SummaryA model consisting of an equation that includes graphene thickness distribution is used to calculate theoretical 002 X-ray diffraction (XRD) peak intensities. An analysis was performed upon graphene samples produced by two different electrochemical procedures: electrolysis in aqueous electrolyte and electrolysis in molten salts, both using a nonstationary current regime. Herein, the model is enhanced by a partitioning of the corresponding 2θ interval, resulting in significantly improved accuracy of the results. The model curves obtained exhibit excellent fitting to the XRD intensities curves of the studied graphene samples. The employed equation parameters make it possible to calculate the j-layer graphene region coverage of the graphene samples, and hence the number of graphene layers. The results of the thorough analysis are in agreement with the calculated number of graphene layers from Raman spectra C-peak position values and indicate that the graphene samples studied are few-layered.
There are several accepted methods used for X-ray diffraction analysis on graphene layers and sample's stacking height L C. The Scherrer equation is avoided since the layers in the graphene samples are non-uniformly distributed and therefore the samples have non-uniform thickness. Instead, a model that includes thickness distribution is used to calculate the average number of layers and then the stacking height. The analysis was performed on 12 graphene samples produced by high-temperature electrolysis in molten salts. Another method that was used to calculate the number of layers and hence the samples' stacking height, was Raman spectra C-peak position method. It served as a control model for the analysed samples, since for four samples the corresponding parts of the Raman spectra were not usable due to the very low-frequency region. However, the obtained results of both methods were in agreement, and indicate that studied graphene samples are few layered.
Long-term and short-term effi ciency and effectiveness of a working team depend on an optimal Roles distribution within it. Therefore, having a model which enables such corresponding distribution is of a high interest to any quality manager. Two main concepts, the Roles concept of Adizes and Working styles concept of Julie Hay, are involved to create an integral model with an original approach to the Roles distribution in any working team. The greatest advantage of this model is that it is predictive instead of experiential: it makes it possible to make a corresponding Roles distribution in advance within the team, without previously monitoring the activities of the potential team members. A discussion to the relation between the possible outcomes and the level of prediction is given.Furthermore, an application of the integral model in an organization is presented. The application is rather simple and is very informative of the working behavior style of those to whom it is applied. The results and outcome from the model are compared to the results from Adizes questionnaire. Limitations to the application are pointed out. Finally, a managing team in the organization is proposed.
This work is concerned with the production of graphene using electrolysis in aqueous electrolytes with a reverse change of the potential. As electrodes and precursors for the graphene production highly oriented graphite was used. The electrolytes used were: H 2 SO 4 (pH ¼ 0.5); H 2 SO 4 + KOH (pH ¼ 1.2) and H 2 SO 4 + NaOH (pH ¼ 1.2). The produced graphene samples were characterized by means of scanning and transmission electron microscope (SEM and TEM) and Raman spectroscopy. The size of the crystallites and the number of layers of the studied graphene samples was determined. It was found that by the proposed electrochemical method graphene with few layers only can be produced.
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