BaFe12 O19纳米粉体的制备与表征

利用Fe(OH)(HCOO)2和Ba(CH3COO)2为原料,C7H8O7.H2O为螯合剂,制得了均一的柠檬酸盐前驱体溶液,将所得的溶液进行喷雾干燥制得了含铁和钡的柠檬酸盐粉体。以制得的粉体为固相反应的前驱体,通过简单的固相分解反应制得了片状的BaFe12O19纳米粉体。同时利用高沸点的液体石蜡对前驱体进行预处理,进一步热分解,得到棒状的BaFe12O19纳米粉体。对前驱体进行了红外(IR)表征。利用热重(TG)技术和X射线粉末衍射(XRD)技术跟踪了前驱体的热分解过程并对所得产物的物相进行了确定。所得产物的形貌由透射电镜(TEM)给出。     

球形纳米BaFe12O19的制备及表面改性

采用柠檬酸盐溶胶-凝胶法、快速升温和预烧热处理工艺合成球形BaFe12O19纳米粒子,并通过硅烷偶联剂进行表面改性。用热重-差热分析、Fourier红外光谱、X射线衍射、扫描电镜、振动样品磁强计和激光纳米粒度仪表征样品的结构、形貌、粒度分布及磁性能。结果表明:750℃可以合成高纯度球形BaFe12O19纳米粒子,粒径为30～50nm,饱和磁化强度为43.95A/(m·kg)。粒子经表面改性后,成功接枝上功能基团—NH—和—NH2,饱和磁化强度增大至49.36A/(m·kg)。热处理温度越高,BaFe12O19的饱和磁化强度越高。     

BaFe12O19/SiO2玻璃陶瓷的合成工艺及电磁特性研究

研究了柠檬酸溶胶-凝胶工艺制备BaFe12O19／SiO2玻璃陶瓷的条件。在SiO2的摩尔分数为50%和67％，铁和钡的摩尔比为5：1～7：1，绕结温度为1000～1100℃时，得到了杂质含量很少的BaFe12O19玻璃陶瓷。测定了玻璃陶瓷在100MHz～6GHz下的复介电常数和磁导率。结果表明：其复介电常数、磁导率实部随测试频率的增加而下降；磁导率虚部数值在0左右波动。     

溶胶-凝胶法制备Y3Al5O12粉体的研究

本文以Y2O3、硝酸铝以及柠檬酸为起始原料，采用溶胶一凝胶法合成了YAG粉体，研究了烧成温度及烧成时间对YAG粉体形成的影响，并利用SEM和XRD等实验技术对粉体进行了表征。结果表明，用溶胶一凝胶法成功地合成了纳米YAG粉体(50～70nm)，且随着烧结温度的升高和烧结时间的延长，颗粒尺寸不断增大。     

α-Fe／BaFe12O19复合粉体的有机凝胶-热还原法制备及磁性能

以柠檬酸和金属盐为原料,采用有机凝胶-热还原法制备了a-Fe／BaFe12O19软硬磁复合粉体。通过X射线衍射、扫描电子显微镜和振动样品磁强计对还原产物的物相、形貌及磁性能进行了表征。结果表明：复合粉体的磁性能与两相的组成及还原工艺有关。随着还原温度升高和时间延长,复合粉体的饱和磁化强度逐渐升高,矫顽力却先下降后上升。在氢气-氮气中经375℃还原1h后,制备的a．Fe／BaFe12O19复合粉体的比饱和磁化强度为58．04A·m^2／kg,矫顽力为32．54kA／m,比剩余磁化强度为24．6Am^2,／kg。     

柠檬酸法合成高性能BaFe12O19超微粉

本文利用柠檬酸法合成了ＢａＦｅ１２Ｏ１９超微粉末，借助于Ｘ－射线衍射法，透射电子显微镜，振动样品磁强计等技术，对粉末的结构，形貌，粒径和磁学性能进行了研究。     

纳米氧化锡粉体的制备及其表征

以廉价的无机盐SnCl4·5H2O为原料,采用溶胶-凝胶法制备出粒度均匀的超细SnO2粉体,考察了制备工艺对纳米SnO2粉体大小及分散状态的影响,并用BET、XRD、TEM等技术对SnO2纳米粒子进行了表征.实验结果表明:采用NH3·H2O作为沉淀剂,控制反应终点pH为2.5,500℃焙烧3h,可制备颗粒尺寸约10nm的SnO2超细粉体.     

Bi4Si3O12纳米粉体的制备与表征

以正硅酸乙酯和Bi2O3为原料,采用溶胶-凝胶法制备了硅酸铋(Bi4Si3O12)纳米粉体.通过X射线衍射和电子显微镜分析了合成粉体的相结构和形貌,测定了粉体的粒度分布曲线,研究了正硅酸乙酯用量对产物相组成的影响.结果表明:干凝胶粉末在750℃热处理2 h,得到了粒径为40～100nm的粉体.正硅酸乙酯的实际用量为理论用量的6倍时,可以制备出相组成为Bi4Si3O1 2的纳米粉体.纳米尺度的Bi4Si3O12材料的激发光谱和发射光谱相对于晶体材料发生了蓝移.     

纳米氧化铪粉体的制备及表征

以HfOI4为原料.NaBH4为沉淀剂,聚乙二醇(PEG)为表面活性剂,分别采用溶胶-凝胶法和沉淀法制备出HfO3纳米粉.并采用TG一DTA、XRD、SEM方法,对制备的前驱体、纳米粉体进行了分析和表征.研究了不同的制备方法对粉体粒径、粒子的影响.结果表明:溶胶-凝胶法制备出纳米粉体呈单斜晶型,平均粒径为20nm左右,粒子为球形,分散性较好,加入表面活性剂聚乙二醇,粒径变大,分散性变差,而化学沉淀法制备出纳米粉体,有少量晶须生成,晶须直径30nm,长度200nm.     

溶胶–凝胶法制备纳米羟基磷灰石粉体

以四水合硝酸钙和五氧化二磷为原料,无水乙醇为溶剂,采用溶胶一凝胶法制备了含co}的羟基磷灰石（hydroxy印atite,HAP）粉体。采用热重-差热分析、X射线衍射、透射电子显微镜、Fourier变换红外光谱等研究了反应体系pH值、反应温度及前驱体热处理温度等因素对产物结构与性能的影响规律,结果表明：采用溶胶-凝胶工艺,调控反应体系的pH、反应温度及前驱体的热处理温度是获得纯度高、分散性较好的纳米HAP粉体的关键。pH值为8．0、反应温度为30℃,经600℃热处理可获得到粒径为40~50nm的HAP纳米粉体。     

Metal-oxide doping enhances electromagnetic wave absorption performance of BaFe12O19 glass-ceramics

Elimination or reduction of electromagnetic wave pollution is receiving increasing attention; development of high-performance wave-absorbing materials has become key to solving this problem. In this study, BaFe₁₂O₁₉ crystals were precipitated in a BaO–Fe₂O₃–B₂O₃–SiO₂ glass system using the melt-quench-second heat treatment method. The microstructure and magnetic properties of the BaFe₁₂O₁₉ glass ceramics and their electromagnetic wave loss characteristics were analyzed. The composition of the crystals in the glass can be modified by introducing other metal oxides, such as ZrO₂ (BFO-Z), TiO₂ (BFO-T), and Al₂O₃ (BFO-A), to enrich the heterogeneous interfaces and increase the dielectric loss of the material. The maximum effective absorption bandwidth of BaFe₁₂O₁₉ glass-ceramics with addition of ZrO₂ (BFO-Z) was increased to 3.20 GHz; the minimum reflection loss was reduced to −45.60 dB. This simple method represents a new direction for fabricating high-performance wave-absorbing materials.     

聚苯胺/钡铁氧体的制备及性能研究

分别采用柠檬酸溶胶-凝胶法和原位聚合法制备了钡铁氧体粒子和聚苯胺-钡铁氧体复合物。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、四探针测试仪等分析手段表征了复合材料的结构,观察了其形貌,测试了其性能。结果表明,钡铁氧体粒子为M型六角晶系片状晶相结构,粒径在10μm～50μm。聚苯胺/钡铁氧体复合材料的电导率随钡铁氧体含量的增加而下降,当BaFe12O19质量分数增加到10%时,电导率从8.85×10-2S/cm急剧下降到2.98×10-2S/cm。而后,随着钡铁氧体含量的增加,电导率变化不大。     

磁铅石型BaFe12O19的制备及性能研究进展

磁铅石型BaFe12O19具有高的居里温度、高的微波磁损、磁化强度大、化学稳定性好,作为一种永磁材料广泛应用于磁记录材料、微波器件、微机电系统（MEMS）等许多领域。本文综述了BaFe12O19的基本制备方法及主要的性能研究,并指出了磁铅石型BaFe12O19制备领域的发展方向。     

Fabrication and characterization of ferrimagnetic bioactive glass-ceramic containing BaFe12O19

Bioactivity of ferrimagnetic glass-ceramics is useful as thermo seeds for hyperthermia treatment of cancer. Ferrimagnetic glass-ceramics were prepared from the BaFe₁₂O₁₉(BF)–SiO₂–CaO–Na₂O–P₂O₅ system using the incorporation method. The mixture was then further sintered at 800 °C to form the glass-ceramic samples. The structure and microstructure of the samples were characterized by X-ray diffraction, energy dispersive X-ray analysis (EDXA) and scanning electron microscopy. Magnetic hysteresis loops of the glass-ceramic samples were obtained with maximum field of 10 kOe, in order to evaluate the potential of these samples for hyperthermia treatment of cancer. In vitro bioactivity was investigated in simulated body fluid (SBF) for 14 days. The results showed that Na₂Ca₂Si₃O₉ and BaFe₁₂O₁₉ were the main phases in the glass-ceramic samples. Apatite was formed on the surface layers of the glass-ceramics, confirming their biocompatibility. It was found that the bioactivity increased with an increase in BF contents.     

Ag2O/BaFe12O19 nanoheterojunctions for rapid photoelimination of atrazine herbicide in water under visible light

The progress in ceramic oxide photocatalysts is a central issue in the environmental remediation of herbicides in water. Atrazine (ATZ) is a potential herbicide applied in different cultivation and food-based manufacturing processes. This paper introduces a solution-based route to synthesize barium hexaferrite (BhF) nanostructures. Formerly, trace amounts (0.4–2.0 wt%) of silver oxide (Ag₂O) were deposited on BhF to produce Ag₂O/BhF nanoheterojunctions. Characterization of the produced materials significantly introduced Ag₂O to the BhF photoactivity without altering the main structural or surface properties. The 1.2 wt%-added Ag₂O/BhF favored light harvesting and reduced the bandgap to 1.56 eV. The dose optimization (0.8 L^–1) of Ag₂O/BhF exhibited rapid photoelimination of ATZ in 40 min with exceptional stability after five cycles. The photocatalytic competence enhancement of Ag₂O/BhF is regarded as the efficient separation of photogenerated carriers by p-n nanojunction construction. This work presents the application of nanoheterojunction oxides for eco-friendly herbicide remediation.     

BaFe9(Ti0.5Mn0.5)3O19铁氧体粉末的合成及磁性能研究

采用溶胶-凝胶自蔓延法合成了BaFe9(Ti0.5Mn0.5)3O19铁氧体粉末,利用XRD、TEM和VSM对样品进行表征及磁性能研究。结果表明,合成样品为均匀单一的纳米级铁氧体粉末,平均粒径80nm,焙烧温度对磁能影响显著,焙烧温度过高不利于提高样品磁性能。     

热处理温度对M型BaFe12O19铁氧体空心微球结构和静磁特性的影响

采用共沉淀火焰喷雾工艺合成了M型BaFe12O19铁氧体空心微球。用热重-差热,X射线衍射和扫描电子显微镜表征了产物的结构,并用振动样品磁强计测量了它的静磁性能。结果表明：当热处理温度为800-1100℃,保温3h时,能形成单相M型铁氧体空心微球。随着热处理温度的升高,晶体结构越完整,饱和磁化强度增大,矫顽力减小。     

Magnetic properties and remanence analysis in permanently magnetic BaFe12O19 foams

In the present study, magnetic properties of barium ferrite foams were investigated. We especially examine the effects of porosity on interparticle interactions and remanence properties of these materials. It was observed that magnets become harder with porosity. On the other hand, saturation magnetization decreases slightly. Existence of porosities increases the strength of demagnetising-like interactions of neighboring particles.