Texture (crystalline)

About: Texture (crystalline) is a research topic. Over the lifetime, 22138 publications have been published within this topic receiving 351826 citations.

Total pattern fitting for the combined size-strain-stress-texture determination in thin film diffraction

Abstract: A global approach has been developed to analyze complex thin film structures by X-ray diffraction The method is based on the fitting of multiple data, diffraction pattern and/or images, collected at different orientation of the sample to obtain all the information needed It requires the knowledge of the crystal structure for the phases present in the film, or if the amount/film thickness is sufficient, the crystal structure can be also determined or refined Reflectivity patterns can be added to the global refinement to improve the accuracy of the thickness determination and when coupled with total X-ray fluorescence can give the in depth chemical concentrations In addition, it constraints the solution for the quantitative phase analysis obtained from the diffraction patterns The principles of the analysis with the main methods will be presented from the theoretical point of view These cover the models from crystal structure to texture, residual strain/stresses, crystallite sizes and microstrains To make the method more effective, some specific models have been developed in the past few years Then some experimental/analysis examples will be given to enlighten how the method works and what kind of information can be obtained Not every model suits every analysis or kind of thin film and the examples will cover different cases from multiple phases to strong texture, epitaxial thin films or multilayers

High critical current density superconducting tapes by epitaxial deposition of YBa2Cu3Ox thick films on biaxially textured metals

Abstract: A method to obtain long lengths of flexible, biaxially oriented substrates with smooth, chemically compatible surfaces for epitaxial growth of high‐temperature superconductors is reported. The technique uses well established, industrially scalable, thermomechanical processes to impart a strong biaxial texture to a base metal. This is followed by vapor deposition of epitaxial buffer layers (metal and/or ceramic) to yield chemically compatible surfaces. Epitaxial YBa2Cu3Ox films grown on such substrates have critical current densities exceeding 105 A/cm2 at 77 K in zero field and have field dependencies similar to epitaxial films on single crystal ceramic substrates. Deposited conductors made using this technique offer a potential route for the fabrication of long lengths of high‐Jc wire capable of carrying high currents in high magnetic fields and at elevated temperatures.

High critical currents in Y‐Ba‐Cu‐O superconductors

Abstract: Melt‐textured growth of polycrystalline YBa2Cu3O7−δ superconductor using directional solidification created an essentially 100% dense structure consisting of long, needle‐ or plate‐shaped crystals preferentially aligned parallel to the a‐b conduction plane. The new microstructure, which completely replaces the previous granular and random structure in the sintered precursor, exhibits dramatically improved transport Jc values at 77 K of ∼17 000 A/cm2 in zero field and ∼4000 A/cm2 at H=1 T (as compared to ∼500 and ∼1 A/cm2, respectively, for the as‐sintered structure), with the severe field dependence of Jc (‘‘weak‐link’’ problem) no longer evident in the new melt‐textured material. The improvement in Jc is attributed to the combined effects of densification, alignment of crystals, and formation of cleaner grain boundaries. Microstructure and distribution of various phases present in the melt‐textured material are discussed in relation to the superconducting properties.

Bimodal Character of Stress Transmission in Granular Packings

Abstract: The correlation between contact forces and the texture of a packing of rigid particles subject to biaxial compression is analyzed by means of numerical simulations. Four different aspects are investigated: stress tensor, dissipation due to friction, angular distribution of forces, and fabric tensor characterizing the anisotropy of the texture. All of them provide evidence that the contact network can be decomposed unambiguously into two subnetworks with complementary mechanical properties.