Phase transition in Pb(4.9)A(0.1)Ge(2.7)Si(0.3)O(11) (A = Ca, Sr, Ba) ferroelectrics

Polycrystalline samples of modified lead germanate Pb(4.9)A(0.1)Ge(2.7)Si(0 .3)O(11) (A = Ca, Sr, Ba) have been prepared by solid-state reaction techni que. X-ray studies have been carried out to check the formation of single-p hase composition and to obtain preliminary structural data. Measurements of dielectric permittivity (epsilon) and loss (tan delta) have been studied b oth as a function of frequency (10(2)-10(4) Hz) and temperature (room tempe rature to 180 degrees C). Phase transition was observed in all three cases but with different T-c value. From the plots of conductivity vs, temperatur e using dielectric data, collected at 10 kHz activation energy was calculat ed to investigate the conduction mechanism in them. (C) 1999 Elsevier Scien ce Ltd. All rights reserved.