Structural and dielectric properties of Pb(1−x)(Na0.5Sm0.5) x TiO3 ceramics

Abstract

Abstract:A correlation between structure and vibrational properties related to a ferroelectric to paraelectric phase transition in perovskite Pb (1-x) (Na 0.5 Sm 0.5 ) x TiO 3 (0≤x≤0.5) (PNST-x) polycrystalline powders is discussed. Substitution leads to reduction of tetragonality which is associated with a shift of the phase transition to lower temperatures. The nature of the phase transition gets diffused with increasing substitution.Keywords: Structural properties, Raman spectroscopy, Dielectric, Phase transition. IntroductionPbTiO 3 is known to be a strong ferroelectric perovskite compound. A structural phase transition from tetragonal (P4mm) to cubic (Pm3m) phase at 763K is observed in PbTiO 3 . Tetragonality, measured by c/a ratio is frequently related to ferroelectric properties. For PbTiO 3 , c/a ratio is ~1.06 at room temperature [1][2][3][4][5]. Properly substituted PbTiO 3 has different applications as capacitors, nonvolatile memories, ultrasonic transducers, pyroelectric infrared sensors, piezoelectric actuators due to their highly anisotropic nature of elastic, piezoelectric, and electro-optic properties etc. [6][7][8].Physical properties and device applications of ferroelectric perovskite (ABO 3 ) compounds like PbTiO 3 and BaTiO 3 have been studied extensively due to their technological importance. Based on the fact that PbTiO 3 is toxic and volatile in nature and not environmental friendly many reduced lead content ferroelectric materials has been investigated, such as

Solid state synthesis of lead-free Sm-doped Na0.5Bi4.5Ti4O15 ceramics for enhanced dielectric and electrical properties

“…The drastic progress in electrical properties of bismuth-based compounds may be due to the Sm influence in the structure, which improves the density of the compound by reducing the bismuth evaporation from the material. Reduction in bismuth volatilization at high temperatures slows down the formation of oxygen vacancies in the compounds and improves the dielectric constant [ 39 ]. The generation of oxygen vacancies in bismuth-contained compounds is through the following way [ 40 ]: is 1st ionized oxygen vacancy and 2nd ionized oxygen vacancy.…”

Structural and ferroelectric properties of perovskite Pb(1−x)(K0.5Sm0.5)xTiO3 ceramics

“…6,7 But, Pb not being an environmental friendly material due to highly toxic nature of Pb, there is a necessity to reduce the Pb content for applications from the point of view of safety and health concerns. [8][9][10][11][12][13][14][15][16][17][18][19] By making isovalent or aliovalent substitution on the Pb 2+ site, lattice anisotropy is reduced. A polar tetragonal to nonpolar cubic phase transition decreases to lower temperatures mostly decreases with substitution as most substitution reduces the lattice strain.…”