Qingle Pang,Wenlei Liu,Jianxing Shen,Tailin Wang,Chuanbing Cheng,Yuanhui Liu,Xiujun Han
Yttrium aluminum garnet (YAG) phosphor transparent ceramics prepared via vacuum hot pressing (HP) suffer from carbon contamination owing to the graphite mould used in the HP system. The conventional method was to dope LiF as a decarburizing agent, but carbon contamination cannot be effectively prevented when preparing Ce:YAG ceramics via a solid-phase reaction combined with HP sintering. In this study, we report the fabrication of highly transparent Ce:YAG ceramics via HP sintering with a flexible hexagonal boron nitride (BN-h) wrapping, which prevents carbon contamination of the samples caused by the graphite mould used in the process. High-transmittance Ce:YAG ceramics were prepared at a medium temperature of 1600 °C and a low vacuum pressure of 10 −1 Pa.
Molten CaCl2 is a viable solvent and electrolyte for extracting target elements from their oxides through electrolysis. However, the accumulation of O2– during electrolysis presents a significant challenge for the commercial application of CaCl2-based technologies. Understanding the behavior of O2– in the melt is crucial for optimizing the process. To address this, we developed an electromotive force (EMF) measuring system to monitor O2– behavior during the Si electrodeposition in molten CaCl2. We explored the thermodynamic properties of O2– in molten CaCl2–CaO (XO2– < 0.03) at 1123 K. The relationship between activity and molar fraction of O2– was established as aO2– = XO2–2.2, indicating strong interactions between O2– and other ions in the melt. EMF measurements confirmed the accumulation of O2– during the electrolysis in molten CaCl2–CaO–SiO2, as evidenced by the significant increase in aO2–. Notably, this accumulation becomes more pronounced with larger cathode areas, which leads to greater carbon contamination. Further investigation revealed that solid SiO2 effectively reduces aO2– in molten CaCl2–CaO to lower levels. By immersing solid SiO2 in melt during electrolysis, the accumulation rate of O2– is slowed, thereby inhibiting carbon contamination and improving current efficiency. These findings provide valuable insights into the use of the EMF measuring system as an effective tool for revealing O2– behavior and optimizing electrolysis processes in molten CaCl2.
Xincheng Cai,Junjing Duan,Zhangyi Huang,Zhenyu Zhang,Shengquan Yu,Xiaoqiang Li,Jianqi Qi,Tiecheng Lu
Y 2 O 3 -MgO composites are promising for mid-infrared windows and domes in harsh environments. However, the insufficient transmittance range (the transmittance >30 % only in ∼2–7 μm) and strong absorption peak (the transmittance <32 % at 7.0 μm) of Y 2 O 3 -MgO composites severely limit their application range because of agglomerations and carbon contamination from organics in the raw materials, currently. In this study, utilizing carbon-free raw materials and high molecular motions, the reduction of carbon contamination and agglomerations within the as-synthesized nanopowers was achieved via the modified co-precipitation synthesis. A highly mid-infrared transparent (the maximum transmittance of 79 % at 6.0 μm) Y 2 O 3 -MgO composite with wide transmittance range (the transmittance >30 % in 2.2–9.7 μm) and weak absorption peaks (the transmittance ≈68.57 % at 7.0 μm) was fabricated by the hot-pressing sintering method using the as-obtained nanopowders in the absence of exogenous dopants. And the modified co-precipitation synthesis is a method with great potential for the development of mid-infrared transparent Y 2 O 3 -MgO composites with wide transmittance range and weak absorption peaks.
Kai Li,Jie-Yin Zhang,Shannan Chang,Hao Wei,Jian-Jun Zhang,Yaping Dan
Self-assembled molecular monolayer doping may find important applications in doping FinFET and nanowire transistors due to its nature of being conformal, nondestructive, and self-limiting. However, carbon contamination from the dopant carrier molecules is often introduced into silicon, which will affect the device performance. Herein, we use carbon-free phosphorus chloride (PCl3) molecules as dopant carrier molecules to avoid the introduction of carbon contamination. The Hall effect measurements and secondary ion mass spectrometry show that the dopant activation rate is close to full activation even for samples with a low doping concentration.
危险品化学品经营许可证（带存储）