From Multiferroic Composite Oxides to Composite Thin Films Fabrication

************这项研究的目的是生产电子传感器，这反过来将有助于建立一个基于多铁性的新的加拿大电子工业。多铁性材料，或多铁性材料（MF），包括陶瓷化合物及其在适当衬底上的薄膜，具有电子和磁性。我们寻找至少表现出两种铁磁性行为的材料，如铁磁性（永久磁矩）和铁电性（自发电极化）。有几种单相氧化物表现出多铁性；然而，这些行为在室温下是观察不到的，这对于任何应用程序来说都是一个重要的要求，比如可以电写入和磁读取的存储设备。***复合材料（含有两种或两种以上化合物的材料）的新研究表明，人们可以创造一种环境，使复合材料中的磁相影响复合材料中的电相，反之亦然；这被称为磁电效应（ME）。科学家们一直在关注CoFe2O4-BaTiO3、Pb(ZrTi)O3 （PZT）、铁氧体和BaTiO3等化合物的陶瓷复合材料，它们在陶瓷和衬底薄膜中都表现出MF/Me效应。***目前这些复合材料是通过在铁电材料中引入磁性颗粒或磁性纳米纤维或通过制造复合材料薄膜形成两相层来形成的。我们建议制造核壳，其中粒子的核由磁性材料的纳米颗粒组成，壳（核表面的厚层）由铁电材料组成。这一过程可以通过湿化学技术和控制合成因素来实现。使用这种方法，我们期望制造纳米复合材料形状，并在两相之间创建一个相干界面。我们计划使用这些复合纳米颗粒来制造高密度陶瓷片，这对于薄膜制造至关重要，如CoFe2O4/BiFeO3， La2/3Sr1/3MnO3/ Pb(ZrTi)O3和新的四方钨青铜。我们还将继续寻找新的单一多铁材料化合物。我们关注的是具有对观察铁电性很重要的结构的材料。它还应该包含具有高磁矩的元素（过渡金属或稀土），以观察铁磁性。我们的计划是使用脉冲激光沉积或射频溅射技术生产这些化合物的薄膜，在我的实验室中表征它们的物理、电子和磁性能，并研究它们可能的应用。最终的结果将是使用多铁性材料（MF）生产电子传感器。*****

SUMMARY************The purpose of this research is to produce electronic sensors which in turn will help foster a new Canadian electronic industry based on multiferroics. Multiferroic materials, or multiferroics (MF), which include ceramic compounds and their thin films on an appropriate substrate, show both electronic and magnetic properties. We look for materials that show at least two ferroic behaviors such as ferromagnetism (permanent magnetic moment) and ferroelectricity (spontaneous electric polarization). There are several single-phase oxides that show multiferroic behaviors; however, these behaviors are not observed at room temperature, which is an important requirement for any application purposes such as memory devices that can be electrically written and magnetically read.***New research on composite materials (material containing two or more compounds) indicates that one can create an environment where the magnetic phase in the composite affect electric phase in the composite and vise-versa; this is called the magnetoelectric effect (ME). Scientist have been focusing on ceramic composites of several compounds such as CoFe2O4-BaTiO3, Pb(ZrTi)O3 (PZT), Ferrite and BaTiO3 which show MF/Me effects both in ceramics and thin films on substrates.***Currently these composite materials are formed by introducing magnetic particles or magnetic nanofibers into ferroelectric materials or creating two-phase layers by fabricating thin film of composites. We propose to fabricate core-shells where the core of the particle is made up of nanoparticles of magnetic materials and the shell (a thick layer on the surface of the core) is made up of ferroelectric materials. This process can be achieved by a wet chemical technique and by controlling the synthesizing factors. Using this method, we anticipate fabricating nanocomposite shapes and create a coherent interface between the two phases. We are planning to use these composite nanoparticles to fabricate high density ceramic tablets, essential for film fabrication, such as CoFe2O4/BiFeO3, La2/3Sr1/3MnO3/ Pb(ZrTi)O3 and new tetragonal tungsten Bronzes.***We also continue our quest to find new single multiferroic material compounds. We are focusing on materials with a structure which is important for the observation of ferroelectricity. It should also contain elements with high magnetic moments (transition metal or rare earth) for observing ferromagnetism. Our plan is to produce the thin films of these compounds using pulse laser deposition or RF-sputtering techniques, to characterize their physical, electronic and magnetic properties in my lab, and to examine their possible applications. The ultimate outcome will be the production of electronic sensors using multiferroic materials (MF).*****