scholarly journals Effect of processing parameters on microstructural properties of lead magnesium niobates

2017 ◽  
Vol 73 (6) ◽  
pp. 1095-1104 ◽  
Author(s):  
Ashok Bhakar ◽  
Adityanarayan H. Pandey ◽  
M. N. Singh ◽  
Anuj Upadhyay ◽  
A. K. Sinha ◽  
...  
Keyword(s):  
Rietveld Refinement ◽  
Rhombohedral Phase ◽  
Average Crystallite Size ◽  
Cubic Phase ◽  
Gaussian Component ◽  
Processing Temperature ◽  
Microstructural Properties ◽  
Weight Percentage ◽  
Lead Magnesium ◽  
Xrd Patterns

The synchrotron powder X-ray diffraction (XRD) and subsequent detailed Rietveld analysis of lead magnesium niobate (PMN) samples were performed to study the microstructural properties of polar nanoregions (PNRs) of the R3m phase. PMN samples were synthesized under different sample processing conditions. The line profile broadening analysis of room-temperature synchrotron powder XRD patterns was performed using the multi-phase Rietveld refinement method for isotropic microstructural evaluation of different PMN samples. The two phases of perovskite PMN considered in the Rietveld refinement approach for satisfactorily fitting the XRD patterns are the paraelectric cubic phase (Pm\overline 3m) and the local rhombohedral phase (R3m) which corresponds to the PNRs. It is observed that the contributions of the Gaussian component of size broadening of the polar rhombohedral phase (R3m) and the Lorentzian component of strain broadening of the paraelectric cubic phase (Pm\overline 3m) are apposite for satisfactory Rietveld refinement of the synchrotron XRD data for all PMN samples. The volume-average crystallite size of PNRs (R3m phase) is almost invariant (approximately 12 nm) with increasing processing temperature while their weight percentage increases. The values of the apparent microstrain in the paraelectric cubic phase (Pm\overline 3m) are larger for hot-pressed samples.

Morphology and microstructural properties of TiO2 nanopowders doped with trivalent Al and Ga cations

2000 ◽  
Vol 15 (10) ◽  
pp. 2080-2086 ◽  
Author(s):  
L. E. Depero ◽  
A. Marino ◽  
B. Allieri ◽  
E. Bontempi ◽  
L. Sangaletti ◽  
...  
Keyword(s):  
Average Crystallite Size ◽  
Microstructural Properties ◽  
Crystallite Growth ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microstructural Parameters ◽  
Different Temperatures ◽  
Trivalent Cations ◽  
Tio2 Nanopowders ◽  
Xrd Patterns

The effects of doping on the morphological and microstructural properties of TiO2 nanopowders produced by laser pyrolysis were investigated mainly by x-ray diffraction (XRD) and electron microscopy. Samples of TiO2 powders were prepared by doping with different trivalent cations (Al and Ga). The powders were calcined at different temperatures in the range 400–1000 °C for 18 h, as well as at constant T = 700 °C up to 160 h. After each thermal treatment, XRD patterns were collected. The analysis of XRD patterns allowed us to estimate the microstrains and average crystallite size and to observe the evolution of the microstructural parameters with temperature. Both Al and Ga inhibited the crystallite growth of TiO2 anatase and the rutile phases, this effect being larger in the Al-doped powders.

Rietveld refinement and diffuse phases transition of Ba1-XBixTi0.8Fe0.2O3 ceramics at x=0.00, 0.05, 0.10 and 0.15 prepared by solid state method.

2020 ◽  
Author(s):  
Najwa Gouitaa ◽  
LAMCHARFI Taj-dine ◽  
Mfadal BOUAYAD ◽  
ABDI Farid ◽  
Mustapha Haddad
Keyword(s):  
Phase Transitions ◽  
Rietveld Refinement ◽  
Tetragonal Phase ◽  
Structural Parameters ◽  
Hexagonal Phase ◽  
Complex Impedance ◽  
Rhombohedral Phase ◽  
Cubic Phase ◽  
Solid State Method ◽  
X Ray

Abstract The effect of substitution of Baryum by Bismut in site A and titanium by iron in site A on structural, physical and electrical properties of Ba1-xBixTi0.80Fe0.20O3 ceramics at (x=0.00, 0.05, 0.10 and 0.15) was investigated by X-ray diffraction, Scaning Electron Microscopy (SEM) as well as dielectric characterizations. The crystal phase was studied by using rietveld refinement. The result of rietveld refinement of X-ray powders diffraction of Ba1-xBixTi0.80Fe0.20O3 shows that these compounds crystallize in tetragonal (P4mm) and hexagonal (P63mmc) for x=0.00 and 0.05 while at x=0.10 and 0.15 the hexagonal phase disappears and the tetragonal phase is stabilized. The structural parameters and the R-factors of these ceramics were succefully determined by the rietveld refinement. The Raman spectra confirms the disappearance of hexagonal phase in benefit of tetragonal phase as the Bi substitution increases. The dielectric measurements as function of temperature are studied and showed tree diffuse phase transitions transition from the ferroelectric rhombohedral phase to the ferroelectric orthorhombic TR-O phase and the second one is from the ferroelectric orthorhombic phase to the ferroelectric TO-T tetragonal phase. While the third one at high temperatures is the phase transition from the ferroelectric tetragonal phase to the paraelectric cubic phase Tm. These phases transition were displaced to the lower temperature with increasing of Bi substitution. And the value of dielectric permittivity increases gradually with increasing of Bi2+ contents. All these phase transitions showed a diffused phenomenon which can be well described by fitting the modified Ushino relation, 1/ε’r = 1/ε’r,max [ 1+ ((T-Tm)/2δ)γ]. The complex impedance Cole–Cole plots showed negative temperature coefficient of resistivity (NTCR) behavior of the Ba1-xBixTi0.80Fe0.20O3 for x=0.05 to 0.15 materials and decrease in grain and grain boundaries resistivity. The relaxation behavior in the test materials is found to be of Debye type.

scholarly journals Role of Ti3AlC2 MAX phase on characteristics of in-situ synthesized TiAl intermetallics. Part II: Phase evolution

2021 ◽  
Vol 1 (4) ◽  
pp. 211-216
Author(s):  
Maryam Akhlaghi ◽  
Esmaeil Salahi ◽  
Seyed Ali Tayebifard ◽  
Gert Schmidt
Keyword(s):  
Crystallite Size ◽  
Rietveld Refinement ◽  
Phase Evolution ◽  
Xrd Analysis ◽  
Max Phase ◽  
Max Phases ◽  
Weight Percentage ◽  
Refinement Method ◽  
Xrd Patterns

In this research, the 2nd part of a series of papers on the processing and characterization of TiAl–Ti3AlC2 composites, the phase evolution during the manufacturing process was investigated by X-ray diffraction (XRD) analysis and Rietveld refinement method. Metallic Ti and Al powders with different amounts of previously-synthesized Ti3AlC2 additives (10, 15, 20, 25 and 30 wt%) were ball-milled and densified by spark plasma sintering (SPS) under 40 MPa for 7 min at 900 °C. Before the sintering process, XRD test verified that the powder mixtures contained metallic Ti and Al as well as Ti3AlC2 and TiC (lateral phase synthesized with Ti3AlC2) phases. In the sintered composites, the in-situ synthesis of TiAl and Ti3Al intermetallics as well as the presence of Ti3AlC2 and the formation and Ti2AlC MAX phases were disclosed. The weight percentage of each phase in the final composition of the samples and the crystallite size of different phases were calculated by the Rietveld refinement method based on the XRD patterns. The size of Ti3AlC2 crystallites in sintered samples was compared with the crystallite size of synthesized Ti3AlC2 powder.

Structural and morphological characterization of CdS nanoparticles

2020 ◽  
Vol 10 ◽  
Author(s):  
Manish Dwivedi ◽  
Vijay Tripathi ◽  
Dhruv Kumar ◽  
Dwijendra K. Gupta
Keyword(s):  
Blue Shift ◽  
Chemical Precipitation ◽  
Morphological Characterization ◽  
Precipitation Method ◽  
Cds Nanoparticles ◽  
Cubic Phase ◽  
Simple Chemical ◽  
Xrd Patterns ◽  
Average Size ◽  
Physical Tools

Aims: CdS nanoparticles are an attractive material having application in various field like as pigment in paints, biotag for bioimaging and many more optoelectronic as well as biological applications. Present study aims to synthesize and characterize the CdS nanoparticles to make it applicable in different areas Objectives: Preparation CdS nanoparticles by using simple and facile chemical methods and further physical and structural characterization using various physical tools Methods: In present work CdS nanoparticles has been synthesized by using rationally simple chemical precipitation method with some modi-fication on temperature and incubation time in existed methods. Characterizations were done by employing XRD, SEM, TEM, AFM tech-niques Results: Simple chemical method produces the CdS nanoparticles with the size about 100-200 nm in length and 5-10 nm in diameter. The SEM studies show that the CdS nanoparticles can agglomerate and form a continuous network like structure. The X-ray diffraction (XRD) measurements show the single-phase formation of CdS nanoparticles with the structure of cubic phase, and the broadening of XRD patterns indicates that the prepared samples are nanostructured. Our analysis on CdS nanoparticles by using transmission electron microscope and atomic force microscope (AFM) revealed that the nanoparticles form both spherical and nearly rod shaped with the average size applicable for biotagging. UV-Vis spectroscopic analysis reveals blue shift in the absorption peak probably caused by quantum confinement Conclusion: The observed CdS nanoparticles were appeared yellow in color. The XRD pattern of the CdS nanoparticles showed that the materials were of nanometric sized regime with a predominantly cubic phase along with the rod and round morphology. The study and char-acterization of CdS nanoparticles will bring us a new approach to understand biological problem by tagging nanoparticles with biomolecules and further suggests that the CdS nanoparticles formulate it more suitable biocompatible nanomaterial for biotagging and bioimaging

STRUCTURE AND MAGNETIC PROPERTIES OF MECHANICAL ALLOYED Mn-15at.%Al

2013 ◽  
Vol 12 (01) ◽  
pp. 1350006
Author(s):  
AHMED E. HANNORA ◽  
FARIED F. HANNA ◽  
LOTFY K. MAREI
Keyword(s):  
Thermal Analysis ◽  
Room Temperature ◽  
Average Crystallite Size ◽  
Al Alloy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Milled Sample ◽  
Powder Samples ◽  
Xrd Patterns ◽  
Method Analysis

Mechanical alloying (MA) method has been used to produce nanocrystallite Mn -15at.% Al alloy. X-ray diffraction (XRD) patterns for the as-milled elemental α- Mn and aluminum powder samples show a mixture of α + β- MnAl phases after 20 h of milling and changes to a dominant β- MnAl phase structure after 50 h. An average crystallite size of 40 nm was determined from Hall–Williamson method analysis after 5 h of milling. Moreover, the thermal analysis results using differential thermal analysis (DTA), suggested a possible phase transformation after 20 h of milling. Isothermal treatments are carried in the temperature range of 450°C to 1000°C. Room-temperature vibrating sample magnetometer (VSM) measurements of the hysteretic response revealed that the saturation magnetization Bs and coercivity Hc for 10 h ball milled sample are ~ 2.1 emu/g and ~ 92 Oe, respectively.

scholarly journals FTIR and Optical Properties of NiO Doped Cr2O3 Nanopar-ticles Synthesis by Hydrothermal Method

2018 ◽  
Vol 29 (1) ◽  
pp. 168
Author(s):  
Tunis Balassim Hassan
Keyword(s):  
Optical Band Gap ◽  
Average Crystallite Size ◽  
Structural Behavior ◽  
X Ray Diffraction ◽  
Nanopar Ticles ◽  
Hydrothermal Technique ◽  
X Ray ◽  
Cr2o3 Nanoparticles ◽  
Xrd Patterns ◽  
Scanning Electron

Pure and Nickel oxide doped chromium (III) oxide (Cr2O3) nanoparticals are synthesized by hydrothermal technique. The effect of dopant Ni concentration on the structural behavior of Cr2O3 nanoparticles was examined by X-ray diffraction. The average crystallite size of the synthesized nanoparticles was measured from XRD patterns using Scherrer equation and was decreased from 22nm to 12.9 nm with the increasing Nio concentration in Cr2O3 from (0, 0.01, 0.06, and 0.10). Morphologies and compositional elements of the synthesized nanoparticles were observed by the field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) spectroscopy, respectively. The optical property of the samples was measured by ultraviolet - visible (UV-Vis.) absorption spectroscopy. The observed optical band gap value ranges from 2.3eV to 2.5eV for Ni doped nanoparticles

Synthesis and Characterization of Cadmium with Titanium Oxide (Cd-TiO2) Nanocomposite: Testing its Antibacterial Effect

2021 ◽  
Vol 12 (4) ◽  
pp. 2523-2529
Author(s):  
Daniel Sam N ◽  
Anish C I ◽  
Sabeena G ◽  
Rajaduraipandian S ◽  
Manobala ◽  
...  
Keyword(s):  
Sol Gel ◽  
Gram Negative Bacteria ◽  
X Ray Diffraction ◽  
Sem Images ◽  
Gram Negative ◽  
X Ray ◽  
Weight Percentage ◽  
Inhibition Concentration ◽  
Xrd Patterns

Sol gel methods were used for the study of the antimicrobial activity of Cd-TiO2 against gram-negative and positive bacteria. These Cd-TiO2 have been characterized by various optical and techniques. They have been exhibited by X-ray diffraction, scanning electron microscopy, ultraviolet spectroscopy, and infrared spectroscopy. The structures of the various XRD patterns indicate that the product has a structure. The particle size of Cd-TiO2 is 35nm. The SEM images confirm the spherical appearance of the sample. The energy X-ray spectra have been confirmed as well and then C, O, Ti, Cd, Pt element are present in Cd-TiO2. The weight percentage of Cadmium is 5.8%, Ti is 51.03%, C is 5.13% and O is 31.75% in Cd-TiO2. BET image shows that the major pore size distribution of Cd-TiO2 is ranged from 2.24 nm. The Cd-TiO2 that the antibacterial activity when tested against the pathogens only gram-negative bacteria such as Pseudomonas. The zone of minimum inhibition concentration was measured in a range of 20mm in 25μl and 30mm in 100μl.

Corroboration of Structural Properties of Dy2O3-TiO2 Nanocomposites through X-Ray Diffraction and Raman Spectroscopy

2017 ◽  
Vol 17 ◽  
pp. 127-130
Author(s):  
J. Dhanalakshmi ◽  
D. Pathinettam Padiyan
Keyword(s):  
Raman Spectroscopy ◽  
Crystallite Size ◽  
Structural Properties ◽  
Oxygen Vacancies ◽  
Raman Band ◽  
Anatase Phase ◽  
Average Crystallite Size ◽  
X Ray Diffraction ◽  
X Ray ◽  
Weight Percentage

Dy2O3-TiO2 nanocomposites with different weight percentage (0, 2, 4, 8 & 10)Dy were synthesized bysol-gel method and named as 0DT, 2DT, 4DT, 6DT, 8DT and 10DT. The structural properties of these nanocomposites are characterized by X-ray diffraction (XRD) and Raman spectroscopy. XRD results show that Dy2O3-TiO2 nanocomposites have anatase phase with tetragonal structure. The average crystallite size of the Dy2O3-TiO2 nanocomposites lies between 10 to 18 nm.Coupling of Dy with TiO2 shifts the Raman band to higher wavenumber side indicating the creation of oxygen vacancies in the TiO2 lattice.

New insight into structural transformation in Li-rich layered oxide during the initial charging

2015 ◽  
Vol 3 (23) ◽  
pp. 12220-12229 ◽  
Author(s):  
Chong-Heng Shen ◽  
Shou-Yu Shen ◽  
Fang Fu ◽  
Chen-Guang Shi ◽  
Hui-Yi Zhang ◽  
...  
Keyword(s):  
Structural Transformation ◽  
Rhombohedral Phase ◽  
Cubic Phase ◽  
Charged State ◽  
Layered Oxide ◽  
Lattice Fringe ◽  
Insight Into

In Li1.2Ni0.12Co0.15Mn0.53O2 oxide, four lines of lattice fringe from O3 rhombohedral phase are squeezed into two lines from spinel cubic phase at 4.70 V charged state under the effect of microstress.

Electron-probe micro-analysis of the iron–titanium oxides in some New Zealand ironsands

1965 ◽  
Vol 35 (272) ◽  
pp. 604-621 ◽  
Author(s):  
J. B. Wright ◽  
J. F. Lovering
Keyword(s):  
Electron Probe ◽  
Bulk Composition ◽  
Rhombohedral Phase ◽  
Cubic Phase ◽  
Titanium Oxides ◽  
Titaniferous Magnetite ◽  
Compositional Changes ◽  
Compositional Variations ◽  
Micro Analysis ◽  
Synthetic Work

SummaryThe electron probe was used to analyse for Fe, Ti, Mg, Al, and Mn. Vanadium could not be determined because of interference from Ti. Calcium was shown to be present only in inclusions of apatite and silicate; it does not oceur in the titanomagnetite structure.Homogeneous grains (magnetite-ulvöspinel solid solutions) do not vary greatly in bulk composition, averaging close to 61% Fe and 8 % TiO2. Inhomogeneous grains contain variable amounts of hematite-ilmenite lamellae produced by progressive oxidation of the homogeneous grains. In the early stages there is rapid build-up of titanium in the rhombohedral lamellae, which are initially relatively poor in iron. As oxidation proceeds the almost titanium-free cubic phase becomes strongly enriched in magnesium, aluminium, and manganese, while the iron: titanium ratio in the rhombohedral phase increases. The end-product may be a homogeneous titanhematite, if initial concentrations of Mg, Al, and Mn are low. Otherwise residuals of a relatively iron-poor almost titanium-free (Mg, Al, Mn)-enriched cubic phase remain in the titanhematite. The behaviour of iron and titanium agrees with recent synthetic work in the system. Some of the oxidized grains contain transparent spinel lamellae exsolved from the cubic phase. Exsolution may commence at different stages in the oxidation process, but the reason is not clear—there are no significant differences in the composition of phases with and without spinel lamellae.Analyses and normative compositions are presented for the different phases in each grain, where possible. The compositional changes accompanying oxidation satisfactorily explain the slope of the thermomagnetic curves : there is no need to invoke bulk compositional variations within a given ironsand sample.Samples from an ilmenite and a non-titaniferous magnetite concentrate were also briefly examined.

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