Owing to the high market values of natural sunstones in Oregon, a kind of artificially diffused red feldspar exhibited at the Tucson Exhibition at the beginning of this century, whose color origin is the same as that of natural sunstone (copper nanoparticles). However, the details of the artificial diffusion process are less disclosed, there is no systematic method to obtain such gemstones. In this paper, we developed the high-temperature copper diffusion process for the surface recoloring of faceted labradorites, which are partly buried in the diffusant. By optimizing the experimental parameters of high-temperature copper diffusion, we successfully recolored the faceted labradorites to red and light red. The gemological and spectroscopic characteristics of the recolored faceted labradorite were further characterized. The red and light-red faceted labradorites exhibited the unique surface plasmon resonance absorption peaks of copper nanoparticles near 580 nm, which is the origin of red color. The typical inclusions formed in the faceted labradorite is in the shape of “fire cloud”. The interface of red and light-red faceted labradorite that is in contact with the diffusant is less contaminated, we believe that the contamination could be further reduced or eliminated by optimizing the high-temperature copper diffusion process. The way that the sample is in contact with the diffusant partly is versatile and promising in the surface treatment of materials that have already been processed.Keywords:labradorite;faceted;copper diffusion;recoloring
Zou Jian,Wu Zhenrui,Tang Ruilin,Ren Zhenzhen,Niu Xiaobin,Wang Liping
Copper sulfide (CuS) is a promising cathode for lithium-ion batteries (LIBs) due to its impeccable theoretical energy density (∼ 1015 Wh·kg −1 and 4743 Wh·L −1 ). However, it suffers from voltage decay leaded energy density loss and low energy efficiency, which hinders its application. In this work, with combined ex-situlin-situ X-ray diffraction (XRD) and electrochemical analysis, we explore detailed degradation mechanisms. For the voltage decay, it is attributed to a spontaneous reaction between CuS cathode and copper current collector (Cu CC). This reaction leads to energy density loss and active materials degradation (CuS → Cu 1.81 S). As for energy efficiency, CuS undergoes a series of phase transformations. The main phase transition processes are CuS → α -LiCuS → Li 2− x Cu x S + Cu → Li 2 S + Cu for discharge; Li 2 S + Cu → Li 2− x Cu x S → β -LiCuS → CuS for charge. Here, α -LiCuS, β -LiCuS, and Li 2− x Cu x S are newly identified phases. These phase changes are driven by topotactic-reaction-related copper diffusion and rearrangement. This work demonstrates the significance of transition-metal diffusion in the intermediates formation and phase change in conversion-type materials.
危险品化学品经营许可证（带存储）