A sol-gel derived 0.9Pb(Mg1/2Nb2/3)O-3-0.1PbTiO(3) ceramic

Using inorganic chemicals, such as niobium pentachloride, titanium tetrachl oride, lead nitrate, and magnesium nitrate, as the starting materials, 0.9P MN-0.1PT has been fabricated via a simple and low cost sol-gel processing r oute. A colloidal solution was first prepared by adding an aqueous lead nit rate solution into an ethanol solution of niobium and titanium chlorides. M agnesium nitrate was then mixed into the solution when chloride ions were r emoved buy forming precipitates of PbCl2 with the excess lead nitrate, The gelation of the colloidal solution was facilitated in the presence of a sma ll amount of polyethylene glycol (PEG 300) at 70 degrees C. A fine perovski te 0.9PMN-0.1PT powder was obtained when the resulting gel was dried at 300 degrees C for 4 h and subsequently calcined. It was observed that the sol- gel derived precursor underwent a pyrochlore phase at 500-600 degrees C, pr ior to the formation of a perovskite single phase at a calcination temperat ure of 850 degrees C, A sintered density of similar to 98% theoretical dens ity was obtained when the fine 0.9PMN-0.1PT powder was sintered at 1250 deg rees C for 2 h and the sintered ceramic shows a maximum dielectric constant of 26,682, together with a room temperature dielectric constant of 19,206 at 1 kHz. The superb dielectric properties are correlated to the microstruc tural features of the sol-gel derived 0.9PMN-0.1PT, which has been characte rized using techniques such as XRD, SEM, and TEM.