scholarly journals Structural and Magnetic Studies on Pb4+ Substituted Cobalt Ferrite System

2019 ◽  
pp. 230-236
Author(s):  
B K Labde ◽  
A S Padampalle ◽  
N M More
Keyword(s):  
Single Phase ◽  
Iron Ions ◽  
X Ray Diffraction ◽  
Magnetic Studies ◽  
X Ray ◽  
Saturation Magnetic Moment ◽  
Spin Ordering ◽  
High Field Magnetization ◽  
Curie Temperatures ◽  
Single Phase Formation

The polycrystalline samples of Co1+xPbxFe2-2xO4 with x = 0.0,0.1,0.2,0.3,0.4, and 0.5 varying in the steps of 0.1 were prepared by using solid state reaction technique. The structural and magnetic properties have been investigated by means of X-ray diffraction, high field magnetization and a. c. susceptibility measurements. The X-ray analysis confirmed the single-phase formation of the samples. The distributions of divalent, trivalent and tetravalent cations among the tetrahedral (A) and octahedral (B) sites have been obtained from the observed and calculated intensity ratios. The X- ray intensity indicates that tetravalent Pb4+ ions occupy both A and B sites replacing iron ions. The added Co2+ ions also occupy at A sites with replacing iron ions for x = 0.0, 0.1 and 0.2 and there after very small amount of Co2+ migrate from A sites to B sites replacing Fe3+ ions for the composition x = 0.3, 0.4, 0.5. The variation of saturation magnetic moment per formula unit at room temperature with Pb4+ content is satisfactorily explained on the basis of Neel’s collinear spin ordering model for all the samples. The Curie temperatures decreases almost linearly with increase of Pb4+ content from x = 0.0 to 0.5.

scholarly journals X-ray, IR and SEM studies on some Li-Cd ferrites

YMER Digital ◽  
2021 ◽  
Vol 20 (12) ◽  
pp. 333-340
Author(s):  
Sudhir Kulkarni ◽  
Keyword(s):  
Grain Size ◽  
Room Temperature ◽  
Single Phase ◽  
Lattice Parameter ◽  
Lithium Ferrite ◽  
Cadmium Content ◽  
X Ray Diffraction ◽  
Ceramic Method ◽  
X Ray ◽  
Single Phase Formation

Lithium-Cadmium ferrites with general formula Li0.5-x/2 Fe2.5-x/2 Cdx O4 (with x = 0,0.1,0.2....,0.7) were prepared by standard ceramic method. X-ray diffraction studies confirms single phase formation and lattice parameters were calculated. The crystal structure is cubic and lattice parameter increases with increasing Cd content. The infrared absorption (IR) spectra of all the samples were recorded in the range 200-800 cm-1 at room temperature in the KBr medium. Lithium ferrite shows four principal bands and some shoulders have been observed. The force constants Kt and Ko were calculated using Waldron's analysis. Scanning electron microscopy studies shows increase in grain size up to x = 0.1 and then the grain size decreases with increase in cadmium content.

scholarly journals Ferroelectric Properties of Strontium Bismuth Titanate (SrBi4Ti4O15) Synthesized Using Solution Combustion Technique

Nano Hybrids ◽  
2013 ◽  
Vol 3 ◽  
pp. 67-79 ◽  
Author(s):  
Saransh Shrivastava ◽  
Oroosa Subohi ◽  
M.M. Malik
Keyword(s):  
Single Phase ◽  
Bismuth Titanate ◽  
Ferroelectric Properties ◽  
X Ray Diffraction ◽  
Solution Combustion ◽  
X Ray ◽  
Low Dielectric ◽  
Combustion Technique ◽  
Single Phase Formation ◽  
Ferroelectric Transition Temperature

The ferroelectric properties of layer-structured Strontium Bismuth Titanate (SBT) have been investigated in this study. SBT was prepared using solution combustion technique with glycine as a fuel. Single-phase formation of the layer-structured compound of SBT with orthorhombic structure was achieved after calcinations at 800 °C, and was confirmed by x-ray diffraction studies. Scanning electron micrograph shows that the grains exhibit a plate like morphology and possesses ne particle size. The as prepared sample exhibits ferroelectric properties with remnant polarization of 2Pr = 1.84 μC/cm2at coercive field 2Ec= 2.61 kV/cm and displays low dielectric loss. Its ferroelectric transition temperature (Tc) is found to be 450 °C.

Enhancement in Curie Temperature with Magnesium Substituted in Sintered MgxMn1-xFe2O4 Pellets of Nanopowders

2016 ◽  
Vol 43 ◽  
pp. 38-45 ◽  
Author(s):  
Sohrab Manouchehri ◽  
Seyed Taghi Mohammadi Benehi ◽  
Mohammad Hassan Yousefi
Keyword(s):  
Curie Temperature ◽  
Lattice Constant ◽  
Single Phase ◽  
Lattice Models ◽  
Substitution Effect ◽  
Magnesium Content ◽  
X Ray Diffraction ◽  
X Ray ◽  
Increasing Trend ◽  
Single Phase Formation

Ferrites nanopowder of spinel MgxMn1-xFe2O4 (with x=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) synthesized by the coprecipitation method and pellets of nanopowder sintered at temperature 1250 °C. The X-ray diffraction results confirmed the single phase formation of the samples. The lattice constant and interionic distances decreased with increase in magnesium content that can be originated by strengthening of A–B interaction. The substitution effect of nonmagnetic Mg2+ ions was studied on Curie temperature of sintered pellets. Curie temperature measurements exhibit increasing trend with increase in magnesium content. Enhancement in Curie temperature can be explained on the basis of strengthening of A–B interaction and Neel’s two sub-lattice models.

Promotion of phase transformation and single-phase formation in silver-doped Tl–Ba–Ca–Cu–O superconducting thin films

1999 ◽  
Vol 14 (5) ◽  
pp. 1727-1731 ◽  
Author(s):  
Horng-Show Koo ◽  
Tseung-Yuen Tseng
Keyword(s):  
Phase Transformation ◽  
Single Phase ◽  
Superconducting Thin Films ◽  
X Ray Diffraction ◽  
Critical Transition Temperature ◽  
X Ray ◽  
Annealing Temperatures ◽  
Multiple Phase ◽  
Single Phase Formation ◽  
Resultant Film

Phase transformation and physical characteristics of the spray-pyrolyzed Tl–Ba–Ca–Cu–O superconducting films with 3 mol% silver dopant have been studied using electrical resistivity, x-ray diffraction, and scanning electron microscopy. The major phase formed in the resultant film, annealed at a temperature of 885 °C for 3 min, was found to be the nearly single-phase, high-Tc Tl2Ba2Ca2Cu3Oy (Tl-2223). The multiple phase of Tl2Ba2Ca2Cu3Oy and TlBa2Ca2Cu3Oy (Tl-1223) appeared at annealing temperatures lower and higher than 885 °C. It was also observed that Ag dopant effectively reduces normal resistivity at 300 K and enhances the phase transformation of single-Tl-layer Tl-1223 to double-Tl-layer Tl-2223 phases and further helps to form the nearly single-phase Tl-2223 within a short duration. Critical transition temperature (Tc,zero) and current density (Jc, 77 K, 0 Tesla) of the best resultant film were shown to be 123 K and 5.7 × 104 A/cm2, respectively.

EFFECT OF PROCESSING CONDITIONS ON DIELECTRIC PROPERTIES OF CaCu3Ti4O12 CERAMICS

2011 ◽  
Vol 25 (08) ◽  
pp. 1049-1059 ◽  
Author(s):  
RAMAN KASHYAP ◽  
O. P. THAKUR ◽  
N. C. MEHRA ◽  
R. P. TANDON
Keyword(s):  
Dielectric Properties ◽  
Room Temperature ◽  
Single Phase ◽  
Solid State Reaction Method ◽  
Processing Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sintering Time ◽  
Different Temperatures ◽  
Single Phase Formation

Samples of CaCu 3 Ti 4 O 12 (CCTO) ceramics were prepared by solid state reaction method. X-ray diffraction analysis confirmed single phase formation for the powder calcined at 1173 K. Sintering was done at different temperatures viz. 1348 K, 1373 K and 1398 K with a fixed heating rate of 3 K/min. Detailed study of dielectric properties was carried out for the CCTO samples sintered at 1373 K for different duration of holding times (2 h and 10 h). It is found that dielectric properties are sensitive to both sintering time and temperature. With increasing sintering time from 2 h to 10 h dielectric constant increases from ∼2.1 × 104 to ∼2.5 × 104 measured at 1 kHz at room temperature. Impedance spectroscopy has been used for separating out of grain and grain boundary contributions to the overall electrical properties.

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.

Observation of pseudo 10-fold symmetry in the ordered iron-zinc delta phase

1992 ◽  
Vol 50 (1) ◽  
pp. 36-37
Author(s):  
L. A. Giannuzzi ◽  
A. S. Ramani ◽  
P. R. Howell ◽  
H. W. Pickering ◽  
W. R. Bitler
Keyword(s):  
Single Phase ◽  
X Ray Diffraction ◽  
Rich Region ◽  
Average Cell ◽  
X Ray ◽  
Delta Phase ◽  
Cell Dimensions ◽  
Δ Phase ◽  
Morphological Differences ◽  
Concentration Discontinuity

The δ phase is a Zn-rich intermetallic, having a composition range of ∼ 86.5 - 92.0 atomic percent Zn, and is stable up to 665°C. The stoichiometry of the δ phase has been reported as FeZn7 and FeZn10 The deviation in stoichiometry can be attributed to variations in alloy composition used by each investigator. The structure of the δ phase, as determined by powder x-ray diffraction, is hexagonal (P63mc or P63/mmc) with cell dimensions a = 1.28 nm, c = 5.76 nm, and 555±8 atoms per unit cell. Later work suggested that the layer produced by hot-dip galvanizing should be considered as two distinct phases which are characterized by their morphological differences, namely: the iron-rich region with a compact appearance (δk) and the zinc-rich region with a columnar or palisade microstructure (δp). The sub-division of the δ phase was also based on differences in diffusion behavior, and a concentration discontinuity across the δp/δk boundary. However, work utilizing Weisenberg photographs on δ single crystals reported that the variation in lattice parameters with composition was small and hence, structurally, the δk phase and the δp phase were the same and should be thought of as a single phase, δ. Bastin et al. determined the average cell dimensions to be a = 1.28 nm and c = 5.71 nm, and suggested that perhaps some kind of ordering process, which would not be observed by x-ray diffraction, may be responsible for the morphological differences within the δ phase.

scholarly journals Preparation of high-entropy carbides by different sintering techniques

2021 ◽  
Vol 56 (19) ◽  
pp. 11237-11247 ◽  
Author(s):  
Johannes Pötschke ◽  
Manisha Dahal ◽  
Mathias Herrmann ◽  
Anne Vornberger ◽  
Björn Matthey ◽  
...  
Keyword(s):  
Grain Size ◽  
Single Phase ◽  
X Ray Diffraction ◽  
Vacuum Sintering ◽  
X Ray ◽  
High Entropy ◽  
Mean Grain Size ◽  
The Mean ◽  
Gas Pressure Sintering ◽  
Hardness Values

AbstractDense (Hf, Ta, Nb, Ti, V)C- and (Ta, Nb, Ti, V, W)C-based high-entropy carbides (HEC) were produced by three different sintering techniques: gas pressure sintering/sinter–HIP at 1900 °C and 100 bar Ar, vacuum sintering at 2250 °C and 0.001 bar as well as SPS/FAST at 2000 °C and 60 MPa pressure. The relative density varied from 97.9 to 100%, with SPS producing 100% dense samples with both compositions. Grain size measurements showed that the substitution of Hf with W leads to an increase in the mean grain size of 5–10 times the size of the (Hf, Ta, Nb, Ti, V,)C samples. Vacuum-sintered samples showed uniform grain size distribution regardless of composition. EDS mapping revealed the formation of a solid solution with no intermetallic phases or element clustering. X-ray diffraction analysis showed the structure of mostly single-phase cubic high-entropy carbides. Hardness measurements revealed that (Hf, Ta, Nb, Ti, V)C samples possess higher hardness values than (Ta, Nb, Ti, V, W)C samples.

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.

Impedance Spectroscopy Study of LiTaO3 Powder Synthesized via Sol-Gel Method

2012 ◽  
Vol 545 ◽  
pp. 275-278 ◽  
Author(s):  
Lili Widarti Zainuddin ◽  
Norlida Kamarulzaman
Keyword(s):  
Room Temperature ◽  
Single Phase ◽  
Sol Gel ◽  
Rhombohedral Structure ◽  
Spectroscopy Study ◽  
X Ray Diffraction ◽  
Gel Method ◽  
X Ray ◽  
Sol Gel Method ◽  
Impedance Spectroscopy Study

A ceramics sample of LiTaO3 was prepared using a sol-gel method. The sample is annealed at 750 °C for 48 hours. X-ray diffraction analysis indicate the formation of single phase, rhombohedral structure. An ac impedance study was used to analyse the conductivity of LiTaO3 at room temperature and at various temperatures.

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