We report a simple, economical and low temperature route for phase-pure synthesis of two distinct phases of Cu–Sb–S, chalcostibite (CuSbS2) and tetrahedrite (Cu12Sb4S13) nanostructures. Both compounds were prepared by the decomposition of a mixture of bis(O-ethylxanthato)copper(II) and tris(O-ethylxanthato)antimony(III), without the use of solvent or capping ligands. By tuning the molar ratio of copper and antimony xanthates, single-phases of either chalcostibite or tetrahedrite were obtained. The tetrahedrite phase exists in a cubic structure, where the Cu and Sb atoms are present in different coordination environments, and tuning of band gap  energy was investigated by the incorporation of multivalent cationic dopants, i.e. by the formation of Zn-doped tetrahedrites Cu12−xZnxSb4S13 (x = 0.25, 0.5, 0.75, 1, 1.2 and 1.5) and the Bi-doped tetrahedrites Cu12Sb4−xBixS13 (x = 0.08, 0.15, 0.25, 0.32, 0.4 and 0.5). Powder  X-ray diffraction (p-XRD) confirms single-phase of cubic tetrahedrite structures for both of the doped series. The only exception was for Cu12Sb4−xBixS13 with x = 0.5, which showed a secondary phase, implying that this value is above the solubility limit of Bi in Cu12Sb4S13 (12%). A linear increase in the lattice parameter a in both Zn- and Bi-doped tetrahedrite samples was observed with increasing dopant concentration. The estimated elemental compositions from EDX data are in line with the stoichiometric ratio expected for the compounds formed. The morphologies of samples were investigated using SEM and TEM, revealing the formation of smaller particle sizes upon  incorporation of  Zn. Incorporation of Zn or Bi into Cu12Sb4S13 led to an increase in band gap energy. The estimated band gap energies of Cu12−xZnxSb4S13 films ranges from 1.49 to 1.6 eV, while the band gaps of Cu12Sb4−xBixS13 films increases from 1.49 to 1.72 eV with increasing x.

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In recent years, an increasing number of studies utilizing in situ liquid and/or gaseous cell scanning/transmission electron microscopy (S/TEM) have been reported. Because of the difficulty in the preparation of suitable specimens, these environmental S/TEM studies have been generally limited to studies of nanoscale structured materials such as nanoparticles, nanowires, or sputtered thin films. In this paper, we present two methodologies which have been developed to facilitate the preparation of electron-transparent samples from conventional bulk metals and alloys for in situ liquid/gaseous cell S/TEM experiments. These methods take advantage of combining sequential electrochemical jet polishing followed by focused ion beam extraction techniques to create large electron-transparent areas for site-specific observation. As an example, we illustrate the application of this methodology for the preparation of in situ specimens from a cold-rolled Type 304 austenitic stainless steel sample, which was subsequently examined in both 1 atm of air as well as fully immersed in a H2O environment in the S/TEM followed by hyperspectral imaging. These preparation techniques can be successfully applied as a general procedure for a wide range of metals and alloys, and are suitable for a variety of in situ analytical S/TEM studies in both aqueous and gaseous environments.

In situ transmission electron microscopy (TEM) has become an increasingly important research area in materials science with the advent of unique microscope platforms and a range of specialized in situ specimen holders. The ability to image and perform x-ray energy dispersive spectroscopy (XEDS) analyses of metals in liquids are particularly important for detailed study of the metal-environment interactions with specific microstructural features. In particular, these capabilities now make it feasible to explore what has been termed "SCC precursor phenomena"-that is, those sub-micron scale reactions between an alloy of interest and the environment. This topic is especially timely for this Swann Memorial Symposium, as Peter Swann's activities in this area, particularly in the 1970's concerning the initiation and early stages of transgranular SCC in austenitic stainless steels, were clearly prescient. In this study, we have used liquid cell TEM with XEDS to explore the "precursor phenomena" that can promote the development of defect initiation in Type 304 austenitic stainless steel. For this work, the FIB lift-out technique was used to extract specimens to be studied in the liquid cell TEM specimen holder. This technique has been applied to examine the localised dissolution of MnS inclusions, which can lead to pit initiation.

Sucrose‐6‐acetate, a short‐chain monoester, is an important intermediate for the preparation of sucralose. Regioselective transformations of mono‐ and oligosaccharides by enzymes have been performed in organic solvents. The present study was carried out with Candida rugosa lipase to synthesize sucrose‐6‐acetate by transesterification of sucrose and vinyl acetate in a two‐phase system consisting of a buffer solution and an organic solvent. The screening results revealed that 2‐butanol/Tris‐HCl was the optimal two‐phase system for biocatalysis, and other factors influencing the synthesis of sucrose‐6‐acetate were also studied. Three major factors (temperature, initial buffer pH, and molar ratio of substrates) were identified through Plackett–Burman design, and the response surface methodology was employed to optimize the reaction process. Under optimal conditions, the yield of sucrose‐6‐acetate reached up to 57.42%. The aqueous two‐phase system was successfully applied to the synthesis of sucrose‐6‐acetate with high yield, low toxicity, good resolution, low cost, and simple scale‐up.