Structural, microstructure and ac impedance spectroscopy investigation of parent and M-doped forsterite Mg1.9M0.1SiO4 (M= Co, Ni and Mn)

Structural, microstructure and electrical properties of un-doped forsterite (Mg2SiO4) and M-doped forsterite (Mg2-xMxSiO4; M = Co, Ni and Mn; x = 0.1) synthesized by sol-gel method were investigated. The X-ray diffraction analysis confirmed the successful formation of single-phase forsterite, which belongs to the orthorhombic symmetry with Pbnm space group. The microstructure results indicated the preparation of dense ceramics and the average grain size was found to have the highest value for Mg1·9Ni0·1SiO4. Impedance spectroscopy investigation revealed the dominance of the grain contribution for all samples in the studied temperature (300–400 °C) and frequency (100–106 Hz) ranges. Furthermore, we found that the doping with transition metals (Co, Ni and Mn) increases the electrical conductivity of the ceramics. For the sample doped with Ni, the electrical conductivity has the highest values with the lowest activation energies for both the conduction and relaxation mechanisms.