[en] Monoclinic bismuth vanadate (BiVO₄) powders were prepared by a mild hydrothermal method, using an aqueous solution of bismuth nitrate and two different vanadium sources (V₂O₅ and NaVO₃). The characterization of as-prepared BiVO₄ was carried out by X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). The results revealed that in the present work the temperature of 200 and 140 deg. C are sufficient to prepare phase pure BiVO₄ powders from V₂O₅ and NaVO₃, respectively. The BiVO₄ sample prepared from V₂O₅ consists of an agglomeration of small rod-like particles. When BiVO₄ was prepared from NaVO₃, monoclinic BiVO₄ powder with a plate form is obtained

[en] Pseudocubic Pb_1-xLa_xTi_1-x/4O₃ (PLT, x=0.28) powders were prepared by a sol-gel-hydrothermal method using KOH as mineralizer. Characterization via X-ray diffraction and Raman spectroscopy indicate that, KOH mineralizer plays two important roles in this work. First, it favors the crystallization of PLT; second, it promotes La to be solved in the lattice which consequently resulted in the phase transition from tetragonal structure to pseudocubic structure

[en] A mild hydrothermal method has been adopted to prepare La_0.5Sr_0.5MnO₃ and La_0.5Ba_0.5MnO₃, which is of interest for a number of possible applications. The results from X-ray diffraction (XRD) indicate that in the present work the temperature of 200 and 240 deg. C are sufficient to prepare phase pure La_0.5Sr_0.5MnO₃ and La_0.5Ba_0.5MnO₃ crystals. At 200 deg. C, La_0.5Sr_0.5MnO₃ nanowires are obtained. The average width and length of the nanowires are 40 nm and 4 μm, respectively. At 240 deg. C, La_0.5Ba_0.5MnO₃ powders obtained have a cubic structure with the average size of 3-5 μm

[en] Well-crystallized γ-MnS films in a pure phase have been deposited on commercial glass substrates by chemical bath deposition. The structure and morphology of the obtained γ-MnS film were characterized, and the results showed that the film was composed of asymmetric hexagonal crystals with a size of 500-1000 nm. The photoluminescence of the γ-MnS film has been studied from 295 K down to 30 K and exhibited two emission bands centered at 1.8 and 1.66 eV, respectively. The temperature dependence of photoluminescence was also observed and interpreted using the spin-wave-assist photoluminescence model

[en] With the gradual maturity of nuclear power technology, the original design of nuclear power has been less and less, but in the operation of nuclear power plant equipment safety and quality incidents have occurred, Some aspects of a single event may be a small problem or a small exception to a simple device, but if we put these abnormal problems and not do in-depth analysis, there is no effective treatment programs and solutions, just simple replacement of spare parts processing, so these devices often small problems or small, will eventually produce Many a little make a mickle. Many a little make a mickle. great security risks, the sale operation of nuclear power. In this paper, combined with the actual situation of the power plant equipment defects, how to solve the problem of equipment defects from the root of the method, and stand in the field of maintenance to elaborate on how to better guard the nuclear safety. (author)

[en] A novel method which is based on the hydrothermal reaction was employed to synthesize LiV₃O₈. First, the mixture solution of LiOH, V₂O₅, and NH₄OH was subjected to the hydrothermal reaction. The hydrothermal treatment yielded a clear, homogeneous solution. The evaporation of this solution led to the formation of a precursor gel. The gel was then heated at different temperatures in the range of 300-600 deg. C. The characterization by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) indicated that LiV₃O₈ nanorods have been obtained by this novel synthesis method. The electrochemical performance of the LiV₃O₈ nanorods have been investigated, which indicates that the highest discharge specific capacity of 302 mAh/g in the range of 1.8-4.0 V was obtained for the sample heated at 300 deg. C, and its capacity remained 278 mAh/g after 30 cycles

[en] Due to ionic migration and adsorption, an electrical double layer with a thickness scaled by the Debye length is formed at the hydrogel-solution interface. For a thin temperature-pH dual sensitive hydrogel whose chickness is comparable to the Debye length, its mechanical behavior may be affected by the electrical double layer. In this paper, by incorporating electromagnetic field theory into thermodynamic theory, we develop a coupled field theory for a temperature-pH dual sensitive hydrogel, and we take into account the electrical double layer. The proposed model can be used to analyze the influences of the size effect, ionic concentration, ambient temperature and solution pH value on the swelling of a thin layer of the temperature-pH sensitive hydrogel.

[en] High purity tetragonal tungsten-bronze type K₂Nb₄O₁₁ fine powders were synthesized via an economical sol–gel route and the crystal structure was solved by Rietveld refinement of X–ray powder diffraction. Structural evolution during calcination was found to occur via translation of the edge shared octahedra into a corner sharing coordination. Using nano-structured powder as precursor, dense K₂Nb₄O₁₁ ceramics were successfully fabricated by pressure-less sintering. This maiden achievement allowed for primary dielectric characterization of this ceramic compound. The quantitative analysis based on empirical parameters, ΔT_m and γ, reveals a relaxor nature in the temperature region below 200 K. More remarkably, the dielectric constant and loss are almost frequency independent in the wide range of 1 Hz–1 MHz at room temperature and a high dielectric constant and low loss (ε_r = 200 and tan δ = 0.007) makes them good materials for dielectric components for embedded capacitors and multilayer ceramic capacitors. - Highlights: • Pure K₂Nb₄O₁₁ fine powders were synthesized via an economical sol-gel route. • Dense K₂Nb₄O₁₁ ceramics were fabricated by conventional sintering methods. • Relaxor behavior of K₂Nb₄O₁₁ ceramics exists at low temperature around 160 K

[en] Core-shell nano-ring α-Fe_2O_3@Carbon (CSNR) composites with different carbon content (CSNR-5%C and CSNR-13%C) are synthesized using a hydrothermal method by controlling different amounts of glucose and α-Fe_2O_3 nano-rings with further annealing. The CSNR electrodes exhibit much improved specific capacity, cycling stability and rate capability compared with that of bare nano-ring α-Fe_2O_3 (BNR), which is attributed to the core-shell nano-ring structure of CSNR. The carbon shell in the inner and outer surface of CSNR composite can increase electron conductivity of the electrode and inhibit the volume change of α-Fe_2O_3 during discharge/charge processes, and the nano-ring structure of CSNR can buffer the volume change too. The CSNR-5%C electrode shows super high initial discharge/charge capacities of 1570/1220 mAh g"−"1 and retains 920/897 mAh g"−"1 after 200 cycles at 500 mA g"−"1 (0.5C). Even at 2000 mA g"−"1 (2C), the electrode delivers the initial capacities of 1400/900 mAh g"−"1, and still maintains 630/610 mAh g"−"1 after 200 cycles. The core-shell nano-rings opened during cycling and rebuilt a new flower-like structure consisting of α-Fe_2O_3@Carbon nano-sheets. The space among the nano-sheet networks can further buffer the volume expansion of α-Fe_2O_3 and facilitate the transportation of electrons and Li"+ ions during the charge/discharge processes, which increases the capacity and rate capability of the electrode. It is the first time that the evolution of core-shell α-Fe_2O_3@Carbon changing to flower-like networks during lithiation/de-lithiation has been reported.

[en] Highlights: • Li_4Ti_5O_1_2 (LTO) spheres are prepared by molten-salt and TiO_2 spheres as template. • The LTO spheres are potential for using as anode for AC//LTO hybrid capacitor. • The AC//LTO hybrid supercapacitor presents good electrochemical performance. - Abstract: There is a growing demand for hybrid supercapacitor systems to combine the advantages of both lithium-ion battery and supercapacitors for the application of electric vehicles. We describe in this paper one kind of hybrid supercapacitor comprising spherical Li_4Ti_5O_1_2 as negative electrode and activated carbon (AC) as positive electrode in the non-aqueous electrolyte. The Li_4Ti_5O_1_2 spheres were synthesized using a LiCl-KCl molten-salt method and TiO_2 spheres as the template. The Li_4Ti_5O_1_2 spheres revealed high discharge capacity (168 mAh g"−"1 at 0.2 C), and a good capacity retention with high coulombic efficiency after cycling, which can be potential anode material for lithium ion batteries and negative material for hybrid supercapacitor. The AC//LTO hybrid supercapacitor exhibits excellent capacity retention of 93% after 500 cycles and offers higher energy density and power density than the AC//AC symmetric supercapacitor. The presented AC//LTO hybrid supercapacitor could be a competitive candidate for the promising energy storage devices