title: Bismuth Oxide Nanoparticles Partially Substituted with EuIII, MnIV, and SiIV: Structural, Spectroscopic, and Optical Findings.
abstract: Interest in nanostructured partially substituted bismuth oxides has been increasing over the last years. Research on new synthesis methods, properties, and possible uses for these oxides is needed. The objective of this paper is to synthesize β-Bi2O3, β-Bi2O3:Eu3+, β-Bi2O3:Mn4+, Bi12Bi0.8O19.2, Bi12Bi0.8O19.2/Li+, Bi12MnO20, and Bi12SiO20nanoparticles and to investigate their structural, spectroscopic, and optical changes. Some of the causes that generated their properties are also discussed. These materials are important because the doping or partial substitution of bismuth oxide with these cations (Eu3+, Mn4+, and Si4+) modifies some properties such as optical absorption, reactivity toward CO2, among others. X-ray diffraction (in powders), high-resolution transmission electron microscopy, Fourier transform infrared (FTIR), resonance Raman scattering, diffuse reflectance, and solid-state magic-angle-spinning29Si NMR were used for the characterization of the synthesized materials. We found that partial substitution of yellow Bi12Bi0.8O19.2with Mn4+and Si4+changed the color to green and whitish, respectively. New bands in the Raman scattering and FTIR spectra of these oxides are deeply discussed. Raman scattering spectroscopy was a valuable and reliable technique to detect the Eu3+and Mn4+cations as dopants in the bismuth oxides. The29Si chemical shift (δ) in Bi12SiO20was -78.16 ppm, whereas in SiO2, it was around -110 ppm. This considerable shift in Bi12SiO20occurred because of an increased shielding of the Si nucleus in the Si(O)4tetrahedron. This shielding was provided by the low-electronegativity and highly polarizable Bi cations. The isovalent doping of β-Bi2O3nanoparticles with Eu3+enhanced their thermal stability over 400 °C. Variation in the optical absorption and reactivity toward the acidic CO2molecule of the partially substituted bismuth oxides was explained on the basis of the optical basicity and ionic-covalent parameter concepts. Some possible uses for the synthesized oxides are suggested.
authors.forename: José-Luis
authors.initials: JL
authors.lastname: Ortiz-Quiñonez
authors.forename: Inti
authors.initials: I
authors.lastname: Zumeta-Dubé
authors.forename: David
authors.identifier: http://orcid.org/0000-0001-6927-5887
authors.initials: D
authors.lastname: Díaz
authors.affiliation: Instituto Mexicano del Petróleo , Eje Central Lázaro Cárdenas Norte 152, CP 07730 San Bartolo-Atepehuacan, G. A. Madero, Mexico City, Mexico.
authors.forename: Noel
authors.initials: N
authors.lastname: Nava-Etzana
authors.forename: Epifanio
authors.initials: E
authors.lastname: Cruz-Zaragoza
authors.forename: Patricia
authors.initials: P
authors.lastname: Santiago-Jacinto