Magnetic Co2Y ferrite, Ba2Co2Fe12O22 fibres produced by a blow spun process

Gel fibres of Co2Y,Ba2Co2Fe12O22, were blow spun from an aqueous inorganic sol and calcined at temperatures of up to 1200°C. The ceramic fibres were shown by X-ray diffraction to form crystalline Co2Y at 1000°C, and surface area and porosity measurements indicated an unusually high degree of sintering at this temperature. The fibres also demonstrated a small grain size of 1–3 m across the hexagonal plane and 0.1–0.3 m thickness at 1000°C. This only increased to 3 m in diameter and 1 m thickness even at temperature up to 1200°C. The fibrous nature combined with the improved microstructures could be an important factor in improving the magnetic properties of this material.     

静电纺丝法制备磁铅石型Ba0.5Sr0.5Fe12O19纳米纤维及其磁性研究

采用静电纺丝结合溶胶-凝胶技术于800℃煅烧制备了铁氧体Ba0.5Sr0.5Fe12O19纳米纤维,利用XRD、SEM、EDS、TEM分别对样品的物相、形貌、结构等进行了表征.结果表明,所得产物为六方磁铅石型Ba0.5Sr0.5Fe12-O19多晶纤维,纤维直径为100～500nm,Scherrer公式计算晶粒尺寸为40nm.采用振动样品磁强计(VSM)表征样品的磁性能,饱和磁化强度、剩余磁化强度和矫顽力分别为66.659emu/g、35.093emu/g和5097.2Oe,与用传统溶胶-凝胶法在相同温度下煅烧制得的粉体样品相比,磁性能明显提高.     

利用还原共沉淀法制备纳米四氧化三铁磁性粉体

利用还原共沉淀法制备了纳米四氧化三铁。采用FT-IR、TEM、XRD、VSM和比表面积测试表征样品的性质。结果表明该方法制备的四氧化三铁颗粒程球形,平均粒径大约21nm。红外光谱表明了样品离子可以被表面活性刺有效包袱。磁滞回线测试结果表明该样品具有超顺磁性,其饱和磁化强度达到37．34Am^2／kg。     

BaPbZnCo-Y型铁氧体的柠檬酸溶胶-凝胶合成及其微波性能研究

采用柠檬酸sol-gel工艺合成了Ba2-ZpBZzN1.2Co0.8Fe12O22(z=0.0、0．5、1．0、1．5）Y型铁氧体。采用XRD、SEM对其相成分、显微结构进行研究。并对其复介电常数和复磁导率在1MHz-6GHz下的变化规律进行了研究。结果表明，铁氧体的复介电常数基本不随测试频率的变化而变化，其μ″谱上显示出非常明显的由自然共振引起的共振峰，该共振峰随铁氧体粉末热处理温度的升高移向低频。     

Ba2ZnZCo2-ZFe12O22-SiO_2微晶玻璃陶瓷的sol-gel合成及性能研究

采用柠檬酸sol-gel工艺合成了Ba₂Zn_ZCo_2-zFe₁₂O₂₂-SiO₂微晶玻璃陶瓷;采用XRD、SEM对其相成分、显微结构进行了分析,结果表明,1200°C/5h得到的Ba₂Zn_ZCo_2-zFe₁₂O₂₂-SiO₂微晶玻璃陶瓷的平均晶粒尺寸在0.3μm左右;采用HP8753E网络分析仪测定了微晶玻璃陶瓷在100MHz～6GHz范围内的介电常数及其磁导率,其复介电常数值、磁导率实部都随测试频率的增加而减小,其磁导率虚部～f曲线上显示出明显的自然共振峰。     

溶胶自燃烧法制备纳米Mn0.5Zn0.5Fe2O4和BaZn2Fe16O27粉体

以柠檬酸与硝酸盐为原料通过溶胶自燃烧法制备出纳米Mn0.5Zn0.5Fe2O4和BaZn2Fe16O27粉体.采用XRD、TG-DSC、TEM、AA、BET及VSM等方法对产物进行了表征,结果表明,在1000℃灼烧后分别得到了单相尖晶石型Mn0.5Zn0.5Fe2O4纳米粒子和六角磁铅石型BaZn2Fe16O27纳米粒子,其晶型完整,分散性好.     

Sol-gel自蔓延燃烧制备CaCu3Ti4O12纳米粉体及其介电性能研究

以硝酸钙、硝酸铜、钛酸四丁酯、冰乙酸和无水乙醇为原料,采用溶胶-凝胶自蔓延燃烧反应成功地制备了平均粒径为60～80nm的CaCu3Ti4O12纳米粉体.采用XRD、TEM和IR对纳米粉体的结构、形貌和光谱特性进行了分析和表征,并借助TG-DSC研究了干凝胶的自蔓延特性和晶化过程.采用传统烧结工艺制备了陶瓷,测得其在室温、lkHz时的介电常数为6×104.     

Synthesis of Nanosized Ba2LaZrO5.5 Ceramic Powders through a Novel Combustion Route

A single-step process for the preparation of nanoparticles of Ba₂LaZrO_5.5 is reported in this paper. The process is a modification of the combustion method, which resulted in Ba₂LaZrO_5.5 phase without a calcination step. This complex perovskite ceramic oxide thus obtained is characterized by high-resolution transmission-electron microscopy, X-ray and electron diffraction, thermal analysis, FT-IR spectroscopy, surface area measurements, and particle-size analysis. The particle size of Ba₂LaZrO_5.5 was in the range 10–70 nm and were of regular shape with well-defined grain boundaries.     

原位生长法制备Fe3O4/TiO2纳米磁性复合体及其表征

采用原位生长法,以钛氧有机化合物为前驱物低温液相在磁性Fe3O4的表面直接形成纳米TiO2,制得Fe3O4/TiO2纳米磁性复合体,利用XRD、SEM、DLS、XPS和PPMS(磁性材料综合物性测量系统)对样品的结构和性能进行表征,并讨论Ti-O-Fe键的形成机理。结果表明:Fe3O4表面被锐钛型的TiO2包覆,且包覆效果良好。该磁性复合体颗粒分布均匀,平均粒径为59nm,饱和磁化强度为3.2emu/g,矫顽力为21Oe。     

Influence of manganese dioxide and Ba2Co2Fe12O22‐additives on the magnetic power loss of Ni0.8Zn0.2Fe2O4 ferrites

Manganese dioxide and Ba₂Co₂Fe₁₂O₂₂ added Ni_0.8Zn_0.2Fe₂O₄ ferrites were prepared by solid state reaction process. The structure and magnetic properties of the ferrites were investigated by X‐ray diffractometer and magnetic flux density‐magnetic field analyzer. It was found that the magnetic loss shows increase‐decrease‐increase variation trend with the increase of manganese dioxide additive concentration, and the optimal concentration of manganese dioxide doping is about 1.2 wt.%. Compared with the sample without manganese dioxide doping, further investigation revealed that the hysteresis loss coefficient and eddy current loss coefficient decreased in 1.2 wt.% manganese dioxide doping nickel zinc ferrite, but the residual loss coefficient increased with manganese dioxide doping.     

反应时间对Ba_2Co_(0.4)Zn_(1.0)Cu_(0.6)Fe_(12)O_(22)(Co_2Y)铁氧体性能的影响

采用化学共沉淀法制备Y型平面六角铁氧体(Ba2Co0.4Zn1.0Cu0.6Fe12O22)前驱体,并通过激光粒度分析仪(LPS)、扫描电子显微镜(SEM)、X射线衍射仪(XRD)、振动样品磁强计(VSM)和E4991A精密阻抗分析仪等手段研究了共沉淀反应时间对粉体及烧结样品的粒径、表面形貌、晶体结构和磁性能的影响。结果表明,当共沉淀反应时间为90 h时,得到的前驱体粉体粒径分布均匀,平均粒径约为1μm。在900℃烧结后能够得到较纯相的Y型平面六角铁氧体。烧结样品的相对密度超过95%,频率为1 GHz时,起始磁导率μi≈3.7,品质因数Q≈5.8,共振频率fr2.5 GHz,截止频率在3 GHz左右。     

超声波化学法制备纳米铁酸锌粉末的影响因素

超声辐射Fe(NO3)3·9H2O、不同锌盐和脲的混合水溶液得到前驱体,再经过高温焙烧得到纳米ZnFe2O4粉末.得到的纳米ZnFe2O4粉末用X射线衍射(XRD),傅立叶转换红外光谱(FT-IR)表征得到确认.系统研究了超声波化学法制备纳米铁酸锌粉末工艺中不同锌盐、超声波辐射时间、焙烧温度和焙烧时间等影响因素,结果表明:Fe(NO3)3·9H2O与Zn(NO3)2·6H2O为原料,超声波辐射为4h,焙烧温度为950q℃,焙烧时间为14h可制备结晶良好、分散性好、粒度小于100nm的尖晶石型铁酸锌粉末.     

Magnetic Properties of Y3Fe5O12 Nanoparticles Doped Bi and Ce Ions

Y_2.9-xCe_0.1Bi_xFe₅O₁₂ (x = 0-0.5) nanoparticles ranging from 58 to 63 nm were fabricated by a sol-gel method, and their crystallite structures and magnetic properties were investigated by X-ray diffraction (XRD), IR spectroscopy, and vibrating sample magnetometer (VSM). Results of VSM show that the saturation magnetization intensity increased with increase in Ce content (0.1), decrease in Bi concentration (x), and increase in particle size of the formulation.     

Synthesis and Magnetic Properties of SrO–Fe2O3–B2O3 Glass-Ceramics

Glasses with nominal compositions of SrFe₁₂O₁₉ + 8SrB₂O₄ (I) and SrFe₁₂O₁₉ + 12Sr₂B₂O₅ (II) are prepared by rapid quenching from the liquid state and are converted to glass-ceramics containing fine magnetic particles of SrFe₁₂O₁₉ by heat treatment between 600 and 950°C. The materials are characterized by x-ray diffraction, differential thermal analysis, electron microscopy, and magnetic measurements. The phase transformations accompanying glass crystallization are identified. The glass composition and heat-treatment conditions are shown to influence the aspect ratio of the forming submicron-sized strontium hexaferrite particles. The strongest coercive fields reached in glass-ceramics I and II are 504 and 456 kA/m, respectively.     

Magnetic Properties of Fe 3 O 4 Nanoparticles Synthesized by Coprecipitation Method

In this paper, we elucidate several specific magnetic properties of Fe ₃ O ₄nanoparticles synthesized by coprecipitation method. The characterizations by X-ray diffraction technique (XRD) and scanning electron microscopy (SEM) showed the particles to be of spinel structure and spherical shapes whose diameter could be controlled in the range from 14 to 22 nm simply by adjusting the precursor salts concentration and coprecipitation temperature. Magnetic properties of the Fe ₃ O ₄ nanoparticles measured by using vibration sample magnetometer (VSM) indicated the saturation magnetization and blocking temperature to increase with the particles size. Fe ₃ O ₄ nanoparticles with crystal size smaller than 22 nm exhibits superparamagnetic behavior at room temperatures. Characteristic magnetic parameters of the particles including saturation magnetization, effective anisotropy constant, and magnetocrystalline anisotropy constant have been determined. The observed decrease of saturation magnetization was explained on the base of core-shell model. A simple analysis indicated that the shell thickness decreases with an increase in particle size.     

Fe2O3/TiO2和ZnO/TiO2纳米颗粒薄膜的亲水性能和光催化性能的研究

采用溶胶-凝胶法在玻璃上制备了锐钛矿型TiO_2和过渡金属铁、锌离子掺杂的TiO_2薄膜,并通过XRD、XPS、AFM表征了合成的薄膜。结果表明铁和锌离子掺入后,TiO_2薄膜变的更加致密。铁离子和锌离子分别以Fe_2O_3和ZnO的形式存在,在紫外光照射下,TiO_2薄膜表现明显的亲水性,金属离子掺杂的TiO_2薄膜,亲水性能明显增强,铁离子掺入对光催化降解甲基橙有一定的抑制作用;少量的锌离子掺入对光催化降解甲基橙有促进作用,锌离子掺入量增大后,效果并不明显。