Thermoelectric and structural correlations in (Sr1−x−yCaxN

Abstract

Structural and thermoelectric properties are reported for a specially designed class of A-site substituted perovskite titanates, (Sr 1-x-y Ca x Nd y )TiO 3 . Two series synthesized with various A-site Sr-rich or Ca-rich (Sr-poor) concentrations were investigated using high resolution neutron powder diffraction as a function of temperature and Nd doping. Each series was designed to have a nominally constant tolerance factor at room temperature. We determine the room temperature structures as tetragonal I4/mcm and orthorhombic Pbnm for the Sr-rich and Ca-rich series, respectively. Three low temperature orthorhombic structures, Pbnm, Ibmm and Pbcm were also observed for the Sr-rich series; whereas, the symmetry of the Ca-rich series remains unchanged throughout the full measured temperature range. Thermoelectric properties of (Sr 1-x-y Ca x Nd y )TiO 3 were investigated and correlated with the structural variables. We succeeded in achieving a relatively high figure of merit ZT=0.07 at ~400 K in the Sr-rich Sr 0.76 Ca 0.16 Nd 0.08 TiO 3 composition which is comparable to that of the best n-type TE SrTi 0.80 Nb 0.20 O 3 oxide material reported to date. For a fixed tolerance factor, the Nd doping enhances the carrier density and effective mass at the expense of the Seebeck coefficient.Thermal conductivity greatly reduces upon Nd doping in the Ca-rich series. With an enhanced Seebeck coefficient at elevated temperatures and reduced thermal conductivity, we predict that Sr 0.76 Ca 0.16 Nd 0.08 TiO 3 and similar compositions have the potential to become some of the best materials in their class of thermoelectric oxides.

Graphene/Strontium Titanate: Approaching Single Crystal–Like Charge Transport in Polycrystalline Oxide Perovskite Nanocomposites through Grain Boundary Engineering

“…These include high temperature superconductivity, ferroelectricity, the colossal magnetoeffect, and many other attractive properties . Because of these properties, oxide perovskites are promising candidates for thermoelectricity, catalysis, fuel cells, and solar cells . High‐mobility electronic transport is crucial for all these applications.…”

Effect of Two‐Dimensional Crystal Orbitals on Fermi Surfaces and Electron Transport in Three‐Dimensional Perovskite Oxides

“…Perovskite oxides span numerous compositions and are heavily studied as materials for catalytic, fuel cell, thermoelectric, and oxide electronics applications . SrTiO 3 is a particularly promising candidate for electronics, because it supports two‐dimensional electron gases at its surfaces and interfaces, which may lead to new device applications .…”

Effect of Two‐Dimensional Crystal Orbitals on Fermi Surfaces and Electron Transport in Three‐Dimensional Perovskite Oxides

“…Perovskite oxides span numerous compositions and are heavily studied as materials for catalytic, [1][2][3][4] fuel cell, [5][6][7][8] thermoelectric, [9][10][11][12] and oxide electronics applications. [13][14][15][16] SrTiO 3 is ap articularly promising candidate for electronics, because it supports two-dimensional electron gases at its surfaces and interfaces, [17][18][19] which may lead to new device applications.…”