PACS: 66.30; 61.7; 82.45
Springer Online Journal Archives 1860-2000
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
2 SO4:(x)Me2 SO4 (where Me = Na, K, Rb, and Ag; x=0.0025to0.09) is systematically investigated by using complex impedance spectroscopy. The solid solubility limit up to 2 mole% of Me2SO4 in β-Li2SO4 is determined by X-ray powder diffraction, scanning electron microscopy, and differential scanning calorimetry techniques. The partial replacement of Li+ with Me+ of bigger ionic size increases the conductivity due to lattice opening. The maximum conductivity enhancement is achieved by Ag+ substitution. A simple model, based on change in entropy and Coulomb interaction, is applied to understand the increase in conductivity. A semi-quantitative treatment provides some useful conclusions such as the decrease in activation energy of ion conduction and increase in ion jump probability after doping. It is found that the normal expansion of the lattice by substituting larger isovalent ions alone is not sufficient, but requires a proper ionic size for conductivity enhancement in β-Li2SO4.
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