Mössbauer Investigation of Hafnium Oxide-Hematite Nanoparticles

Hafnium-oxide-doped hematite, xHfO2*(1-x)-alpha-Fe2O3, with molar concentrations x=0.1, 0.3, 0.5, and 0.7 was prepared by high-energy ball milling at sample times of BMT=0, 2, 4, 8 and 12 hours. The Mössbauer spectra of the nanoparticle systems were parameterized using NORMOS-90. It can be said that concentrations of x=0.1, 0.3 and 0.5 show general trends, but once concentration rose to x=0.7 the sample had more subspectra, allowing new phases to be identified. Each concentration at BMT=0 had one sextet, pertaining to hematite. As the BMT and the concentration of the sample increased, the splitting increased, denoting a greater substitution of the hafnium ions into the hematite lattice. Concentration x=0.1 did not show additional splitting until reaching BMT=4 hours, where the data split from one sextet to two sextets then split further by BMT=12 hours resulting in four sextets and a doublet. Concentration x=0.3 was similar, with BMT=0 displaying only one sextet but BMT=12 hours resulted in five sextets and a doublet necessary for an accurate fit. Concentrations higher than x = 0.3 at BMT=0 required one sextet and one doublet, but no other time had such a pattern aligned with it.