Quispe Luis T, Mamani L G Luza, Baldárrago-Alcántara A A, Félix L León, Goya Gerardo F, Fuentes-García J A, Pacheco-Salazar D G, Coaquira J A H
Laboratorio de Películas Delgadas, Escuela Profesional de Física, Universidad Nacional de San Agustín de Arequipa, Av. Independencia s/n, Arequipa, Perú.
Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, 50018 Zaragoza, Spain & Departamento de Física de la Materia Condensada, Facultad de Ciencias, Universidad de Zaragoza, E-50009 Zaragoza, Spain.
Nanotechnology. 2022 May 25;33(33). doi: 10.1088/1361-6528/ac6c93.
P-type and n-type metal oxide semiconductors are widely used in the manufacture of gas sensing materials, due to their excellent electronic, electrical and electrocatalytic properties. Hematite (-FeO) compound has been reported as a promising material for sensing broad types of gases, due to its affordability, good stability and semiconducting properties. In the present work, the efficient and easy-to-implement sol-gel method has been used to synthesize-FeOnanoparticles (NPs). The TGA-DSC characterizations of the precursor gel provided information about the phase transformation temperature and the mass percentage of the hematite NPs. X-ray diffraction, transmission electron microscopy and x-ray photoelectron spectroscopy data analyses indicated the formation of two iron oxide phases (hematite and magnetite) when the NPs are subjected to thermal treatment at 400 °C. Meanwhile, only the hematite phase was determined for thermal annealing above 500 °C up to 800 °C. Besides, the crystallite size shows an increasing trend with the thermal annealing and no defined morphology. A clear reduction of surface defects, associated with oxygen vacancies was also evidenced when the annealing temperature was increased, resulting in changes on the electrical properties of hematite NPs. Resistive gas-sensing tests were carried out using hematite NPs + glycerin paste, to detect quaternary ammonium compounds. Room-temperature high sensitivity values ( ∼ 4) have been obtained during the detection of ∼1 mM quaternary ammonium compounds vapor. The dependence of the sensitivity on the particle size, the mass ratio of NPs with respect to the organic ligand, changes in the dielectric properties, and the electrical conduction mechanism of gas sensing was discussed.
P型和n型金属氧化物半导体因其优异的电子、电学和电催化性能，被广泛应用于气敏材料的制造。赤铁矿（α-Fe₂O₃）化合物因其价格低廉、稳定性好和半导体性能，已被报道为一种有前景的广谱气体传感材料。在本工作中，采用了高效且易于实施的溶胶-凝胶法合成α-Fe₂O₃纳米颗粒（NPs）。前驱体凝胶的热重-差示扫描量热法（TGA-DSC）表征提供了有关赤铁矿纳米颗粒相变温度和质量百分比的信息。X射线衍射、透射电子显微镜和X射线光电子能谱数据分析表明，当纳米颗粒在400℃进行热处理时，形成了两种氧化铁相（赤铁矿和磁铁矿）。同时，在500℃至800℃以上进行热退火时，仅确定为赤铁矿相。此外，微晶尺寸随热退火呈增加趋势且无确定的形态。当退火温度升高时，还证明了与氧空位相关的表面缺陷明显减少，导致赤铁矿纳米颗粒的电学性能发生变化。使用赤铁矿纳米颗粒+甘油糊剂进行了电阻式气敏测试，以检测季铵化合物。在检测约1 mM季铵化合物蒸气时，获得了室温下的高灵敏度值（约为4）。讨论了灵敏度对粒径、纳米颗粒相对于有机配体的质量比、介电性能变化以及气敏导电机理的依赖性。
