Manganese oxides synthesized via microwave-assisted hydrothermal method: phase evolution and structure refinement

Abstract

Manganese oxides were synthesized during 40 min at 140 ºC via Microwave-Assisted Hydrothermal (MAH) method and treated at different temperatures in order to evaluate the phase evolution using structure refinement (Rietveld method). The samples obtained were heat treated at temperatures defined by means of thermal analysis (160 ºC, 480 ºC, 715 ºC, 870 ºC, 920 ºC and 1150 ºC) and analyzed by X-Ray Diffractometry (XRD), X-Ray Fluorescence (XRF), Fourier Transform Infrared (FTIR) spectroscopy, Raman scattering, UV-Vis absorption and Scanning Electron Microscopy (SEM). Structural characterizations allowed to identify five distinct phases:

Manganese Nanoparticles: Synthesis, Mechanisms of Influence on Plant Resistance to Stress, and Prospects for Application in Agricultural Chemistry

“…A pulsed microwave synthesis of single-phase tetragonal Mn 3 O 4 NPs with an average size of about 30 nm, called hausmannite, under argon atmosphere was described by Bousquet–Berthelin and Stuerga . Various Mn oxides in nanoscale form (α-MnO 2 , Mn 3 O 4 , Mn 5 O 8 , Na 2 Mn 5 O 10 , and Na 4 Mn 9 O 18 ) were synthesized for 40 min at 140 °C using hydrothermal heating by microwaves followed by heat treatment (160, 480, 715, 870, 920, and 1150 °C) . Copper (Cu) oxide/Mn dioxide (CuO/MnO 2 ) NCs were obtained by a simple method of synthesis using microwave radiation in a conventional household microwave oven and used for an electrochemical supercapacitor …”

“…50 Various Mn oxides in nanoscale form (α-MnO 2 , Mn 3 O 4 , Mn 5 O 8 , Na 2 Mn 5 O 10 , and Na 4 Mn 9 O 18 ) were synthesized for 40 min at 140 °C using hydrothermal heating by microwaves followed by heat treatment (160, 480, 715, 870, 920, and 1150 °C). 51 Copper (Cu) oxide/Mn dioxide (CuO/ MnO 2 ) NCs were obtained by a simple method of synthesis using microwave radiation in a conventional household microwave oven and used for an electrochemical supercapacitor. 52 Thus, the review demonstrates that both elemental Mn NPs and its oxides, and compounds with other elements or biomolecules, for example, MnS NPs and CS-MnO 2 NCs, can be synthesized.…”