S.B.R.S. Adnan

Citrate sol–gel synthesised Li4SiO4: conductivity and dielectric behaviour

Abstract Pure Li4SiO4 ceramic material is obtained using citrate sol–gel method followed by sintering at 750°C. The crystallographic phase of the material is investigated by X-ray diffraction. The conductivity of the ceramic material is determined at different temperatures. Meanwhile, the dielectric properties are observed in order to obtain further information on ion dynamics in the material. The X-ray diffraction result shows the formation of a pure monoclinic Li4SiO4 crystal structure with lattice parameters a = 5·140 Å, b = 6·094 Å, c = 5·293 Å and β = 90°. The conductivity of the material increases linearly with the increase in temperature. The conductivity of the sample is 1·16×10−4 S cm−1 at 100°C. The frequency dependence of conductivity follows the universal power law variation σac (ω) = σo+Aωs. The plot of pre-exponent s versus temperature suggests that the conduction mechanism in the system can be described using correlated barrier hopping model. The increase in dielectric constant and dielectric loss and the peak shift of tan δ to higher frequencies with temperature indicate that the increase in conductivity with temperature is due to the increase in number and hopping rate of charge carriers with temperature.

Mg 2− x Mn x SiO 4 compound obtained via sol–gel method: structural, morphological and electrochemical properties

AbstractProspective cathode materials Mg2-xMnxSiO4 (0.0 ≤ x ≤ 0.4) for magnesium-ion secondary battery were synthesized using sol gel method. Crystalline structure, morphology, particle size, electrical and electrochemical properties of the samples were investigated. X-ray diffraction patterns of the materials exhibited no extra peak for x ≤ 0.6 indicated that Mg2-xMnxSiO4 materials were successfully synthesized. Mn doping in magnesium site did not affect the formation of single phase, and this probably due to the low concentration of Mn to induces structural changes. Mn doping contributed to the enhancement of the electrochemical performance of Mg2SiO4. For this work, Mg1.4Mn0.6SiO4 which possesses the largest unit cell volume, smallest charge transfer resistance, and highest conductivity value showed the most promising electrochemical performance compared to the other samples. These results indicated the suitability of the Mg2-xMnxSiO4 to be exploiting further for potential applications as solid electrolytes in electrochemical devices and strengthen the fact that doping could be an effective way to enhanched the structural, electrical and electrochemical performance of materials.

Structural, electrical and electrochemical properties of Li4ZrxSi1-xO4 (0.02 ≤ x ≤ 0.06) ceramic electrolytes

The aim of this work was to investigate the structural, electrical and electrochemical properties of Li4ZrxSi1-xO4 (0.02 ≤ x ≤ 0.06) compounds prepared via sol gel method. The X-ray Diffraction results showed that all compounds can be indexed to monoclinic structure in space group P21/m. The Li4Zr0.06Si0.94O4 compound showed highest bulk, grain boundary and total conductivity values of 1.19 × 10−4 S cm−1, 4.75 × 10−5 S cm−1 and 3.41 × 10−5 S cm−1 respectively. The insertion of Zr4+ is found to enhance conductivity of the parent sample Li4SiO4. Linear sweep voltammetry results showed that Li4Zr0.06Si0.94O4 ceramic electrolytes was electrochemically stable up to 5.07 V versus a Li+/Li+ reference electrode.