Magnetic Field-assisted Chemical Vapor Deposition of Transition Metal Oxides and in situ Investigations on Electronic Structure by X-ray

过渡金属氧化物的磁场辅助化学气相沉积及X射线电子结构原位研究

• 批准号: 319443528
• 负责人: Professor Dr. Sanjay Mathur
• 金额: --
• 依托单位: Institut für Anorganische Chemie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/319443528?language=en
• 关键词: Magnetic; Field; assisted; Chemical; Vapor

Compared to conventional experimental parameters of chemical vapor deposition (CVD) such as temperature, pressure and precursor chemistry, investigations on effects of extrinsic parameters (e.g., magnetic field) are less studied. The results obtained in the initial phase of the SPP on the CVD of transition metal demonstrated strong effects of external magnetic fields on the phase composition, grain growth and densification processes significantly altering the morphology, chemical topography and functional properties of the obtained films. Magnetic field-assisted CVD (mfCVD) of Cr(OBut)4 showed a remarkable modulation of the chemical composition from antiferromagnetic Cr2O3 (zero field) to ferromagnetic Cr3C2 (1.0 Tesla). Similarly, the growth of iron oxide in mfCVD showed strong anisotropy effects in films responsible for enhanced photoelectrochemical properties. The scientific objectives of this application is to (i) correlate the field effects to homogeneous and heterogeneous nucleation by using higher field strengths (up to 4 Tesla) and higher precursor fluxes (University of Cologne) and (ii) understand the growth process and magnetic field effect on an atomistic level by synchrotron based operando X-Ray spectroscopy (PGI-6, Research Center Jülich). For this purpose, conversion of spinel precursor molecules containing both d- and p-block elements ([CoAl2(OR)8] vs. [CoFe2(OR)8] into solid films will be systematically studied with respect to phase segregation and transformation phenomena. This will link the intrinsic properties (e.g., magnetism) of molecular ions and particles to their macroscopic manifestation (grain size and crystallographic structure). The mfCVD experiments together with operando X-ray absorption spectroscopy during film growth will decipher how nucleation, surface diffusion, redox processes and lattice-level interactions are influenced by applied magnetic fields and thus provide a holistic understanding of surface chemistry and precipitation phenomena in growing oxides. This research will demonstrate whether external magnetic fields can expand the experimental space of CVD and provide an additional control parameter for influencing the characteristics of as-grown thin films. Moreover, magnetic field-assisted phase segregation and interfacial reactions in transition metal spinels carrying paramagnetic and diamagnetic central atoms (CoFe2O4 vs. CoAl2O4) will be investigated. For the validation of changes in the chemical topography and surface properties, operando X-Ray spectroscopy of the activation of small molecules (e.g., H2O, CO2) will be performed on films grown in field-enhanced and zero-field conditions. The project activities are supported by the complementary expertise of the SPP members in the field of advanced magnetization measurements of mfCVD samples (RG Gutfleisch), magnetic ordering in thin film samples by solid-state NMR studies (RG Wurmehl) and microstructural changes via high-resolution SEM/TEM (RG Volkert).

与化学气相沉积（CVD）的常规实验参数如温度、压力和前体化学相比，对外部参数（例如，磁场）研究较少。在SPP的过渡金属CVD的初始阶段中获得的结果表明，外部磁场对相组成，晶粒生长和致密化过程的强烈影响显着改变所获得的薄膜的形态，化学形貌和功能特性。磁场辅助化学气相沉积（MFCVD）的Cr（OBut）4显示出显着的调制的化学组成从反铁磁性Cr2 O3（零场）铁磁性Cr 3C 2（1.0特斯拉）。同样，在mfCVD的氧化铁的生长表现出强烈的各向异性效应，负责增强光电化学性能的膜。本申请的科学目标是（i）通过使用更高的场强（高达4特斯拉）和更高的前体通量（科隆大学）将场效应与均质和非均质成核相关联，以及（ii）通过基于同步加速器的操作X射线光谱（PGI-6，研究中心Jülich）在原子水平上了解生长过程和磁场效应。为此，将系统地研究含有d-和p-区元素的尖晶石前体分子（[CoAl 2（OR）8]与[CoFe 2（OR）8]）转化为固体膜的相分离和转变现象。这将链接固有属性（例如，分子离子和粒子的宏观表现（晶粒尺寸和晶体结构）。在薄膜生长过程中的mfCVD实验与操作X射线吸收光谱一起将破译成核，表面扩散，氧化还原过程和晶格级相互作用如何受到外加磁场的影响，从而提供了一个整体的理解表面化学和沉淀现象在生长氧化物。这项研究将证明是否外磁场可以扩大CVD的实验空间，并提供一个额外的控制参数，影响生长的薄膜的特性。此外，磁场辅助的相分离和界面反应在过渡金属尖晶石携带顺磁性和反磁性中心原子（CoFe 2 O 4与CoAl 2 O 4）将进行研究。为了验证化学形貌和表面性质的变化，小分子（例如，H2O，CO2）将在场增强和零场条件下生长的薄膜上进行。该项目活动得到SPP成员在以下领域的互补专业知识的支持：mfCVD样品的先进磁化测量（RG Gutfleisch），通过固态NMR研究（RG Wurmehl）在薄膜样品中的磁有序化以及通过高分辨率SEM/TEM（RG Wurmeert）的微观结构变化。