The　cubic　pyrochlore　structure　of　Bi1.5Zn1.0Nb1.5O7　was　investigated.　The　crystal　chemical　formula　of　this　material　was　determined　as　Bi1.5Zn0.5(Zn0.5Nb1.5)O-7　by　comparing　the　calculated　theoretical　X-ray　diffraction　intensities　with　the　observed　ones.　Crystal　structure　parameters　were　refined　by　Rietveld　method.　The　(Bi-1.5-2yZn1+2yNb1.5)O7-y　crystalline　samples　were　also　examined　by　Raman　spectroscopy　to　look　for　further　short　range　structural　information.　The　results　show　that　the　Nb-O　and　Zn-O　stretching　modes　in　the　B　site　oxide　octahedral　almost　do　not　change　with　the　chemical　constitution　changing.　It　is　reasonable　that　the　movable　Zn2+　is　inclined　to　occupy　B　site　first　and　then　enter　into　A　site　after　the　B　site　was　stuffed.　(C)　2002　Elsevier　Science　B.V.　All　rights　reserved.