Fits of the γ-MnO2 Structure Model to Disordered Manganese Dioxides

Abstract

This paper defines F-MnO2 as a manganese dioxide phase with a structure based on an intergrowth of ramsdellitic and pyrolusitic domains, a model initially proposed by de Wolff [Acta Cryst. (1959), 12, 341-345].This model consists of a stochastic stacking of four different types of layers, each of which is based on the same underlying two-dimensional periodic lattice. An analytic expression for the scattered intensity as a function of scattering vector is given; the subsequent powder averaging to obtain the intensity as a function of scattering angle has to be performed partly numerically. This formalism is then utilized to fit experimentally observed powder X-ray diffraction patterns of typical disordered manganese dioxides with the F-MnO2 model. The model fits the chemically prepared manganese dioxide investigated here fairly well; heating it increases the pyrolusitic character. However, the structure of electrolytically prepared manganese dioxides (EMD) is not well described by this model, implying that there are other types of disorders in EMDs.

Titanium Containing γ‐MnO2 (TM) Hollow Spheres: One‐Step Synthesis and Catalytic Activities in Li/Air Batteries and Oxidative Chemical Reactions

“…The phase purity of the products was investigated by conventional XRD experiments, as shown in Figure . All of the peaks match the reference data of a pure γ‐MnO 2 phase 39. The broadening of the (201) peak is known to occur for certain types of random intergrowths of ramsdellite (1 × 2) tunnel structure and pyrolusite (1 × 2 tunnel structure) of manganese dioxide based on the “De Wolff model” published in 1959 40.…”

Enhanced Interactions between Gold and MnO2 Nanowires for Water Oxidation: A Comparison of Different Chemical and Physical Preparation Methods

“…Unfortunately, the Au 4f doublet overlaps with the Mn 3s multiplet splitting peaks from the support . Through assuming the same Mn 3s/Mn 2p intensity ratio for all Au attached samples and constraining the relative position and intensity of the two Au 4f 7/2 and Au 4f 5/2 components to the respective expected BE of 3.6 eV and 1.33, the peak position and area of the Au 4f and Mn 3s doublet can be successfully obtained via curve fitting procedure (see Figure b–d) . According to the previous literature, the BE separation between the two peaks of the Mn 3s doublet (Δ E 3s) shows an inverse linear relationship with the averaged Mn valence (υ Mn ).…”

Effect of Non-ionic Surfactants and Its Role in K Intercalation in Electrolytic Manganese Dioxide

“…The rich chemistry and diverse crystalline structures of MnO 2 offer a versatility that allows its use in a range of applications. [1] Of the different types of MnO 2 , such as natural manganese dioxide (NMD), chemical manganese dioxide (CMD), activated manganese dioxide (AMD), and electrolytic manganese dioxide (EMD), EMD is most widely applied in battery industries. [2,3] EMD is composed predominantly of the c-phase and may be produced cost effectively with low environmental impact.…”