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

Orientation related phase transitions of 0.76Pb(Mg1/3Nb2/3)O3-0.24PbTiO3 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(Mg1/3Nb2/3)O3-0.24PbTiO3 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.