Microscopy simple or advance technique of material characterization

Optical microscopy with respect to advanced scientific research can be referred to as the basic techniques for the characterization of materials. Optical microscopy is expected to remain useful in the science world for a long time. Despite being presumed a basic tool, it is capable of giving very detailed information that reveals a lot about the materials preparations, heat treatment prior to observation, defects in the material as well as alloy composition. Relatively hard metals such as titanium, tungsten and steels are easy to prepare for microscopic examination unlike soft materials such as tin and aluminum that pose serious challenges during their preparation leading to defects such as deep scratch lines, embedded abrasive particles, dust particles, as well as water marks covering the polished surface. The material used in this study Cu50Ti25Zr15Ni10 was produced by arc melting. The alloy ingots were re-melted at least 4 times for homogenization of the master alloy. The alloy ingot was then suction cast into a 3mm rod. The alloy metals used for the ingots had purities greater than 99.9% and were purchased from Zhongnuo Advanced Materials (Beijing) Technology Co. Ltd China. The objective of this work was to show the importance of proper and correct specimen preparation in revealing the basic and detailed information concerning the structure, as well as its morphology. A perfectly ground and polished surface is free from defect arising from preparation method hence the presumption that microscopy is a basic science does since even advanced structures can be revealed. It is imperative that a good quality optical microscope be purchased especially when resources are scarce and advanced materials characterization techniques are not available. In can be concluded that with a good quality optical microscope, microscopy as a technique will continue to play a critical role during decision making and that a polished surface will only give accurate information about a given specimen if all preparation stages and steps are taken into consideration, adhered to and carefully and professionally done.

New Developments in Material Preparation Using a Combination of Ionic Liquids and Microwave Irradiation

During recent years, synthetic methods combining microwaves and ionic liquids became accepted as a promising methodology for various materials preparations because of their high efficiency and low energy consumption. Ionic liquids with high polarity are heated rapidly, volumetrically and simultaneously under microwave irradiation. Hence, combination of microwave irradiation as a heating source with ionic liquids with various roles (e.g., solvent, additive, template or reactant) opened a completely new technique in the last twenty years for nanomaterials and polymers preparation for applications in various materials science fields including polymer science. This review summarizes recent developments of some common materials syntheses using microwave-assisted ionic liquid method with a focus on inorganic nanomaterials, polymers, carbon-derived composites and biomass-based composites. After that, the mechanisms involved in microwave-assisted ionic-liquid (MAIL) are discussed briefly. This review also highlights the role of ionic liquids in the reaction and crucial issues that should be addressed in future research involving this synthesis technique.

Composites of metal–organic frameworks and carbon-based materials: preparations, functionalities and applications

This review summarizes the recent progress in preparations, functionalities and applications of composites of metal–organic frameworks (MOFs) and carbon-based materials.

Growth of Bismuth Telluride Thin Films by Hot Wall Epitaxy, Thermoelectric Properties

It is well known that bismuth telluride (Bi2Te3), its isomorphs (Bi2Se3 and Sb2Te3) and their alloys have the optimum bandgap (0.13 eV to 0.21 eV) for efficient solid state cooling applications around 300 K. Recently interesting work argued that the use of quantum well structures can enhance the figure of merit ZT as a result of the improvement of carrier charge density of state and the reduction of the thermal conductivity. However, for the production of such structures it is necessary to establish the optimum growth conditions and the doping levels of thin films based on Bi2Te3 and its isomorphs.In this paper we report on the growth characteristics of Bi2Te3 ternary alloys (even quaternary) thin films elaborated by the Hot Wall Epitaxy (HWE) technique. Ternary alloys based on bismuth telluride have been deposited as thin films on silicon and silica substrates. Hot Wall Epitaxy have been demonstrated to be a suitable technique in chalcogenides growth. These films are formed in a closed chamber, that make possible to keep substrates at relatively high temperature Ts without selective loss of individual components from condensate. Experimental procedures, such as substrate and source materials preparations, have been described in our previous publications. Thin films obtained are well oriented (001) and have block single-crystal structure. These films were studied by microstructural investigations and electrical measurements (electrical conductivity σ, Hall coefficient RH and Hall mobility μn) in the temperature range from liquid nitrogen to 570 K.