nitric acid. BaTiO₃ powders could be synthesized through a simple reflux method using the titania nano-sol and barium hydroxide. As decreasing the titanium concentration, the particle size of the resulting spherical BaTiO₃ powder was increased from 40 to 130 nm and the porosity also increased. It was revealed that the smaller as-prepared BaTiO₃ powder was less porous and became more tetragonal with less intragranular pores after annealing. With this method, a highly tetragonal BaTiO₃ powder ( c / a ∼1.008) with a particle size of 120.0 nm was successfully prepared and would be very suitable for the thinner dielectrics in higher capacitance multilayer ceramic capacitors.     

Preparation of BaTiO3 by the hydrothermal method

The results of hydrothermal preparation of BaTiO₃ fine powders are reported. The effects of the reaction temperature, the molar ratio of Ba/Ti in the precursors, the chemical form of the precursors on the phase composition, the size and the morphology of the products are presented. The higher the temperature, the higher the basicity and the greater the molar ratio of Ba/Ti in the precursor, the easier the formation of the perovskite type BaTiO₃ crystallite will be. It was found that BaTiO₃ microcrystals(150–300 nm) could be synthesized through the hydrothermal reaction of commercial TiO₂ with Ba(OH)₂ aqueous solution, while the hydrothermal reaction of the newly prepared Ti(OH)₄ gel with the Ba(OH)₂ solution produced highly crystallized, well dispersed perovskite type BaTiO₃ crystallites with very fine (< 100 nm) particles. The newly prepared Ti(OH)₄ gel proved to be suitable precursor for the hydrothermal preparation of BaTiO₃ fine powders. X-ray diffraction (XRD) of the hydrothermal BaTiO₃ powders reveals a simple cubic perovskite structure. Above that, the lattice constant decreased with the increase of the reaction temperature. These abnormal crystallographic features are assumed to result from lattice defects, due to OH⁻ incorporation in the perovskite lattice.     

Sintering Behavior of Nanocrystalline Zirconia Prepared by Chemical Vapor Synthesis

Powder synthesis and ceramic processing methods have to be improved to take full advantages of new, improved properties of nanocrystalline ceramics. Sintered nanocrystalline ceramics of pure, undoped zirconia are formed from nanocrystalline powder of optimized quality obtained by the chemical vapor synthesis (CVS) method. The as-synthesized CVS ZrO₂ powder is nonagglomerated with a crystallite size of about 5 nm, narrow size distribution, and high crystallinity. On uniaxial compaction a transparent green body of ultrafine, uniform microstructure and narrow pore size distribution corresponding to the grain size distribution is formed, which is sintered under vacuum at 950°C into a transparent, fully dense ZrO₂ ceramic with a grain size of 60 nm.     

硅酸铋(Bi4Si3O12)粉体制备的研究进展

Bi₄Si₃O₁₂晶体作为一种性能优异的新型闪烁体,在各个方面有着重要的作用,粉体制备有着重要的意义。本文综述了硅酸铋粉体的制备技术,有固相法、高能球磨法、溶胶-凝胶法、水热法和化学溶液分解法等,同时讨论了各个方法的优缺点,最后展望了硅酸铋粉体制备的未来发展趋势。     

Solid-State Synthesis of Ultrafine BaTiO3 Powders from Nanocrystalline BaCO3 and TiO2

Barium titanate has been prepared by solid-state reaction of nanocrystalline TiO₂ (70 nm) with BaCO₃ of different particle size (650, 140, and 50 nm). The results give evidence of a strong effect of the size of BaCO₃ in the solid-state synthesis of barium titanate. The use of nanocrystalline BaCO₃ already leads to formation of the single-phase BaTiO₃ after calcination for 8 h at 800°C. The final powder consists of primary particles of ≈100 nm, has a narrow particle size distribution with d ₅₀=270 nm, and no agglomerates larger than 800 nm. For the coarser carbonate, 4 h calcination at 1000°C are required and the final powder is much coarser. Solid-state reaction of nanocrystalline BaCO₃ and TiO₂ represents an alternative to chemical preparation routes for the production of barium titanate ultrafine powders.     

Hydrothermal Synthesis of Spherical Perovskite Oxide Powders Using Spherical Gel Powders

Spherical perovskite oxide powders, composed of fine particulates, were prepared by using spherical gel powders under hydrothermal conditions. Spherical PbTiO₃, BaTiO₃, and SrTiO₃ powders were synthesized from spherical TiO₂ gel powders, and spherical PbZrO₃ powder from spherical ZrO₂ gel powder. Spherical Pb(Zr_0.5, Ti_0.5)O₃ and Ba(Zr_0.5,Ti_0.5)O₃ powders were prepared from spherical ZrTiO₄ gel powders. Lead acetate trihydrate, barium hydroxide octahydrate, and strontium hydroxide octahydrate were used as the sources of A-site ions in each perovskite oxide (ABO₃). The spherical TiO₂ and ZrO₂ gel powders were prepared by thermal hydrolysis of titanium tetrachloride and zirconium oxychloride, respectively, and spherical ZrTiO₄ gel powder by thermal hydrolysis of a mixture of them in alcohol-water mixed solvent. During the hydrothermal treatment, the spherical gel powders retained their spherical shape to produce spherical perovskite oxide powders, composed of nanometer-sized particulates.     

氮化硅粉体制备技术及粉体质量研究进展

氮化硅(Si₃N₄)具有优异的物化性能,在国防、电子信息等关键领域都占据重要的地位。高质量粉体是制备高性能Si₃N₄陶瓷的首要前提。通常高质量Si₃N₄粉体需要满足粒径细、分布窄、α相含量高、杂质含量低等条件。基于合成反应体系综述了当前国内外制备Si₃N₄粉体的方法,着重从强化传热与传质角度介绍了改善粉体质量的研究进展,并介绍了当前工业生产现状,展望了高质量Si₃N₄粉体制备技术的发展趋势和方向。