Rocha Leandro S R, Amoresi Rafael A C, Moreno Henrique, Ramirez Miguel A, Ponce Miguel A, Foschini Cesar R, Longo Elson, Simões Alexandre Z
Department of Chemistry, Federal University of São Carlos (UFSCar), São Carlos, São Paulo 13565-905, Brazil.
School of Engineering, Sao Paulo State University (UNESP), Guaratinguetá, São Paulo 12516-410, Brazil.
ACS Omega. 2020 Jun 15;5(25):14879-14889. doi: 10.1021/acsomega.9b04250. eCollection 2020 Jun 30.
The modification of CeO with rare-earth elements opens up a wide range of applications as biomedical devices using infrared emission as well as magnetic and gas-sensing devices, once the structural, morphological, photoluminescent, magnetic, electric, and gas-sensing properties of these systems are strongly correlated to quantum electronic transitions between rare-earth f-states among defective species. Quantitative phase analysis revealed that the nanopowders are free from secondary phases and crystallize in the fluorite-type cubic structure. Magnetic coercive field measurements on the powders indicate that the substitution of cerium with lanthanum (8 wt %), in a fluorite-type cubic structure, created oxygen vacancies and led to a decrease in the fraction of Ce species in the 3+ state, resulting in a stronger room-temperature ferromagnetic response along with high coercivity (160 Oe). In addition to the magnetic and photoluminescent behavior, a fast response time (5.5 s) was observed after CO exposure, indicating that the defective structure of ceria-based materials corresponds to the key of success in terms of applications using photoluminescent, magnetic, or electrical behaviors.
用稀土元素对CeO进行改性，为其作为生物医学设备（利用红外发射）以及磁敏和气敏设备开辟了广泛的应用前景，因为这些体系的结构、形态、光致发光、磁性、电学和气敏特性与缺陷物种之间稀土f态的量子电子跃迁密切相关。定量相分析表明，纳米粉末不含次生相，以萤石型立方结构结晶。对粉末进行的磁矫顽场测量表明，在萤石型立方结构中用镧（8 wt%）替代铈会产生氧空位，并导致三价铈物种的比例降低，从而产生更强的室温铁磁响应以及高矫顽力（160 Oe）。除了磁性和光致发光行为外，在接触一氧化碳后观察到快速响应时间（5.5秒），这表明基于氧化铈材料的缺陷结构是利用光致发光、磁性或电学行为进行应用取得成功的关键。
