Influence of Na, Sm substitution on dielectric properties of SBT ceramics

Sodium, Samarium substituted Strontium Bismuth Titanate (Sr1-xNaxSmxBi4Ti4O15-SNSBT where x = 0.1, 0.2, 0.3, 0.4) piezoelectric ceramics are synthesized by solid-state sintering route using high energy planetary ball mill for 20 h in presence of Acetone and Aqua media. Calcination and sintering are carried out at 800 degrees C and 1160 degrees C respectively in Air using programmable furnace. 1 mm thickness and 10 mm diameter circular pellets are prepared by uniaxial hydraulic press at 4 tons/cm(2) pressure. Larger surfaces of the sample are coated with silver in order to have good electric contact for properties study. X-Ray Diffraction and Scanning Electron Microscopy studies are carried out to identify the orthorhombic structure, grain size and grain orientation. SEM shows densified and plate like structure of SNSBT. Experimental density is found to be more than 95% of theoretical density. Tolerance factor is decreased with increase of Na, Sm concentrations of SNSBT ceramics. Dielectric measurements are conducted as function of temperature at various frequencies and phase transition temperature (T-c) is enhanced by addition of Na, Sm of SBT.