Mg2＋-ion Conducting Polymer Electrolytes： Materials Characterization and All-Solid-State Battery Performance Studies

For All-Solid-State battery applications, Mg2＋-ion conducting polymer electrolytes and Mg-metal electrode are currently considered as alternate choices in place of Li＋-ion conducting polymer electrolytes/Li-metal electrode. Present paper reports fabrication of All-Solid-State battery based on the following Mg2＋-ion conducting nano composite polymer electrolyte （NCPE） films： [85PEO： 15Mg（C104）2] ＋ 5% TiO2 （〈 100 nm）, [85PEO： 15Mg（CIO4）2] ＋ 3% SiO2（-8 nm）. [85PEO： 15Mg（CIO4）2] ＋ 3% MgO （〈 100 nm）, [85PEO：15Mg（C1O4）2] ＋ 3% MgO （-44 μm）. NCPE films were prepared by hot-press technique. Solid Polymer Electrolyte （SPE） composition： [85PEO： 15Mg（CIO4）2], identified as high conducting film at room temperature, has been used as ISt--phase host and nano/micro particles of active （MgO）/passive （SiO2, TiO2） fillers as IInd-phase dispersoid. Filler particle dependent conductivity studies identified above mentioned NCPE films as optimum conducting composition （OCC） at room temperature. Ion transport behavior of SPE/NCPE film materials was investigated previously. Present paper reports materials characterization and cell performance studies on All-Solid-State batteries： Mg （Anode） Ⅱ SPE or NCPE films tt C＋MnO2＋Electrolyte （Cathode）. Open circuit voltage （OCV） obtained was in the range： 1.79-1.92 V. The batteries were discharged at room temperature under different load conditions and some important battery parameters have been evaluated from plateau region of cell-potential discharge profiles. All the batteries performed quite satisfactorily specially under low current drain states.

Growth and Characterization of Holmium Oxalate Heptahydrate Crystals

Single crystals of holmium oxalate heptahydrate are grown by gel diffusion method using organic agar gel as a medium of growth. The crystals grow in the agar gel with hexagonal morphology having well defined habit faces Powder X-ray diffraction results show that the crystals belong to monoclinic system bearing the space group P21/c with cell parameters;a = 12.197? , b = 11.714 , c = 6.479 , α = 90°, β = 120.12°, γ = 90°, V = 799.6? 3. Fourier transform Infrared spectrum of the crystals shows the presence of water and other associated functional groups. Thermogravimetric analysis support the presence of 7 H2O molecules associated with holmium oxalate crystal lattice. The thermal decomposition in the nitrogen atmosphere leads to the formation of holmium oxide as the final product.

Gas-phase synthesis of Ti_(2)CCl_(2) enables an efficient catalyst for lithiumsulfur batteries

MXenes have aroused intensive enthusiasm because of their exotic properties and promising applications.However,to date,they are usually synthesized by etching technologies.Developing synthetic technologies provides more opportunities for innovation and may extend unexplored applications.Here,we report a bottom-up gas-phase synthesis of Cl-terminated MXene(Ti_(2)CCl_(2)).The gas-phase synthesis endows Ti_(2)CCl_(2) with unique surface chemistry,high phase purity,and excellent metallic conductivity,which can be used to accelerate polysulfide conversion kinetics and dramatically prolong the cyclability of Li-S batteries.In-depth mechanistic analysis deciphers the origin of the formation of Ti_(2)CCl_(2) and offers a paradigm for tuning MXene chemical vapor deposition.In brief,the gas-phase synthesis transforms the synthesis of MXenes and unlocks the hardly achieved potentials of MXenes.

Structural stability improvement, Williamson Hall analysis and band-gap tailoring through A-site Sr doping in rare earth based double perovskite La2NiMnO6

The structural,morphological and optical properties of single-phase polycrystalline La2-xSrxNiMnO6(x=0,0.3 and 0.5),synthesized by solid state reaction were investigated.The samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM)/energy dispersive analysis of X-rays(EDAX),Raman spectroscopy and diffuse reflectance spectroscopy(DRS)to elucidate the role of A-site Sr-doping in double perovskite La2 NiMnO6.Rietveld analysis of XRD patterns revealed that all the samples have monoclinic structure with space group P21/n.Positive gradient in the Williamson Hall plots revealed the presence of tensile strain in all the samples.The morphological studies revealed that average grain size increases along with appreciable decrease in porosity with Sr doping.The Ni/Mn antisite disorder was introduced in the La2 NiMnO6 by Sr-doping confirmed by an increase in the full width at half maximum(FWHM)and decrease in intensity of the Raman modes at around 540 and 665 cm-1 which correspond to the antisymmetric stretching and symmetric stretching modes,respectively.DRS results reveal that the band gap in La2 NiMnO6 can be tuned down by Sr-doping to a value of1.37 eV(very close to 1.40 eV,considered as optimum value for better efficiency of a solar cell).Thus,Sr-doped La2 NiMnO6 may be of prime importance for applications in solar cells.

Dielectric and conducting behavior of gadolinium–terbium fumarate heptahydrate crystals

Gadolinium-terbium fumarate heptahydrate crystals were grown in silica gel by using single gel diffusion technique.The crystals were characterized by different physico-chemical techniques of characterization.Powder X-ray diffraction results showed that the grown material is purely crystalline in nature.Elemental analyses suggested the chemical formula of the compound to be Gd Tb(C_(4)H_(2)O_(4)_(3)·7H_(2)O.Energy dispersive X-ray analysis confirmed the presence of Gd and Tb in the title compound.The dielectric and conductivity studies of the grown compound were carried as function offrequency of applied field and the temperature.The grown material showed a dielectric anomaly which was correlated with its thermal behavior.The ac conductivity of the material showed Jonscher's power law behavior:σ(ω)=σ_(0)+Aω^(s),with a temperature-dependent power exponent s(<1).The conductivity was found to be a function of temperature and frequency.

Electrical and mechanical studies on ferroelectric lithium rubidium sulphate crystals

Slow evaporation method was used to grow single crystals of lithium rubidium sulphate with high transparency.Single crystal X-ray diffraction analysis shows that at room temperature,the crystal belongs to a monoclinic system with the space group P21/n.Some physical parameters like plasma energy,Penn gap,Fermi energy and electronic polarizability have been evaluated for the grown crystal.The relation between electronic polarizability and diamagnetic susceptibility for the crystal has been established on the basis of Kirkwood’s semiempirical equation.The ac conductivity and dielectric behavior of the grown crystal were systemically investigated as a function of frequency and temperature.The title compound obeys Jonscher’s power law relations:
ð(ω)=σo+Aω^(s),with exponent s<1.From the conduction study,it is observed that both small and large polarons take part in conduction process,and at low temperature,both the band and hopping mechanisms are responsible for conduction.From impedance and modulus studies,it is observed that only one conduction relaxation is observed in the crystal at low frequency.The activation energy of the dielectric relaxation(0.41 eV)and that of the conduction(Econd¼0:43 eV)are in agreement,as a result,there is no difference among the conduction and relaxation species at high temperature.Differential scanning calorimetric analysis of the crystal shows three endothermic peaks at 166℃,185℃,and 202℃,from which various thermodynamic parameters such asΔH,ΔS andΔC_(p) have been calculated.From Vickers hardness test,we have determined the mechanical strength,and other parameters which include fracture toughness,brittleness index,yield strength,and stiffness constant for the crystal.