ORTHORHOMBIC-TO-TETRAGONAL PHASE TRANSITION IN 6.8-nmPbTiO3 NANOPARTICLES

Abstract

Crystalline 6.8-nm PbTiO 3 (PT) nanoparticles were prepared through a modified solgel method. The samples showed high homogeneity and in orthorhombic phase. We examined the structural and phonon characteristics in PT nanoparticles with various grain sizes, finding that the orthorhombic phase begins to emerge at room temperature when particle size reduces to 11 nm. In the 6.8-nm PT nanoparticles, an orthorhombic-to-tetragonal phase transition at 190°C was detected by recording the Raman spectra as a function of temperature. The thermal properties of PT nanocrystals were also studied, demonstrating that the orthorhombic-to-tetragonal phase transition in the 6.8-nm PT nanoparticles is a second-order phase transition with continuous change in lattice parameter.