Synergetic effect of stannate with o-aminophenol on inhibiting H2 evolution of A1 anode in strong alkaline media

The performance of Al-alloy anode in 4 mol/L KOH with and without stannate and o-aminophenol at 25℃ and 55℃ was studied by hydrogen collection, potentiodynamic polarization and electrochemical impedance spectrum, o-aminophenol acts as a perfect inhibitor because of its adsorbability and forming chelate complex at its optimum concentration of 0.4 mol/L. Stannate enhances the inhibition of o-aminophenol and improves the activity of Al-alloy because of its reduction to tin. There is synergetic effect of stannate with o-aminophenol on the behavior of Al-alloy, and the inhibitive efficiency at 55℃ is better than that at 25 ℃.

Microwave hydrothermal synthesis and characterization of rare-earth stannate nanoparticles

Rare-earth stannate（Ln_2Sn_2O_7（Ln = Y, La–Lu）） nanocrystals with an average diameter of 50 nm were prepared through a facile microwave hydrothermal method at 200°C within 60 min. The products were well characterized. The effect of reaction parameters such as temperature, reaction time, p H value, and alkali source on the preparation was investigated. The results revealed that the p H value plays an important role in the formation process of gadolinium stannate（Gd_2Sn_2O_7） nanoparticles. By contrast, the alkali source had no effect on the phase composition or morphology of the final product. Uniform and sphere-like nanoparticles with an average size of approximately 50 nm were obtained at the p H value of 11.5. A possible formation mechanism was briefly proposed. Gd_2Sn_2O_7：Eu^（3＋） nanoparticles displayed strong orange-red emission. Magnetic measurements revealed that Gd_2Sn_2O_7 nanoparticles were paramagnetic. The other rare-earth stannate Ln_2Sn_2O_7（Ln = Y, La–Lu） nanocrystals were prepared by similar approaches.

High-entropy rare earth stannate ceramics:Acid corrosion resistant radiative cooling materials with high atmospheric transparency window emissivity and high near-infrared solar reflectivity

In response to the development of the concepts of“carbon neutrality”and“carbon peak”,it is critical to developing materials with high near-infrared(NIR)solar reflectivity and high emissivity in the atmospheric transparency window(ATW;8–13μm)to advance zero energy consumption radiative cooling technology.To regulate emission and reflection properties,a series of high-entropy rare earth stannate ceramics(HE-RE_(2)Sn_(2)O_(7):(Y_(0.2)La_(0.2)Nd_(0.2)Eu_(0.2)Gd_(0.2))_(2)Sn_(2)O_(7),(Y_(0.2)La_(0.2)Sm_(0.2)Eu_(0.2)Lu_(0.2))_(2)Sn_(2)O_(7),and(Y_(0.2)La_(0.2)Gd_(0.2)Yb_(0.2)Lu_(0.2))_(2)Sn_(2)O_(7))with severe lattice distortion were prepared using a solid phase reaction followed by a pressureless sintering method for the first time.Lattice distortion is accomplished by introducing rare earth elements with different cation radii and mass.The as-synthesized HE-RE_(2)Sn_(2)O_(7)ceramics possess high ATW emissivity(91.38%–95.41%),high NIR solar reflectivity(92.74%–97.62%),low thermal conductivity(1.080–1.619 W·m^(−1)·K^(−1)),and excellent chemical stability.On the one hand,the lattice distortion intensifies the asymmetry of the structural unit to cause a notable alteration in the electric dipole moment,ultimately enlarging the ATW emissivity.On the other hand,by selecting difficult excitation elements,HE-RE_(2)Sn_(2)O_(7),which has a wide band gap(Eg),exhibits high NIR solar reflectivity.Hence,the multi-component design can effectively enhance radiative cooling ability of HE-RE_(2)Sn_(2)O_(7)and provide a novel strategy for developing radiative cooling materials.

Formation free energy of sodium stannate measured using β-β″-Al_2O_3 ceramic electrolyte

β-β″-Al2O3precursor powder was successfully prepared by a solid-phase sintering method with Li2CO3, Na2CO3 （as the sources of Li20 and Na20, respectively） and β″-Al2O3 powder as the raw materials. The precursor was characterized by X-ray diffraction （XRD） and scan- ning electron microscope （SEM）. The results indicate that the amount of Na20 in the raw materials has a great effect on the formation of β″-Al2O3 in the β-β″-Al2O3 precursor. When Na20 content is 10 wt%, the content of β″-Al2O3 phase reaches the maximum value of 86.24 wt% in the precursor. The β-β″-Al2O3 ceramic was prepared from β-β″-Al2O3 precursor powder by isostatic pressing and burying sintering process. The conductive property of the β-β″-Al2O3 ceramic was examined by electrochemical impedance spectroscopy （EIS） method, and the density was measured by the Archimedes method. The results reveal that when 10 wt% Na20 was added, the sample exhibits the best performance with the lowest resistivity of 4.51.cm and the highest density of 3.25 g.cm 3. A solid electrolyte battery of PtlSnQ, Na2SnO3113 β-β″-Al2O3 Na CrO2, Cr2lO3 Pt was assembled by the β-β″-Al2O3 electrolyte tube to measure the open potential of the resulting battery, and the formation free energy of sodium stannate was calculated In the temperature range of 1273-773 K, the relationship between formation free energy of sodiumstannate and temperature was generated as follows：△GNa2SnO3 0=-1040.83＋0.2221T±7.54.

Zinc Stannate Nanostructures for Energy Conversion

To date,ternary metal oxide semiconductor materials have attracted extensive attention worldwide due to their unique optoelectronic properties.As a classical ternary oxide,Zn2SnO4 is featured with the high electron mobility,wide band gap,negligible visible light absorption and tailorable electronic band structures.Thus,it is an ideal material for practical use in solar cells,lithium batteries,sensors,and photo-catalysts.In this review,we summarize the recent research progress of this material with the focus on the synthesis methods,nanostructures,and the resulting effects on the crystal structure,optical properties,and photoelectrochemical properties.Moreover,their potential applications in different devices are highlighted and carefully discussed.

尖晶石型掺镉锡酸锌光催化剂制备与活性研究

采用化学共沉淀法制备掺镉锡酸锌光催化剂,通过X射线粉末衍射(XRD)、扫描电镜(SEM)表征,该催化剂平均粒径小于30nm,属立方晶系。以波长λ=312 nm的光源分别对甲基橙和茜素红水溶液进行光催化降解,结果发现Cd2+的加入使Zn2SnO4对甲基橙和茜素红两种染料的光催化活性明显提高。

Hydrothermal Synthesis of Zn2SnO4/Few-Layer Boron Nitride Nanosheets Hybrids as a Visible-Light-Driven Photocatalyst

Zn2SnO4/few-layer boron nitride nanosheets (FBNNS) hybrids were synthesized via a one-step hydrothermal method. The structures, morphology, optical properties, electron transformation and separation of the as-prepared products were characterized by X-ray diffraction, transmission electrical microscopy, UV-vis diffuse reflectance spectroscopy and electrochemical impedance spectroscopy, respectively. Rhodamine B was used to evaluate the photocatalytic activities of the as-prepared samples under visible light illumination. The photocatalytic mechanism was also explored. Experimental results showed that the degradation efficiency of rhodamine B was firstly increased and then decreased with increasing the usage amount of FBNNS. When it was 9 wt% based on the weight of Zn2SnO4, the degradation efficiency of the as-prepared Zn2SnO4/FBNNS-9 wt% composites reached to the maximum of 97.5 % in 180 min, which was higher than 39.2 % of pure Zn2SnO4. Moreover, the holes played mainly active roles in photocatalytic reaction process. In addition, the as-prepared hybrids could enhance the separation efficiency of photoexcited carriers compared to pure Zn2SnO4.

First-principles calculation of structural and electronic properties of pyrochlore Lu_2Sn_2O_7

A Density functional theory method within generalized gradient approximation has been performed to obtain the static lattice parameters, oxygen positional parameter, bond length and bond angle and electronic properties of ideal Lu2Sn207 pyrochlore. The results are in excellent agreement with available experimental measurements. Density of states （DOS） of this compound was presented and analysed. We also notice the presence of the hybridization between oxygen and Lu metal. The band structure calculations show that the compound has direct band gap of 2.67 eV at the F point in the Brillouin zone and this indicates that the material has a semi-conducting feature.

Synthesis and Humidity Sensing Investigations of Nanostructured ZnSnO₃

In this paper zinc stannate (ZnSnO3) nanoparticles was synthesized by a chemical precipitation method. The synthesized samples were characterized using X-ray powder diffraction (XRD), Differential scanning calorimetry (DSC) and UV-Visible absorption spectroscopy. Sensing material was made as pellet by hydraulic press machine under uniform pressure of 616 MPa. Then the material was annealed at 600。C. Surface morphologies of the samples were analyzed using Scanning electron microscopy (SEM) for pellet of different weight ratio annealed at 600。C. The XRD pattern indicates that ZnSnO3 has a perovskite phase with an orthorhombic structure having minimum crystallite size 4 nm. Further, humidity sensing investigations of these sensing materials were done. Our result indicate that ZnSnO3 in form of pellet annealed at 600。C for 1:4 weight ratio was most sensitive of humidity in comparison to pure SnO2 under same conditions. Maximum sensitivity of the sample was 3 GΩ/% RH which is better in comparison to pure SnO2. The results were reproducible up to ± 77% after 2 months of observations.

Accelerating electron transport in Eosin Y by bidentately bridging on BaSnO_(3)for noble-metal-free photocatalytic H 2 production

The separation and transport of photogenerated carriers is regarded as a curial factor in photocatalytic H_(2)pro-duction.As known in solar cells and photoelectron-chemistry,to strengthen the electron conduction for effective utilization of carriers,the electron transport material(ETM)is widely applied.Herein,inspired by the function of ETM,we adopted barium stannate(BaSnO_(3),labeled as BSO)as an excellent ETM which had the merits of high electron mobility,suitable conduction band position and simple preparation,to adjust the carrier kinetics of dye Eosin Y(EY)-sensitized photocatalytic system.Detailly,the photocatalytic system with the spatial sepa-ration sites of photogenerated carriers excitation and water reduction reaction was elaborately constructed,that was,dye EY-sensitized BSO(EY/BSO)for photocatalytic H_(2)production.The photocatalytic H_(2)-production rate of EY/BSO(257𝜇mol·h^(−1)·g EY^(−1))in the absence of noble metals was 28.6 times higher than that of single EY(∼9𝜇mol·h^(−1)·g EY^(−1))under visible-light irradiation.With systematic and comprehensive characterizations,the formed electron transport channel by the bidentate bridging of EY on BSO could accelerate the transfer of photogenerated electrons from EY to BSO,promoting the effective separation of photogenerated carriers for the enhanced pho-tocatalytic performance.Moreover,the water reduction reaction for H_(2)production proceeded on the surface of BSO that acted as the H_(2)-evolution cocatalyst,avoiding the use of high-cost noble metals.Furthermore,based on the well-proved ETM-based concept in the EY/BSO system,La-doped BaSnO_(3)(LBSO)with better electron trans-port ability was adopted to construct EY/LBSO system(344𝜇mol·h^(−1)·g EY^(−1))which showed better photocatalytic activity than EY/BSO.

Jonscher indices for dielectric materials

Two parameters are proposed as Jonscher indices,named after A.K.Jonscher for his pioneering contribution to the universal dielectric relaxation law.Time domain universal dielectric relaxation law is then obtained from the asymptotic behavior of dielectric response function and relaxation function by replacing parameters in Mittag–Leffler functions with Jonscher indices.Relaxation types can be easily determined from experimental data of discharge current in barium stannate titanate after their Jonscher indices are determined.

Synthesis and Properties of BaSn_(0.75)B_(0.25)O_(3-d)(B=La,Gd,Y,In…) Proton Conductors

1 Results We study the synthesis,the structural and transport properties of acceptor-doped barium stannate BaSn0.75B0.25O3-d (B=La,Y…) compounds.Some of these materials were presented few years ago as good proton conductors with some interest for the fuel cell community[1-2].Nevertheless,these studies were only limited to two kinds of dopants and the elaboration was far from being optimised leading to poor properties.So the main objective of the present study is to extend the study of acceptor-doped bar...

RELAXOR FERROELECTRIC MATERIALS FOR MICROWAVE TUNABLE APPLICATIONS

With strong dependences of dielectric constant on external applied electric fields,relaxor barium zirconium titanate(BaZr_(x)Ti_(1-x)O_(3)or BZT)and barium stannate titanate(BaS_(n)xTi_(1-x)O_(3)or BTS),in both bulk ceramic and thinfilm forms,are increasingly being recognized as potential candidates of microwave tunable materials for device applications.This paper is aimed to review the recent progress in understanding the dielectric properties(such as tunability,dielectric loss and dielectric constant)of these relaxor materials.However,due to their relatively high dielectric constant and loss tangent,pure Ba(Zr,Ti)O_(3) and Ba(Sn,Ti)O_(3) do not fully satisfy the requirements of practical device applications.Therefore,various strategies have been developed to improve the dielectric properties of these two groups of relaxor materials.In this paper,wefirst discussed the dielectric tunability characteristics of pure Ba(Zr,Ti)O_(3) and Ba(Sn,Ti)O_(3) and then summarized the strategies that have been used,including(i)small amount acceptor or donor doping(such as rare-earth ions and transition metal ions)and(ii)forming composites with low loss and low dielectric constant microwave dielectric materials(such as MgO,MgTiO_(3) and so on).At the same time,the relationship between relaxor behavior and dielectric tunability was also discussed.

Dielectric tunable characteristics of compositional-gradient BaTi_(1-x)Sn_(x)O_(3)thin films

Compositional-gradient BaTi_(1-x)Sn_(x)O_(3)thin films on Pt(100)/Ti/SiO_(2)/Si substrates are fabricated with sol-gel using spin coating.All of the structures of the prepared thin films are of single-phase crystalline perovskite with a dense and crack-free surface mor-phology.BTS10/15/20 thin film exhibits enhanced temperature stability in its dielectric behavior.The temperature coefficient of capacitance TCC_(20-150)in the temperature range from 20°C to 150°C is−0.9×10^(−4)/°C and that of TCC20-(-95)in the temperature range from 20°C to−95°C is−3.8×10^(−4)/°C.Furthermore,the thin films show low leakage current density and dielectric loss.High and stable dielectric tunable performances are found in BTS10/15/20 thin films:the dielectric tunability of the thin films is around 20.1%under a bias voltage of 8 V at 1 MHz and the corresponding dielectric constant is in the range between 89 and 111,which is beneficial for impedance matching in circuits.Dielectric tunability can be obtained under a low tuning voltage,which helps ensure safety.The simulated resonant frequency of the compositional-gradient BTS thin films depends on the bias electric field,showing compositional-gradient BTS thin films could be used in electrically tunable components and devices.These prop-erties make compositional-gradient BTS thin films a promising candidate for dielectric tuning.