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。     

纳米NiZn铁氧体纳米晶的制备及表征

应用化学共沉淀法制备了NiZn铁氧体的前驱体粉末。对前驱体在900℃热处理后,得到尖晶石型NiZn铁氧体样品。用X射线衍射（XRD）和电子扫描显微镜（SEM）对其进行表征,结果表明：样品的晶体形貌为准六角形,粒径大小Dsem≈3.5μm,而Dxrd≈80nm,即Dsem≈44Dxrd这是NiZn铁氧体制备领域一个新颖的结果。采用该方法制备的样品可能具有一定的实用价值与经济价值。     

微波烧结Mn-Zn 铁氧体的微观结构演变特征

以传统氧化物法合成的Mn-Zn铁氧体前驱体和外购前驱体为实验原料,经压制成形后用频率为2.45 GHz的微波在1 200~1 400℃烧结制备Mn-Zn铁氧体软磁材料.对烧结过程样品的微观结构和形貌进行了研究,并探究了烧结过程致密化特性及微波加热温度对Mn-Zn铁氧体密度的影响.研究表明:微波烧结的Mn-Zn铁氧体具有典型的尖晶石结构,样品主体相为Mn0.4Zn0.6Fe2O4;用SEM观察样品形貌,发现在1 350~1 400℃烧结的样品结晶状况良好,晶界平直,烧结组织均匀;微波烧结温度对密度有较大影响,在1 200~1 400℃,随着烧结温度升高样品密度增高,密度为4.80~5.28 g/cm3,在1 400℃烧结样品比较致密.微波烧结可以实现样品的快速致密.     

气泡液膜法制备Ni_(0.7)Zn_(0.3)Fe_2O_4铁氧体的前驱体纳米粒子

采用新颖的气泡液膜法,将Zn2+、Ni2+和Fe3+与OH-的共沉淀反应在气泡液膜中完成,制备了Ni0.7Zn0.3Fe2O4铁氧体前驱体纳米粒子,经元素分析、FT-IR、XRD和SEM等表征。实验结果表明,前驱体较精确地保持了原料溶液中Zn2+、Ni2+和Fe3+的配料摩尔比。前驱体分别经300、400、500、600、700或800℃烧结,制得Ni0.7Zn0.3Fe2O4铁氧体,用XRD和VSM表征。结果表明,在700℃烧结制得的Ni0.7Zn0.3Fe2O4铁氧体的粒径为26.92nm,磁饱和磁化强度sσ=64.22A.m2/kg,剩余磁化强度rσ=14.25A.m2/kg,内秉矫顽力jHc=16kA/m。将这种Ni-Zn铁氧体分散到合成油中,制成耐高温磁性液体。     

铝单醇盐Sol-Gel法合成镁铝尖晶石纳米粉及烧结行为的研究

以四氢呋喃作稳定剂，通过异丙醇铝在硝酸镁溶液中水解的Sol-Gel过程合成了MgAl2O4尖晶石纳米粉体，采用DTA、XRD及TEM等分析手段研究了其前驱体的晶化过程和不同煅烧温度对尖晶石粉体晶粒尺寸及烧结性能的影响。结果表明，该方法能明显降低MgAl204的合成温度，在900℃已能得到单一尖晶石相纳米粉体，一次粒子平均粒径约为20nm．并且，900℃煅烧的粉体烧结活性最高，在1600℃烧结即能获得相对密度为99％的致密尖晶石陶瓷。     

自燃/球磨法制备NiZn系铁氧体

以金属硝酸盐和柠檬酸为原料,用溶胶凝胶自燃烧法制备NiZn系铁氧体前驱体粉末(Ni0.4Zn0.6Fe2O4,Ni0.2Zn0.6Cu0.2Fe2O4,Ni0.33Zn0.59Cu0.11Fe1.97O4(Bi2O3)0.002和Ni0.33Zn0.59Cu0.11 Fe1.97O4(Bi2O3)0.002(MnO2)0.02),然后经30小时高能球磨,从X-ray衍射谱中发现前驱体粉末虽然基本上是尖晶石结构,但是还有一些杂相,经过球磨,杂相明显减少,结构更加完整,颗粒减小.前驱体粉末Ni0.33Zn0.59Cu0.11Fe1.97O4(Bi2O3)0.002经30小时球磨后,在空气中退火,退火温度分别为400℃,600℃,800℃,900℃,1000℃.用X-ray衍射谱分析其物相,发现在800℃退火得到单相的尖晶石结构,无杂相.该样品的最佳退火温度低于1000℃.用振动样品磁强计分别测量制备态和退火态样品粉末的磁性,可以看出,随退火温度的升高,比饱和磁化强度σs逐渐增大,矫顽力Hc逐渐减小,当900℃退火后,比饱和磁化强度已接近块状NiZn系铁氧体.1000℃退火后,上述四种样品中Ni0.4Zn0.6Fe2O4具有最高的比饱和磁化强度σs=65.09emu/g.本文为NiZn铁氧体的低温烧结提供了有用的实验数据.     

固相反应法、柠檬酸盐法制备(NaBi)0.5TiO3陶瓷及性能表征

分别用固相反应法和柠檬酸盐法合成了(NaBi)0.5TiO3陶瓷前驱体,并烧制成相应的陶瓷。用激光粒度分析仪、XRD、SEM分别对前驱体和陶瓷的粒度、相组成、显微结构等进行表征,并检测不同烧结温度下的压电常数d33。研究表明,用柠檬酸盐法合成的NBT前驱体所需合成温度低于固相反应法;所制陶瓷具有更高的压电常数d33,在1150℃下烧结,d33可达61.6pc/n。     

复合纳米纤维静电纺丝法的制备及其磁性

以聚乙烯吡咯烷酮（PVP）和金属盐为原料,利用静电纺丝法成功制备出了摩尔比为1：1的SrTiO3-SrFe12O19磁电复合纳米纤维。并通过FT-IR,XRD,SEM和VSM等技术对纤维前驱体及其产物的结构、热处理产物的物相、形貌及磁性能进行了表征。结果表明,样品经900℃焙烧2h后,即可得到纯的SrTiO3和SrFe...     

以碳酸氢铵为沉淀剂制备纳米钇铝石榴石粉体

以碳酸氢铵为沉淀剂,硝酸盐为原料,采用沉淀法,通过仔细控制沉淀过程的工艺参数,得到了煅烧后可直接生成纯相YAG的前驱体沉淀物,前驱体经过900℃煅烧即可获得纳米YAG粉体.BET,TEM和XRD的测试结果表明纳米YAG粉体的晶粒尺寸为67～175nm,晶粒形态为球形,分散性良好.粉体达到完全致密化的最低烧结温度为1450℃.所获得的粉体经过1700℃真空烧结3h,烧结体具有一定的透明度.研究表明,这种纳米YAG粉体所具有的良好烧结活性与粉体的纳米晶粒尺寸,球形晶粒形态及极佳的分散性有关.     

共沉淀法制备Ce掺杂的Gd_3(Al,Ga)_5O_(12)粉体（英文）

通过在含有钆、镓、铝离子的硝酸混合溶液中滴加氨水,共沉淀生成Ce掺杂的Gd_3(Al,Ga)_5O_(12)(GAGG)前驱体,并采用TG/DTA对GAGG前驱体进行表征。分别在800℃、850℃、900℃、1000℃、1100℃及1200℃对GAGG前驱体进行煅烧处理,采用XRD对GAGG粉体的物相进行表征,结果显示制备出纯相的GAGG粉体。采用SEM对GAGG粉体的颗粒大小以及微观形貌进行观察。GAGG粉体的荧光谱图显示在560 nm处有一个很强的发射峰。在900℃煅烧处理的GAGG粉体所烧结的陶瓷具有最高的透明度。     

铁氧体－微晶玻璃纳米复合材料的结构与性能

采用溶胶-凝胶工艺首先合成了NICuZn铁氧体纳米粉末和MgO－Al2O3-SiO2(MAS)凝胶玻璃粉末,将两种粉末按一定比例均匀混合,烧结后得到了由NiCuZn铁氧体和堇青石微晶体两相共存的铁氧体一微晶玻璃纳米复合材料。该材料具有可调控的电磁性能,其起始磁导率高于3、介电常数低于6、截止频率高于2GHz,可望用作持高频多层片式电感介质材料．     

Combustion synthesis and characterization of NiCuZn ferrite powders

In this paper, the feasibility of synthesizing NiCuZn ferrite powders by combustion synthesis (CS) reaction is demonstrated through igniting the mixtures of iron, iron oxide, copper oxide, zinc oxide and copper carbonate under different oxygen pressure values. The ferrite powders produced directly from the CS reaction and after annealing at 800 °C for 2 h are characterized by XRD, SEM, XPS and VSM. The results show that the spinel phase in the combustion products increases with the decrease of the diluent content and the increase of the oxygen pressure. Heating the as-synthesized ferrite at 800 °C for 2 h affords pure crystalline NiCuZn ferrite, which possesses better magnetic properties. XPS studies confirm that copper ions in the as-synthesized ferrite are present in the different ionic states of the A- and B-sites, while copper ion is divalent in the B-sites only for the annealed products.     

铁氧体-微晶玻璃纳米复合材料的结构与性能

采用溶胶-凝胶工艺首先合成了NICuZn铁氧体纳米粉末和MgO－Al₂O₃-SiO₂(MAS)凝胶玻璃粉末,将两种粉末按一定比例均匀混合,烧结后得到了由NiCuZn铁氧体和堇青石微晶体两相共存的铁氧体一微晶玻璃纳米复合材料。该材料具有可调控的电磁性能,其起始磁导率高于3、介电常数低于6、截止频率高于2GHz,可望用作持高频多层片式电感介质材料．     

High performance sintering NiCuZn ferrites absorber sheet for HF application

By using a new and simple blade casting method, a lighter, thinner and higher absorption property sintering NiCuZn ferrite electromagnetic wave absorber sheet was first demonstrated. The electromagnetic wave absorption ability was enhanced by sintered NiCuZn ferrite absorbent. The experiment results reveal that NiCuZn ferrite with thickness 0.1 mm absorber sheet achieves its maximum reflection loss value above 0.5 dB at 13.46 MHz. Meanwhile, the absorption bandwidth is larger than 1 MHz is profitable for wideband electromagnetic wave absorbing. The absorption properties could be controlled by the variation of Nickel content in the spinel lattice and the sintering temperature of NiCuZn ferrites. More homogenous microstructure of SEM micrograph and better crystalline XRD pattern may be responsible for the best absorption ability at 1,150 °C sintering temperature. The absorption properties were also successfully analyzed in this work, which took into account both the frequency at the reflection loss minimum (f _r) shift correlated with the value of inductance (L) and impedance (Z) of sintered toroidal cores and the power reflection loss (Γ) depending on ε″, μ″, and $\sqrt {\varepsilon \mu }$ , where ε and μ are complex relative dielectric permittivity and permeability, respectively, for the attenuation material. The sintering NiCuZn ferrites could merit to be potential candidates as electromagnetic attenuation materials to meet the demands for miniaturization, broader relative bandwidths at HF (3–30 MHz) and beneficial for fabrication of radio frequency identification metal tag.     

Co-Firing Behavior and Interfacial Structure of BaO-TiO2-B2O3-SiO2 Glass-Ceramics/NiCuZn Ferrite Composites

This paper presents the co-firing behavior and interfacial structure of BaO-TiO₂-B₂O₃-SiO₂ glass-ceramics/NiCuZn ferrite multi-layer composites. Several effective methods, such as sandwich stacking structure and sintering shrinkage modification, are proposed to prevent the camber problem due to the mismatched shrinkage during sintering process to fabricate high-frequency chip inductors that are composite by NiCuZn ferrite and dielectric glass ceramic.     

CaCu3Ti4O12/NiCuZn铁氧体基磁电复合材料研究

将CCTO(CaCu3Ti4O12)与NiCuZn铁氧体进行复合,系统地研究了组分变化对这种新型磁电复合材料的烧结性能、晶相结构、显微结构和磁电性能的影响。随后,为了实现复合材料的低温烧结以及综合考虑复相陶瓷的磁电性能,选取80%(质量分数,下同)NiCuZn铁氧体/20%CCTO组分,以BBSZ(Bi2O3-H3BO3-SiO2-ZnO)玻璃作为助熔剂,研究了CCTO/NiCuZn铁氧体基复合材料的烧结行为和磁电性能。结果表明,掺杂BBSZ后,900℃下烧结的所有样品的密度均达到了复相陶瓷理论密度的95%,且复相陶瓷的介电常数和磁导率在1～30 MHz范围内均不依赖于频率的变化。在10 MHz的频率下,当BBSZ的含量从0增加到3%时,复相陶瓷磁导率μ从13.2增加到47.9,磁损耗tanδμ从0.022下降到0.017,同时,样品的谐振频率从109Hz左右移动到3.2×108Hz。相应地,复相陶瓷的介电常数ε从9.2增加到16,介电损耗tanδε从0.069下降到0.012。这一优异的整体性能使其有望实际应用。     

多层片式电感器用NiCuZn铁氧体的低温烧结

本文利用Bi₂O₃作为烧结促进剂实现了NiCuZn铁氧体在900℃以下烧结．利用TG、DTA、DDTA等分析手段研究Bi₂O₃的低温烧结机理,并确定最佳烧结温度范围在840～900℃之间．X－ray分析结果表明：加入Bi₂O₃后生成另相化合物Bi₃₆Fe₂O₅₇烧结后期少量Fe的固溶有助于稳定高温γ－Bi₂O₃相的立方结构,避免了冷却过程中的晶型转变．Bi36Fe₂O₅₇另相的存在能有效地阻止晶粒长大,从而达到改性的目的．     

Stress relaxation phenomena in NiCuZn ferrites induced by annealing

The present study deals with the detection and correlation of the stress relaxation phenomena that are induced in NiCuZn ferrites, as an effect of an additional annealing process that takes place after sintering. The effect of annealing on the magnetic permeability and losses of NiCuZn ferrite materials is investigated and the microstructural changes of the samples are examined by transmission electron microscopy. The ferrite specimens were synthesized by the conventional ceramic method. Sintering temperatures between 1025 and 1100 °C were applied and the sintered samples were further annealed at temperatures 50 °C lower than the sintering ones. Results revealed an improvement of the power losses at low frequencies (50 kHz), while at the high frequency range (1 MHz) the relative loss factors increased. These results were in agreement with the detected microstructural changes in the polycrystalline microstructure that occurred due to the annealing process. The relation between the annealed microstructure, the specific resistivity and the magnetic losses of the NiCuZn ferrites specimens is discussed. It appears that the stress relaxation mechanism induced by annealing is attributed to the elimination of grain dislocations, which justifies the decrease of the specific resistivity of the specimens. The stress relaxation contributes to a reduction of the low frequency hysteresis losses while the decrease of the resistivity to an increase of the high frequency eddy current losses.     

Effects of nanocrystalline ferrite particles on densification and magnetic properties of the NiCuZn ferrites

Effects of nanocrystalline ferrite particles addition on densification behavior and magnetic properties of the NiCuZn ferrites were investigated. It was confirmed that nanocrystalline ferrite particles enhanced densification of the samples obviously. The reason was attributed to the nanocrystalline particles, which spread around the micron-sized ferrite particles, increased contacting area and inter-diffusion of the particles. When the amount of nanocrystalline particles addition reached to 30 wt%, the samples obtained an approximate densification behavior as the 1.5 wt% Bi₂O₃ added samples. Due to relatively bigger grain size, higher sintering density and no different chemical composition sintering aids added, the sample with 30wt% nanocrystalline ferrite particles got the highest permeability and relatively high Q-factor when sintered at 900.     

铁电陶瓷/铁氧体复合材料的相结构与介电性能

研究了铁电陶瓷/铁氧体混合烧结体的相结构与介电性能。在900℃制备出铁电陶瓷/铁氧体复合材料,该复合材料是介电材料相与铁氧体材料相共存的复相陶瓷。铁电陶瓷/铁氧体复合材料的介电性能在低温区域主要是介电材料相起作用,而铁氧体材料主要在高温部分对复合材料的介电性能起作用。采用两相混合分布的介电常数计算公式拟合了复相陶瓷的介温曲线,并提出修正指数因子α和β,建立修正方程。