scholarly journals Structural and Electron-Hopping Studies of Pr and Nd Substituted La2/3Ba1/3MnO3 Manganites

2009 ◽  
Vol 282 ◽  
pp. 1-8
Author(s):  
Abdullah Huda ◽  
S.A. Halim
Keyword(s):  
Electrical Resistance ◽  
Single Phase ◽  
Microstructural Properties ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Resistivity Measurements ◽  
Structural And Electrical Properties ◽  
Lower Temperature ◽  
Xrd Patterns ◽  
Semiconducting Behavior

The significance of substituting concentrations of Pr and Nd at La-sites, in La0.67Ba0.33MnO3 perovskite compounds, for the structural and electrical properties have been studied. Polycrystalline samples (La1-x Prx)0.67Ba0.33MnO3 and (La1-x Ndx)0.67Ba0.33MnO3 with x = 0.00, 0.167, 0.333, 0.5, 0.667, 0.833 and 1.0 were synthesized via conventional solid-state reaction in the bulk. All of the samples were calcined at 900oC for 12 hours, pelletized and sintered at 1300oC for 24 hours and investigated. In this paper the structural patterns and microstructural properties of bulk samples have been investigated via x-ray diffractometry (XRD) and scanning electron microscopy (SEM). XRD patterns show that these systems are single-phase, with orthorhombic distorted perovskite structures. The electrical property, Tp, was determined by using standard four-point probe resistivity measurements in the temperature range of 20 K to 300 K. The result shows that Pr and Nd dopants shift the value of TP to a lower temperature. When the temperature is above Tp, T > Tp, the variation of the electrical resistance was found to follow the an Arhenius-type law, ρ = ρo exp (-Ea/KBT). It was used to calculate the activation energy of every sample. The resistivity curves show semiconducting behavior of all samples above their Tp.

The Microwave Electromagnetic Properties of Sr2+ Doped DyFeO3

2011 ◽  
Vol 197-198 ◽  
pp. 405-408
Author(s):  
Shao Teng Yan ◽  
Xiao Gu Huang ◽  
Feng Dai ◽  
Peng De Han ◽  
Li Xi Wang ◽  
...  
Keyword(s):  
Single Phase ◽  
Intermediate Phase ◽  
Electromagnetic Properties ◽  
Network Analyzer ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Xrd Patterns ◽  
Perovskite Type ◽  
Peak Value

Perovskite type ferrite doped with Sr2+, Dy1-xMxFeO3(x = 0.0, 0.05, 0.15, 0.25) were prepared by the conventional solid-state reaction. The structure and electromagnetic properties of the calcined samples were studied using powder X-ray diffraction (XRD, Rigaku D/Max-2500) and network analyzer (Agilent 8722ET). All the XRD patterns showed the single phase of the perovskite type ferrite without other intermediate phase when x≤0.25. The electromagnetic properties of the samples have been studied at the frequency range from 2 GHz to 18 GHz. The ε′ and ε′′ values were improved significantly. Both the values of ε′ and ε′′ increase with the increasing content of the doped cations Sr2+, and the peak value of ε′′ was about 2.2 at 12.1 GHz position when x = 0.25.

Raman And Fluorescence Spectra Observed in Laser Microprobe Measurements of Several Compositions in the Ln-Ba-Cu-O System

1990 ◽  
Vol 48 (2) ◽  
pp. 278-279
Author(s):  
Edgar S. Etz ◽  
Thomas D. Schroeder ◽  
Winnie Wong-Ng
Keyword(s):  
Fluorescence Spectra ◽  
Single Phase ◽  
X Ray Diffraction ◽  
Ceramic Powders ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Raman Microprobe ◽  
Methods Of Synthesis ◽  
Compositional Homogeneity ◽  
Processing Techniques

We are investigating by Raman microprobe measurements the superconducting and related phases in the LnBa2Cu3O7-x (for x=0 to 1) system where yttrium has been replaced by several of the lanthanide (Ln = Nd,Sm,Eu,Ho,Er) elements. The aim is to relate the observed optical spectra (Raman and fluorescence) to the compositional and structural properties of these solids as part of comprehensive materials characterization. The results are correlated with the methods of synthesis, the processing techniques of these materials, and their superconducting properties. Of relevance is the substitutional chemistry of these isostructural systems, the differences in the spectra, and their microanalytical usefulness for the detection of impurity phases, and the assessment of compositional homogeneity. The Raman spectra of most of these compounds are well understood from accounts in the literature.The materials examined here are mostly ceramic powders prepared by conventional solid state reaction techniques. The bulk samples are of nominally single-phase composition as determined by x-ray diffraction.

scholarly journals Influence of Li2CO3 addition on electrical and magnetic properties of Ni0.6Mg0.4Fe2O4

2020 ◽  
Vol 10 (03) ◽  
pp. 2050003
Author(s):  
M. R. Hassan ◽  
M. T. Islam ◽  
M. N. I. Khan
Keyword(s):  
Magnetic Properties ◽  
Single Phase ◽  
Low Frequency ◽  
Solid State Reaction Method ◽  
Charge Carriers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electrical And Magnetic Properties ◽  
Frequency Regime ◽  
Xrd Patterns

In this research, influence of adding Li2CO3 (at 0%, 2%, 4%, 6%) on electrical and magnetic properties of [Formula: see text][Formula: see text]Fe2O4 (with 60% Ni and 40% Mg) ferrite has been studied. The samples are prepared by solid state reaction method and sintered at 1300∘C for 6[Formula: see text]h. X-ray diffraction (XRD) patterns show the samples belong to single-phase cubic structure without any impurity phase. The magnetic properties (saturation magnetization and coercivity) of the samples have been investigated by VSM and found that the higher concentration of Li2CO3 reduces the hysteresis loss. DC resistivity increases with Li2CO3 contents whereas it decreases initially and then becomes constant at lower value with temperature which indicates that the studied samples are semiconductor. The dielectric dispersion occurs at a low-frequency regime and the loss peaks are formed in a higher frequency regime, which are due to the presence of resonance between applied frequency and hopping frequency of charge carriers. Notably, the loss peaks are shifted to the lower frequency with Li2CO3 additions.

Analysis of Selected Area Diffraction Patterns With Winjade

1998 ◽  
Vol 4 (S2) ◽  
pp. 342-343 ◽  
Author(s):  
S. D. Walck ◽  
P. Ruzakowski-Athey
Keyword(s):  
Single Phase ◽  
Xrd Analysis ◽  
Analysis Program ◽  
X Ray Diffraction ◽  
Program Module ◽  
Vast Number ◽  
One Dimensional ◽  
X Ray ◽  
Diffraction Patterns ◽  
Xrd Patterns

The analysis of Selected Area Diffraction (SAD) patterns that are collected from a single phase material having sufficient crystallites to provide continuous rings is relatively straightforward. However, when this condition is not met and there may be several phases present having rings of a spotty nature, the pattern is complex and can be quite difficult to analyze manually because of the vast number of discrete spots. WinJade from MDI is an X-ray diffraction (XRD) analysis program with an Electron Diffraction Program Module (EDPM) that can be used to aid in the analysis of SAD patterns. The EDPM produces Integrated Circular Density Plots (ICDP), which are one-dimensional intensity profiles plotted as a function of equivalent XRD 20 values or crystal d-spacings. These ICDP's can be overlayed with XRD patterns or with reference lines from the NIST and JCPDS crystalline databases for direct comparisons.

Reactive DC Magnetron Sputtered ZnO Thin Films for Piezoelectric Application

2018 ◽  
Vol 17 (03) ◽  
pp. 1760047
Author(s):  
M. Abinaya ◽  
K. M. Dhanisha ◽  
M. Manoj Cristopher ◽  
P. Deepak Raj ◽  
K. Jeyadheepan ◽  
...  
Keyword(s):  
Electrical Resistance ◽  
Zno Thin Films ◽  
Zno Films ◽  
Sem Images ◽  
X Ray ◽  
Glass Substrates ◽  
Uv Visible ◽  
Xrd Patterns ◽  
Spherical Grains ◽  
Enhanced Crystallinity

Zinc oxide (ZnO) films have been sputter coated over glass substrates at different cathode powers. Influence of cathode power on physical characteristics of ZnO samples was analyzed using X-ray diffractometer (XRD), field emission-scanning electron microscopy (FE-SEM), UV-Visible spectrophotometer and four-point probe (FPP) method. XRD patterns exhibited [Formula: see text]-axis-oriented ZnO and enhanced crystallinity with increase in cathode power due to the increase in adatom mobility. Uniformly arranged spherical grains were observed from FE-SEM images. The grain size increased from 25 to 40[Formula: see text]nm with increase in power. All samples exhibited high electrical resistance (G[Formula: see text]) which is compatible for piezoelectric application.

REBa2ZrO5.5 (RE = La, Ce, Eu, and Yb): Synthesis, characterization, and their potential use as substrates for YBa2Cu3O7–δ superconductors

1997 ◽  
Vol 12 (11) ◽  
pp. 2976-2980 ◽  
Author(s):  
R. Jose ◽  
Asha M. John ◽  
J. Kurian ◽  
P. K. Sajith ◽  
J. Koshy
Keyword(s):  
Single Phase ◽  
Detrimental Effect ◽  
Solid State Reaction Method ◽  
Dielectric Constants ◽  
X Ray Diffraction ◽  
X Ray ◽  
Resistivity Measurements ◽  
New Class ◽  
Zero Resistance ◽  
Potential Use

A new class of complex perovskites REBa2ZrO5.5 (where RE = La, Ce, Eu, and Yb) have been synthesized and sintered as single phase materials by the solid state reaction method. The structure of these materials was studied by x-ray diffraction, and all of them were found to be isostructural, having a cubic perovskite structure. X-ray diffraction and resistivity measurements have shown that there is no detectable chemical reaction between YBa2Cu3O7–delta; and REBa2ZrO5.5 even under severe heat treatment at 950 °C, and that the addition of REBa2ZrO5.5 up to 20 vol.% in YBa2Cu3O7–δ shows no detrimental effect on the superconducting properties of YBa2Cu3O7-δ. Dielectric constants and loss factors are in the range suitable for their use as substrates for microwave applications. Thick films of YBa2Cu3O7–δ fabricated on polycrystalline REBa2ZrO5.5 substrates gave a zero resistance transition temperature Tc(0) ∼ 92 K, indicating the suitability of these materials as substrates for YBa2Cu3O7–δ.

Photoluminescence Properties of Ba-Substituted SrAl2O4:Eu Phosphor

2004 ◽  
Vol 449-452 ◽  
pp. 745-748 ◽  
Author(s):  
W.S. Park ◽  
S.J. Kim ◽  
Ji Soon Kim
Keyword(s):  
Single Phase ◽  
Measuring System ◽  
Microstructural Properties ◽  
Photoluminescence Properties ◽  
X Ray ◽  
Sintering Condition

The synthesis of Sr1-XBaXAl2O4 :Eu 2+ (x = 0, 0.1, 0.2 and 0.3 mol) phosphor and its properties of photoluminescence and long-phosphorescence were investigated as a function of sintering condition. The single phase of SrAl2O4 was obtained by sintering the mixtures of SrCO3, BaCO3, Eu2 O3, Al2O3 and 3wt% B2 O3 powders over 1100°C in Ar/H2 atmosphere. Stuctural properties were analyzed by a X-ray diffractometer, microstructural properties by a SEM, and photoluminescent properties by a PL measuring system. The optimum sintering condition for the long-phosphorescent phosphor of Sr1-XBaXAl2O4:Eu2+ was found at 1400 °C. Substitution of Ba about 0.2mol in SrAl2O4 :Eu 2+ enhanced the photoluminescence and long-phosphorescence.

scholarly journals Microstructures, Magnetic Properties and Microwave Absorption Characteristics of Ti2+ -Mn4+Substituted Barium Hexaferrite

2016 ◽  
Vol 14 (1) ◽  
pp. 15 ◽  
Author(s):  
Maykel Manawan ◽  
Azwar Manaf ◽  
Bambang Soegijono ◽  
Asep Yudi Hercuadi
Keyword(s):  
Crystallite Size ◽  
Microwave Absorption ◽  
Single Phase ◽  
Barium Hexaferrite ◽  
Grain Morphology ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
X Ray ◽  
Xrd Patterns ◽  
Substituted Barium Hexaferrite

The effect of Ti2+-Mn4+substitution on microwave absorption has been studied for BaFe12-2xTixMnxO19 ferrite, where x varies from 0.2, 0.4, 0.6 and 0.8.Ti2+-Mn4+ ions were obtained from TiO and MnO2 precursors which were mechanically alloyed together with BaCO3 and Fe2O3 precursors. X-ray diffraction (XRD) patterns for sintered samples confirmed that the materials are consisted with single phase BHF structure. Unit cell volume and crystallite size was found increase with increasing x. Crystallite size for all samples below 70 nm, but the grain morphology shown that the grains is in range of 200 - 400 nm, which concluded that each grain are polycrystalline. The saturation magnetization is increases up to x = 0.4 and decrease for higher x values, while the coercivity remains decreases monotonically. These results were interpreted in terms of the site preferential occupation of Ti2+ and Mn4+ at low level substitution.These substitution revealed of enhanced reflection loss (RL) up to 25 dB forx=0.6.It suggested that the synthesized can be employed as effective microwave absorbers in various devices.

scholarly journals Fabrication and Characterization of CoFe2O4/CoFe2/SiO2 Nanocomposite Particles

2020 ◽  
Vol 36 (4) ◽  
Author(s):  
Tran Thi Viet Nga
Keyword(s):  
Magnetic Properties ◽  
Single Phase ◽  
Sol Gel ◽  
Calcination Time ◽  
Nanocomposite Particles ◽  
X Ray ◽  
Fabrication And Characterization ◽  
Xrd Patterns ◽  
20 Nm

The CoFe2O4/CoFe2/SiO2 nanocomposite particles were synthesized using a sol- gel method and calcination in hydrogen. The magnetic properties and structure of nanocomposite particles calcinated at 600 oC and 900 oC in range of calcination time from 1 h to 4 h were investigated. The phase composition, surface morphology and magnetic properties of the nanocomposites were investigated using X-ray powder diffraction, scanning electron microscopy and vibrating sample magnetometer. The XRD patterns indicate the existence of both CoFe2O4 and CoFe2 phases in the nanocomposite after reducing at 600 oC for 2 h and 3 h. The single phase CoFe2 was obtained after reducing at 900 oC. The average particles size was evenly distributed in the range of 20 nm to 120 nm. The magnetization increases significantly with increasing of reduction temperature.

Structural, dielectric, ferroelectric and impedance spectroscopic studies on Ba1−xSrxTiO3(0.15 ≤ x ≤ 0.35)

2019 ◽  
Vol 33 (17) ◽  
pp. 1950193 ◽  
Author(s):  
Shukdev Pandey ◽  
Om Parkash ◽  
Devendra Kumar
Keyword(s):  
Equivalent Circuit Model ◽  
Solid State Reaction Method ◽  
Spectroscopic Studies ◽  
Frequency Range ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
X Band ◽  
Xrd Patterns ◽  
Diffuse Phase

Compositions with x = 0.15, 0.20, 0.25, 0.30 and 0.35 were synthesized in the system [Formula: see text] using conventional solid state reaction method and characterized by X-Ray Diffraction (XRD), Raman spectroscopy and Scanning Electron Microscopy (SEM). Tetragonal phase was confirmed in all the samples using Rietveld refinement of the XRD patterns and observation of their Raman spectra. Dielectric and impedance measurements were carried out in the temperature range 300–723 K in the frequency range 1 Hz to 1 MHz. The samples exhibit diffuse phase transition (DPT). Equivalent circuit model involving combination of Constant Phase angle Elements (CPE) and resistances (R) was developed which represents the data well. Expressions for the values of resistances (R) were established in terms of composition and temperature empirically. P-E loops indicated normal ferroelectric behavior for all the samples. Dielectric constant was also measured in the frequency range 8–12 GHz in the X band of microwaves.

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