Size Effects on Optical and Electrical Properties of Ferroelectric Thin Films and Nano-Crystalline Materials

9801759 Katiyar这个项目解决了铁电薄膜和纳米晶体材料的加工、结构和性能之间的基本关系。更多地了解生长条件如何影响薄膜结构(相、应变、颗粒尺寸和不均匀性)以及介电和FE特性。在薄膜厚度/FE行为、界面结合、薄膜取向、FE涨落和相变、钙钛矿相的稳定性以及有序-无序行为与相变动力学的关系等方面将获得新的信息。计划研究尺寸效应对钙钛矿型铁电(FE)薄膜和纳米材料如PbTiO_3、BaTiO_3、Pb(Zr，Ti)_3、(Ba，Sr)TiO_3、(Pb，Ba)TiO_3、(Pb，La)TiO_3光学和电学性能的影响。这些材料的性能强烈依赖于微观结构和晶粒度，因此采用Sol-Gel和传统的陶瓷加工技术可以制备出不同晶粒度的Fe纳米晶材料。通过对不同温度、不同时间的样品进行退火处理，研究了晶粒度的变化。采用溶胶凝胶法、射频溅射法和脉冲激光沉积法(PLD)沉积/生长不同厚度和不同衬底的Fe薄膜。表征将包括几种显微镜--X射线衍射仪、X射线光电子能谱、扫描电子显微镜、能谱分析和原子力显微镜，以及激光拉曼共聚焦显微镜和傅里叶变换红外显微光谱分析。将对薄膜进行介电、磁滞、压电、热释电、电光和差热测量，以定量评估光电和相关的物理性能。该项目解决了材料科学中具有很高潜在技术相关性的主题领域的基础研究问题。被研究的材料具有大的介电、热释电、压电和非线性光学系数，可以在光电子和微电子技术(例如，存储器、智能微传感器和执行器、多层电容器和电光调制器)中有效地利用。这项研究将在基础水平上贡献基本的材料科学知识；从研究中获得的新知识和理解有望为设计和生产改进的材料和材料组合提供坚实的基础，从而有助于提高先进器件和电路的性能和稳定性。该计划的一个重要特点是通过在一个具有根本意义和技术意义的领域对研究生和本科生进行培训，将研究和教育结合起来。***

9801759 Katiyar This project addresses basic relationships between processing, structure, and properties of ferroelectric thin films and nanocrystalline materials. Greater understanding of how growth conditions affect film structure (phase, strain, grain size, and inhomogeneity) and dielectric and FE properties is sought. New information will be acquired on film thickness/FE behavior, interfacial bonding, film orientation, FE fluctuations and phase transitions, stability of the perovskite phase, and order- disorder behavior relationships to phase transition dynamics. Studies of size effects on optical and electrical properties of perovskite-type ferroelectric (FE) thin films and nano-crystalline materials, such as PbTiO3, BaTiO3, Pb(Zr,Ti)03, (Ba,Sr)TiO3, (Pb,Ba)TiO3, (Pb,La)TiO3 are planned. Properties of these materials are strongly dependent on microstructure and grain size; hence FE nano-crystalline materials with different grain sizes will be prepared using Sol-Gel and conventional ceramic processing techniques. Grain size variation will also be studied by annealing samples at different temperatures and time durations. Deposition/growth of FE thin films with different thicknesses and substrates will be carried out using sol-gel, RF Sputtering, and pulsed laser deposition (PLD) techniques. Characterization will include several microscopies--XRD, XPS, SEM/TEM, EDX, and AFM, along with laser Raman confocal microprobe and FTIR microspectroscopy. Dielectric, hysteresis, piezoelectric, pyroelectric, electro-optic, and differential thermal measurements on films will be carried out to quantitatively assess opto-electronic and related physical properties. %%% The project addresses basic research issues in a topical area of materials science having high potential technological relevance. The materials to be studied possess large dielectric, pyroelectric, piezoelectric, and nonlinear optical coefficients that can be usefully exploited in opto-electronic and microe lectronic technologies (e.g., memories, smart microsensors and actuators, multi-layer capacitors, and electro-optical modulators). The research will contribute basic materials science knowledge at a fundamental level; the new knowledge and understanding gained from the research is expected to contribute to improving the performance and stability of advanced devices and circuits by providing a firm basis for designing and producing improved materials, and materials combinations. An important feature of the program is the integration of research and education through the training of graduate and undergraduate students in a fundamentally and technologically significant area. ***