Calcium sulfates are widely distributed in Gale crater and Endeavour crater on Mars. However, the mole ratios of Ca2+ and SO3 in some Sr–Ba-rich sulfate veins are less than 1. This indicates that there may be additional solid solution phases on Mars, including Ca–Sr, Ba–Sr, and Ca–Ba sulfates, which, on Earth, are typically found in marine environments. In this study, we synthesized a series of Ca–Sr, Ba–Sr, and Ca–Ba sulfate solid solutions in the laboratory. These synthesized solid solutions were then characterized using various techniques, including X-ray powder diffraction (XRD), Raman, mid-infrared, and visible and near-infrared. Our results show that the XRD and Raman spectra of Ca–Sr and Ba–Sr sulfates varied with their cation contents. In particular, the linear relationships (R2 ≥ 0.98) between the mole ratios of cation ions and peak positions of {{\rm{SO}}}_{4}^{2{-}} tetrahedron (v1) in Raman spectra were obtained. The mole content of Ca2+, Sr2+, and Ba2+ can be precisely constrained in Ca–Sr, Ba–Sr, and Ca–Ba sulfate solid solution phases through linear relationships, respectively. These results are the experimental basis for analyzing in situ detection data (e.g., SHERLOC, SuperCam, and Oxia planum) and can be used to precisely constrain the mineral phases of calcium sulfate veins on Mars.
Lei Guo,Shuaibo Gao,Zuojun Hu,Yongxin Wu,Fangzhao Pang,Huayi Yin,Dihua Wang
Green metal-electrode batteries call for the clean production of s-block metals. Herein, we developed an electrolysis–displacement–distillation (EDD) approach for producing s-block metals with low-carbon emissions and no chlorine gas evolution. The clean production stems from the choice of a molten NaCl–Na2CO3 electrolyte to prevent chlorine gas evolution, an inert nickel-based anode to produce oxygen, and a liquid metal cathode to make the cathodic product (e.g., Na–Sn) sit at the bottom of the electrolytic cell. Later, M–Sn (M = Li, Mg, Ca, Sr, and Ba) alloys were successfully prepared by a displacement reaction between the Na–Sn alloy and molten NaCl–LiCl, NaCl–MgCl2, NaCl–CaCl2, NaCl–SrCl2, or NaCl–BaCl2 with a displacement efficiency of >96.0%. Furthermore, Li, Mg, Ca, Sr, and Ba metals were separated from M–Sn alloys using vacuum distillation with a separation rate of >95.0%. We achieved a current efficiency of 81.0% for the electrolytic production of 100 kg of a liquid Na–Sn alloy, which holds promise to produce s-block metals at a large scale.
The SrO-BaO-Nb 2 O 5 -SiO 2 glass-ceramics with different (Sr, Ba)/Nb ratio were prepared by the melting-crystallized process. With the decrease of (Sr, Ba)/Nb, the bonding species and crystallization activation energy of the glass-ceramics were changed obviously, which caused the change of phase compositions and microstructures on a microscopic scale and the fluctuations of dielectric constant and breakdown strength on a macroscopic scale. Finally, the theoretical energy storage density was up to 18.93 J/cm 3 with a dielectric constant of 84 and breakdown strength of 2256.73 kV/cm. What is more, the dielectric loss was less than 0.004 at room temperature. Furthermore, under the electric field of 640 kV/cm the discharge energy density of the optimal sample (S5) reached 1.14 J/cm 3 which overtopped what has been reported and the discharge time (t 0.9 ) was less than 16 ns. Above analysis suggested that the alkali-free niobate-based glass-ceramics have broad application prospects.
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