Synthesis and Electrical Analysis of Ba₅GdTi₃V₇O₃₀Ceramics

A polycrystalline sample of Ba5GdTi3V7O30 was prepared using a mixed oxide method at high temperature (i.e., at 950℃). The formation of single-phase compound with orthorhombic structure at room temperature was confirmed from preliminary X-ray diffraction study. Detailed studies of dielectric properties of Ba5GdTi3V7O30, investigated in a wide frequency range (102 - 106 Hz) at different temperatures (33℃ - 500℃) showed that these properties of the material are strongly dependent on frequency and temperature. The existence a dielectric anomaly suggests that the compound has a transition temperature at ~385℃. The nature of the variation of conductivity and value of activation energy in different regions, calculated from the temperature dependence of ac conductivity (dielectric data) suggest that the conduction process is of mixed type (i.e., ionic-polaronic and space charge generated from the oxygen ion vacancies). The ac conductivity spectrum obeys Jonscher’s universal power law.

Enhanced photocatalytic degradation of 4-nitrophenol using polyacrylamide assisted Ce-doped YMnO_(3) nanoparticles

This research article mainly reports on the precise structural,optical,and photocatalytic properties of cerium(Ce)-substituted yttrium manganite(YMnO_(3))nanoparticles synthesized by the polyacrylamide gel method.The characteristics of YMnO_(3)were investigated by the substitution of Ce into the Y site at various molar percentages.The Raman and X-ray diffraction(XRD)analyses confirmed the pure phase of hexagonal YMnO_(3),supported by the Rietveld refinement.The microstructural studies indicate inhomogeneous and irregular particle distribution.The X-ray photoelectron spectroscopy(XPS)results show the presence of two ionic states of Mn and Ce along with Y^(3+)state and oxygen vacancies.Extensive optical exploration using photoluminescence(PL)spectroscopy and UV-Vis-NIR analysis indicates that the intensity of absorption peak increases in the visible region,while the bandgap decreases from 1.42 to1.30 eV with the Ce ion doping(5 mol%-15 mol%).Photocatalytic properties of the polycrystalline nanoparticles were investigated by degradation of the pollutant 4-nitrophenol.The process of amplified photocatalysis process was elucidated by the lowered bandgap and rate of charge carrier recombination.It can be conjugated from this study that the synthesized nanoparticles may be employed as highly efficient(92.8%)visible light-triggered photocatalysts in a variety of real-world applications.

Electrical properties of rare earth based tungsten bronze vanadates

Barium based tungsten bronze （TB） oxides having high dielectric constant and low loss, can be effectively used as transducers, actuators, capacitors and also in memory devices. All these characteristics stimulated the researchers to replace toxic and hazardous lead based materials by barium based TB materials from industry. In the present research work, polycrystalline samples of BaaSrRTi3VTO30 （R=Dy, Sm, La） were synthesized by a high temperature solid state reaction technique. Preliminary structural （X-ray diffraction） analyses of these com- pounds showed the formation of single-phase orthorhombic structures at room temperature having average crystallite size of the order of some nanometer for all the compounds. The scanning electron micrographs （SEM） provided information on the quality of the samples and showed more or less homogeneous distribution of grains over the entire surface of the samples. Detailed dielectric study in a wide temperature range （30-500 ℃） showed ferro to para phase transition for Dy and Sm substituted samples whereas no such transition was observed for La substituted samples. Both the grain and grain boundary resistances exhibited negative temperature coefficient of resistance behavior much like semiconductors. The dc conductivity of all the compounds obeyed Arrhenius relation.

Complex impedance properties of LiSr_(2)Nb_(5)O_(15) ceramic

The polycrystalline sample of LiSr2Nb5O15(LSN)was prepared by a high-temperature solid state reaction technique.The impedance parameters were studied using an impedance analyzer in a wide range of frequencies(102-106 Hz)at different temperatures(28-500℃).Nyquist plot reveals the presence of bulk effect only.The bulk resistance of the compound decreases with rise in temperature which shows the negative temperature coefficient of resistance(NTCR)like a semiconductor.The ac conductivity spectrum was found to obey Jonscher’s universal power law.DC conductivity(bulk)with temperature demonstrates that the compound exhibits Arrhenius type of electrical conductivity and the activation energy found to be 0.97 eV.

Impedance spectroscopy study of Na_(2)SmV_(5)O_(15) ceramics

The polycrystalline Na_(2)SmV_(5)O_(15)(NSV),a new member of the tungsten bronze(TB)family,was prepared by a mixed-oxide technique.The room-temperature X-ray diffraction(XRD)confirmed the formation of single phase compound with orthorhombic crystal structure.The scanning electron microscopy(SEM)analysis indicated that the compound has homogeneous micrograph with a uniform distribution of small grains over the entire surface of the sample.The analysis of impedance spectra of NSV in a low-temperature range(-100℃to 100℃)at different frequencies exhibited interesting electrical properties like the contribution of bulk effect in conduction process.The study of imaginary part of the impedance at different temperatures showed existence of relaxation peak with its shift towards higher frequency on increasing temperature.This suggested the presence of frequency and temperature dependent relaxation process in the material.The loss peak spectra were found to abide by Arrhenius law with small activation energy of 0.12 eV.The temperature dependence of AC and DC electrical conductivity(σ_(AC) and σ_(DC))was also obtained.

Nuclear structure study of some bubble nuclei in the light mass region using mean field formalism

We study the structural properties of some light mass nuclei using two different formalisms（i） a recently developed simple effective interaction in the frame work of microscopic non-relativistic Hartree-Fock method and（ii）the well-known relativistic mean field approach with NL3 parameter set. The bulk properties like binding energy, root mean square radii and quadrupole deformation parameter are estimated and compared with the available experimental data. The predicted results of both the formalisms are well comparable with the experimental observations. The analysis of density profiles of these light mass nuclei suggest that22 O,23F,34 Si and46Ar have bubble like structure.

Hexagonal yttrium manganite:A review on synthesis methods,physical properties and applications

Hexagonal rare-earth manganites have attracted considerable interest due to their complex multiferroic properties,and they possess a spontaneous electric polarization and may be utilized in various technological applications ranging from solar cells to non-volatile memories and light polarizers.The narrow bandgap of hexagonal rare-earth manganite-based compounds can perform remarkable optical anisotropy properties,which make these very efficient photovoltaic materials in parallel with the widely used TiO_(2)-based materials.Substantial enlargement of the traditional field of hexagonal rare-earth manganite photocatalysis also arose in the last decade.This article imparts an extensive review of the rational synthesis,optical properties,structural characterization,and applications of hexagonal rare-earth manganite.Fundamental properties of hexagonal rare-earth perovskite manganite are also emphasized,and a range of unique applications in photocatalysis and photovoltaics are discussed.Eventually,we wind up this review with some linear perspectives and future research in this area.