ORNL has extensive expertise in the area of texture control in metals and ceramics as well as in grain boundary engineering as a direct result of texture control. Crystallographic texture is of interest in many applications of materials. For example, it can be used to provide a desired physical property, such as mechanical, thermal, electric, etc., by varying crystallographic direction and plane. In some cases, the nature of grain boundaries in a polycrystalline material can adversely affect the physical property of interest, such as current transport, or act as a defect trap in a semiconductor device (such as in photovoltaics) or result in selective corrosion. Finally, texture control is also necessary during deformation of materials, such as in rolling processes used in materials manufacturing. ORNL’s expertise in texture control has been used in many novel applications—many of which are currently being used in industry. For example, texture techniques developed by ORNL have been used in fabrication of kilometer-long lengths of single-crystal-like, metallic substrates for heterepitaxial growth of superconductors, and they are being applied to other electronic materials such as ferroelectrics, multiferroics, and photovoltaics.
ORNL has also developed very unique expertise in taking long-lengths of single-crystal-like, flexible substrates and performing roll-to-roll deposition (physical chemical and solution) at low, medium and high temperatures to realize multilayer, heteroepitaxial devices on these substrates. A full set of tools necessary to perform such depositions, along with roll-to-roll characterization of chemistry and crystallography have been developed in-house. Deposition tools include pulsed-laser ablation, sputtering, e-beam evaporation, chemical solution slot-die coating and dip coating and chemical vapor deposition. Roll-to-roll Auger and full single-crystal characterization tools have also been developed. We have also developed techniques and methodologies to characterize texture in detail and also to characterize assemblages of grain boundaries to relate them to the physical property of interest. The expertise in this area spans from developing textured metals and alloys, developing processes to realize thin sheets of materials (such as lightweight materials), techniques for heteroepitaxial deposition, advanced manufacturing via roll-to-roll deposition, modeling of complex multi-layer device structures on textured substrates and roll-to-roll characterization of device layers.
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