Orientation related electrocaloric effect and dielectric phase transitions of relaxor PMN-PT single crystals.

Orientation related phase transitions of 0.76Pb(Mg 1/3 Nb 2/3 )O 3 -0.24PbTiO 3 single crystals are studied. Values of the relaxation parameters ( γ = 1.87–1.97) estimated from linear fits of the modified Curie-Weiss law indicate the relaxor nature. For (110) oriented single crystal, typical oxygen vacancies related high temperature dielectric relaxation behaviors are observed and analyzed. Orientations dependent electrocaloric effects of 0.76Pb(Mg 1/3 Nb 2/3 )O 3 -0.24PbTiO 3 single crystals are first studied and reported, large reversible adiabatic temperature change (0.80 K) and isothermal entropy change (0.66 J K −1 kg −1 ) are observed. Giant refrigeration efficiency (43.52) and high electrocaloric coefficient (0.041 K cm kV −1 ) exceed the electrocaloric effect values in most bulk ferroelectrics in previous reports. [ABSTRACT FROM AUTHOR]