The accuracy and precision of Cd isotope measurement at different injecting sample sizes.

The δ 114/110 Cd values of thirty-four environmental and geological reference materials, including rocks, sediments, soils and biological samples, were determined on a Neptune Plus MC-ICP-MS instrument using a 111 Cd-113 Cd double spike technique. An intermediate measurement precision of better than AE 0.074‰ (2s) was achieved with different reference materials (RMs) of highly variable matrices and Cd contents. The uncertainty of δ 114/110 Cd values was assessed by calculating the 95% confidence interval of the results from this study and the literature using Student's t-test. Our measurements of nine previously analysed RMs yielded δ 114/110 Cd values that were indistinguishable from previous results. New reference values for the thirty-four geological and biological RMs are reported here. The comprehensive data set for these RMs provides guidelines for quality assurance and inter-laboratory comparison for Cd isotope determination. The large range of δ 114/110 Cd values in rock (-0.001 to +0.287‰) and biological RMs (-0.806 to +0.142‰) suggests that Cd isotope ratio measurement results are a useful tool to study biogeochemical processes.

Double spike (DS) method has been extensively used in determining stable isotope ratios of many elements. However, challenges remain in obtaining high-precision isotope data for ultra-trace elements owing to the limitations of instrumental signal-to-noise ratios and the systematics of precision of DS-based measurements. Here, the DS-standard addition (SA) (DSSA) technique is proposed to improve measurements of isotope compositions of ultra-trace elements in natural samples. According to the U-shaped relationship between DS measurement uncertainty and the spike/ sample ratio, theoretical equations and an error propagation model (EPM) were constructed comprehensively. In our method, a spiked secondary standard solution with a high, precisely known spike/sample ratio is mixed with samples such that the mixtures have spike/sample ratios within the optimal range. The abundances of the samples relative to the added standards (sample fraction; f spl ) and the samples' isotope ratios can then be obtained exactly using a standard DS data reduction routine and the isotope binary mixing model. The accuracy and precision of the DSSA approach were verified by measurements of cadmium and molybdenum isotopes at as low as 5 ng levels. Compared with traditional DS measurements, the sample size for isotope analysis is reduced to 1/6−1/5 of the original with no loss of measurement precision. The optimal mixing range f spl = 0.15−0.5 is recommended. The DSSA method can be extended to isotope measurement of more than 33 elements where the DS method is applicable, especially for the ultra-trace elements such as platinum group and rare earth element isotopes.

Yb:YAG laser ceramic nanopowders were synthesized by the carbonate altogether precipitation method, and the thermal properties with structure and morphology characterized and analyzed by the measurements of TG-DTA, XRD, IRS, SEM. The results show that well-crystallized Yb:YAG nanopowders calcined at 900°C are obtained with higher sintering performance and purity, and the average diameter is in the range of 100 nm. The crystalline size grew with the increase of the heat treatment temperature. The size of powder calcined at 1100°C is about 70-150 nm with higher purity, regular shape and even particle size distribution, which is favorable for good sinterability of Yb:YAG ceramics.Key words: Yb; YAG laser ceramic powders; nanopowders synthesis; carbonate altogether precipitation method;

“Lvwen stone” is a yellow-green carbonate jade gemstone. In this study, the gemological characteristics and color genesis of Lvwen stone were investigated using conventional gemological testing methods and analytical techniques, such as X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–VIS), laser ablation plasma mass spectrometry (LA-ICP-MS), and scanning electron microscopy (SEM). The chemical composition of Lvwen stone is mainly Ca, with lesser amounts of Mg, Mn, Cu, Zn, Fe, and other trace elements. The rare earth element distribution pattern indicates that Lvwen stone is characterized by MREE depletion and a positive Ce anomaly. The mineralogic composition of Lvwen stone is calcite, and trace-element- and crystal-size-induced colors result in its characteristic banded appearance. The white (or light green) bands consist of comparatively coarse calcite crystals (~100 μm) that are oriented perpendicularly to the band plane, accounting for their poor light transmittance. In contrast, the dark green matrix is composed of cryptocrystalline calcite crystals that are uniform in size (~10 μm) and tightly packed, resulting in superior light transmittance. Lvwen stone has a 6A1→4E(4D)d-d intra-ion electronic transition absorption band of Fe3+ at ~380–450 nm and a 2E→2T2(2D)d-d intra-ion electronic transition absorption band of Cu2+ at ~580–780 nm. This indicates that both the intra-ion electronic transitions of Fe3+ and Cu2+ give rise to the unique yellow-green color of the material. Lvwen stone is produced by ultra-high-pressure tectonic fluids in a relatively closed, reducing environment, and the green matrix was formed earlier than the white bands.