Structure, Seebeck coefficient and DC electrical conductivity of Bi 2 Mn 4 O 10 prepared by mechanochemical method

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.