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

9801759 Katiyar该项目涉及铁电薄膜和纳米晶材料的加工，结构和性能之间的基本关系。生长条件如何影响薄膜结构（相，应变，晶粒尺寸和不均匀性）和介电和FE性能的更好的理解是寻求。将获得关于膜厚度/FE行为、界面结合、膜取向、FE波动和相变、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的新信息。 本文主要研究了钙钛矿型铁电薄膜和纳米晶材料PbTiO_3、BaTiO_3、Pb（Zr，Ti）O_3、（Ba，Sr）TiO_3、（Pb，Ba）TiO_3、（Pb，La）TiO_3的尺寸效应。这些材料的性能是强烈依赖于微观结构和晶粒尺寸，因此FE纳米晶材料具有不同的晶粒尺寸将使用溶胶-凝胶和传统的陶瓷加工技术制备。还将通过在不同温度和持续时间下退火样品来研究粒度变化。将使用溶胶-凝胶、RF溅射和脉冲激光沉积（PLD）技术来沉积/生长具有不同厚度和衬底的FE薄膜。 表征将包括几个显微镜-XRD，XPS，SEM/TEM，EDX和AFM，沿着激光拉曼共焦显微探针和FTIR显微光谱。将对薄膜进行介电、磁滞、压电、热电、电光和差热测量，以定量评估光电和相关物理性能。 该项目解决了材料科学领域的基础研究问题，具有很高的潜在技术相关性。 待研究的材料具有大的介电、热释电、压电和非线性光学系数，这些系数可以有效地用于光电子和微电子技术（例如，存储器、智能微传感器和致动器、多层电容器和电光调制器）。该研究将在基础层面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通过为设计和生产改进的材料和材料组合提供坚实的基础，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基础和技术重要领域培养研究生和本科生来整合研究和教育。 ***

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. ***