31 research outputs found
Critical Behavior Near the Paramagnetic to Ferromagnetic Phase Transition Temperature in Sr1.5Nd0.5MnO4 Compound
Atomic scale imaging of competing polar states in a RuddlesdenâPopper layered oxide
Layered complex oxides offer an unusually rich materials platform for emergent phenomena through many built-in design knobs such as varied topologies, chemical ordering schemes and geometric tuning of the structure. A multitude of polar phases are predicted to compete in RuddlesdenâPopper (RP), A(n+1)B(n)O(3n+1), thin films by tuning layer dimension (n) and strain; however, direct atomic-scale evidence for such competing states is currently absent. Using aberration-corrected scanning transmission electron microscopy with sub-Ă
ngstrom resolution in Sr(n+1)Ti(n)O(3n+1) thin films, we demonstrate the coexistence of antiferroelectric, ferroelectric and new ordered and low-symmetry phases. We also directly image the atomic rumpling of the rock salt layer, a critical feature in RP structures that is responsible for the competing phases; exceptional quantitative agreement between electron microscopy and density functional theory is demonstrated. The study shows that layered topologies can enable multifunctionality through highly competitive phases exhibiting diverse phenomena in a single structure
Isobaric heat capacity and standard thermodynamic properties of NaLaTiO4 and Na2La2Ti3O10 over the range of (7â670) K
Formation mechanism of Ruddlesden-Popper-type antiphase boundaries during the kinetically limited growth of Sr rich SrTiO3 thin films
Calibrating the Extended HĂźckel Method to Quantitatively Screen the Electronic Properties of Materials
Lowering the thermal conductivity of Sr(Ti0.8Nb0.2)O3 by SrO and CaO doping: microstructure and thermoelectric properties
Excess SrO and CaO were added to the Sr(Ti0.8Nb0.2)O3 thermoelectric material, which was structurally compensated by the formation of RuddlesdenâPopper-type planar faults with the compositions SrO and/or (Sr, Ca)O. Both types of doping significantly changed the original isotropic Sr(Ti0.8Nb0.2)O3 microstructure and resulted in the formation of lamellar RuddlesdenâPopper-type phases within the Sr(Ti0.8Nb0.2)O3 grains. Three-dimensional networks of single RuddlesdenâPopper-type faults were also observed in the Sr(Ti0.8Nb0.2)O3 for both types of doping. The combination of both structural features significantly lowered the thermal conductivity in comparison with Sr(Ti0.8Nb0.2)O3 due to the enhanced phonon scattering observed at the planar faults, which proves that introducing such defects is a promising method for lowering the thermal conductivity of the Sr(Ti0.8Nb0.2)O3 thermoelectric material. The highest figure of merit (ZT = 0.08) was achieved with CaO doping, since the significantly reduced thermal conductivity was accompanied by an increased power factor