Frequency and temperature response based electrical properties of samarium modified bismuth ferrite-lead titanate material

摘要

In this work, samarium substituted bismuth ferrite (BiSmFeO3) modified lead-titanate (PbTiO3) ceramic compound ((Pb0.8Sm0.1Bi0.1)(Fe0.2Ti0.8)O-3) is fabricated by mixed-oxide technique. The structure analysis of the synthesized compound is done by XRD, morphology by SEM, dielectric and electrical analysis by LCR measurements. Polycrystalline sample having distorted tetragonal symmetry and uniform compact microstructure has been formed. This Sm substituted BFPT compound possesses good room temperature dielectric properties (dielectric constant = 324, dielectric loss = 0.013, 1 MHz frequency). The conductivity spectrum confirms the negative temperature coefficient of resistance (NTCR)/semiconducting behaviour of this compound. The frequency dependent ac conductivity obeys Jonscher power law. The electrical conduction in this ceramic is the cumulative result of hopping of charge carriers across the barrier potential and tunnelling of polarons formed due to lattice distortion at high temperatures. Both dielectric and conductivity relaxation processes are observed in this BFPT compound. The observed relaxation phenomenon in this ceramic compound deviates from ideal Debye-type behaviour, validated from impedance spectroscopic analysis. The transformation from long range motion to short range motion of charge carriers is noticed from frequency variation of complex electric modulus.