Abstract

This paper investigates the physicochemical characteristics and gas-sensitivity mechanisms of nickel oxide (NiO) and nickel ferrite (NiFe₂O₄) obtained by levitation-jet synthesis LJS). Properties of synthesized materials were examined using various spectroscopic methods. XPS showed that the presence of Ni³⁺ ions in samples reduced significantly with an increase in the specific surface area of the powders and a decrease in the average diameter of their particles. In this regard, it can be concluded that the number of uncompensated Ni²⁺ vacancies in such samples also decreases and the concentration of O^2– vacancies, on the contrary, increases significantly. The Raman spectra of nanoscale NiO lacked a magnon band, which is usually observed at v = 1500 cm^–1, whereas the spectrum of nanoferrite sample had a pronounced 2M band, which indicates an increase in spin correlation. According to the analysis of UV spectra of the samples, there is an increase in reflectivity values with an increase in wavelength for large nanoparticles when compared to the corresponding values for small particles. In this regard, we suggested that Ni-based oxide nanoparticles are semiconductors with an indirect transition to band-gap energy, and this is in sharp contrast to the data obtained earlier by other researchers. The gas sensitivity of nanoscale powders was investigated in relation to carbon monoxide and nitrogen dioxide at operating temperatures of 350–500°C. An evaluation of the results made it possible to conclude that the operating characteristics of the sensors that we propose are superior in a number of parameters to the similar characteristics of sensors made of commercial powders, as well as of powders obtained by other synthetic methods.

中文翻译：

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用于CO和NO 2气体传感器的纳米级含镍粉末

摘要

研究了悬浮喷射合成LJS获得的氧化镍（NiO）和铁酸镍（NiFe ₂ O ₄）的理化特性和气体敏感性机理。使用各种光谱方法检查了合成材料的性能。XPS表明，随着粉末比表面积的增加和颗粒平均直径的减小，样品中Ni ³⁺离子的存在显着减少。在这方面，可以得出结论，此类样品中未补偿的Ni ²⁺空位的数量也减少了，并且O ^2–相反，职位空缺显着增加。纳米级NiO的拉曼光谱缺乏磁能带，通常在v = 1500 cm ^–1处观察到，而纳米铁氧体样品的光谱具有明显的2M谱带，表明自旋相关性增加。根据样品的紫外光谱分析，与小颗粒的相应值相比，大颗粒的反射率值随波长的增加而增加。在这方面，我们认为镍基氧化物纳米颗粒是具有向带隙能量的间接过渡的半导体，这与其他研究人员早先获得的数据形成鲜明对比。研究了在350–500°C的工作温度下，纳米级粉末相对于一氧化碳和二氧化氮的气体敏感性。