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The recent interests in bridging intriguing optical phenomena and thermal energy management has led to the demonstration of controlling thermal radiation with epsilon‐near‐zero (ENZ) and the related near‐zero‐index (NZI) optical media. In particular, the manipulation of thermal emission using phononic ENZ and NZI materials has shown promise in mid‐infrared radiative cooling systems operating under low‐temperature environments (below 100 °C). However, the absence of NZI materials capable of withstanding high temperatures has limited the spectral extension of these advanced technologies to the near‐infrared (NIR) regime. Herein, a perovskite conducting oxide, lanthanum‐doped barium stannate (La:BaSnO3 [LBSO]), as a refractory NZI material well suited for engineering NIR thermal emission is proposed. This work focuses on the experimental demonstration of superior high‐temperature stability (of at least 1000 °C) of LBSO films in air and its durability under intense UV‐pulsed laser irradiation below peak power of 9 MW cm−2. Based on the low optical‐loss in LBSO, a selective narrow‐band thermal emission utilizing a metal‐insulator‐metal (MIM) Fabry–Pérot nanocavity consisting of LBSO films as metallic component is demonstrated. This study shows that LBSO is an ideal candidate as a refractory NZI component for thermal energy conversion operating at high temperatures in air and under strong light irradiations. [ABSTRACT FROM AUTHOR]

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]

4-Nitroaniline (4-NA) compounds are considered highly hazardous to the environment and can be found in various chemical products, including pigments, dyes, fungicides, and pesticides. The presence of 4-NA in water poses significant carcinogenic risks to humans. Therefore, there is an urgent need to monitor and detect the environmentally hazardous 4-NA, especially in water samples. In this study, we have developed a novel nanocomposite based on barium stannate/halloysite-based (BaSnO 3 /HNTs) with a nanotube structure. The nanocomposite was synthesized using natural deep eutectic solvents (NADESs) and aimed at the selective electrochemical detection of 4-NA in water samples. Morphological studies clearly revealed the random incorporation of BaSnO 3 nanoparticles (NPs) with diameters ranging from ∼10–50 nm onto the surface of HNTs. The incorporation of BaSnO 3 NPs created more active sites and facilitated fast electron transport, as confirmed by EIS. Under a saturated N 2 condition and at pH 7.0, the BaSnO 3 /HNT/SPCE exhibited excellent electrochemical performance with a very low limit of detection and a wide linear range of 2 nM and 0.009–1126 μM, respectively. Additionally, the proposed sensor for 4-NA demonstrated good anti-interference ability, repeatability (RSD ∼1.31%), and stability (RSD ∼1.09%). The obtained electrochemical analytical results of the synthesized composite validate its superior potential for real-time applications. [Display omitted] • BaSnO 3 /HNT nanocomposite was prepared by using deep eutectic solvents to detect hazardous organic pollutant (4-NA). • The nanocomposite was prepared using the co-precipitation method. • The 4-NA sensor showed a good limit of detection of about 2 nM. • The observed linear range (LR) is about 0.009–1126 μM. • The proposed sensor was successfully applied for real-time applications in river and pond water. [ABSTRACT FROM AUTHOR]

Cubic perovskite oxides are attracting wide attention for applications in electronics and optoelectronics due to their high electronic mobility, however, realization of p -type conductivity in these oxides is still a matter. Barium stannate (BaSnO 3) is one of such materials, wherein low-amount of lanthanum-doping can induce an extremely high room-temperature electron mobility. In this work, anion-doping strategy was explored to realize the p -type conductivity in BaSnO 3 , and the underlying physics of transport was investigated. It is found that nitrogen substitution for oxygen can induce the p -type conductivity in BaSnO 3 thin films. By analyzing the temperature-dependent resistance and negative magnetoresistance data, Efros-Shklovskii variable-range hopping conduction is identified as the dominant transport mechanism in p -type BaSnO 3 thin films. Additionally, nitrogen-doped BaSnO 3 homojunctions exhibit good rectifying and photo-response properties. This study provides an alternative strategy for realizing the p -type conductivity in stannate-based perovskite oxides, and is helpful for designing the properties of stannate-based devices. [ABSTRACT FROM AUTHOR]

The implications of acceptor-bound ionic defects in the hydration of acceptor-doped cubic perovskite BaSnO 3 are elucidated based on the thermogravimetric analysis of water uptake and the authors' recent statistical theory. The oxides BaSn 1–x Sc x O 3–δ (0.10 ≤ x ≤ 0.37) and BaSn 0.9 Sc 0.1–x In x O 3–δ (x = 0.05, 0.10) were synthesized and experimentally studied. The thermogravimetric measurements showed very good hydration properties of BaSn 1–x Sc x O 3–δ : the low-temperature hydrogen concentration was close to the nominal dopant content for all doping levels. The obtained data pertaining to the dopant concentration effect on the hydration isobars are well described by the exploited theory that accounts for the trapping of protons and oxygen vacancies by acceptors. The experimental findings on the effect of scandium substitution with indium on the hydrogen dissolution in the BaSn 0.9 Sc 0.1–x In x O 3–δ oxides are also in good agreement with our theoretical predictions. In addition, we discuss the impact of trapping on the hydration enthalpy, entropy and Gibbs free energy of BaSnO 3 doped with various acceptors, and establish the type and concentration of acceptor impurities which enhance or inhibit hydration. Our results testify to the pivotal role of the defects' trapping by acceptors in the hydration of barium stannate, and demonstrate that this effect is important for understanding and prediction of the hydration properties of acceptor-doped perovskites. Image, graphical abstract [ABSTRACT FROM AUTHOR]

In this study, electrically conductive perovskite lanthanum-doped barium stannate, La x Ba 1- x SnO 3-δ (x = 0, 0.05, 0.1 and 0.15) ceramics were synthesized through polymerized complex method. The evolution of BaSnO 3 phase with temperature and effect of La doping was investigated. Doping of La increased the lattice parameter from 4.1165 to 4.1208 Å, up to solubility limit (x = 0.1); doping further, secondary phase La 2 Sn 2 O 7 appeared. BaSnO 3 phase crystallization initiated at ∼528 °C from the reaction of BaCO 3 and SnO 2 and was retarded by La doping causing an increment in phase formation temperature from 528.4 to 531.1 °C. Fourier transform infrared spectroscopy evidence substantial increment in (SnO 3)2- absorption band with temperature strengthening diffraction responses. An incremental response in the electrical conductivity was observed by La doping with a maximum value of ∼25 S cm−1, attributed to the generation of charge carriers by substitution of Ba with La ion and oxygen vacancies. In parallel, generated charge carriers also contributed towards the ionic reduction of Sn4+ to Sn2+ aiding the lattice enhancement. La-doped BaSnO 3 ceramics can have a potential application in optoelectronic, thermoelectric devices and humidity sensors. [ABSTRACT FROM AUTHOR]

Abstract Recently electrostrictive effect in ferroelectrics has attracted much attention, since the electric field-induced strain based on such an effect possesses an ultra-low hysteresis, which is of special interest to both fundamental research and potential application in high-precision actuators. In this paper, we propose a strategy to obtain high electrostrictive properties in ABO 3 perovskite structure BaTiO 3 (BT)-based ferroelectric ceramics by means of doping. The doping element, amount, valence as well as position are specified according to this strategy. It is suggested that B-site Sn4+-doped BT, i.e., Ba(Ti 1- x Sn x)O 3 (BTS), would possess superior electrostrictive properties. The structural evolution and electrical properties of BTS ferroelectric ceramics were investigated in detail in order to verify this deduction. Besides the ferroelectric-to-relaxor transition with respect to the increase of x from 0.06 to 0.11, expected and high electric field-induced strain (> 0.08% at 40 kV/cm) with a very ultra-low hysteresis (< 8%) is obtained in x = 0.10–0.11 compositions. High longitudinal electrostrictive coefficient Q 33 ranges from to 0.0398 m4/C2 to 0.0515 m4/C2 accompanying with temperature- and composition-insensitive characteristics. These results not only prove the effectiveness of this strategy, but also pave a way to search for novel kinds of electrostrictive systems in ferroelectrics. [ABSTRACT FROM AUTHOR]

Highly performance of flexible transparent conductive Cu-based ZnO multilayer thin films are achieved by barrier layer of amorphous thin films based on barium stannate. The flexible multilayers exhibit high figure of merit (FoM) of 20.38 × 10 −3 Ω −1 with the sheet resistance of 6.19 Ω/sq. and resistivity of 5.28 × 10 −5 Ω cm, while the average optical transmittance is about 81.3% in the visible range. The FoM value is the highest among all the reported Cu-based transparent conductive thin films. The influence mechanism of BS barrier layers on electrical and optical properties of the multilayers is also proposed. Our results demonstrate that BS barrier layer is an effective way in tuning/improving the optical and electrical performances in the Cu-based ZnO multilayer thin films. [ABSTRACT FROM AUTHOR]

We report synthesis of pure and rare earth ion Er 3+ /Yb 3+ co-doped barium stannate (BaSnO 3 ) nano-crystallites by facile wet chemical route. The nano-crystallites at the Ba 2+ lattice site substitution of 0.1 and Er/Yb ratio of 0.00, 0.11, 0.18 and 0.25 exhibited band gap of 3.64, 3.66, 3.67 and 3.68 eV, respectively. The electrical conductivity of the nano-crystallites was found to increase with increase in Er/ Yb content ratio. All samples revealed a broad emission peak between 380 and 400 nm at the excitation wavelength of 350 nm. The up-conversion emission intensity has been found to increase with Er 3+ /Yb 3+ content for the excitation wavelength of 980 nm. Further, the influence of the up-conversion behavior on the photovoltaic performance of dye-sensitized solar cell has been investigated. The highest photon conversion efficiency of 4.2% was observed for the composition of Ba(Er/Yb: 0.25)SnO 3 with J SC = 9.69 mA/cm 2 , V oc = 0.63 V, FF = 0.690, which was about 40% increase in efficiency in comparison to pristine BaSnO 3 (3.0%). [ABSTRACT FROM AUTHOR]

Barium stannate is a mixed-metal oxide with a perovskite structure and unique electric, catalytic, and sensing properties. Surface chemistry determines gas sensing behavior, which depends on materials synthesis and processing methods. A novel technique was invented for obtaining BaSnO 3 nanoparticles using a hydrogen peroxide assisted sol-gel process. However, to date, the sensing behavior of such prepared barium stannate nanoparticles has not been investigated. In this work, we obtained pure and La-modified BaSnO 3 by the hydrogen peroxide-assisted sol-gel method and comparatively studied the composition, microstructure, and gas sensing behavior using as a reference barium stannate prepared by a conventional hydrothermal route. The increased sensitivity and selectivity to H 2 S were observed for the sol-gel obtained BaSnO 3 , and the sensing behavior was improved at temperatures higher than 150 °C by La(5%)-modified of barium stannate. The sensing mechanism was revealed by in situ infrared and Raman spectroscopy. The superior sensitivity and selectivity of the sol-gel obtained materials were attributed to lower surface contamination by adsorbed carbonate groups compared to hydrothermally obtained BaSnO 3. The surface modification by La3+ species further reduced the carbonate impurity and enhanced the adsorption and oxidation of H 2 S gas at the BaSnO 3 surface. [Display omitted] • Nanosized BaSnO 3 was obtained by peroxide sol-gel and hydrothermal methods. • Doped BaSnO 3 with uniform La-distribution was synthesized by sol-gel method. • Sol-gel prepared BaSnO 3 has high sensitivity and selectivity to H 2 S. • The sensitivity to H 2 S improved with La-doping of sol-gel obtained BaSnO 3. • It was due to less surface contamination by CO 3 2- in contrast to hydrothermal BaSnO 3. [ABSTRACT FROM AUTHOR]

In this study, we report that the carrier mobility of 2%-La-doped BaSnO3 (LBSO) films on (001) SrTiO3 and (001) MgO substrates strongly depends on the thickness, whereas it is unrelated to the film/substrate lattice mismatch (+5.4% for SrTiO3 and −2.3% for MgO). The films exhibited large differences in lattice parameters, lateral grain sizes (∼85 nm for SrTiO3 and ∼20 nm for MgO), surface morphologies, threading dislocation densities, and misfit dislocation densities. However, the mobility dependences on the film thickness in both cases were almost the same, saturating at ∼100 cm2 V−1 s−1, while the charge carrier densities approached the nominal carrier concentration (=[2% La3+]). Our study clearly indicates that the carrier mobility of LBSO films strongly depends on the thickness. These results would be beneficial for understanding the carrier transport properties and fruitful to further enhance the mobility of LBSO films. [ABSTRACT FROM AUTHOR]

BaSnO 3 has attracted attention as a transparent conducting oxide with high room temperature carrier mobility. We report a series of measurements that were carried out to assess the structure of BaSnO 3 over a variety of length scales. Measurements included single crystal neutron and x-ray diffraction, Rietveld and pair distribution analysis of neutron powder diffraction, Raman scattering, and high-pressure x-ray diffraction. Results from the various diffraction probes indicate that both the long-range and local structures are consistent with the cubic symmetry. The diffraction data under pressure was consistent with a robustly cubic phase up to 48.9 GPa, which is supported by density functional calculations. Additionally, transverse phonon velocities were determined from measured dispersion of the transverse acoustic phonon branches, the results of which are in good agreement with previous theoretical estimates and ultrasound measurements. [ABSTRACT FROM AUTHOR]

In present work, correlation of structural and optical behavior of pristine and lanthanum containing barium stannate nanoparticles (synthesized via cetyltriammonium bromide (CTAB) assisted facile wet chemical route), and its effect on photovoltaic properties of dye‐sensitized solar cell are reported. Thermo‐gravimetric analysis of the dried compound presumably BaSn(OH)6, leads to the formation of BaSnO3 nanoparticles through three endothermic decomposition processes, via liberation of one mole of water in each step, together with removal of remaining CTAB in initial cycle. The X‐ray diffraction patterns reveal that substitution of Ba2+ lattice sites by La3+ (upto ≈6 at.%), the lattice retains its cubic Pm3m symmetry, however, unit cell contracts. The dye sensitized solar cells are fabricated using pristine and La‐ containing BaSnO3 as photo anode; platinum coated FTO as counter electrode, N719 dye as sensitizer and I−/I3− as electrolyte. These show the highest power conversion efficiency (≈9.2%) at the La content of 6 at.% which is about threefold increase in efficiency in comparison to pristine BaSnO3. The electron transport properties of these DSSC devices are investigated by electro chemical impedance spectroscopy. [ABSTRACT FROM AUTHOR]

Density-functional theory calculations are performed to examine how two characteristics of a trivalent dopant (the one, physical – the ionic radius, the other, chemical – the electronegativity) impact the thermodynamics of doping, the defect association energy and the hydration energy in barium stannate, a perovskite oxide candidate as an electrolyte for Solid Oxide or Protonic Ceramic Fuel Cells. The formation energies of several trivalent dopants currently used in experimental works are computed in different external conditions and on the two possible sites (Ba, Sn), in their ionized state. These dopants cover a wide range of ionic radii (from 0.62 to 1.03 Å) and can be divided in two families according to their electronegativity: elements of group IIIA (Ga, In), versus IIIB transitions metals and Rare Earths (Sc, Lu, Y, Gd, Sm, La). The oxygen vacancy and the protonic defect are also studied, either isolated or in the vicinity of the dopant substituted on Sn site (1st & 2nd neighbors). The association energy between the dopant and both the oxygen vacancy and the proton, as well as the formation energy of the dopant on the Ba site, are mainly governed by the ionic radius of the dopant, with the exception that electronegative dopants stabilize more the oxygen vacancy in their vicinity. Therefore, a subtle interplay between elastic effects and chemistry is found to control the hydration energy/enthalpy, the more electronegative dopants – indium particularly – producing, at given radius, a less stable hydrated state . We provide with general trends likely to help experimentalists in the design of new materials, regarding the choice of dopant. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) exceeding a power conversion efficiency (PCE) of 20% have mainly been demonstrated by using mesoporous titanium dioxide (mp-TiO2) as an electron-transporting layer. However, TiO2 can reduce the stability of PSCs under illumination (including ultraviolet light). Lanthanum (La)–doped BaSnO3 (LBSO) perovskite would be an ideal replacement given its electron mobility and electronic structure, but LBSO cannot be synthesized as well-dispersible fine particles or crystall [ABSTRACT FROM AUTHOR]

Perovskite-structured oxides are promising materials for proton conduction. We use first-principles calculations to investigate the chemical stability and proton conductivity of doped barium hafnate (BaHfO 3 ) and barium stannate (BaSnO 3 ). Previously, we [RSC Adv. 3 , 3333 (2013)] reported first-principles calculations examining the chemical stability and proton conductivity of B-site doped BaZrO 3 and found that Ga-doping gives the highest chemical stability and La-doping provides the highest proton conductivity in BaZrO 3 . We use density functional theory (DFT) calculations to examine two other host materials, BaHfO 3 and BaSnO 3 , using these two dopants, Ga and La. We find that doped BaHfO 3 is promising to study further in co-doping case, because Ga-doped BaHfO 3 demonstrates the high stability and La-doped BaHfO 3 shows the high proton conductivity compared to doped BaSnO 3 and doped BaZrO 3 . [ABSTRACT FROM AUTHOR]

We report a study on a series of lanthanum doped barium stannate-titanate ceramics towards correlating their microstructure with ferroelectric properties. The samples were prepared by solid state reaction technique and the X-Ray Diffraction analysis indicated predominantly single phase microstructure. Scanning Electron Microscopy revealed that while a low La doping of 1 atomic % yielded inhibited grain growth, higher amounts of La doping in barium stannate-titanate yield larger leafy grains. This peculiar grain growth and microstructure evolution could be attributed to the combination of the following two competing factors: (i) suppression of O vacancies due to La doping leading to grain growth inhibition and (ii) enhancement of mechanism leading to nucleation and growth of 2-dimensional (leafy) grains for La doping higher than 2 atomic % due to eutectic phenomena. Dielectric permittivity measurements indicate that addition of La enhances diffused phase transition in barium stannate-titanate, but its frequency dependence is observed only at 2 atomic % La doping. This signature relaxor behaviour and the increase in the intensity of a particular Raman peak with La doping, as well as non-saturated PE hysteresis loops confirm the presence of polar nano-regions for 2 and 3 atomic % La doped barium stannate-titanate. However significant enhancement in dielectric permittivity could not be achieved due to reduced grain size. [ABSTRACT FROM AUTHOR]

We report on structural and magnetic properties in Fe/Co substituted BaSnO 3 polycrystalline samples synthesized by conventional nitrate route method. The substitution of Fe/Co at Sn site and the phase formation is confirmed by X-ray diffraction and microstructural measurements. The sample crystallizes to cubic perovskite structure indexed to Pm 3 ̅ m space group. Fe/Co substituted BaSnO 3 exhibit ferromagnetism at room temperature and ferromagnetic property varies gradually with increase in substitution of Co content. The observed enhancement of ferromagnetism in the studied samples can be explained due to F-Center exchange interactions. The presence of F-centers is evidenced by the electron spin resonance (ESR) spectrum on the studied samples, which also provides supporting evidence for the observed ferromagnetism. [ABSTRACT FROM AUTHOR]

In order to build bulk pieces using the slip casting technique, barium stannate (BaSnO 3 ) ceramic powders were synthesized using two chemical methods (controlled precipitation and Pechini). Differences in the electrical behavior of the pieces, depending on the synthesis method employed, were then determined. For the analysis, a stable suspension of the synthesized ceramic powder (or 57.6% solids slip) was obtained using water as solvent; the slip was poured into a mold to produce parallelepiped shaped green pieces. The electrical behavior in air at 300 °C was determined for pieces sintered using a range of temperatures. The results of this electrical characterization showed that the method of synthesis has strong effects on the electrical behavior of the sintered samples. [ABSTRACT FROM AUTHOR]

BaSnO 3 (BSO) films were grown epitaxially on MgO substrate under a wide range of pressures (from 20 to 0.03 Pa) by pulsed laser deposition. The structural, electrical, and optical properties of films were investigated. X-ray diffraction characterization reveals that the film unit cell volume increases gradually with decreasing the growth oxygen pressure while preserving the perovskite structure. The transport property measurement suggests that the film resistivity was tuned with variation from nearly insulator to metallic conductor by controlling the grown oxygen pressure, which was attributed to the presence of more oxygen vacancies in films during deposition. Remarkably, the lowest room-temperature resistivity of 8.07 × 10 −4 Ω cm was obtained in film grown in 0.3 Pa without any dopant, with the carrier concentration and mobility of 7.60 × 10 20 cm −3 and 10.81 cm 2 /V respectively. All the BSO films have high transmittance of more than 80% in the visible range regardless of the oxygen pressure, whereas the optical band gaps increase from 3.49 to 3.70 eV, which was explained by the Burstein-Moss effect. [ABSTRACT FROM AUTHOR]

Epitaxial La-doped BaSnO 3 thin films were grown by radio-frequency (RF) magnetron sputtering technique on (LaAlO 3 ) 0.3 (SrAl 0.5 Ta 0.5 O 3 ) 0.7 (001) substrates. The n -type degenerate semiconductor was demonstrated in the La-doped BaSnO 3 thin film from Hall-effect measurement, and its electron effective mass ∼0.396 m 0 ( m 0 , the free electron mass) was determined from combined Seebeck coefficient and carrier density. Additionally, the local current–voltage curve measured using conductive atomic force microscopy exhibits non-linear characteristic and the transport mechanism at high bias is found to be the Fowler-Nordheim tunneling. [ABSTRACT FROM AUTHOR]

Nanocrystalline perovskite-type BaSnO3 was obtained via microwave-assisted hydrothermal route followed by annealing at variable temperature. The samples composition and microstructure were characterized. Particle size of 18-23 nm was unaffected by heat treatment at 275-700 °C. Materials DC-conduction was measured at variable temperature and oxygen concentration. Barium stannate exhibited n-type semiconductor behavior at 150-450 °C with activation energy being dependent on the materials annealing temperature. Predominant ionosorbed oxygen species types were estimated. They were shown to change from molecular to atomic species on increasing temperature. Comparative test of sensor response to various inorganic target gases was performed using nanocrystalline SnO2-based sensors as reference ones. Despite one order of magnitude smaller surface area, BaSnO3 displayed higher sensitivity to SO2 in comparison with SnO2. DRIFT spectroscopy revealed distinct interaction routes of the oxides surfaces with SO2. Barium-promoted sulfate formation favoring target molecules oxidation was found responsible for the increased BaSnO3 sensitivity to ppm-range concentrations of SO2 in air. [ABSTRACT FROM AUTHOR]

Ceramic powders of pure barium stannate (BaSnO 3 ) were synthesized using two wet chemical methods: controlled precipitation and polymeric precursor (Pechini). The obtained ceramic powders were characterized using IR spectroscopy, DTA–TGA, XRD and SEM. Using the precipitation and Pechini methods, single phase BaSnO 3 powders were achieved at temperatures of 1250 °C and 1000 °C respectively—substantially lower than the temperatures required for conventional synthesis (> 1350 °C). Leading from these results, the physicochemical mechanisms that lead to BaSnO 3 formation in the processes of synthesis employed in this work are proposed. This constitutes important information both for determining the advantages and disadvantages of each method and for controlling the characteristics of the powder end product. [ABSTRACT FROM AUTHOR]

Time domain measurement is an indispensable experimental method for ultralow frequency region (even lower than 1 Hz) and nonlinearity study of ferroelectric materials. The charging and discharging currents of BaTi1-xSnxO3 (BTS) ceramics have been collected in both paraelectric and ferroelectric phases. Kohlrausch-Williams- Watts (KWW) relation with two parameters (β and τ) was employed in discharging current analysis. Our results show that the higher β values in paraelectric phase indicate near Debye relaxation behavior, and lower βvalues in ferroelectric phase tie with possible diffusion controlled universal relaxation law (URL). [ABSTRACT FROM AUTHOR]

Ba 1− x La x SnO 3 compounds were prepared by a conventional solid-state reaction method and their structural, electrical and optical properties were analyzed in this work. X-ray diffraction investigations revealed that La substitution in BaSnO 3 led to the increase of cubic lattice parameters, whereas secondary phase appeared at x =0.1 or above. Evidences of the Sn 4+ state and oxygen vacancies were clearly observed in X-ray photoelectron spectroscopy. The semiconductor behavior in temperature-dependent resistivity was found to obey the variable-range hopping conduction mechanism. With the help of absorption spectra, smaller band-gap energy and larger Urbach tail energy were observed in Ba 0.93 La 0.07 SnO 3 , as compared with Ba 0.97 La 0.03 SnO 3 , which was discussed in the frame of the role of structural disorder. [ABSTRACT FROM AUTHOR]

In this study the structural and optical properties of lanthanum-doped BaSnO 3 powder samples and thin films deposited on fused silica were investigaed using laser ablation. Under an oxygen pressure of 5×10 −4 mbar, phase pure BaSnO 3 films with a lattice constant of 0.417 nm and grain size of 21 nm were prepared at 630 °C. The band gap of BaSnO3 powder sample and thin films was calculated to be 3.36 eV and 3.67 eV, respectively. There was a progressive increase in conductivity for thin films of BaSnO 3 doped with 0~7 at% of La. The highest conductivity, 9 Scm −1 , was obtained for 7 at% La-doped BaSnO 3 . Carrier concentration, obtained from Burstein-Moss (B-M) shift, nearly matches the measured values except for 3 at% and 10 at% La-doped BaSnO 3 thin films. [ABSTRACT FROM AUTHOR]

Heteroepitaxial growth of BaSnO3 and Ba1-xLaxSnO3 (x = 7%) lanthanum doped barium stannate thin films on different perovskite single crystal (SrTiO3 (001) and SmScO3 (110)) substrates has been achieved by pulsed laser deposition under optimized deposition conditions. X-ray diffraction measurements indicate that the films on either of these substrates are relaxed due to the large mismatch and present a high degree of crystallinity with narrow rocking curves and smooth surface morphology while analytical quantification by proton induced X-ray emission confirms the stoichiometric La transfer from a polyphasic target, producing films with measured La contents above the bulk solubility limit. The films show degenerate semiconducting behavior on both substrates, with the observed room temperature resistivities, Hall mobilities, and carrier concentrations of 4.4 mΩ cm, 10.11 cm² V-1 s-1, and 1.38 × 1020 cm-3 on SmScO3 and 7.8 mΩ cm, 5.8 cm² V-1 s-1, and 1.36 × 1020 cm-3 on SrTiO3 ruling out any extrinsic contribution from the substrate. The superior electrical properties observed on the SmScO3 substrate are attributed to reduction in dislocation density from the lower lattice mismatch. [ABSTRACT FROM AUTHOR]

The results of X-ray, dilatometric and dielectric measurements of the Ba(Ti0.90Sn0.10)O3, (BTS10) polycrystalline sample are presented. A cubic symmetry at room temperature (Tr) was determined. The dielectric measurements showed the influence of Sn addition on the character of the phase transition in the BaTiO3structure. A diffuse phase transition (DPT) for BTS10 was found. In the paraelectric phase the change of theγparameter at Burns temperature (TB) takes place. This temperature corresponds to the glass temperature (Tg), which was observed by dilatometric measurements. [ABSTRACT FROM AUTHOR]

Dielectric and impedance spectroscopy studies of barium stannate (BaSnO3) and barium orthostannate (Ba2SnO4) nano-grained ceramics were performed in 300–1000 K temperature and 20 Hz–1 MHz frequency ranges. No dielectric anomalies were observed. Both materials are sensitive to humidity of air. Conductivity is dominated by electronic conductivity at low temperatures, but above 700 K it could be either intrinsic electronic conductivity or ionic one. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we report on structural and optical properties of terbium and europium doped barium stannate phosphors (BaSnO3) synthesised by conventional solid state reaction method. We have studied those materials by using X-ray diffraction (XRD), radioluminescence (RL) and photoluminescence (PL) techniques. XRD patterns confirm that the BaSnO3 sintered at 1400°C exhibit orthorhombic structure and that the Tb3+ and Eu3+ substitution of Ba2+ does not change the structure of the BaSnO3 host. The optical emission spectrum is characterized a broad band centered at 897nm (1.38eV), with a high-energy tail approximately 750nm from the host lattice. Other emission signals that are characteristic of the 3+oxidation state of rare earth elements were generated by Eu and Tb doping. Luminescence measurements show that the series of emission states 5D4 → 7F6, 5D4 → 7F5, 5D4 → 7F4 and 5D4 → 7F3 corresponding to the typical 4f→4f infra-configuration forbidden transitions of Tb3+ are appeared and the major emission peak at 540nm is due to 5D4 → 7F5 transitions of Tb3+. On the other hand, the emission spectrum of Eu doped BaSnO3 phosphor exhibits a series of emission bands, which are attributed to the 5D0 → 7F j (j =0–4) transitions of Eu3+ ions. The dominant emission of Eu3+ corresponding to the electric dipole transition 5D0 → 7F2 is located at 613nm. The sharp emission properties exhibited demonstrate that the BaSnO3 is a suitable host for rare-earth ion doped phosphor material. This work clearly confirms the unusual near infrared (NIR) PL discovered by H. Mizoguchi et al. in BaSnO3 at room temperature. [Copyright &y& Elsevier]

Highlights: [•] (Ba, La)SnO3–ZnO 1D heterostructures were successfully synthesized using a two-step process. [•] The (Ba, La)SnO3 shell covering the ZnO core had a polycrystalline morphology. [•] Nanoscale-(Ba, La)SnO3 particles decorating the surfaces of the ZnO nanostructures significantly affect electrical responses to test gases. [Copyright &y& Elsevier]

BaTiO3 and BaSnO3 samples doped with Eu3+ ions were prepared using glycine-nitrate gel combustion method. Relative intensities and line shapes of magnetic dipole allowed 5D0 → 7F1 and electric dipole allowed 5D0 → 7F2 transitions of Eu3+ from the hosts, BaTiO3 and BaSnO3, are significantly different. Based on detailed structural investigations, it is confirmed that synthesized BaTiO3 sample is tetragonal with no center of symmetry around Ba2+ ions. Unlike this BaSnO3 is cubic with centrosymmetric Ba2+ site. From X-ray diffraction and experimentally obtained Judd-Ofelt parameters (Ω2 and Ω4 values), it is confirmed that in BaTiO3 there is a decrease in the average Ba- O and Ba- Ba distances compared with that in BaSnO3. This leads to higher Eu- O bond polarizability and adds to the distortion in its environment around Eu3+ in BaTiO3: Eu compared with BaSnO3: Eu. This is responsible for the observed difference in the luminescence properties. [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]

Abstract: Thermoelectric properties and figure of merit were evaluated from the Seebeck coefficient S, electrical conductivity σ, and thermal conductivity κ measured at high temperatures for perovskite-type ceramics of Ba1−x La x SnO3 with x=0.002, 0.005, and 0.008, which were prepared by a polymerized complex method and a subsequent spark plasma sintering technique. All the polycrystalline dense ceramics showed n-type degenerate semiconducting behavior in the temperature range of 373–1073K. The La content dependence of the S values revealed successful increase in the electron carriers with the La doping in this x range. The κ values remained almost unchanged with x showing ~9.6Wm−1 K−1 at room temperature and decreased with increasing temperature. The electronic thermal conductivities calculated by the Wiedemann–Franz law as well as the T −1 dependence of the κ values indicate that the phonon thermal conductivity was dominant. The dimensionless figure of merit ZT increased with increasing temperature for all the ceramics and showed ~0.1 at 1073K for the ceramics with x=0.002 and 0.005. [Copyright &y& Elsevier]

Abstract: Tin doped barium titanate ceramics has been obtained by solid state reaction method followed by high energy ball milling. The effect of heavy dose gamma ray irradiation on the ferroelectric and piezoelectric properties of the synthesized barium stannate titanate ceramics has been observed. It has been found that on irradiation the ferroelectric property decreases with decreasing values of P r and E c . The piezoelectric properties including d 33, electrostrictive strain and electromechanical coupling coefficient (K p ) also decrease following the same trend of P r and E c . Grain size decreases and grain patterns become irregular after irradiation as observed from SEM micrographs. The Thermoluminescence (TL) property of the barium stannate titanate ceramics has also been investigated and reported. [Copyright &y& Elsevier]

Highlights: [•] Deposition of BaSnO3 on a substrate like fused silica is more economical than other single crystalline substrates currently being used. [•] 5at% Fe doped barium stannate thin films exhibit maximum crystallinity and transparency over 85% in the visible region. [•] Room temperature ferromagnetism exhibited by 5 and 10at% Fe doped barium stannate powder and film. [•] The surface roughness of the films revealed low surface roughness for all films investigated. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the synthesis, structural and electrical properties of BaSn0.75M0.25O3− δ (M=Fe, Sc, In, Y, Gd, Sm, Nd and La) compounds have been investigated. Single phase powders of these materials were successfully synthesized by a gel polymerization route and sintered to obtain dense pellets. X-ray diffraction reveals that all compounds crystallise in a cubic perovskite like-structure (space group: ) at room temperature. However, cell parameters of the substituted compounds do not evolve in accordance with the substituent radius, i.e. an abnormal drop was observed for elements with a large radius, i.e. Sm, Nd and La. A possible interpretation could be the partial incorporation of substituents into the Ba-site. The site incorporation selectivity of substituents into the Ba- and Sn-sites was investigated based on the study of lattice parameters and empirical defect models. Experiments show that the thermal expansion coefficients and electrical properties have no specific correlation with the nature of the substituent. [Copyright &y& Elsevier]

The diffusion barriers of protonic defects in Gd-doped BaCeO3, a compound candidate as electrolyte for protonic ceramic fuel cells, have been investigated by density functional theory calculations, starting from a previously computed energy landscape consisting of 16 kinds of stable sites (eight close to dopants and eight far from them). The simplified string method has been used to determine accurately the minimum energy paths between those sites that might imply either proton reorientations, intraoctahedral, or interoctahedral hopping mechanisms. At contrast with simple cubic perovskites such as barium stannate or barium zirconate, very different values for energy barriers (from 0.02 to 0.58 eV) are found in this highly distorted orthorhombic perovskite, and no specific process appears to be clearly rate limiting. Some interoctahedral hoppings (when possible) are found to be more favorable than the intraoctahedral ones, while reorientations exhibit a wide range of energy barriers. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we present a complete study of BaSn1−xYxO3−δ (x=0–0.50) compounds putting emphasis on transport properties as determined by impedance spectroscopy under controlled atmosphere. The measurements of transport properties reveal a p-type behavior in oxidative atmosphere and a pure ionic behavior in slightly reducing one. In strongly reducing conditions, the samples tend to be electron-conductive at high temperature. In wet atmosphere, the thermogravimetry and electrical measurements confirm the incorporation of protons and their predominance as charge carrier at low temperature. The higher bulk proton conductivities are observed for the higher yttrium contents, which is due to the increased amount of charge carriers. After applying different thermal treatments, we confirm that these samples tend to decompose in wet conditions and that low yttrium contents are desirable to increase the stability. The good stability in CO2-containing atmosphere is also confirmed. This work illustrates that an optimal value for yttrium content exists that allows obtaining a significant proton conductivity and sufficient stability. [Copyright &y& Elsevier]

We report our investigation on the low temperature scaling behavior of niobium-doped barium stannate. Electrical properties of the system BaSn1-xNbxO3 (with x = 0.001, 0.005, 0.010, 0.050, and 0.100), prepared by the solid-state route, were studied employing impedance spectroscopy in the temperature range 123-273 K and frequency range 10-2 Hz to 3 MHz. Conductivity spectra for all the compositions were found to follow Jonscher's power law, σ = σdc[1 + (v/vH)p. We found that the hopping frequency vH, obtained from fitting this equation to the conductivity spectra, can be used as a scaling factor. All the compositions follow the time-temperature-superposition principle, with vH as the scaling frequency. Moreover, the conductivity spectra of compositions with x ≤ 0.010 and with 0.010 < x ≤ 0.100 were separately found to show compositional scaling behavior with respect to the hopping frequency vH. This system showed a change in the charge compensation mechanism from electronic to ionic in its temperature dependence of the dc conductivity as the concentration changed from x = 0.010 to x = 0.050. The shape of the conductivity spectra also changed as the concentration changes from x = 0.010 to x = 0.050. We conclude that in this system, when the conduction mechanism does not change, vH can be used as a universal scaling parameter. [ABSTRACT FROM AUTHOR]

Abstract: Nanocrystalline Barium stannate (BaSnO3) was synthesized through auto-ignited combustion technique. The X-ray diffraction studies of BaSnO3 nanoparticles reveals that the nanopowder is single phase, crystalline, and has a cubic perovskite structure with a lattice constant a =4.115Å. The average particle size calculated from full width half maximum (FWHM) using Scherer formula is ∼25nm. The phase purity of the powder was further examined using Fourier transform infrared spectroscopy, Raman spectroscopy and transmission electron microscopic techniques. XRD pattern of BaSnO3 was refined for atomic coordinates, lattice parameters and occupancies using Rietveld analysis. Vibrational analysis of sample shows that there is a phase transition from distorted cubic to ideal cubic structure during heat treatment. The thermal stability of BaSnO3 nanopowder has been confirmed using thermo gravimetric analysis (TGA) and differential thermal analysis (DTA). The particle size of the as-prepared powder from transmission electron microscopy was found to be in the range 20–30nm. The absorption spectra and photoluminescence spectra of the sample were also studied. The band gap determined was 2.887eV and found to be a semiconductor. [ABSTRACT FROM AUTHOR]

Abstract: To elucidate the thermoelectric properties at high temperatures, perovskite-type La-doped BaSnO3 ceramics were fabricated by a polymerized complex (PC) method and subsequent spark plasma sintering (SPS) technique. Fine powders of Ba1−x La x SnO3 (x =0.00–0.07) were prepared by the PC method using citrate complexes, and SPS treatment converted the powders into dense ceramics with relative densities of 93–97%. The La content dependence of the lattice parameter suggested that the solubility of La for Ba sites was approximately x =0.03. The temperature dependence of the electrical conductivity σ and Seebeck coefficient S showed that each La-doped ceramic was an n-type degenerate semiconductor in the measured temperature range of 373–1073K. The La content dependence of the S values indicated that the electron carrier concentration increased successively up to x =0.03, which was the solubility limit of the La atoms. The thermoelectric power factors S 2 σ increased drastically with La doping, and reached a maximum for x =0.01 with values of 0.8×10−4 Wm−1 K−2 at 373K to 2.8×10−4 Wm−1 K−2 at 1073K. [ABSTRACT FROM AUTHOR]

Tin-based nanoparticles, proposed to be barium stannate, have been formed in YBCO films fabricated by metal-organic deposition, through modification of the precursor solution. These randomly-oriented 30-50 nm particles are dispersed throughout the film thickness, providing an enhancement in the isotropic flux pinning relative to undoped YBCO. For a low level, of nanopartide addition of 2 vol%, a flux-pinning force enhancement of up to 32% is achieved. We report field and field-angle dependence of the transport critical current, transmission electron microscopy, and x-ray diffraction of our YBCO films on RABiTS substrates, and compare with similar barium zirconate additions. [ABSTRACT FROM AUTHOR]

Abstract: Nanoscaled Ba(Ti1−x−y Sn x Ge y )O3 (BTSG− x − y, x =0–0.1, y =0–0.05) powders were synthesized by a sol–gel method (SG) and, as a reference, coarse powders by a mixed-oxide method (MO). The particle sizes were determined by XRD, BET, photon correlation spectroscopy (PCS) and scanning electron microscopy (SEM). The sol–gel method supplied globular particles with narrow fractions in the range between 53nm and 125nm. However, from the mixed-oxide method irregularly grown particles were generated with diameters between 300nm and 700nm. The SG powders showed a higher sintering activity and, additionally, Sn4+ ions were incorporated at lower temperatures into the BaTiO3 structure. The addition of at least 2mol% BaGeO3 (BG) resulted in ceramics of densities as high as 96% even at 1050°C. Furthermore, the cubic⇆tetragonal phase transition temperatures were measured by dilatometry, differential thermal analysis (DTA) and dielectric measurements. The temperature and sharpness of the transition are dependent on tin and germanium content. Increasing tin and germanium concentration causes the phase transition temperature to decrease and more diffuse transition. [Copyright &y& Elsevier]

Abstract: Microstructure and electrical conduction behaviour in the system BaSn1−x Nb x O3 (x ≤0.10) have been correlated with the defect structure. In the SEM micrographs, average grain size of the samples with composition x ≤0.010 was found to be about 3μm whereas the average grain size of the samples with compositions x ≥0.050 was found to be much less than 1μm. Similar trend of variation in the diffraction domain sizes or crystallite size is observed from powder X-ray diffraction data. It has been reported earlier that charge compensation mechanism in this system changes from electronic for x ≤0.01 to ionic for x =0.050 and 0.100. This results a change in the nature of conduction from n- to p-type in going from x =0.010 to 0.050. [Copyright &y& Elsevier]

Abstract: The possibility of formation of a solid solution in the system BaSn1−x Ni x O3 has been explored up to x ≤0.20. It has been confirmed that single phase solid solution forms up to x ≤0.10. Dielectric and ac conductivity of the samples have been studied in the temperature range 350–650K and frequency range 10Hz–2MHz and dc conductivity of the samples have been measured in the temperature range 550–1100K. Seebeck coefficient ‘α’ of the samples have been measured in the temperature range 350–650K. Negative value of ‘α’ in the entire range of temperature measurement shows that conducting species are negatively charged. On the basis of value of activation energy for dc conduction and sign of Seebeck coefficient, conduction in the low temperature region (below 500K) is attributed to hopping of weakly bonded electrons among Sn2+ ⇔Sn4+ or Sn3+ ⇔Sn4+ sites and that in the high temperature region (above 500K) to hopping of doubly ionized oxygen vacancies (Vo x plane impedance analysis have been made to understand the conduction behaviour of grain and grain boundaries separately. [Copyright &y& Elsevier]