PbBi2Nb2O9　nanocrystals　with　a　perovskite-type　structure　were　successfully　synthesized　at　a　relative　low　temperature　via　a　citrate　complex　method.　Metal　ions　were　dispersed　by　citric　acid　in　ethanol　and　ethylene　glycol　solvent,　and　then　reacted　with　NH4H2[NbO(C2O4)(3)center　dot　3H(2)O]　to　form　the　gel.　XRD　results　showed　that　pure　PbBi2Nb2O9　nanocrystals　could　be　obtained　after　calcined　treatment　of　xerogel　at　800　degrees　C.　The　average　particles　size　was　57　nm.　Scanning　electron　microscopy　(SEM)　and　transmission　electron　microscopy　(TEM)　revealed　that　the　sintering　process　led　to　the　agglomeration　of　the　nanoparticles.　The　photocatalytic　test　showed　that　the　sample　prepared　by　the　citrate　complex　method　exhibited　a　higher　photocatalytic　activity　than　that　of　the　sample　prepared　by　the　solid-state　reaction.　(C)　2007　Elsevier　B.V.　All　rights　reserved.