Micro-Macro Domain Switching and Thermoelastic Martensitic Transformation in $PbZrO_3$-doped $Pb(Ni_{1/3}Nb_{2/3})O_3-PbTiO_3$ System

$PbZrO_3$가 첨가된 $Pb(Ni_{1/3}Nb_{2/3})O_3-PbTiO_3$ 계의 미소-거시 분역 반전과 열탄성 마르텐사이트 변태

The possiblity of the existence of a spontaneous relaxor-normal ferroelectric transition was proposed and examined using 1~5 mol% PbZrO3-doped Pb(Ni1/3Nb2/3)O3-PbTiO3 (PNN-PT) systems having tetragonal symmetry at rom temperature. On cooling, the system with 60mol% Pb(Ni1/3Nb2/3)O3 underwent a spontaneous transition from a relaxor to a normal ferroelectric state. A microscopic examination demonstrates that the relaxornormal ferroelectric transition corresponds to a micro-macro domain switching accompanied with thermoelastic martensitic transformation. The long-range macrodomains below the transition temperature were characterized by twinlike 90$^{\circ}$macrodomains with tetragonal symmetry. The relaxor-normal ferroelectric transition was further correlated with the rhombohedral-tetragonal first-order structural transition.