Bismuth Oxide Nanoparticles Partially Substituted with Eu^III, Mn^IV, and Si^IV: 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-BiO, β-BiO:Eu, β-BiO:Mn, BiBiO, BiBiO/Li, BiMnO, and BiSiO nanoparticles 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 (Eu, Mn, and Si) modifies some properties such as optical absorption, reactivity toward CO, 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-spinning Si NMR were used for the characterization of the synthesized materials. We found that partial substitution of yellow BiBiO with Mn and Si 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 Eu and Mn cations as dopants in the bismuth oxides. The Si chemical shift (δ) in BiSiO was -78.16 ppm, whereas in SiO, it was around -110 ppm. This considerable shift in BiSiO occurred because of an increased shielding of the Si nucleus in the Si(O) tetrahedron. This shielding was provided by the low-electronegativity and highly polarizable Bi cations. The isovalent doping of β-BiO nanoparticles with Eu enhanced their thermal stability over 400 °C. Variation in the optical absorption and reactivity toward the acidic CO molecule 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.

Dissolution of metal oxides in task-specific ionic liquid

“…In agreement with this, the IR spectrum inFig. 3is typical for this compound according to literature,18 indicating the absence of solid bismuth(III)-betaine complex compounds. The repetition of the reaction under argon ow reveals a signicantly lower reactivity of the reactants.…”

“…S5, ESI †). Bi 2 O 3 is known to readily react with the acid anhydride CO 2 to (BiO) 2 CO 3 ,18 however, [Hbet][NTf 2 ], apparently, signicantly catalyses this reaction. In agreement with this, the IR spectrum inFig.…”

Transformation of Bismuth and β-Bi2O3 Nanoparticles into (BiO)2CO3 and (BiO)4(OH)2CO3 by Capturing CO2: The Role of Halloysite Nanotubes and “Sunlight” on the Crystal Shape and Size

“…A typical preparation process used to obtain bismuth subcarbonate was similar to the previously informed process. 33 Bi(NO 3 ) 3 •5H 2 O (0.1 mmol, 48.5 mg) was dissolved in 200 mL of deionized H 2 O in an Erlenmeyer flask. This solution was heated at 70 °C for 40 min to dissolve all the salt.…”

Luminescence properties of Eu3+‐ and Tb3+‐doped δ‐Bi2O3 stabilized by Th4+ substitution

“…While Bi 2 O 3 is stabilized in the δ polymorph form by most rare earths, Eu 3+ and Tb 3+ tend to stabilize the β form. This presents a challenge to use Eu 3+ and Tb 3+ luminescence to study the oxygen‐deficient δ ‐Bi 2 O 3 . Rhenium ions when co‐doped with larger lanthanides has been found to dramatically increase the oxygen ion conductivity of δ ‐Bi 2 O 3 as compared with singly rare‐earth ion‐doped δ ‐Bi 2 O 3 systems .…”

“…This presents a challenge to use Eu 3+ and Tb 3+ luminescence to study the oxygen-deficient δ-Bi 2 O 3 . 1,[3][4][5][20][21][22][23][24][25][26] Rhenium ions when codoped with larger lanthanides has been found to dramatically increase the oxygen ion conductivity of δ-Bi 2 O 3 as compared with singly rare-earth ion-doped δ-Bi 2 O 3 systems. 27 Inspired from such co-doping approach, it was planned to stabilize δ-Bi 2 O 3 firstly by substituting with Th 4+ , followed by doping it with spectroscopically rich trivalent lanthanides such as europium and terbium to further study their luminescent characteristics.…”