ABSTRACT
Laser processing of carbon compounds towards the formation of graphene-based structures gains ground in view of the practicality that lasers offer against other conventional graphene preparation methods. The current work explores the viability of low-cost lasers, operating at ambient conditions, for the transformation of various graphitic materials to structures with graphene-like atomic arrangements. Starting materials are at two opposing sides. On one side stands the typical graphite crystal with Bernal stacking and strong sp 2 character, while nanocrystalline graphitic powders are also investigated. It is demonstrated that graphene-like structures can be prepared either by starting from a well-organized Bernal-stacked network or by irradiating nanocrystalline carbon. The current findings document that laser processing at minimal chamber conditions shows high potential for preparing high-quality graphene-based structures starting from low-cost materials. Apart from being scalable, the proposed method is adaptable to current technological platforms emerging as a viable and eco-friendly graphene production technology.
ABSTRACT
A transmission environmental scanning electron microscope with use of a scintillation gaseous detection device has been implemented. This corresponds to a transmission scanning electron microscope but with addition of a gaseous environment acting both as environmental and detection medium. A commercial type of low vacuum machine has been employed together with appropriate modifications to the detection configuration. This involves controlled screening of various emitted signals in conjunction with a scintillation gaseous detection device already provided with the machine for regular surface imaging. Dark field and bright field imaging has been obtained along with other detection conditions. With a progressive series of modifications and tests, the theory and practice of a novel type of microscopy is briefly shown now ushering further significant improvements and developments in electron microscopy as a whole.
ABSTRACT
One dimensional (1D) nanostructures of semiconducting oxides and elemental chalcogens culminate over the last decade in nanotechnology owing to their unique properties exploitable in several applications sectors. Whereas several synthetic strategies have been established for rational design of 1D materials using solution chemistry and high temperature evaporation methods, much less attention has been given to the laser-assisted growth of hybrid nanostructures. Here, we present a laser-assisted method for the controlled fabrication of Te nanotubes. A series of light-driven phase transition is employed to controllably transform Te nanotubes to core-Te/sheath-TeO(2) and/or even neat TeO(2) nanowires. This solid-state laser-processing of semiconducting materials apart from offering new opportunities for the fast and spatially controlled fabrication of anisotropic nanostructures, provides a means of simultaneous growing and integrating these nanostructures into an optoelectronic or photonic device.
