scholarly journals Crystallographic and optical studies on Cr doped ZnS nanocrystals

Cerâmica ◽  
2014 ◽  
Vol 60 (355) ◽  
pp. 425-428 ◽  
Author(s):  
M. R. Bodke ◽  
Y. Purushotham ◽  
B. N. Dole
Keyword(s):  
Grain Size ◽  
Fourier Transforms ◽  
Chemical Species ◽  
Lattice Parameter ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
Cubic Form ◽  
Zns Nanocrystals ◽  
Cr Concentration ◽  
Co Precipitation

Chromium doped ZnS nanocrystals with pure and 10% compositions were synthesized by chemical co-precipitation route. Samples were characterized by X-ray diffraction (XRD) technique, Fourier transforms infrared spectroscopy (FTIR) and UV-Visible spectrometer. Lattice parameter 'a' decreases and grain size increases with increasing Cr concentration. XRD study shows that both the samples have cubic structure. Grain size increases due to ionic radius. The functional groups and chemical species of Cr doped ZnO samples were determined using FTIR data. UV-Vis study revealed that red shift is clearly observed in absorption band. Surface morphology of pure and 10% Cr doped samples was investigated by SEM technique and it is confirmed that images exibit cubic form of the samples. Using EDS, percentage of chemical compositions of material recorded.

scholarly journals Structural and Magnetic Property of Cr3+ Substituted Cobalt Ferrite Nanomaterials Prepared by the Sol-Gel Method

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2095 ◽  
Author(s):  
Jinpei Lin ◽  
Jiaqi Zhang ◽  
Hao Sun ◽  
Qing Lin ◽  
Zeping Guo ◽  
...  
Keyword(s):  
Saturation Magnetization ◽  
Sol Gel ◽  
Combustion Method ◽  
Lattice Parameter ◽  
Cubic Phase ◽  
Cobalt Chromium ◽  
X Ray Diffraction ◽  
Chromium Doping ◽  
Auto Combustion ◽  
Cr Concentration

Cobalt-chromium ferrite, CoCrxFe2−xO4 (x = 0–1.2), has been synthesized by the sol-gel auto-combustion method. X-ray diffraction (XRD) indicates that samples calcined at 800 °C for 3 h were a single-cubic phase. The lattice parameter decreased with increasing Cr concentration. Scanning electron microscopy (SEM) confirmed that the sample powders were nanoparticles. It was confirmed from the room temperature Mössbauer spectra that transition from the ferrimagnetic state to the superparamagnetic state occurred with the doping of chromium. Both the saturation magnetization and the coercivity decreased with the chromium doping. With a higher annealing temperature, the saturation magnetization increased and the coercivity increased initially and then decreased for CoCr0.2Fe1.8O4.

scholarly journals Dielectric and electrical properties of Cr substituted Mg ferrites

2015 ◽  
Vol 39 (1) ◽  
pp. 1-12 ◽  
Author(s):  
AKM Zakaria ◽  
Faizun Nesa ◽  
MA Saeed Khan ◽  
SM Yunus ◽  
NI Khan ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
Loss Tangent ◽  
Dielectric Loss Tangent ◽  
Lattice Parameter ◽  
Activation Energies ◽  
X Ray Diffraction ◽  
Constant E ◽  
Cr Concentration ◽  
Academy Of Sciences

The spinel ferrites MgCrxFe2-xO4 (0.0 ? × ?1.0) were prepared through the solid state reaction using conventional ceramic method at 1300°C in air. The homogeneous phase of the ferrite samples was observed from the X-ray diffraction study. Lattice parameter of the samples was found to decrease with increasing Cr concentration in the system obeying Vegard’s law. The ac electrical resistivity, measured as a function of temperature, decreases with the increase of temperature indicating the semiconducting nature of all the samples. The activation energies were calculated and found to decrease with increasing Cr content. The lower activation energies are associated with higher electrical conductivity. With the increase of temperature, dielectric constant (e`) and dielectric loss tangent are observed to be increased; while with the increase of frequency, dielectric constant (e`) and dielectric loss tangent decrease for all the samples.Journal of Bangladesh Academy of Sciences, Vol. 39, No. 1, 1-12, 2015

Consolidation and properties of Gd0.1Ce0.9O1.95 nanoparticles for solid-oxide fuel cell electrolytes

2006 ◽  
Vol 21 (1) ◽  
pp. 119-124 ◽  
Author(s):  
A.I.Y. Tok ◽  
L.H. Luo ◽  
F.Y.C. Boey ◽  
J.L. Woodhead
Keyword(s):  
Grain Size ◽  
Ionic Conductivity ◽  
Sintering Temperature ◽  
Spherical Shape ◽  
Impedance Analysis ◽  
Lattice Parameter ◽  
Narrow Particle Size Distribution ◽  
Precipitation Process ◽  
Boundary Area ◽  
Co Precipitation

Gd-doped ceria solid solutions have been recognized to be leading electrolytes for use in intermediate-temperature fuel cells. In this paper, the preparation, solubility, and densification of Gd0.1Ce0.9O1.95 ceramics derived from carbonate co-precipitation are reported. The dissolution of Gd2O3 in CeO2 lattice was identified to be completed during the co-precipitation process by studying the lattice parameter as a function of temperature. After calcination at 800 °C for 2 h, the nano-sized Gd0.1Ce0.9O1.95 powder (∼33 nm) with a nearly spherical shape and a narrow particle-size distribution was obtained. This calcined powder has high sinterability and maximum densification rate at ∼1000 °C. Sintering at 1300 °C for 4 h yielded over 97% relative density with near maximum. The grain size increased with increases in sintering temperature. The ionic conductivity of these pellets was tested by alternating current impedance spectroscopy to elucidate the contribution of intragranular and intergranular conductivity to the total ionic conductivity. It was found that sintering temperature does not affect intragranular conductivity, though intergranular conductivity was strongly influenced by grain size, grain boundary area, and relativity density. This pellet sintered at 1500 °C for 4 h showed a high ionic conductivity of 5.90 × 10−2 s/cm when measured at 750 °C. The characterization and structural evaluation of the as-received powders were carried out using x-ray diffraction, transmission electron microscopy, Brunauer–Emmett–Teller, and dilatometer and impedance analysis.

On the Structure and Some Properties of LaCo Co-substituted NiZn Ferrites Prepared Using the Standard Ceramic Technique

2016 ◽  
Vol 35 (4) ◽  
pp. 417-423 ◽  
Author(s):  
Xiaofei Niu ◽  
Xiansong Liu ◽  
Xin Huang ◽  
Kai Huang ◽  
Yuqi Ma ◽  
...  
Keyword(s):  
Grain Size ◽  
Power Loss ◽  
Low Frequency ◽  
Secondary Phase ◽  
Lattice Parameter ◽  
Initial Permeability ◽  
High Resistivity ◽  
X Ray Diffraction ◽  
Ferrite Sample ◽  
Higher Power

AbstractZn0.5Ni0.5-xCoxFe2-yLayO4 ferrites (with x=0, 0.02 and y=0, 0.02) were prepared by an industrial method using the standard ceramic technique and sintered at 1,250°C in air. X-ray diffraction (XRD) was used to obtain the phase formation of the NiZn ferrites. The microstructure of ferrites was investigated by scanning electron microscopy (SEM). The XRD reveals that lattice parameter (a) is decreased and a secondary phase (LaFeO3) is formed in the La–Co co-substituted NiZn ferrite sample, meanwhile, the grain size (D) of this sample decreased obviously by observing SEM photographs. Vibrating sample magnetometry (VSM), B-H analyzer, impedance analyzer and electrometer were carried out in order to characterize some properties of the ferrites. This investigation indicates that, La–Co co-substituted NiZn ferrite sample has higher power loss (Pcv) than other samples at low frequency with an increase in coercive field (Hc) and magnetocrystalline anisotropy (K1), a decrease in initial permeability (μi) and saturation magnetization (Ms). However, at high frequency, the power loss of La–Co co-substituted sample is low, which is attributed to high resistivity (ρ), small grain size (D), less number of Fe2+ ions and low porosity (P).

The Mixed Magnetic Property of Co0.76Cu0.74[Fe(CN)6]·7.5H2O

2018 ◽  
Vol 71 (11) ◽  
pp. 914
Author(s):  
Yanfang Xia ◽  
Min Liu ◽  
Duxin Li
Keyword(s):  
Magnetic Field ◽  
Magnetic Moment ◽  
Effective Magnetic Moment ◽  
Lattice Parameter ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Patterns ◽  
Co Precipitation ◽  
The Magnetic Field

Co0.76Cu0.74[Fe(CN)6]·7.5H2O was prepared as a powder by a chemical co-precipitation method. The powder X-ray diffraction patterns were indexed to the typical face-centred cubic structure with the lattice parameter a 10.55(2) Å. The temperature dependence of the χ−1 curve obeys the Curie–Weiss law (χ = C/(T – θ)) in the temperature range of 180–300 K. According to Curie–Weiss law, the calculated θ value is −54.82 K. In the paramagnetic state at 300 K, the effective magnetic moment (μeff = (8χT)1/2) is 3.58 μB per formula unit. The calculated theoretical effective magnetic moment is 4.06 μB. The magnetic field cooling measurements under a 200 Oe applied magnetic field show that the saturation magnetization value at 2 K of the complex Co0.76Cu0.74[Fe(CN)6]·7.5H2O is 1.528 emu g−1.

Structural, Mechanical and Magnetic Properties of Mechanically Alloyed Fe40Co60 Powders

2011 ◽  
Vol 312-315 ◽  
pp. 743-747 ◽  
Author(s):  
Fadhela Otmane ◽  
S. Bergheul ◽  
M. Zergoug ◽  
M. Azzaz
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Magnetic Measurements ◽  
Lattice Parameter ◽  
Internal Strain ◽  
Morphological Aspect ◽  
Micro Hardness ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
X Ray

In this work we report on the structural, mechanical and magnetic properties of mechanically alloyed Fe40Co60 powders. Alloying formation, grain size, lattice parameter and internal strain were investigated using X-Ray Diffraction (XRD) measurements. The morphological aspect of the nanostructured powders was analysed by means of the Scanning Electron Microscopy (SEM). Compacted pastilles with circular shape have been under Vickers test of micro Hardness and magnetic measurements of Hysterisis loops. Discussed results according to milling time show that after 60 h milling the grain refinement is about 15.59 nm with internal strain of around 0.5809 %. The micro hardness increases with the decrease of the grain size and the hysterisis loop at 60 h milling is enhanced in term of decreased coercivity.

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.

MAGNETIC PROPERTIES AND STRUCTURE OF NANO-SIZE NiZn FERRITE SYNTHESIZED BY THE REFLUXING CO-PRECIPITATION METHOD

2009 ◽  
Vol 23 (04) ◽  
pp. 633-642 ◽  
Author(s):  
YI ZHANG ◽  
QIGANG JIAO ◽  
YA ZHAI ◽  
XIAOJUN BAI ◽  
JUN DU ◽  
...  
Keyword(s):  
Room Temperature ◽  
Hyperfine Magnetic Field ◽  
Lattice Parameter ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Tetrahedral Sites ◽  
Zn Concentration ◽  
Zn Content ◽  
Co Precipitation ◽  
Nano Size

A series of nanoparticle powders of Ni 1-x Zn x Fe 2 O 4 (x = 0, 0.3, 0.4, 0.5, 0.6 and 0.7) ferrites were synthesized by the refluxing method at relatively low temperatures. X-ray diffraction measurements were performed to yield the grain size of the particles as a function of the amount x of Zn substitution and the lattice parameter was found to increase with increasing x. Mössbauer spectroscopy was performed at room temperature. The spectra exhibit ferromagnetic hyperfine splitting sextet peaks with a doublet peak overlapped at its center as Zn contents x < 0.6. The fitted hyperfine magnetic field of the octahedral sublattice and tetrahedral sublattice all decrease with increasing Zn content. The area of the tetrahedral sublattice decreases with increasing x and that of the octahedral sites increases for low Zn concentration, as a result of substitution of iron by zinc in the tetrahedral sites. The area of the doublet increases constantly. Systematic magnetization measurements gave evidence that the doublet in the spectra originated from the superparamagnetism of the particles at room temperature as Zn content x < 0.6.

XRD and Photoluminescence Studies of Pure and In2O3 Doped ZnO Nanophases

2005 ◽  
Vol 480-481 ◽  
pp. 393-398 ◽  
Author(s):  
N. Boulares ◽  
K. Guergouri ◽  
Nouar Tabet ◽  
A. Lusson ◽  
F. Sibieude ◽  
...  
Keyword(s):  
Grain Size ◽  
Spinel Phase ◽  
Lattice Parameter ◽  
Solar Furnace ◽  
X Ray Diffraction ◽  
Drastic Reduction ◽  
Grain Sizes ◽  
Oxide Powders ◽  
Excitonic Emission ◽  
Photoluminescence Studies

ZnO oxide is a promising material for optoelectronics because of its wide and direct gap (Eg=3.4 eV). Pure and doped zinc oxide powders of various grain sizes have been synthesized by vaporisation-condensation method using a solar furnace. The initial powders contained from 0 to 5 In2O3 mol % . X-ray diffraction technique (XRD) has been used to measure the lattice parameter and the grain size as a function of the composition, the results show the appearance of the spinel phase Zn5In2O8 in the micopowders and the decrease of the grain size of nanopowders as the In concentration increases for all considered compositions. The photoluminescence spectra revealed the presence of two main transitions at 3.31 and 3.36 eV, a shift of the excitonic peaks towards the lower energies, a drastic reduction of the exciton bound to donor emission from the doped material and a large broadening of the excitonic emission in In doped nanopowder.

A Comparison of X-Ray and Neutron Diffraction Measurement of Lattice Parameters for the Determination of Residual Stress and Chemical Composition in Zirconium Alloy Tubes

1991 ◽  
Vol 35 (A) ◽  
pp. 475-480
Author(s):  
M. Griffiths ◽  
J.E. Winegar ◽  
J.F. Mecke ◽  
T.M. Holden ◽  
R.A. Holt
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Zirconium Alloys ◽  
Lattice Parameter ◽  
Lattice Parameters ◽  
Surface Relaxation ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
X Ray

AbstractIntergranular residual stresses can exist in zirconium alloys, especially when there is a large distribution of grain orientations. The stresses result from the anisotropic plasticity and thermal expansion of the hexagonal close-packed crystal structure of α-zirconium. Apart from complicating the characterisation of materials using lattice parameter measurements, the intergranular stresses can significantly affect material behaviour, especially in nuclear reactor environments, and there is therefore a great deal of interest in their measurement.The effects of specimen preparation and surface relaxation on X-ray diffraction measurements of lattice parameters of zirconium alloys have been investigated by comparing bulk neutron diffraction with X-ray diffraction on identical materials. The results show that: (i) intergranular or interphase residual stresses exist in dual-phase Zr-2.5Nb pressure tubes; (ii) the stresses normal to the surface of an X-ray diffraction specimen are not relieved completely when there are intergranular residual stresses in the material. One can conclude that intergranular stresses have to be considered when determining chemical compositions from lattice parameter measurements and also when measuring macroscopic residual stress using X-ray diffraction.

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