The results of measurements of dielectric constants, in the vicinity o
f ambient temperature, are presented for eight barium titanium niobium
oxides (BaTi1+2nNb4O13+4n for n = 0, 1, 2, 3, 4; Ba3Ti4Nb4O21, Ba3Ti5
Nb6O28, and Ba6Ti2Nb8O30) in polycrystalline ceramic form. The dielect
ric constants are in the range of 30 to 70. The results of dielectric
measurements on solid solutions obtained by partial substitution of Ta
for Nb are also reported. These substitutions do not dramatically inc
rease the dielectric constants. One material, Ta-substituted Ba3Ti5Nb6
O28, has a very low temperature coefficient of dielectric constant at
K approximate to 45.