Preparation and characterization of Fe1+xMn3-xSi2Sn7O16 mixed metal oxides

Abstract

High temperature superconductivity, giant magnetoresistance and ferroelectricity are properties exhibited by solid state inorganic clusters that have allowed researchers to design many specialized ceramic materials used in today's computing and semiconductor industries. Mixed transition metal clusters with novel geometric structures such as layering are interesting candidates for magnetic semiconductor materials as the arrangement and electronic environment of transition metal nuclei will dominate the control of electrical and magnetic properties of the new clusters. The determination of an appropriate behavioral model in a material for each of these properties will allow researchers to tune the structure and control the electromagnetic properties, eventually allowing them to introduce new ones as well. The layered oxide structure of the Fe*Si2Sn7O16 described by Söhnel et. al. is extremely stable below temperatures of 600C, and provides a large number of interesting targets to experimentally investigate as sources that might produce novel properties( For this investigation we explored the substitution effects in the oxide layer Fe positions using Mn in an effort to disrupt the Fe magnetic coupling so as to allow the magnetic moments of the transition metals to align and break the strong paramagnetism observed. The general preparation method involved the samples being placed in a furnace and heated to 900C over a period of 200 hours and allowed to cool to 700C over a period of 200 hours before the reaction products were recovered for diffraction and spectroscopic materials characterization. The reactions produced five different phases with the general formula Fe1+xMn3-xSi2Sn7O16 (X=0, 0.82, 1.65, 2.52, 2.54) that using the results of diffraction investigations was determined to be isostructural to the Fe1Si2Sn7O16 phase; Space group P-3m1 (164). Each of these phases showed a novel combination of changes in unit cell parameters, electronic absorbance and magnetic behavior that were shown to be dependent on the transition metal ratio of the oxide layers, This investigation also showed that oxygen modification is possible which could be used in future investigations as a novel mode of tuning electronic properties in the Fe1+xMn3-xSi2Sn7O16 system.