多铁性磁电复合材料的结构与性能研究
发布时间：2019-04-09 20:32
【摘要】：多铁性磁电材料是集磁有序和电有序共存于一体的材料。CoFe2O4/BaTiO3复合块体材料作为多铁性磁电复合材料的代表体系,烧结致密过程中两相之间的离子扩散和体系过高的漏电流是导致材料铁电耦合系数较低的主要原因。因此,研究CoFe2O4/BaTiO3陶瓷体系在高温烧结过程中两相之间的离子扩散和反应机理对于提高其磁电性能具有重要的意义。以溶胶凝胶法为基础,通过改变BaTiO3在CoFe204溶胶凝胶工艺路线中的加入方式,即CoFe2O4凝胶阶段、CoFe2O4前驱体阶段、CoFe2O4粉体合成后,制备了三种复合方式的CoFe2O4/BaTiO3陶瓷,分别标记为CoFe2O4(L)/BaTiO3陶瓷、CoFe2O4(P)/BaTiO3陶瓷、CoFe2O4(E)/BaTiO3陶瓷。研究了不同复合方式的CoFe2O4/BaTiO3陶瓷在烧结过程中结构变化与性能之间的关系。稀土元素在SrFe12O19磁铅矿结构中有一定的固溶度,高含量的稀土掺杂会导致稀土铁酸盐的生成,出现原位共生的SrFe12O19/REFeO3磁电复合体系。采用微波辅助煅烧溶胶凝胶法制备Pr和Dy掺杂的Sr1-xRExFe12O19(x=0.15、0.25、0.5),研究了Pr和Dy在SrFe12O19结构中的固溶度以及掺杂对结构和磁性能的影响。探索了Pr和Dy掺杂的原位共生SrFe12O19 REFeO3/α-Fe2O3三元复合体系的生长机理、磁性能和微观结构之间的联系,主要结论如下：1.烧结过程中的Co2+扩散与烧结温度和复合方式密切相关。离子扩散难以程度决定了六方相BaTiO3的生成温度。1200℃烧结温度下,CoFe2O4(L)/BaTiO3陶瓷最容易发生离子扩散,CoFe2O4(E)/BaTiO3陶瓷界面离子扩散最难,容易生成第三相BaFe12019.2.1020℃下烧结的CoFe2O4(L)/BaTiO3陶瓷的电性能均低于其他两种复合方式,一方面来自于较低的烧结温度导致的低致密化。另一方面源于相对匹配的晶粒尺寸和良好的界面接触导致的渗漏导电和界面极化。3. CoFc2O4(E)/BaTiO3陶瓷的电极化性能较为优异,其中CoFe2O4的极限摩尔复合比例比例低于40%。CoFe204(E)/BaTi03(l:9)陶瓷的电极化性能最大,为5.24μC/cm2。4.Pr3+在磁铅石矿的SrFe12O19结构中固溶度在x=0.25左右,在掺杂比例为x=0.5时,得到了SrFe12019/PrFeO3/α-Fe2O3三相共存的结构,但三相的结构和分布存在较大不同,使得相与相之间的耦合较差,磁性能较差。Dy3+在掺杂比例为x=0.5时,由于DyFeO3和SrFe12O19的同步析出,使得两相颗粒分布均匀,且尺度较小,有助于SrFe12019/DyFeO3/α-Fe2O3三相之间的磁性耦合,其矫顽力高达6783.80e。
[Abstract]:Fe _ 2O _ 4 / BaTiO3 composite block material is the representative system of multi-ferroelectric composite material, which is composed of magnetic order and electric order. The ion diffusion between the two phases and the high leakage current in the sintering process are the main reasons for the low ferroelectric coupling coefficient of the materials. Therefore, the study of ion diffusion and reaction mechanism between the two phases in the sintering process of CoFe2O4/BaTiO3 ceramics at high temperature is of great significance for improving its magnetoelectric properties. Based on the sol-gel method, three kinds of composite CoFe2O4/BaTiO3 ceramics were prepared by changing the adding mode of BaTiO3 in the CoFe204 sol-gel process, I. E., CoFe2O4 gel stage, CoFe2O4 precursor stage and CoFe2O4 powder synthesis. CoFe2O4 (L) / BaTiO3 ceramics, CoFe2O4 (P) / BaTiO3 ceramics and CoFe2O4 (E) / BaTiO3 ceramics were labeled respectively. The relationship between structure change and properties of CoFe2O4/BaTiO3 ceramics with different composite modes during sintering was studied. The rare earth elements have a certain solid solubility in the structure of SrFe12O19 magnetite. High content of rare earth doping will lead to the formation of rare earth ferrate and in situ symbiosis of SrFe12O19/REFeO3 magnetoelectric composite system. The microwave-assisted calcined sol-gel method was used to prepare Pr and Dy doped Sr1-xRExFe12O19 (x = 0.15, 0.25, 0.5). The solid solubility of Pr and Dy in SrFe12O19 structure and the effect of doping on the structure and magnetic properties were studied. The growth mechanism, magnetic properties and microstructure of the in-situ symbiotic SrFe12O19 REFeO3/ 伪-Fe2O3 ternary composite system doped with Pr and Dy were investigated. The main conclusions are as follows: 1. The diffusion of Co2 in sintering process is closely related to sintering temperature and composite mode. The difficult degree of ion diffusion determines the formation temperature of hexagonal phase BaTiO3. When sintered at 1200 鈩，
本文编号：2455517
[Abstract]:Fe _ 2O _ 4 / BaTiO3 composite block material is the representative system of multi-ferroelectric composite material, which is composed of magnetic order and electric order. The ion diffusion between the two phases and the high leakage current in the sintering process are the main reasons for the low ferroelectric coupling coefficient of the materials. Therefore, the study of ion diffusion and reaction mechanism between the two phases in the sintering process of CoFe2O4/BaTiO3 ceramics at high temperature is of great significance for improving its magnetoelectric properties. Based on the sol-gel method, three kinds of composite CoFe2O4/BaTiO3 ceramics were prepared by changing the adding mode of BaTiO3 in the CoFe204 sol-gel process, I. E., CoFe2O4 gel stage, CoFe2O4 precursor stage and CoFe2O4 powder synthesis. CoFe2O4 (L) / BaTiO3 ceramics, CoFe2O4 (P) / BaTiO3 ceramics and CoFe2O4 (E) / BaTiO3 ceramics were labeled respectively. The relationship between structure change and properties of CoFe2O4/BaTiO3 ceramics with different composite modes during sintering was studied. The rare earth elements have a certain solid solubility in the structure of SrFe12O19 magnetite. High content of rare earth doping will lead to the formation of rare earth ferrate and in situ symbiosis of SrFe12O19/REFeO3 magnetoelectric composite system. The microwave-assisted calcined sol-gel method was used to prepare Pr and Dy doped Sr1-xRExFe12O19 (x = 0.15, 0.25, 0.5). The solid solubility of Pr and Dy in SrFe12O19 structure and the effect of doping on the structure and magnetic properties were studied. The growth mechanism, magnetic properties and microstructure of the in-situ symbiotic SrFe12O19 REFeO3/ 伪-Fe2O3 ternary composite system doped with Pr and Dy were investigated. The main conclusions are as follows: 1. The diffusion of Co2 in sintering process is closely related to sintering temperature and composite mode. The difficult degree of ion diffusion determines the formation temperature of hexagonal phase BaTiO3. When sintered at 1200 鈩，
本文编号：2455517
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