The　as-sintered　Pb(Zn1/3Nb2/3)(0.5)(Zr0.47Ti0.53)(0.5)O-3　samples　were　annealed　in　oxygen　and　nitrogen.　Both　annealed　specimens　exhibited　improved　degree　of　relaxation　compared　with　as-sintered　specimens.　However,　the　mechanisms　inducing　enhancement　of　relaxation　were　different　in　the　two　kinds　of　specimens.　For　the　oxygen　annealed　sample,　oxygen　vacancies　were　partially　filled,　which　induced　the　macro-microdomain　transition　and　resulted　in　the　increase　of　relaxation　degree.　Whereas,　for　the　nitrogen　annealed　specimen,　the　emergence　of　pyrochlore　phase　was　inevitable　due　to　the　flowing　reductive　atmosphere,　the　pyrochlore　phase　broke　the　long-range　transition　invariance　of　perovskite　structure　and　played　a　key　role　in　improving　the　relaxation.　(C)　2009　Elsevier　Ltd.　All　rights　reserved.