title: Resolving material-specific structures within Fe₃O₄|γ-Mn₂O₃ core|shell nanoparticles using anomalous small-angle X-ray scattering.
abstract: Here it is demonstrated that multiple-energy, anomalous small-angle X-ray scattering (ASAXS) provides significant enhancement in sensitivity to internal material boundaries of layered nanoparticles compared with the traditional modeling of a single scattering energy, even for cases in which high scattering contrast naturally exists. Specifically, the material-specific structure of monodispersed Fe₃O₄|γ-Mn₂O₃ core|shell nanoparticles is determined, and the contribution of each component to the total scattering profile is identified with unprecedented clarity. We show that Fe₃O₄|γ-Mn₂O₃ core|shell nanoparticles with a diameter of 8.2 ± 0.2 nm consist of a core with a composition near Fe₃O₄ surrounded by a (Mn(x)Fe(1-x))₃O₄ shell with a graded composition, ranging from x ≈ 0.40 at the inner shell toward x ≈ 0.46 at the surface. Evaluation of the scattering contribution arising from the interference between material-specific layers additionally reveals the presence of Fe₃O₄ cores without a coating shell. Finally, it is found that the material-specific scattering profile shapes and chemical compositions extracted by this method are independent of the original input chemical compositions used in the analysis, revealing multiple-energy ASAXS as a powerful tool for determining internal nanostructured morphology even if the exact composition of the individual layers is not known a priori.
authors: NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA. kathryn.krycka@nist.gov
authors: Kathryn L
authors: KL
authors: Krycka
authors: Julie A
authors: JA
authors: Borchers
authors: German
authors: G
authors: Salazar-Alvarez
authors: Alberto
authors: A
authors: López-Ortega
authors: Marta
authors: M
authors: Estrader
authors: Sònia
authors: S
authors: Estradé
authors: Elin
authors: E
authors: Winkler
authors: Roberto Daniel
authors: RD
authors: Zysler
authors: Jordi
authors: J
authors: Sort
authors: Francesca
authors: F
authors: Peiró
authors: Maria Dolors
authors: MD
authors: Baró
authors: Chi-Chang
authors: CC
authors: Kao
authors: Josep
authors: J
authors: Nogués