Structure　and　dielectric　properties　of　pyrochlore　solid　solutions　in　the　Bi2O3-ZnO-Nb2O5-Sb2O3　(BZNS)　system　were　investigated.　The　X-ray　diffraction　technique　was　used　to　analyze　the　phase　structure.　Also,　the　atomic　valence　of　Sb　in　BZNS　pyrochlores　was　confirmed　as　quinquevalent　cation　(Sb5+)　by　X-ray　photoelectron　spectroscopy.　Sb　replacing　Nb　in　the　series　(Bi1.8Zn0.2)(Zn0.6Nb1.4-xSbx)O-7　leads　to　lower　dielectric　constant.　With　increasing　amount　of　Sb5-　ions　substitution　(0　less　than　or　equal　to　x　less　than　or　equal　to　1.4),　the　dielectric　constant　(epsilon)　decreases　linearly　from　100　to　35　associated　with　a　very　low　loss　(tan　delta　less　than　or　equal　to　4　x　10(-4)).　The　temperature　dependence　of　dielectric　constant　varies　systematically　with　x.　The　ceramics　with　a　temperature　coefficient　of　dielectric　constant　(alpha(e))　less　than　+/-15　ppm/degreesC　are　reported.　The　data　suggest　that　the　B-site　cations　play　an　important　role　in　the　determination　of　dielectric　properties　for　the　compounds.　(C)　2002　Elsevier　Science　Ltd.　All　rights　reserved.