Structure of MnO nanoparticles embedded into channel-type matrices

TL;DR

This study investigates the structure of MnO nanoparticles confined within mesoporous silica matrices, revealing different nanoparticle shapes depending on the pore size and providing insights into their physical formation mechanisms.

Contribution

It provides a detailed analysis of MnO nanoparticle shapes in different mesoporous silica matrices using X-ray diffraction and simulations, highlighting the influence of pore size.

Findings

Ribbon-like MnO in SBA-15 with larger channels

Nanowire-like MnO in MCM-41 with smaller channels

Confined nanoparticles are narrower than the channels

Abstract

X-ray diffraction experiments were performed on MnO confined in mesoporous silica SBA-15 and MCM-41 matrices with different channel diameters. The measured patterns were analyzed by profile analysis and compared to numerical simulations of the diffraction from confined nanoparticles. From the lineshape and the specific shift of the diffraction reflections it was shown that the embedded objects form ribbon-like structures in the SBA-15 matrices with channels diameters of 47-87 {\AA}, and nanowire-like structures in the MCM-41 matrices with channels diameters of 24-35 {\AA}. In the latter case the confined nanoparticles appear to be narrower than the channel diameters. The physical reasons for the two different shapes of the confined nanoparticles are discussed.