Structure, Seebeck coefficient and DC electrical conductivity of Bi2Mn4O10 prepared by mechanochemical method
Shereef A. Fareed, Makram Ibrahim, Ahmed E. Hannora, M. M. El‐Desoky
Abstract
Abstract Bismuth and manganese oxides were mixed as source-materials using the mechanochemical technique followed by heat treatment to prepare the phase Bi 2 Mn 4 O 10 . The X-Ray Diffraction (XRD) analysis was carried out to obtain the formed phases during the mechanochemical process. Bismuth manganese oxide phase with the chemical formula Bi 2 Mn 4 O 10 was formed at heat treatment 1073 K and was partially decomposed to γ-Bi 12.8 O 19.2 and α-Mn 2 O 3 after 5 h of milling time. The variation of the crystallite size is obtained at different milling time (1 h, 5 h, 10 h, 15 h, 30 h and 50 h). The temperature dependency of the DC electrical conductivity was observed at different milling times in the temperature range 300–425 K for the samples milled at 5 h, 10 h, 30 h and 50 h. The temperature dependency (300–4 80 K) of the thermoelectric power/Seebeck coefficient ( S ) and its modulus variation with milling time were observed; the modulus varied in the range (45 µV/K-277 µV/K). The concentration of manganese ions ( N ), the average distance between manganese ions ( R ) and the fraction ( C ) of reduced transition ions were calculated for all samples. The hopping carrier mobility (μ) of the samples was also calculated at a fixed temperature. As a result, the conduction mechanism agreed with the non-adiabatic process of small polaron hopping.