Synthesis and transport properties of Al substituted langasite ceramics

This paper reports the study of structural, morphological and dielectric properties of pure and Al substituted Langasite (La3Ga5−xAlx SiO14, x = 0, 0.2, 0.4, 0.6 and 0.8) ceramics, prepared at 1400 °C by solid state reaction method. Phase purity, structure and crystallinity of all the samples were investigated by powder X-ray diffraction study which confirmed the Langasite (LGS) type structure for the synthesized samples. Al substituted ceramics exhibited low dielectric constant than the pure LGS. The ac conductivity values decrease with increase in Al-concentration, but increase with temperature and frequency. The result of Nyquist plot shows the presence of bulk resistive grain contributions and also confirms the increase of resistance with Al content in LGS. Our results may assist a way for the easy fabrication of Langasite based devices with improved resistivity properties by substituting a small amount of Al.