Selected mixtures in 2 l binary and 9 ternary rare-earth oxide syste ms were studied by X-ray diffraction after heat treatment aL 1,650° C and above. Two graphs were drawn to show specific r egions of stability for t he various strucLure types. Each givcs t he a verage ionic rad ius of constiLuent cations versus the mole percent of the smaller cation. One diagram is es~e ntiall :-' divided inLo...

In the aim to stabilize novel three-dimensional perovskite oxides based upon SrCoO3-δ, we have designed and prepared SrCo1-xRexO3-δ phases (x = 0.05 and 0.10), successfully avoiding the competitive hexagonal 2H polytypes. Their performance as cathode materials in intermediate-temperature solid oxide fuel cells (IT-SOFC) has been investigated. The characterization of these oxides included X-ray ...

Organic-inorganic metal halide perovskites are promising semiconductors for optoelectronic applications. Despite the achievements in device performance, the electrical properties of perovskites have stagnated. Ion migration is speculated to be the main contributing factor for the many unusual electrical phenomena in perovskite-based devices. Here, to understand the intrinsic electrical behavior...

Hugoniot equation of state measurements have been performed on pure synthetic single-crystal forsterite (Mg•SiO4) in the pressure range 70-160 GPa (0.7-1.6 Mbar). These and earlier data for polycrystalline forsterite are compared with theoretical Hugoniots for the assemblages 2MgO (rocksalt) + SiO: (stishovite) and MgO (rocksalt) + MgSiO8 (perovskite). The densities attained by single-crystal f...

We report a study of the magnetoresistance (MR) of the metallic perovskite oxide LaNiO3−δ as a function of the oxygen stoichiometry δ (δ ≤ 0.14), magnetic field ( H ≤ 6T ) and temperature (1.5K ≤ T ≤ 25K). We find a strong dependence of the nature of MR on the oxygen stoichiometry. The MR at low temperatures change from positive to negative as the sample becomes more oxygen deficient ( i.e, δ i...

Mixed halide perovskite materials are actively researched for solar cells with high efficiency. Their hysteresis which originates from the movement of defects make perovskite a candidate for resistive switching memory devices. We demonstrate the resistive switching device based on mixed-halide organic-inorganic hybrid perovskite CH3NH3PbI3-xBrx (x = 0, 1, 2, 3). Solvent engineering is used to d...

The temperature-induced antiferrodistortive (AFD) structural phase transitions in CaMnO3, a typical perovskite oxide, are studied using first-principles density functional theory calculations. These transitions are caused by tilting of the MnO6 octahedra that are related to unstable phonon modes in the high-symmetry cubic perovskite phase. Transitions due to octahedral tilting in perovskites no...

Oxygen vacancies play a key role in determining the functionality and performance of many oxide smart materials. In this paper, the crystal structure of an anion-de® cient perovskite-type orthorhombic (with a < b) phase La0.5Sr0.5CoO2.25 (or La8Sr8Co16O36) has been determined for the ® rst time with the combined use of energy-dispersive X-ray spectroscopy, electronenergy-loss spectroscopy, high...

Extending the spectral absorption of organolead halide perovskite solar cells from visible into near-infrared (NIR) range renders the minimization of non-absorption loss of solar photons with improved energy alignment. Herein, we report on, for the first time, a viable strategy of capitalizing on judiciously synthesized monodisperse NaYF4 :Yb/Er upconversion nanoparticles (UCNPs) as the mesopor...