Temperature-dependent synchrotron powder diffraction phase studies of (K0.37Na0.52Li0.03)(Nb0.87Ta0.1Sb0.03)O3 ferroelectric ceramics

Temperature-dependent synchrotron powder diffraction measurements have been performed on lead- free ferroelectric (K0.37Na0.52Li0.03)(Nb0.87Ta 0.1Sb0.03)O3 ce- ramics. The measurement was performed from 20 � Ct o 400 � C with 20 � C steps. The diffraction patterns showed the existence of two phases from 20 � C to 180 � C while the ferroelectric to paraelectric phase transition occurred between 340 � C and 360 � C. Rietveld refinement using the Fullprof software was employed and the two-phase region was refined using a combination of the orthorhombic phase with space group Amm2 (38) and the tetragonal phase with space group P4mm (99) from 20 � C to 180 � C. The tetragonal phase was used for the refinement up to 340 � C while the cubic phase was refined with space group Pmm (221). Good refinement structure parameters were obtained for all temperatures with the average G.O.F being approximately 4.0. Information about the cell para- meters and weight fraction of the phases were obtained as a function of temperature.