EDS quantification of light elements using osmium surface coating

Abstract

This study demonstrates the validity of a thin osmium coating for quantitative energy-dispersive spectroscopic (EDS) analysis, particularly for light elements such as O (and potentially C and N) in natural/synthetic minerals. An osmium coating prepared by chemical vapor deposition provides an extremely thin and uniform layer whose thickness can be controlled simply by coating time. Because of the high reproducibility and reliability of the osmium coating process, users have no difficulty in evaluating the actual coating thickness, which enables strict and precise absorption corrections (for the coating layer), even for low-energy characteristic X-rays, which are susceptible to attenuation by the coating layer itself. Our results show that oxygen concentrations in silicate and oxide minerals can be quantified correctly when using the osmium coating, whereas quantification using a carbon coating afforded values that were a few wt% lower than stoichiometry, probably due to the uncertainty of the actual coating thickness (i.e., the absorption correction was incorrect). The ability to accurately quantify oxygen may stimulate new analytical applications, such as the estimation of Fe 2+ /Fe 3+ concentrations and water content in minerals. Furthermore, the Os-coated samples prepared for EDS analysis are also suitable for electron back-scattered diffraction (EBSD) analysis without re-polishing and re-coating, which are usually routine but time-consuming tasks in the case of carbon-coated samples.

Reexamination of Solvothermal Synthesis of Layered Carbon Nitride

“…It has previously been technically difficult to accurately quantify light elements such as C and N by EDS due to high attenuation nature of the lowenergy characteristic X-rays in the volume excited by electron beam. However, we recently demonstrated that a surface conductive coating of thin osmium layer is effective for EDS quantitative analysis particularly of light elements such as C, N, and O in both inorganic and organic materials [7,38]. The validity of this method for carbon nitride analysis was indeed shown in Kojima and Ohfuji [7], in which the accuracy of quantification for C and N was evaluated to be less than 0.5%.…”

“…Pure SiC and cubic BN standards with the same surface coating were used for quantitative calibration of carbon and nitrogen, respectively. Measurements were made carefully by beam-scanning on each target area of the products (at 1 nA and 15 kV) to avoid potential damage by the electron beam [38], which might result in modification of the C/N ratio. Since EDS cannot technically detect hydrogen, the amount of hydrogen in the products was estimated from the result of the combustion analysis.…”

High-Pressure Coupling Reactions to Produce a Spherical Bulk RexN/Fe3N Composite

“…The homogeneity of the nitride products was investigated by employing scanning electron microscopy (SEM) (JSM-7000F and JSM-IT500HR, JEOL), while the elemental composition was examined by employing energy-dispersive X-ray spectroscopy (EDX) (INCA E250, Oxford Instruments). FeS 2 , Re, and BN were used as EDX standards for the quantification of Fe, Re, and N, respectively . A 5 nm layer of a conductive Pt coating was deposited on the polished sample surface to enhance the conductivity of the sample so that a high-quality SEM analysis could be performed.…”

“…FeS 2 , Re, and BN were used as EDX standards for the quantification of Fe, Re, and N, respectively. 39 A 5 nm layer of a conductive Pt coating was deposited on the polished sample surface to enhance the conductivity of the sample so that a high-quality SEM analysis could be performed. The magnetic properties were measured by employing VSM (MicroSense-VSM-EV9).…”

High-Pressure Synthesis of CeOCl Crystals and Investigation of Their Photoluminescence and Compressibility Properties

“…Pure CeO 2 and NaCl were used as the EDX standards for the quantification of Ce, O, and Cl, respectively. The accuracy of the quantification was estimated to be no more than 0.5%. − The selected area electron diffraction (SAED) was carried out to confirm the crystal structure.…”