scholarly journals Structural Characterization and Physical Properties of Double Perovskite La2FeReO6+δ Powders

Nanomaterials ◽  
2022 ◽  
Vol 12 (2) ◽  
pp. 244
Author(s):  
Qingkai Tang ◽  
Xinhua Zhu
Keyword(s):  
Room Temperature Ferromagnetism ◽  
Double Perovskite ◽  
Solid State Reaction Method ◽  
Dielectric Behavior ◽  
Xps Spectra ◽  
Molar Ratios ◽  
Pbnm Space Group ◽  
Optical Dielectric ◽  
Chemical States ◽  
Re Elements

The structural, optical, dielectric, and magnetic properties of double perovskite La2FeReO6+δ (LFRO) powders synthesized by solid-state reaction method under CO reduced atmosphere are reported on in this paper. Reitveld refinements on the XRD data revealed that the LFRO powders crystallized in an orthogonal structure (Pbnm space group) with column-like morphology. The molar ratios of La, Fe, and Re elements were close to 2:1:1. XPS spectra verified the mixed chemical states of Fe and Re ions, and two oxygen species in the LFRO powders. The LFRO ceramics exhibited a relaxor-like dielectric behavior, and the associated activation energy was 0.05 eV. Possible origins of the dielectric relaxation behavior are discussed based on the hopping of electrons among the hetero-valence ions at B-site, oxygen ion hopping through the vacant oxygen sites, and the jumping of electrons trapped in the shallower level created by oxygen vacancy. The LFRO powders display room temperature ferromagnetism with Curie temperature of 746 K. A Griffiths-like phase was observed in the LFRO powders with a Griffiths temperature of 758 K. The direct optical band gap of the LFRO powders was 2.30 eV, deduced from their absorption spectra, as confirmed by their green photoluminescence spectra with a strong peak around 556 nm.

scholarly journals Magnetic and Dielectric Behavior of the Ruthenium Double Perovskite Oxides R2MRuO6 (R=La, Pr and Nd, M=Mg, Co, Ni and Zn)

2007 ◽  
Vol 32 (1) ◽  
pp. 51-54
Author(s):  
Kenji Yoshii ◽  
Naoshi. Ikeda ◽  
Shigeo Mori ◽  
Yasuhiro Yoneda ◽  
Masaichiro Mizumaki ◽  
...  
Keyword(s):  
Double Perovskite ◽  
Perovskite Oxides ◽  
Dielectric Behavior

Characterization of Antiferromagnetism in Double Perovskites Ba2FeMoO6 Prepared by Solid State Method

2019 ◽  
Vol 891 ◽  
pp. 224-229
Author(s):  
Naphat Albutt ◽  
Vanussanun Aitviriyaphan ◽  
Thanapong Sareein ◽  
Sudarath Suntaropas ◽  
Panakamon Thonglor ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Solid State ◽  
Solid State Reaction ◽  
Double Perovskite ◽  
Solid State Reaction Method ◽  
Double Perovskites ◽  
Solid State Method ◽  
Reaction Method ◽  
State Method

The magnetic properties of Ba2FeMoO6 (BFMO) double perovskite are investigated. BFMO samples were prepared by solid state reaction method through compression. Magnetic properties are influenced by electron environments of the Fe3+ and Mo5+ ions within the perovskite structure. BFMO sintered at 800 oC exhibited the largest hysteresis loop at 50 K. In addition, the values of Ms and Mr indicate ferromagnetic behaviour in BFMO ceramics sintered at 800 oC for different times up to 10 hours. Using the Curie-Weiss law fitting to investigate μeff~30μB high spin of Fe and Mo, and negative θ present the antiferromagnetic characteristics of the BFMO sample.

CHEMICAL COMPOSITION STUDY OF VANADIUM PENTOXIDE XEROGELS DOPED BY BOVINE ALBUMIN

2016 ◽  
Vol 23 (06) ◽  
pp. 1650058
Author(s):  
R. SEREIKA ◽  
S. KACIULIS ◽  
A. MEZZI ◽  
M. BRUCALE
Keyword(s):  
Vanadium Pentoxide ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Thin Layers ◽  
Xps Spectra ◽  
Force Microscopy ◽  
Molar Ratios ◽  
Atomic Force ◽  
Protonated Amine ◽  
Vanadium Ions

Metal–bioorganic compounds of vanadium pentoxide and bovine serum albumin (BSA) (Fraction V) were obtained by using sol–gel method. Series of the samples (BSA)xV2O[Formula: see text]H2O, where [Formula: see text], 0.01 and 0.001, were originally produced by the synthesis of vanadium pentoxide xerogels and subsequent blending with water-dissolved BSA in appropriate molar ratios. It was evident that the gelation process does not occur for [Formula: see text]. For the X-ray photoelectron spectroscopy (XPS) studies, the thin layers of these materials were prepared by drying the gel onto the glass and mica substrates. The surface morphology of the samples was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. It follows from the analysis of experimental XPS spectra of (BSA)xV2O[Formula: see text]H2O that the nitrogen ions in pure albumin and in (BSA)[Formula: see text]V2O[Formula: see text]H2O are present in imine, amine and protonated amine groups. The additional protonated amine arises when the concentration of albumin in (BSA)xV2O[Formula: see text]H2O is low ([Formula: see text]). Increasing the amount of albumin results in decrease of the number of oxygen ions bonded to vanadium. At the same time (with increase of albumin), the component of oxygen bounded to carbon and nitrogen is increasing. In the samples with greater amount of albumin, the reduction of vanadium ions occurs. This means that the trivalent and tetravalent vanadium ions are present together with pentavalent ones.

scholarly journals Structure, dielectric and electrical properties of relaxor lead-free double perovskite: Nd2NiMnO6

2019 ◽  
Vol 13 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Rutuparna Das ◽  
Ram Choudhary
Keyword(s):  
Ac Conductivity ◽  
Negative Temperature Coefficient ◽  
Complex Impedance ◽  
Double Perovskite ◽  
Negative Temperature ◽  
Solid State Reaction Method ◽  
Temperature Coefficient Of Resistance ◽  
X Ray ◽  
Impedance Data ◽  
Nyquist Plots

In this paper, dielectric relaxor, impedance, AC conductivity and electrical modulus of double perovskite Nd2NiMnO6, prepared by a solid state reaction method and sintered at 1250?C, have been reported in the wide temperature (25-150?C) and frequency (1 kHz-1MHz) ranges. From the preliminary X-ray structural analysis, it is found that the structure of the material is monoclinic. In the study of the temperature dependence of the dielectric constant, the relaxor behaviour of the material is observed. Such type of behaviour is explained by a modified Curie-Weiss and a Vogel-Fulcher law. By analysing Nyquist plots, the existence of grain and grain boundary effects is established. The non-Debye type of relaxation is investigated by the analysis of complex impedance and the modulus data. From the study of impedance data, it is found that the grain resistance is reduced with the increase in temperature indicating the existence of negative temperature coefficient of resistance (NTCR) behaviour in the material which also matches with temperature versus AC conductivity plots. From these results, it may be concluded that this compound may have extreme potential for different high temperature applications.

scholarly journals RAMAN SPECTROSCOPY OF CaCu3Ti4O12 CERAMICS REVISITED

2018 ◽  
Vol 34 (3) ◽  
Author(s):  
Nhat Hoang Nam
Keyword(s):  
Raman Spectroscopy ◽  
Room Temperature ◽  
Structural Characteristics ◽  
Double Perovskite ◽  
Solid State Reaction Method ◽  
Excess Oxygen ◽  
Optical Phonons ◽  
Reaction Method ◽  
Colossal Dielectric Constant ◽  
Perovskite Type

The CaCu3Ti4O12 ceramic has been prepared by Solid State Reaction method in excess oxygen. It possesses a well-defined double-perovskite type crystalline structure and exhibits a colossal dielectric constant at around 50000 at room temperature. This paper revised the imprints of Raman spectroscopy of this compound to validate its structural characteristics and optical behaviors. A special attention is paid on the account of optical phonons which show a recognizable agreement with the other results recently reported

scholarly journals Zn-Mn-O: Ferromagnet at room temperature

2007 ◽  
Vol 61 (3) ◽  
pp. 147-151
Author(s):  
Dusan Milivojevic ◽  
Jovan Blanusa ◽  
Vojislav Spasojevic ◽  
Vladan Kusigerski ◽  
Branka Babic-Stojic
Keyword(s):  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Diffraction Method ◽  
Solid State Reaction Method ◽  
Paramagnetic Resonance ◽  
Reaction Method ◽  
X Ray ◽  
Electron Paramagnetic ◽  
Mn Oxides ◽  
Thermally Treated

Semiconductor Zn-Mn-O crystallites were synthesized by a solid state reaction method starting from the thermal decomposition of the appropriate oxalates. Samples were thermally treated in air at temperatures ranging from 400 to 900?C. The nominal concentrations of manganese werex = 0.01, 0.02, 0.04 and 0.10. The samples were investigated by the X-ray powder diffraction method, magnetization measurements and by electron paramagnetic resonance. X-ray diffractgrams show a dominant wurtzite structure of Zn-Mn-O. Room temperature ferromagnetism was observed in Zn-Mn-O samples with manganese concentrations x ? 0.04, thermally treated at low temperature (500?C). The saturation magnetiza?tion for the sample with x = 0.01 was 0.05 ?B/Mn. The room temperature ferromagnetism seems to be due to the diffusion of Zn into the Mn-oxides grains.

Structural, thermal and dielectric properties of Pb(Mg1/3Nb2/3)1‑x TixO3 ceramics at morphotropic phase boundary

2020 ◽  
Vol 92 (1) ◽  
pp. 10902
Author(s):  
Amine Alaoui-Belghiti ◽  
Yassine Tabbai ◽  
Mourad Rkhis ◽  
Said Laasri ◽  
Houda Lifi ◽  
...  
Keyword(s):  
Phase Boundary ◽  
Morphotropic Phase Boundary ◽  
Solid State Reaction Method ◽  
Dielectric Behavior ◽  
Flow Process ◽  
Cooling Systems ◽  
One Dimensional ◽  
Different Temperatures ◽  
Physical Performances ◽  
Ppe Calorimetry

Ceramics arising from Pb(Mg1/3Nb2/3)1‑x TixO3 with composition near the morphotropic phase boundary (MPB) were prepared by the modified solid-state reaction method. The synthesized ceramics were characterized, and then the operating principles of pyroelectric and piezoelectric harvesters are reviewed. In addition, the dielectric behavior is measured to determine the dielectric constant and losses at different temperatures and frequencies. The typical behavior of a ferroelectric relaxer was observed by adding the PbTiO3 phase. The thermal properties are also analyzed by PPE calorimetry, presaging a one-dimensional heat-flow process. As a result, the dielectric and thermal behaviors of the as-prepared ceramics as well as their thermal stability are intimately linked to the PbTiO3 addition to PbMgl/3Nb2/3O3 phase. These materials exhibit good physical performances, which makes them promising candidates for pyroelectric micro-generators (PEG), cooling systems and infrared applications.

scholarly journals Improved adsorption and degradation performance by S-doping of (001)-TiO2

2019 ◽  
Vol 10 ◽  
pp. 2116-2127 ◽  
Author(s):  
Xiao-Yu Sun ◽  
Xiao Sun ◽  
Xian Zhang ◽  
Ni-Xian Qian ◽  
Min Wang ◽  
...  
Keyword(s):  
Oxygen Vacancies ◽  
Photocatalytic Performance ◽  
Lattice Distortion ◽  
Synergistic Effects ◽  
Chemical Vapor ◽  
Surface Chemical ◽  
Ionic Radii ◽  
Thermal Chemical Vapor Deposition ◽  
Molar Ratios ◽  
Chemical States

In this work, sulfur-doped (S-doped) TiO2 with the (001) face exposed was synthesized by thermal chemical vapor deposition at 180 or 250 °C using S/Ti molar ratios R S/Ti of 0, 0.5, 1, 2, 3, 4 and 5. The S-doped samples synthesized at 250 °C exhibit a significantly improved photocatalytic performance. More precisely, S-doping has the following effects on the material: (1) S can adopt different chemical states in the samples. Specifically, it exists in the form of S2− replacing O2− at a ratio of R S/Ti = 1 and also in the form of S6+ replacing Ti4+ at R S/Ti ≥ 2. As a result, S-doping causes a lattice distortion, because the ionic radii of S2− and S6+ differ from that of the O2− and Ti4+ ions. (2) S-doping increases the adsorption coefficient A e for methylene blue (MB) from 0.9% to 68.5% due to the synergistic effects of the oxygen vacancies, increased number of surface chemical adsorption centers as a result of SO4 2− adsorption on the TiO2 surface and the larger pore size. (3) S-doping increases the MB degradation rate from 6.9 × 10−2 min−1 to 18.2 × 10−2 min−1 due to an increase in the amount of •OH and •O2− radicals.

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