Microwave assisted rapid synthesis of Fe2O3@SiO2 core-shell nanocomposite for the persistence of magnetic property at high temperature

A study on the preparation and characterization of maghemite (γ-Fe2O3) particles from iron-containing waste materials

“…As displayed in Figure 3, the characteristic vibrations of γ-Fe-O in all samples are clearly observed at around 565 and 442 cm −1 , and the other peaks at pure maghemite are 475, 617, and 668 cm −1 [45][46][47]. Besides, the bands at 3421 and 3235 cm −1 denote the stretching vibrations of H − O − H and the absorption peaks at around 1638 and 1616 cm −1 are related to the bending vibrations of H − O − H for all γ-Fe 2 O 3 particles, indicating the presence of hydroxyl group on the surface that could be originated from the residual or physisorbed water that reported by other authors [42,[48][49][50]. The absorption peak at 2358 cm −1 in all products may be assigned to the asymmetric stretching vibration of CO 2 present in the atmosphere [42,48,51].…”

“…Besides, the bands at 3421 and 3235 cm −1 denote the stretching vibrations of H − O − H and the absorption peaks at around 1638 and 1616 cm −1 are related to the bending vibrations of H − O − H for all γ-Fe 2 O 3 particles, indicating the presence of hydroxyl group on the surface that could be originated from the residual or physisorbed water that reported by other authors [42,[48][49][50]. The absorption peak at 2358 cm −1 in all products may be assigned to the asymmetric stretching vibration of CO 2 present in the atmosphere [42,48,51]. The FT-IR spectra show no significant impurities such as chloride in the samples (Figure 3).…”

“…We found the five major characteristic diffraction peaks corresponding to the (220), (311), (400), (511) and (440) crystal planes of the standard cubic phase of γ-Fe 2 O 3 were present in all these patterns which confirmed the presence of γ-Fe 2 O 3 in all products (JCPDS card no. 00-39-1346) [33,34,[42][43][44]. Other less intense peaks, for instance, in the case of mill scale source, peak at 2θ = 31.68 º reflected from (221) crystal plane, were also ensured the formation of γ-Fe 2 O 3 particles ( Figure 2).…”

Smart Modification of HZSM-5 with Manganese Species for the Removal of Mercury

“… 21 In addition, the characteristic peak at 543 cm –1 could be attributed to the double six-membered ring, which is indicative of the existence of the micropore structure in HZSM-5, 8a while the band at 1632 cm –1 could be indexed to the vibrations of H 2 O on the sample surfaces. 22 It should be noted that no obvious variations in the characteristic peaks could be observed for the Mn-HZSM-5 sample, suggesting that adsorbent surface functional groups remain almost unchanged regardless of the introduction of manganese species.…”

Síntese e Caracterização de Nanopartículas de CoFe 2O4@SiO2:phen:Eu+3 com Propriedades Magnéticas e Luminescentes

“…As medidas de emissão fotoluminescentes foram realizadas a temperatura ambiente em um fluorímetro HORIBA com comprimento de excitação de 254 nm. As medidas de magnetização foram obtidas em um magnetômetro LakeShore, modelo 7300, com campo aplicado de 1 T. CoFe2O4, não exibindo picos adicionais referentes a formação de outras fases fases referentes aos precursores.Por ser um material amorfo, o SiO2 provoca o e curto alcance das ondas de raios X e reduz a difração destes pelo core 15,11 . Po observa-se que o core-shell apresenta uma banda larga e picos menos intensos óxido puro.…”