Síntese e caracterização estrutural do composto AMn2O4 (A = Ni, Co e Zn)

Abstract

Oxide comp ounds with a spinel-typ e structure show a range of physical prop erties and have many practical applications. In these oxides, ions of different oxidation states o ccupy b oth tetrahedral and o ctahedral sites. Their physical prop erties dep end on the nature of ions as well as the distribuition of these ions in the crystallographic sites. Among these materials, spinel oxides A Mn2O4 (A = Ni, Zn, and Co) have attracted very attention due to Mn ions present different valence states in the structure of oxides. Mn cations influence strongly on the physical properties of these oxide materials. In this work, oxide compounds AMn2O4 (A = Ni, Zn, and Co) were produced by an aqueous sol-gel method using manitol as a gelling agent. X-ray diffraction (XRD) was used to monitor the formation of compounds and identify crystalline structures of the produced materials. The experimentnal XRD patterns were treated by X’Pert High Score Plus r software. Results showed that the NiMn2O4 compound was obtained at 900 ◦C. After this temperature was observed the decomposition of material, where Mn undergoes a segregation, taking the formation of the Mn3O4 phase at 950 ◦C. The CoMn2O4 was formed in the temperature range 850 - 950 ◦C without secondary phases. It was not possible to obtain single-phase ZnMn2O4 compound in the range of calcination temperatures used.