液相包裹法制备Pb(Mg1/3Nb2/3)O3-CoFe2O4磁电耦合材料

以无机盐Nb2O5、Mg(NO3)2、Pb(NO3)4、Co(NO3)2、Fe2(NO3)3为原料,柠檬酸和EDTA为络合剂,分别制备了Nb5+、Mg2+、Pb2+、Co2+、Fe3+等离子的络合溶液。采用络合法制备了铌酸镁-铁酸钴先驱体(MgNb2O6-CoFe2O4,简称MN-CFO)。此先驱体在1000℃煅烧1h后,得到纯净的MgNb2O6-CoFe2O4固溶体。采用液相包裹法制备了铌镁酸铅-铁酸钴(Pb(Mg1/3Nb2/3)O3-CoFe2O4)先驱体,在1000℃煅烧1h,Pb(Mg1/3Nb2/3)O3-CoFe2O4先驱体分解为具有铁电相Pb(Mg1/3Nb2/3)O3和铁磁相CoFe2O4的复相组织。研究了10%过量的PbO对煅烧过程中烧绿石相向铁电相的转变作用,并在700℃煅烧5h条件下制备了不含烧绿石相的Pb(Mg1/3Nb2/3)O3-CoFe2O4固溶体。     

静电纺丝法制备PAN/Fe3O4磁性纳米纤维

采用化学共沉淀法制备纳米四氧化三铁,选用曲拉通X-100为分散剂,利用静电纺丝法制备PAN/Fe3O4磁性纳米复合材料。X射线衍射仪(XRD)验证了四氧化三铁在复合纳米纤维中的存在。同时使用扫描电镜(SEM)和透射电镜(TEM)对复合纳米纤维的微观形貌和Fe3O4在纤维中的分布进行了观察,利用热重(TGA)对纳米复合材料的热稳定性进行分析;通过磁性实验分析了纳米复合材料的磁性性能。结果表明,所制备PAN/Fe3O4磁性纳米纤维成型良好,且Fe3O4磁性颗粒在纤维中分散均匀,其与PAN是物理复合。纳米复合材料具有一定磁性,并可由磁性颗粒的加入量进行控制。     

电纺聚酰胺酸/Fe_3O_4磁性纳米复合纤维的制备与表征

将纳米Fe3O4磁性颗粒加入由PMDA和ODA制备的PAA聚合物溶液中,通过静电纺丝法制备PAA/Fe3O4复合纤维。利用扫描电镜(SEM)和透射电镜(TEM)对复合纳米纤维的微观形貌和Fe3O4在纤维中的分布进行了观察,采用X射线衍射仪(XRD)验证了Fe3O4在复合纳米纤维中的存在,通过磁性实验分析了纳米复合材料的磁性能,同时使用红外光谱仪对纳米复合材料的化学结构进行了分析。结果表明,所制备PAA/Fe3O4磁性纳米纤维成型良好,Fe3O4磁性颗粒已分散在纤维中,与PAA是物理复合,材料具有一定磁性,为进一步制备聚酰亚胺磁性复合纳米纤维做了有益的探索研究。聚合物磁性复合材料由于其独特的物理化学性能及超顺磁性,有着广阔的应用前景。     

(1-x)CaTiO_3/xNi_(0.5)Zn_(0.5)Fe_2O_4复合材料的制备及其性能

采用固相反应法合成了(1-x)CaTiO3/xNi0.5Zn0.5Fe2O4(0≤x≤1.0)复合材料,并研究了复合材料的物相、微观结构、介电性能和磁性能。结果表明:样品中仅含有钙钛矿型CaTiO3和尖晶石型Ni0.5Zn0.5Fe2O4。1260℃保温3h,样品相对密度达到98.91%,颗粒尺寸约为2μm。样品介电常数随Ni0.5Zn0.5Fe2O4含量(x)增加而增大。当x=0.7、测试频率为103 Hz时,样品介电常数(εr)和介电损耗(tanδ)分别为2629.18和1.74。(1-x)CaTiO3/xNi0.5Zn0.5Fe2O4复合材料显示磁性。其中x=0.7时,样品饱和磁化强度(Ms)达到49.07A·m2/kg;这归因于Ni0.5Zn0.5Fe2O4具有优异的磁性能。     

碳纳米管/四氧化三铁复合材料的电磁波吸收性能(英文)

采用水热法制备碳纳米管(MWCNT)/四氧化三铁(Fe3O4)复合材料,运用透射电子显微镜、X射线衍射仪、振动样品磁强计及网络矢量分析仪等,对复合材料的微观结构、磁性能及电磁波吸收性能(8.2～12.4 GHz,X波段)进行研究和分析。结果表明,磁性Fe3O4纳米颗粒能够较好地包覆在MWCNTs表面上,并且随着反应混合液中Fe2+和Fe3+浓度的增加,MWCNT/Fe3O4复合材料中的Fe3O4含量增加,MWCNT/Fe3O4复合材料的磁性能增强;当反应混合液中的Fe2+和Fe3+的浓度分别为0.02和0.04 mol/L时,MWCNT/Fe3O4复合材料的电磁波吸收性能最佳,具体表现为吸收峰峰值最低,吸收频宽最宽。     

磁性Fe_3O_4纳米复合材料的研究进展

磁性纳米复合材料主要包括Fe2O3、Fe3O4、NiO、Co3O4等与其他物质的复合材料,其中最常见的是Fe3O4的复合材料,而制备该类复合材料的方法有:水热合成法、化学共沉淀法、超声化学还原法、溶剂热-水热法等。磁性复合材料不但能在外加磁场的作用下迅速方便地分离,同时还能通过修饰或改性等方法使其带有某些官能团(如C=C、COOH、NH2等),因此磁性纳米复合材料在生物物质的提取与分离、污水净化、生物医学等诸多领域有广泛的应用。介绍了磁性Fe3O4纳米复合材料的制备和应用,并对磁性材料未来在各领域的应用做了展望。     

原位复合钛酸铅/镍(铅)铁氧体复相粉体的制备研究

利用sol-gel法并通过原位复合方法制备了具有铁电性能的PbTiO3和具有铁磁性能的NiFe2O4和PbF12O19多相复合体系陶瓷粉体。利用XRD、SEM对多相复合体系的物相结构和形貌等进行研究。结果表明，在700℃以上则形成铁电（PbTiO3）/（NiFe2O4和PbF12O19）三相复合体系。热处理温度对多相复合体系晶相的形成和生长产生关键性作用，多相复合共存体系中形成的晶相多以固溶体存在，各固溶晶相的晶格常数随固溶量的不同而不同。     

电纺纳米纤维自组装制备含多磁性内核的Fe3O4@SiO2核壳结构纳米粒

通过电纺纳米纤维自组装制备了含多磁性内核的Fe3O4@SiO2核壳结构纳米粒。采用扫描电镜(SEM)表征了电纺纳米纤维的形貌,利用场发射扫描电镜(FE-SEM)、透射电镜(TEM)、傅里叶红外光谱仪(FT-IR)、X晶体衍射仪(XRD)和振动样品磁强计(VSM)分别对纳米粒的形貌、粒度分布、物相组成、化学成分和磁性能等进行了表征。结果显示:采用电纺纳米纤维自组装制备的Fe3O4@SiO2纳米粒为近似球形的结构,其内含有多个磁性内核;粒径分布在50nm左右,主要物相是无定形的SiO2和晶态的Fe3O4,保持了磁性粒子的超顺磁性,是一种优良的生物磁性材料。     

核-壳型罗丹明6G磁性分子印迹固相萃取材料的合成与表征

采用化学共沉淀法制备Fe3O4磁性纳米粒子,以3-氨丙基三乙氧基硅烷(APTES)对其表面进行氨基硅烷化改性,形成Fe3O4@SiO2-NH2纳米粒子。以其作为磁性核,采用表面印迹技术,以罗丹明6G为模板,丙烯酰胺(AM)为功能单体,三羟甲基丙烷三甲基丙烯酸酯(TRIM)为交联剂,在Fe3O4@SiO2-NH2表面形成罗丹明6G分子印迹聚合膜,制备了核-壳型罗丹明6G磁性分子印迹聚合物(Fe3O4@MIPs),对合成条件进行了优化。分别采用红外光谱(FT-IR)、场发射扫描电镜(FESEM)、振动样品磁强分析(VSM)和热重分析(TGA)等仪器分析手段,对Fe3O4@MIPs的结构进行表征。结果表明,所制备的核-壳型磁性分子印迹聚合物具有高吸附容量及显著选择性;在外加磁场作用下Fe3O4@MIPs可快速与样品基质分离,大大提高了实验效率。Fe3O4@MIPs作为一种新型固相萃取材料,可以从样品中选择性分离和富集违规添加的罗丹明6G,可应用于食品的安全检测。     

双微乳液法制备纳米磁性Fe3O4粉体的研究

现代诊断学的发展使得纳米级超顺磁性的Fe3O4粒子在医学领域具有重要应用价值.本实验采用双微乳液法制备纳米磁性Fe3O4粉体.从反应物浓度、表面活性剂用量、油相用量及反应温度等方面讨论对产物粒径的影响,通过正交试验确定了制备纳米Fe3O4粉体的最佳工艺条件.对获得的粉体采用激光散射法粒度测试、XRD物相分析和粒径计算、原子力显微镜(AFM)和透射电子显微镜(TEM)形貌观察、振动样品磁强计磁性测定等进行表征,结果表明制备的Fe3O4粉体平均粒径约为24nm、粒度分布均匀、分布带较窄且产物纯度高;该粉体具有超顺磁性,饱和磁化强度在66A·m2/kg左右.     

BST/YIG复合材料的相结构、介电性能和磁性能的研究

以铁电性的钛酸锶钡（BST）和铁磁性钇铁氧体（YIG）为原料,采用固相反应法,合成了一系列铁电/铁磁复合材料,并对铁电/铁磁复合材料（YIG/BST）的介电性能和磁性能进行了详细地研究. 结果表明：在一定温度下烧结所得的铁电/铁磁复合材料,由铁电相和铁磁相两相组成;xBST-(1-x)YIG(x=0,0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8,0.9,1.0)复合材料具有良好的介电性能和磁性能, 其介电常数实部ε′与虚部ε″均随BST含量的增加而升高,且介电常数的谐振峰随着YIG含量的增加而向频率高的方向移动.磁导率实部μ′与虚部μ″均随BST含量的增加而降低. 在YIG铁氧体中加入适量的陶瓷BST构成复合材料,可以有效地改善截止频率,提高高频电磁特性.     

Characterization and electrical properties of chemical vapor deposited ferroelectric lead titanate films on titanium

Lead titanate thin films were deposited on titanium substrates by a chemical vapor deposition (CVD) process involving the application of vapor mixtures of Pb, ethyl titanate (Ti(C(2)H(5)O) (4)), and oxygen. Auger electron spectroscopy (AES) analyses were performed to determine the chemical composition of lead titanate films. AES analysis revealed that TiO(2) and TiO interlayers formed between the PbTiO(3) and titanium substrate. AES also showed that stoichiometry was obtained in the lead titanate film deposited at 750 degrees C, Ti(C(2)H(2)O)(4) with 0.152, an O(2) partial pressure of 0.06 atm, and a gas flow rate of 800 sccm. The lead titanate with a stoichiometric composition has a DC conductivity of 3.2x10(-12) Omega(-1)-cm(-1) at room temperature. The nonsaturating loops observed in the present investigation may be caused by TiO(2) and TiO layers between the conductive substrate and the PbTiO(3) ferroelectric film. The ferroelectric properties of the stoichiometric PbTiO(3) film included a remanent polarization of 14.1 muC/cm(3) and a coercive field of 20.16 kV/cm.     

铌镁酸铋-钛酸铅压电陶瓷准同型相界附近的性能和相变温度研究

利用传统固相烧结法制备了Bi(Mg_2/3Nb_1/3)O₃-PbTiO₃(BMN-PT)压电陶瓷, 分析了不同PbTiO₃含量对BMN-PT压电陶瓷的晶体结构、介电、压电及铁电性能的影响. XRD结果表明: 合成的BMN-PT陶瓷具有纯钙钛矿结构, 并且在PbTiO₃含量为x=0.60时, 其组分的XRD图谱在衍射角2θ=45°出现明显的分峰, 说明该组分相结构中存在三方和四方相的共存. 压电铁电性能显示, BMN-0.60PT有最大的压电常数d₃₃(~170pC/N)和平面机电耦合系数k_p(0.35), 最小的矫顽场E_c(29.4 kV/cm)及最大的剩余极化P_r(31.4 μC/cm²). 确定了BMN-PT压电陶瓷的准同型相界(MPB)为PbTiO₃含量x=0.60的组分. 介电系数温谱表明介电系数峰值温度(Tm)随着PbTiO₃含量的增大而升高, MPB组分的Tm约为276℃.     

Controllable phase connectivity and magnetoelectric coupling behavior in CoFe(2)O(4)-Pb(Zr,Ti)O(3) nanostructured films

Magnetoelectric CoFe(2)O(4)-Pb(Zr,Ti)O(3) nanostructured films with various phase connectivity patterns were prepared by a pulsed laser deposition method. It was found that the microstructure as well as the phase connectivity pattern of the film varied remarkably with the variation of phase content ratio. All composite nanofilms exhibit evident ferromagnetic and ferroelectric characteristics, as well as distinct magnetoelectric coupling behavior upon increasing the magnetic field. The correlation between the phase connectivity pattern and magnetoelectric coupling behavior for the composite nanofilm was revealed. This work provides an efficient avenue to modulate the magnetoelectric coupling behavior for the ferroelectric-ferromagnetic composite nanofilm.     

Multiferroic oxide composites: synthesis,characterisation and applications

Abstract

The nature of mechanical strain mediated electromagnetic coupling in multiferroic composites has been studied extensively in recent years. This review is on composites with ferromagnetic or ferrimagnetic oxides and ferroelectrics. Systems studied so far include samples with spinel ferrites, hexagonal ferrites or lanthanum manganites for the ferromagnetic phase and barium titanate, lead zirconate titanate (PZT), lead magnesium niobate–lead titanate (PMN-PT) or lead zinc niobate–lead titanate (PZN-PT) for the ferroelectric phase. Bilayer and multilayer heterostructures, bulk composites, core shell nanoparticles and core shell nanotubes and nanowires were investigated for their response to magnetic fields, termed direct magnetoelectric effect (DME). Several systems show a giant low frequency DME and resonance enhancement at bending and electromechanical resonance. The response of the composites to an electric field, called converse ME effect, is found to be strong in several ferrite–ferroelectric composites. The potential for use of the composites for pico-Tesla magnetic sensors and high frequency electric field tunable ferrite signal processing devices are also addressed in this review.     

PZT纳米晶薄膜的Sol—Gel法制备及铁电性质

采用Ｓｏｌ－Ｇｅｌ法，以Ｚｒ的硝酸盐替代醇盐，引入ＰｂＴｉＯ３过渡层的方法成功的制备了纳米晶铁电薄膜。并进行了差热、热重、结构、组分、铁电性能的测定、分析。     

Effect of strain on ferroelectric and magnetic behavior in Pb(Zr0.52Ti0.48)O3-based magnetoelectric heterostructures

In this paper, the "sandwich" structured magnetoelectric composite films of Pb(Zr0.52Ti0.48)O3/ NiFe2O4/Pb(Zr0.52Ti0.48)O3 and Pb(Zr0.52Ti0.48)O3/CoFe2O4/Pb(Zr0.52Ti0.48)O3 are epitaxially grown on SrRuO3/SrTiO3 substrates by pulsed-laser deposition. The crystalline quality and microstructures of these heterostructures are investigated by X-ray diffraction technique. The effects of strain on the ferroelectric, magnetic and magnetoelectric coupling properties of these thin films are systematically studied. The results show that the strain effect induced by lattice mismatch between the ferroelectric/ferromagnetic layers plays an important role in the ferroelectric and magnetic properties of these composite films. Compared to the strained Pb(Zr0.52Ti0.48)O3/ CoFe2O4/Pb(Zr0.52Ti0.48)O3 heterostructure, improved ferroelectric properties with an out-of-plane polarization (2P(r)) of 34.2 microC/cm2 and electric coercivity field of 158 kV/cm are obtained in the strain-free Pb(Zr0.52Ti0.48)O3/NiFe2O4/Pb(Zr0.52Ti0.48)O3 heterostructure. The ME measurement results not only show that the strain induced by lattice mismatch has great influence on the ME behavior, but also provide an understanding of the multilayers with full control over the interface structure at the atomic-scale.     

晶粒可控BaTiO3-CoFe2O4磁电复合陶瓷制备及生长机制研究

采用全溶液络合法合成了BaTiO3-CoFe2O4混合粉体,用X射线衍射仪对反应产物进行了表征,分析了不同热处理温度对粉体合成的影响.用X射线衍射仪、扫描电镜对由前述预制粉体烧成的磁电陶瓷进行了微观表征,观测到由不同热处理粉体烧成的陶瓷晶粒形貌显著不同,形成了可控晶粒的磁电耦合材料.以全溶液法合成的该磁电陶瓷中,两相晶体各自析出长大,同时CoFe2O4依附于BaTiO3上生长,两种晶体因共格而形成良好的相界面层,对获得较好的磁电耦合性能作用明显.     

Study of structural and magnetoelectric properties of 1−x(Ba<Subscript>0.96</Subscript>Ca<Subscript>0.04</Subscript>TiO<Subscript>3</Subscript>)–x(ZnFe<Subscript>2</Subscript>O<Subscript>4</Subscript>) ceramic composites

Multiferroic ceramic composites of (1?x)Ba_0.96Ca_0.04TiO₃–(x)ZnFe₂O₄ (BCT-ZF) were prepared from ferroelectric (FE) barium calcium titanate (BCT) and ferromagnetic (FM) zinc ferrite (ZF) by using the solid state reaction method with different mol% fractions of x (x?=?0.1 and 0.2). The preliminary structural studies carried out by X-ray diffraction at room temperature reveals that the samples have a tetragonal structure along with the cubic spinel ferrite phase. Raman spectra of the composites also confirm the existence of BCT phase and ZF phase. The room temperature ferroelectric polarization measurements as a function of magnetic field show the existence strong magnetoelectric coupling of 10.85 (mV/(cm.Oe).     

单晶PZT-CFO铁电-铁磁复合纳米纤维的制备与磁学性能研究

以不同锆掺杂量的前钙钛矿结构钛酸铅和铁酸钴为原料,采用原位固相烧结法合成了一系列单晶锆钛酸铅-铁酸钴(PZT-CFO)复合纳米纤维。X射线衍射、扫描电子显微镜和能谱分析结果表明,一维单晶PZT-CFO复合纳米纤维同时存在钙钛矿相的锆钛酸铅和尖晶石相的铁酸钴。高分辨透射电子显微镜研究证实锆钛酸铅和铁酸钴之间存在外延生长关系。采用振动样品磁强计对PZT-CFO复合纳米纤维的磁学性能进行测试,发现该复合纳米纤维具有明显的铁磁性能,其剩余磁化强度和矫顽力随着锆掺杂量的增加而增加。