Efficient CO_2 Electrolysis with Fluorite Structure Nanoparticles Modified Perovskite Structure La_(0.75)Sr_(0.25)Cr_(0.5)Mn_(0.5)O_(3-δ) Cathode

Perovskite structure La_（0.75）Sr_（0.25）Cr_（0.5）Mn_（0.5）O_（3-δ）（LSCM） cathode with unique structure can electrolyze CO_2 to CO in solid oxide electrolysers（SOEs）.However,the cell performance is restricted by its electro-catalysis activity.In this work,fluorite structure nanoparticles（CeO_（2-δ）） are impregnated on LSCM cathode to improve the electro-catalysis activity.X-ray diffraction（XRD）,scanning electron microscope（SEM） and X-ray photoelectron spectroscopy（XPS） together approve that the fluorite structure nanoparticles are uniformly distributed on the perovskite structure LSCM scaffold.Electrochemical measurements illustrate that direct CO_2 electrolysis with 10%mol CeO_（2-δ） impregnated LSCM cathode exhibits excellent performance for current density（0.5 A×cm^（-2）） and current efficiency（～95%） at 800 ℃ under 1.6 V.It is believed that the enhanced performance of directed CO_2 electrolysis may be due to the synergetic effect of fluorite structure CeO_（2-δ） nanoparticles and perovskite structure LSCM ceramic electrode.

REPLACED SITE OF Eu^(2+) ION IN THE COMPLEX FLUORIDES WITH THE PEROVSKITE CRYSTAL STRUCTURE

The replaced site of Eu^(2+) ion is dependent on the electronegativity difference of the cations in complex fluorides.In the mixed fluoride KMgF_3:Eu^(2+),Eu^(2+) ion occupies K^+ site,its emission spectrum is a sharp line and its valence-state is stable.

Morphologies and Structures of Perovskite Thin Film on Zn-face and O-face of ZnO Single Crystal

ZnO single crystal was used as the substrate to study the effect of ZnO crystal plane polarity on the morphology and structure of CH_3NH_3PbI_3（MAPbI_3） perovskite film and carrier transport properties,which is meaningful for improving ZnO-based perovskite solar cell. It is found that perovskite thin film has small grain size（about 190 nm） and high coverage rate on the O-face of ZnO single crystal,and the dominant exposed crystal plane of perovskite film is（110） plane. While the MAPbI_3 thin film has large grain size（about 1.03 μm） and low coverage rate on the Zn-face,and the（022） plane is dominantly exposed for the perovskite film. The injection of photogenerated electrons from MAPbI_3 film into the O-face of ZnO single crystal is faster and more effective than that to Zn-face. It is supposed that O-face is more suitable for ZnO single crystal based perovskite cell fabrication than Zn-face.

Research Progress of High Entropy Ceramic Materials

High-entropy materials(HEMs)have better mechanical,thermal,and electrical properties than traditional materials due to their special"high entropy effect".They can also adjust the performance of high entropy ceramics by adjusting the proportion of raw materials,and have broad application prospects in many fields.This article provides a review of the high entropy effect,preparation methods,and main applications of high entropy ceramic materials,especially exploring relevant research on high entropy perovskite ceramics.It is expected to provide reference for the promotion of scientific research and the development of further large-scale applications of high-entropy ceramic materials.

Hydrothermal Synthesis and Characterization of Perovskite Oxide AgTaO_3

The perovskite-type AgTaO3 crystals were prepared by mild hydrothermal method and determined by powder X-ray diffraction. Rietveld refinement indicates that AgTaO3 crystallized in an orthorhombic system with the space group Pcmn. The lattice parameters are a=5.5822（1） nm, b=7.8522（2） nm and c=5.5347（1） nm, with α=β=γ= 90.0o. The compound was characterized by scanning electron microscopy（SEM）, X-ray photoelectron spectroscopy （XPS）, high resolution transmission electron microscopy（HR-TEM） and UV-Vis diffuse reflectance spectrometry （UV-Vis DRS）. The photocatalytic activity of AgTaO3 powder was evaluated by the degradation of Congo red under UV-light irradiation. The result shows that the titled compound has a high photocatalytic activity at room temperature and potential application in photocatalysis.

STRUCTURE AND PROPERTY OF PIEZOELECTRIC CERAMICS OF QUATERNARY SYSTEM

Composite perovskite piezoelectric ceramics of PMMN quaternary system were prepared by cold-pressing and solid-phase sintering. Piezoelectric modulus and density of the samples were measured after polarization. X-ray diffraction analysis and SEM were used to prove the result that the major phase of the piezoelectric ceramic spectimen based on PZT is PZT phase,which is tetragonal system and P-4mm space group.

Effects of Annealing Temperature on Microstructure and Sensing Properties to Alcohol for Nano-La_(0.68)Pb_(0.32)FeO_3

La_(0.68)Pb_(0.32)FeO_3 samples annealed at different temperature were prepared using citrate sol-gel method. With increasing of annealing temperature from 200 to 1000 ℃, the samples crystallize to have single-phase perovskite structure. However, the sensitivity increases at first due to the improvement of crystallization of the perovskite phase, and finally drops attributed to the larger grain size. The optimal sensitivities for La_(0.68)Pb_(0.32)FeO_3 samples annealed at 400, 600, 800, and 1000 ℃ are 12.14, 14.77, 51.07, and 34.55, respectively.

Synthesis and Characterization of a New Fe_2O_3 Pillared Triple-layered Perovskite KSr_2Nb_3O_(10)

A n-Hexyl NH 3Sr 2Nb 3O 10 is obtained by the stepwise ion-exchange reaction,then is dispersed in aqueous solution of trinuclear acetato-hydroxo iron(III) nitrate,[Fe 3(OCOCH 3) 7OH·2H 2O]NO 3,and the interlayer potassium cations of the perovskite niobate are exchanged with the partially hydrolyzed trinuclear acetato complex ions.On heating,the exchanged complex ions are converted into iron oxide pillars which keep the perovskite sheets apart.The product is characterized by XRD,SEM,EDAX and surface area measurement respectively.

Charge-Ordering in La_(0.33) Ca_(0.67) MnO_3 Perovskite

Structure model of charge-ordered La_0.33 Ca_0.67 MnO_3, perovskite is one of current focused study in condensed matter physics. There are great discrepancies in previous studies in this field. Our transmission electron microscopy study confirms Wigner crystal model with transverse displacement and is not consisent with the hi-stripe model with longitudinal displacement. We observed incommensurate modulation and anti-phase domains with a displacement vector a_co/3 in charge--ordered La_0.33 Ca_0.67 MnO_3, perovskite.

Density-functional theory investigation of electronic structure,elastic properties,optical properties,and lattice dynamics of Ba_2Zn WO_6

The electronic structures, optical dielectric functions, elastic properties, and lattice dynamics of Ba2ZnWO6 have been investigated by using the generalized gradient approximation. The density of states and distributions of charge density show that O and Ba tend toward ionic bond, but O and W or Zn display the covalent bond character. The calculated energy band structure shows that Ba2ZnWO6 is a wide indirect band gap semiconductor. The static value 2.28 of the refractive index is attained. The analysis of the elastic properties of Ba2ZnWO6 indicates a rather weak elastic anisotropy. The phonon dispersion is calculated, suggesting no structural instability, which is agreement with the recent low temperature neutron diffraction experiments. The mensurability Cv （phonon heat capacity） as the function of the temperature is also calculated to judge our results for future experiment.

Deep insights into the advancements and applications of perovskite based photovoltaic cells

The organometal halide perovskite materials have a blend of surprising optoelectronic properties, for example high value of absorption coefficient and abrupt optical retention edge, lifetime, long charge carrier diffusion length and many more. Brought in conjunction with the capacity for manufacturing at low temperature, likewise from the solution, devices based on perovskite, particularly solar cells have been contemplated seriously with striking advancements in performance, in the course of recent years. The amalgamation of minimal effort, high efficiency and extra applications gives incredible potential to commercialization of these cells. The applications and performance of perovskite cells frequently relate with the structures of the device. Numerous creative structures of the devices were produced, targeting for vast scale manufacture, diminishing creation cost, upgrading the PCE and subsequently expanding the prospective for future applications. This paper outlines the various advanced structures of PSC, challenges confronted by these PSCs and their future perspectives. The commercial applications of PSC are additionally talked about in this paper.

Organic Cation Effect on the Physical Properties of CH3NH3PbI3 Perovskite from the First-principles Study

The effect of the distribution of organic cations CH3NH3^＋（MA^＋） on the stability,electronic structures and optical properties of CH3NH3 Pb I3 perovskite have been investigated using the plane-wave ultrasoft pseuudopotentials. Generalized gradient approximation and local density approximation are used to optimize the geometries of six models, which are different in the orientation of organic cations. The results show that model C is more stable than others, and the main contribution to the top of valence band is from I 5p states. In the bottom of conduction bands, the main components are Pb 6s states with an overlapping of I 5p states. When the orientation of organic group is transforming, the Pb I6 octahedra will distort and the band structure will alter with it, which affect the generation and migration of photon-generated carriers and optical properties.

Effects of Internal Relaxation under Inplane Strain on the Structural,Electronic and Optical Properties of Perovskite BaZrO3

We present the specific ab-initio calculations that detail the variations of perovskite BaZrO3 caused by in-plane strain. Specifically, the internal relaxation, which was not captured in the widely used biaxial strain model, was included in a complementary manner to lattice relaxation. Density functional theory as well as a hybrid functional method based on a plane wave basis set was employed to calculate the lattice structure, elastic constants, electronic properties and optical properties of perovskite BaZrO3. The lattice parameter c exhibited a clear linear dependence on the imposed in-plane strain, but the Poisson＇s ratio caused by internal relaxation was smaller than the elastic deformation, indicating an ＂inelastic＂ or ＂plastic＂ relaxation manner caused by the introduction of internal relaxation. As a result, the related electronic and optical properties of perovskite BaZrO3 were also strongly affected by the in-plane strain, which revealed an effective way to adjust the properties of perovskite BaZrO3 via internal relaxation.

Selective hydrogenolysis of furfuryl alcohol to 1,5-and 1,2-pentanediol over Cu-LaCoO_3 catalysts with balanced Cu^O-CoO sites

Selective hydrogenolysis of biomass‐derived furfuryl alcohol(FFA)to 1,5‐and 1,2‐pentanediol(PeD)was conducted over Cu‐LaCoO3 catalysts with different Cu loadings;the catalysts were derived from perovskite structures prepared by a one‐step citrate complexing method.The catalytic performances of the Cu‐LaCoO3 catalysts were found to depend on the Cu loading and pretreatment conditions.The catalyst with 10 wt%Cu loading exhibited the best catalytic performance after prereduction in 5%H2‐95%N2,achieving a high FFA conversion of 100%and selectivity of 55.5%for 1,5‐pentanediol(40.3%)and 1,2‐pentanediol(15.2%)at 413 K and 6 MPa H2.This catalyst could be reused four times without a loss of FFA conversion but it resulted in a slight decrease in pentanediol selectivity.Correlation between the structural changes in the catalysts at different states and the simultaneous variation in the catalytic performance revealed that cooperative catalysis between Cu0 and CoO promoted the hydrogenolysis of FFA to PeDs,especially to 1,5‐PeD,while Co0 promoted the hydrogenation of FFA to tetrahydrofurfuryl alcohol(THFA).Therefore,it is suggested that a synergetic effect between balanced Cu0 and CoO sites plays a critical role in achieving a high yield of PeDs with a high 1,5‐/1,2‐pentanediol selectivity ratio during FFA hydrogenolysis.

Phase diagram of the CsBr-CaBr_2 system

The phase diagram of the CsBr-CaBr2 system was re-determined by using differential thermal analysis and high ternperature and room ternperature X-ray diffraction analysis. It is concluded that there are three intermediate compounds in this system： a.congruently melting compound, CsCaBr3, with a melting point of 823℃ and two incongruently melting compounds, Cs2CaBr4 and Cs3Ca2Br7, whose peritectic points being 597℃ and 635℃, respectively. X-ray diffraction analysis indicated that compound CsCaBr3 is of slightly distorted perovskite structure.

Cr doping effect in B-site of La_(0.75)Sr_(0.25)MnO_3 on its phase stability and performance as an SOFC anode

La0.75Sr0.25CryMn1-yO3 （LSCM） （y = 0.0-0.6） composite oxides were synthesized by a complexing process of combining ethylene diamine tetraacetic acid （EDTA） and citrate. X-ray diffraction （XRD）, temperature-programmed reduction, electrical conductivity, I-V polarization, and impedance spectroscopy were conducted to investigate the Cr doping effect of La0.75Sr0.25MnO3 on its phase stability and electrochemical performance as a solid-oxide fuel cell （SOFC） anode. The chemical and structural stabilities of the oxides increased steadily with increasing Cr doping concentration, while the electrical conductivity decreased on the contrary. At y 〉 0.4, the basic perovskite structure under the anode operating condition was sustained. A cell with 0.5-ram-thick scandia-stabilized zirconia electrolyte and La0.75Sr0.25CryMn1-yO3 anode delivered a Dower density of -15 mW-cm^-2 at 850℃.

Preparation and Characterization of Nano-Particles PZT Ferroelectric Thin Films by RF-Magnetron Sputtering

Pt/Ti bottom electrodes were fabricated on SiO2/Si substrates by magnetron dual-facingtarget sputtering system. Lead zirconate titanate（PZT） thin films were deposited on Pt/Ti/SiO2/Si substrates by radio frequency （RF） magnetron sputtering system. The thickness of PZT thin films which were deposited for 5 h was about 800 nm. XRD spectra show that PZT thin films deposited in Ar ambience and rapid-thermal-annealed for 20 min at 700 ℃ have good crystallization behavior and perovskite structure. AFM micrographs show that mean diameter of crystallites is 70 nm and surface structures of PZT thin films are uniform and dense. Raw mean, root mean square roughness and mean roughness of PZT thin films are 34..357 rim, 2. 479 nm and 1. 954 nm respectively. As test frequency is 1 kHz, dielectric constant of PZT thin films is 327.5. Electric hysteresis loop shows that coercive field strength, residual polarization strength and spontaneous polarization strength of PZT thin films are 50 kV/cm, 10μC/cm^2 and 13μC/cm^2 respectively.

An explicit and novel structure,lattice dynamics,and photoemission of La-doped nanocrystalline SrZrO_(3) perovskite

As no complete and comprehensive studies have been previously reported for La-doped nanocrystalline SrZrO_(3)(SZO),we researched herein a detailed investigation for pure and La-doped samples.A modified solid-state reaction process,including successive cycles of milling and sintering at high temperature,was followed to produce SZO and Sr_(0.9)La_(0.1)ZrO_(3)(SLZO)powdered ingots.Rietveld analysis of X-ray diffractometer data predicts that the two samples exhibit orthorhombic structure with an increase in crystallite size by~25%for doped sample.A great reduction in Raman modes intensity(~60%)and an annihilation of several vibration modes were detected using Raman spectroscopy.The degree of ordering on the B-site was recorded to be higher in La-doped sample.According to ultraviolet-visible(UV-Vis)absorption,a decrease in the optical gap width(E_(g))from 4.40 eV to 4.21 eV was achieved by La incorporation due to the presence of additional defect states such as oxygen and Sr vacancies at the band edge.The process of electron-hole recombination was studied using photoluminescence(PL)spectroscopy.Deconvolution of PL spectra yielded four emission bands:one green band,one blue band,and two violet bands.Highly intense violet emission atλ=393 nm approximately five times greater than that detected for pure SZO is realized as La^(3+)substitutes for Sr^(2+).Such property nominates SLZO for technological applications requiring highly intense violet emission,e.g.,light-emitting diodes.

(Zn,Ca) Solid-Solution Behavior and Its Effect on Luminescence Properties in Ca_(1-x)Zn_xTiO_3∶0.002Pr^(3+) Phosphors

Nominal composition of Ca1-xZnxTiO3 ： 0. 002Pr^3 ＋ （x = 0. 000 - 0. 200） phosphors were prepared by conventional solid reaction route. XRD and PL measurements were used to investigate the solid-solution structure and luminescence properties of Zn-doped Ca1-xZnxTiO3：0.002Pr^3＋ phosphors. The effect of solid-solution structure formed by substitution between Ca^2 ＋ and Zn^2＋ ions on the luminescent properties was analyzed. The results reveal that, with the increase of Zn substitution content below 0.010, lattice parameters and the intensity of excitation peak at both 260 and 330 nm as well as the corresponding 610 nm emission intensity are monotonously decreased quickly in a similar tendency. Also, the evolution of luminescence intensity and crystal cell parameters against Zn doping concentration are in good agreement. Above results are closely related with the structure change within Ca1- xZnxTiO3：0.002Pr^3＋ solid-solution phase formed by the Zn ions substitution for the Ca sites. Present study reveals that the solid-solution structure formed by substitution between Ca^2＋ and Zn^2＋ ions has significant effect on the luminescence properties of single phase Ca1-xZnxTiO3：0.002Pr^3＋ phosphors.

Ferroelectric and piezoelectric properties of SrZrO_3-modified Bi_(0.5)Na_(0.5)TiO_3 lead-free ceramics

The lead-free SrZrO3-modified Bi0.5Na0.5TiO3(BNT-SZ100 x, with x=0-0.15) ceramics were fabricated by a conventional solid-state reaction method. The effects of SZ addition on BNT ceramics were investigated through X-ray diffraction(XRD), scanning electron microscopy(SEM), ferroelectric and electric field-induced strain characterizations. XRD analysis revealed a pure perovskite phase without any traces of secondary phases. Ferroelectric and bipolar field induced-strain curves indicated a disruption of ferroelectric order upon SZ addition into BNT ceramics. A maximum value of remnant polarization(32 μC/cm2) and piezoelectric constant(102 pC/N) was observed at 5%(mole fraction) of SZ. Maximum value of the electric field-induced strain(Smax=0.24%) corresponding to normalized strain(Smax/Emax= d*33= 340 pm/V) was obtained at BNT-SZ9.