Substituted barium titanate and barium strontium titanate ferroelectric compositions

摘要

This invention provides the three novel La,Fe, La,Cr and Sm,Fe substituted barium titanate solid solution ferroelectric compositions with the formula Ba_1-xLn_xTi_1-xM_xO₃ wherein when Ln is La, M is Fe or Cr, when Ln is Sm, M is Fe and x is from about 0.02 to about 0.06 and mixtures thereof, the novel La,Fe substituted barium strontium titanate solid solution ferroelectric compositions with the formula (Ba_1-ySr_y)_1-xLa_xTi_1-xFe_x O₃ wherein y is greater than zero and less than about 0.6 and x is from about 0.01 to about 0.06 and the novel La,Al substituted barium strontium titanate solid solution ferroelectric compositions with the formula (Ba_1-ySr_y)_1-xLa_x Ti_{1-x/4 3a/4}Al_a(x-a)/4O₃ wherein denotes a vacancy, y is greater than zero and less than about 0.6, a is from about 0.01 to about 0.06 and x is from 0.02 to about 0.10 with the proviso that x is greater than or equal to a. These low loss tunable ferroelectric compositions are especially useful in tunable microwave thin film devices which fall into three types: interdigital and trilayer capacitors, coplanar waveguides and microstrips.