Sattayaporn Suchinda, Rodporn Somboonsup, Kidkhunthod Pinit, Chanlek Narong, Yonchai Chutarat, Rujirawat Saroj
Synchrotron Light Research Institute, Nakhon Ratchasima 30000, Thailand.
School of Physics, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand.
J Synchrotron Radiat. 2021 Mar 1;28(Pt 2):455-460. doi: 10.1107/S1600577520015696. Epub 2021 Jan 14.
A well designed compact furnace has been designed for in situ X-ray absorption spectroscopy (XAS). It enables various heat ramps from 300 K to 1473 K. The furnace consists of heaters, a quartz tube, a circulated refrigerator and a power controller. It can generate ohmic heating via an induction process with tantalum filaments. The maximum heating rate exceeds 20 K min. A quartz tube with gas feedthroughs allows the mixing of gases and adjustment of the flow rate. The use of this compact furnace allows in situ XAS investigations to be carried out in transmission or fluorescence modes under controlled temperature and atmosphere. Moreover, the furnace is compact, light and well compatible to XAS. The furnace was used to study cationic oxidation states in PrO and NiO compounds under elevated temperature and reduced atmosphere using the in situ X-ray absorption near-edge structure (XANES) technique at beamline 5.2 SUT-NANOTEC-SLRI of the Synchrotron Light Research Institute, Thailand. At room temperature, PrO contains a mixture of Pr and Pr cations, resulting in an average oxidation state of +3.67. In situ XANES spectra of Pr (L-edge) show that the oxidation state of Pr cations was totally reduced to +3.00 at 1273 K under H atmosphere. Considering NiO, Ni species were present under ambient conditions. At 573 K, the reduction process of Ni occurred. The Ni/Ni ratio increased linearly with respect to the heating temperature. Finally, the reduction process of Ni was completely finished at 770 K.
一种精心设计的紧凑型炉已被设计用于原位X射线吸收光谱（XAS）。它能够实现从300 K到1473 K的各种升温速率。该炉由加热器、石英管、循环制冷机和功率控制器组成。它可以通过钽丝的感应过程产生欧姆加热。最大加热速率超过20 K min。带有气体馈通的石英管允许气体混合并调节流速。使用这种紧凑型炉可以在可控温度和气氛下以透射或荧光模式进行原位XAS研究。此外，该炉结构紧凑、重量轻，与XAS兼容性良好。利用泰国同步辐射光研究所5.2 SUT-NANOTEC-SLRI光束线的原位X射线吸收近边结构（XANES）技术，该炉用于研究高温和还原气氛下PrO和NiO化合物中的阳离子氧化态。在室温下，PrO包含Pr和Pr阳离子的混合物，导致平均氧化态为+3.67。Pr（L边）的原位XANES光谱表明，在H气氛下，1273 K时Pr阳离子的氧化态完全还原为+3.00。对于NiO，在环境条件下存在Ni物种。在573 K时，Ni发生还原过程。Ni/Ni比率相对于加热温度呈线性增加。最后，Ni的还原过程在770 K时完全完成。
