Frequency stable npo ceramics

Abstract

Bismuth-containing temperature-stable dielectric ceramics are disclosed herein that are stable over a wide range of frequencies, and thus are suitable for ceramic capacitors and microwave dielectrics. This class of materials is defined by the formula Bi.sub.2 O.sub.3 xTiO.sub.2 wherein x ranges up to 7 and the Ti.sup.4+ ion may be replaced with mixed ions of equivalent charge, thus maintaining charge balance. Suitable replacements for the Ti.sup.4+ ion are: A.sub.1/3.sup.2+ B.sub.2/3.sup.5+, R.sub.2/3.sup.3+ C.sub.1/3.sup.6+, A.sub.1/2.sup.2+ C.sub.1/2.sup.6+, R.sub.1/2.sup.3+ B.sub.1/2.sup.5+, M.sub.1/4.sup.1+ B.sub.3/4.sup.5+, and M.sub.2/5 .sup.1+ C.sub.3/5.sup.6+ ; where M.sup.+ is selected from the group consisting of Li.sup.+, Na.sup.+, K.sup.+, Cu.sup.+, and Ag.sup.+ ; A.sup.2+ is selected from the group consisting of Mg.sup.2+, Zn.sup.2+, Ni.sup.2+ , Co.sup.2+, Cu.sup.2+, and Cd.sup.2+ ; R.sup.3+ is selected from the group consisting of Cr.sup.3+, Mn.sup.3+, Fe.sup.3+, Al.sup.3+, Ga.sup.3+, Zn.sup.3+, Tl.sup.3+, Sb.sup.3+, As.sup.3+, Y.sup.3+, Lu.sup.3+, Yb.sup.3+, Tm.sup.3+, Er.sup.3+, Ho.sup.3+, Dy.sup.3+, Tb.sup.3+, Gd.sup.3+, Eu.sup.3+, and Sm.sup.3+ ; B.sup.5+ is selected from the group consisting of Nb.sup.5+, Ta.sup.5+, and V.sup.5+ ; and C.sup.6+ is selected from the group consisting of W.sup.6+ and Mo.sup.6+.