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In this paper, we theoretically investigate intersubband absorption in La-doped BaSnO3/BaO perovskite-oxide double and triple symmetrical quantum wells. The goal is to assess the emerging possibilities offered by perovskite heterostructures for realization of oxide-based quantum well optoelectronic devices. Properties such as small electron effective mass, very high room-temperature mobility of BaSnO3, large conduction band offset between the two materials, are all promising for technological applications. Some of the possible applications include active n-channel materials in p-n junctions, field-effect transistors, ferroelectric field-effect transistors, sensitive UV photoconductors, and electron transport layers in perovskite solar cells. We are interested in tuning of the absorption spectra via quantum well width modulation, changing of doping density and variation of external electric field along the growth direction which is important for application in electro-optical light modulators. The electronic structure is calculated self-consistently by solving the Schrödinger–Poisson system of equations where the exchange correlation effects are also taken into the account. [ABSTRACT FROM AUTHOR]

The aldol condensation of acetone under supercritical conditions at 300–400°C and 11.0 MPa was carried out on BaSnO3-450 and BaSnO3-750 catalysts prepared by calcination of BaSn(OH)6 at 450 and 750°C, respectively. Conducting the reaction under these conditions makes it possible to overcome the problem of catalyst deactivation by coking and to obtain valuable chemicals with high selectivity. At 300°C, both catalysts provide selectivity of 85–87% to isomeric mesityl oxides (C6 products). At 400°C with the BaSnO3-450 catalyst, the selectivity significantly changes from C6 to C9 (phorones). Powder X-ray diffraction and TEM data attest to the multiphase nature of the samples, which contain barium stannates, barium carbonate, and tin oxide. It was found that the catalyst structure rearranges in situ, which greatly affects the catalytic properties and is most pronounced for BaSnO3-450. [ABSTRACT FROM AUTHOR]

In the present work, gas sensing properties of the screen printed ceria and ruthenate-sensitized BaSnO3 (BSO) with La doping heterostructure sensors towards the detection of ammonia and formaldehyde gases at room temperature were studied. Adhered, porous screen printed films with different morphologies were obtained by depositing the LaxBa1−xSnO3−δ (x = 0 and 0.05) powder particles prepared by the polymerized complex method. Ceria and ruthenate sensitization for screen printed LaxBa1−xSnO3−δ (x = 0.05) film was processed through dip-coating in the 0.03 M aqueous solution of CeCl3 and RuCl3, respectively. La-doped BaSnO3 (LBSO) sensor with smaller crystallites, needle-like morphology and high concentration of oxygen vacancies exhibited superior gas response of 65 and 29 towards 50 ppm of ammonia and formaldehyde gases, respectively. Superabundant sensitization of ceria and ruthenate reduced the oxygen vacancy and structural open porosity in the LBSO sensor; therefore, the ammonia gas response was decreased from 65 to 14 and 3, respectively, whereas the formaldehyde gas response was reduced to less than 1/6th times the LBSO sensor. Limit of detection of LBSO sensors was estimated to be ~ 1 and ~ 2 ppm against ammonia and formaldehyde, respectively. The presence of fluorite structured phase ceria with high oxygen atoms storage capacity facilitates the rapid oxidization of analyte gases and caused the expeditious response (75 s) and recovery (60 s) in CeOx-sensitized LBSO sensor. This study might give a new insight into the development of doped and sensitized BSO-based gas sensors operating at ambient conditions. [ABSTRACT FROM AUTHOR]

Polycrystalline powder of BaSnO was prepared at 1300 °C using a high-temperature solid-state reaction technique. X-ray diffraction analysis indicated the formation of a single-phase cubic structure with lattice parameter: a = (4·1158 ± 0·0003) Å. The synthesized powder was characterized using X-ray diffraction (XRD) scanning electron micrographs, energy dispersive X-ray analysis, differential thermal analysis, thermogravimetric analysis and Fourier transform infrared techniques. Electrical properties were studied using a.c. impedance spectroscopy technique in the temperature range of 50-650 °C and frequency range of 10 Hz-13 MHz. The complex impedance plots at temperature ≥ 300 °C show that total impedance is due to the contributions of grains, grain boundaries and electrode. Resistance of these contributions has been determined. Variation of these resistances with temperature shows the presence of two different regions with different slopes. The nature of variation for the above three resistances, in both the temperature regions confirms that conducting species (phases) responsible for grain, grain boundaries and electrode are the same. Based on the value of activation energy, it is proposed that conduction via hopping of doubly ionized oxygen vacancies ( V $_{\rm{o}}^{\bullet\bullet})$ is taking place in the temperature region of 300-450 °C, whereas in the temperature region of 450-650 °C, hopping of proton, i.e. OH ions occurs. [ABSTRACT FROM AUTHOR]

Here, we report the systematic studies on photoanodes of phase pure polycrystalline microrods of Barium Stannate (BaSnO3) microrods for application in porphyrin dye-sensitized solar cell (DSSC). We were able to establish the effect of vacuum annealing on BaSnO3 thin films on its electrical, optical and adsorption properties using XPS, UV–Vis, photoluminescence and adsorption isotherm studies. Increase in oxygen vacancy with annealing is found to increase the room temperature (RT) electron mobility from 49.1 to 82.4 cm2/V sec whereas macroporous nature of samples were found suitable for faster dye adsorption (~ 30 min). Post TiCl4 treatment studies, the maximum efficiency (η) of 4.7% is achieved in BSO films with current density Jsc ~ value as 10.4 mA/cm2; whereas DSSC fabricated using annealed BSO films gave maximum efficiency of 6.1% with Jsc value as 12.2 mA/cm2, during which the value of FF increased from 73.4 to 81%. The IPCE and proposed electron transfer mechanism suggested the potential application of macroporous BSO with unconventional dyes such as metallised-porphyrin. Our results strengthen the idea of using phase-pure, visible transparent porous BSO nanostructures with induced oxygen vacancies due to annealing process post-synthesis which eventually increased DSSC performance from by 84%. [ABSTRACT FROM AUTHOR]

Doped BaSnO3 has arisen many interests recently as one of the promising transparent conducting oxides for future applications. Understanding the microstructural characteristics are crucial for the exploration of relevant devices. In this paper, we investigated the microstructural features of 0.001% La doped BaSnO3 thin film using both conventional and aberration corrected transmission electron microscopes. Contrast analysis shows high densities of Ruddlesden-Popper faults in the film, which are on {100} planes with translational displacements of 1/2a < 111 > . Atomic EELS element mappings reveal that the Ruddlesden-Popper faults are Ba-O layer terminated, and two kinds of kink structures at the Ruddlesden-Popper faults with different element distributions are also demonstrated. Quantitative analysis on lattice distortions of the Ruddlesden-Popper faults illustrates that the local lattice spacing poses a huge increment of 36%, indicating that large strains exist around the Ruddlesden-Popper faults in the film. [ABSTRACT FROM AUTHOR]