Structural evolution in crystalline MoO₃ nanoparticles with tunable size

详细信息    查看全文

• 作者：Elias de Barros Santos ; Fernando Aparecido Sigoli ; Italo Odone Mazali ; ^{mazali@iqm.unicamp.br}
• 关键词：Nanoparticles ; ¦Á-MoO3 ; Size effect ; Structural evolution
• 刊名：Journal of Solid State Chemistry
• 出版年：2012
• 出版时间：June, 2012
• 年：2012
• 卷：190
• 期：Complete
• 页码：80-84
• 全文大小：992 K

文摘

In this study MoO₃ nanoparticles were prepared in porous Vycor glass by impregnation-decomposition cycles (IDC) with molybdenum(VI) 2-ethylhexanoate. X-ray diffraction data show that the nanoparticles are crystalline and are in the orthorhombic ¦Á-MoO₃ phase. Raman spectroscopy data also indicate the formation of this phase. The profiles in the Raman spectra changed with the number of IDC, indicating a structural evolution of the MoO₃ nanoparticles. The IDC methodology promoted a linear mass increase and allowed tuning the nanoparticle size. Analysis of HRTEM images revealed that for 3, 5 and 7 IDC, the MoO₃ nanoparticle average diameters are 3.2, 3.6 and 4.2 nm. Diffuse reflectance spectroscopy indicates a consistent red shift in the band gap from 3.35 to 3.29 eV as the size increases from 3.2 to 4.2 nm. This observed red shift in the band gap of the MoO₃ nanoparticles is presumably due to quantum confinement effects.