Patent ID: 6207070
Filing Date: 2001-03-27
Classification: H01L

Abstract:
A piezoelectric ceramic composition comprising:a main component expressed with a general expression of aPb(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 -bPb(Yb.sub.1/3 Nb.sub.2/3)O.sub.3 -cPbTiO.sub.3 -dPbZrO.sub.3, where a+b+c+d=1, 0.01.ltoreq.a.ltoreq.0.07, 0.01.ltoreq.b.ltoreq.0.07, 0.35.ltoreq.c.ltoreq.0.55, 0.4.ltoreq.d.ltoreq.0.6; anda subcomponent containing 0.1 to 0.7 wt % of Mn in terms of manganese oxide, 0.01 to 0.3 wt % of Cr in terms of chromium oxide and 0.05 to 0.5 wt % of Co in terms of cobalt oxide per the weight of 1 mol of main component, whereinthe composition has an electromechanical coupling coefficient (kt).gtoreq.40.0%. a coefficient of mechanical quality (Qm).gtoreq.500, a rate of change of kt after heat resistance test is within the range of -2.0% to 2.0% and a rate of change of kt after thermal shock test is within the range of -2.0% to 2.0%.