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Structure, electrical and dielectric properties of praseodymium modified lead potassium niobate ceramic`

T.Swarna Latha

PraseodymiummodifiedLeadPotassium Niobate (Pb1-xK2x-3yMyNb2O6 for x = 0.20, y = 0.10 andM=Pr) ferroelectric ceramic has been prepared by a high temperature solid state reaction technique. X-raydiffraction studies of thematerial at roomtemperature revealed orthorhombic structurewith lattice parameters (a=17.7150A, b= 17.9730A, c=3.889 0A). The grain size of the sample has been found to be 4.46µm by using Scanning Electron Microscopy (SEM).Detailed dielectric study of sintered pellets as a function of temperature at different frequencies (500Hz, 1 KHz, 10 KHz, 20 KHz) and Curie temperature is found to be 3400C. The impedance plots are used as tool to analyze the sample behavior as a function of frequency. The electrical process in the sample has beenmodeled in the formof an electrical equivalent circuitmade up of a series combination of two parallel RC circuits attributed grains and grain boundaries. TheCole-Cole plots (ZÂÂ’ versus ZÂÂ’ÂÂ’) of impedancewere drawn at different temperatures and showed non-Debye type relaxation.Modulus analysis reveals the possibilityof hoppingmechanismfor electrical transport process in the systems.D.C and A.Cconductivities of the sample as a function of temperature (fromroomtemperature (RT) - 5900C) have been studied. The frequency dependant ac conductivity at different temperatures showed the conduction process is thermallyactivated process.