Single crystal

About: Single crystal is a research topic. Over the lifetime, 59617 publications have been published within this topic receiving 870828 citations.

A novel single-crystal adsorption calorimeter and additions for determining metal adsorption and adhesion energies

Abstract: A new microcalorimeter for measuring heats of adsorption on clean single-crystal surfaces is described, and its operational characteristics are presented. The principle is similar to that pioneered by David King’s group: A pulse of gas from a molecular beam adsorbs on an ultrathin single crystal’s surface, causing a measurable transient heat input and temperature rise. Our novel heat detector is a 9 μm thick pyroelectric polymer ribbon, which is mechanically driven to make a gentle mechanical/thermal contact to the back of the single-crystal sample during measurements. Advantages include use of thicker samples (1 μm), sample preparation at very high temperatures, and potential measurements at cryogenic temperatures. A novel chopped molecular beam of metal vapor and a method of correcting for absorbed radiation from the hot effusion cell are also described. This system is applied to study the heats of adsorption of metals on clean, well-defined and single-crystalline surfaces as a detailed function of cove...

Microstructural Observations of “Single Crystal” Positive Electrode Materials Before and After Long Term Cycling by Cross-section Scanning Electron Microscopy

Abstract: Single crystal LiNi0.5Mn0.3Co0.2O2 (SC532), LiNi0.6Mn0.2Co0.2O2 (SC622) and LiNi0.8Mn0.1Co0.1O2 (SC811) electrodes were retrieved from heavily cycled commercial-grade pouch cells at 4.3 V for cross-section scanning electron microscopy (SEM). SEM images indicated the single crystals showed very little microcracking, thought by many researchers to be one of the main reasons for cell degradation when polycrystalline materials are used. SEM images of electrodes from heavily cycled cells were compared to those from fresh cells which showed little visual difference. Parallel microcracks within very few single crystal particles were observed for both fresh and heavily cycled materials and are thought to be caused during the electrode calendaring process. It is believed by the authors that single crystal materials are highly promising positive electrode materials for high energy density and long cycle life lithium-ion cells.

Nonlinear Optical Properties of KNbO 3 Single Crystal in the Orthorhombic Phase

Abstract: Nonlinear optical properties of KNbO3 single crystals were investigated in detail in the orthorhombic phase by using YAG/Nd laser. The refractive indices for some laser wavelengths were measured. The nonlinear optical coefficients of this crystal at room temperature were obtained by means of the Maker fringes technique. Results were as follows: d31=35, d32=-40 and d33=-61 relative to d11 of quartz. These values are comparable with those of Ba2NaNb5O15. The temperature dependences of dij coefficients were measured. Critical and noncritical phase-matching conditions were determined. At room temperature, critical phase-matching was possible for d31 and d32 coefficients. The observed phasematching angles were found to be in good agreement with the values calculated from the refractive index data.