Fabrication and Characterization of Manganese‐based Self‐assembled Cubic Structures

Abstract Self‐assembled cubic structures of manganese‐based nanomaterials were achieved successfully, in case of manganese fluoride, for the very first time. The indirect synthesis of manganese oxide (Mn 2 O 3 ) and manganese fluoride (MnF 2 /MnF 3 ) self‐assembly involved an individual two step synthesis protocol. In first step of the protocol, NH 4 MnF 3 self‐assembled cubic structures were fabricated by a simple liquid phase reaction using polystyrene (PS) as structure directing agent (SDA), while manganese nitrate tetrahydrate (Mn(NO 3 ) 2 .4H 2 O) and ammonium fluoride (NH 4 F) as manganese and fluorine sources, respectively. In second step, the NH 4 MnF 3 was transformed by calcination to manganese oxide (Mn 2 O 3 ) at 450 °C for 5 hours under open atmosphere (air/O 2 ), and individually, to manganese fluoride (MnF 2 /MnF 3 ) at 350 °C for 5 hours under pure molecular fluorine (F 2 ) environment. The temperature regimes for the transformation reactions were deduced from thermogravimetric analysis (TGA). The crystal structures and the compositions of all the samples were established by powder X‐rays diffraction (PXRD). Further, structural characterizations were carried out by spectroscopic analyses. The key objective, preservation of self‐assembled cubic structures in the resulting manganese oxide and fluoride, were confirmed by electron microscopic analyses. The self‐assembly structures formation mechanism was illustrated based on the transmission electron microscopy (TEM) and scanning electron microscopy (SEM) results.