Rietveld Refinement of Sintered Magnesium Substituted Calcium Apatite

2008 ◽  
Vol 396-398 ◽  
pp. 277-280 ◽  
Author(s):  
Marcia S. Sader ◽  
Elizabeth L. Moreira ◽  
Valéria C.A. Moraes ◽  
Jorge C. Araújo ◽  
Racquel Z. LeGeros ◽  
...  
Keyword(s):  
Rietveld Refinement ◽  
Tricalcium Phosphate ◽  
Rietveld Method ◽  
Lattice Parameter ◽  
Commercial Product ◽  
Precipitation Method ◽  
Osteoporosis Therapy ◽  
Biomineralization Process ◽  
Apatite Lattice

The incorporation of magnesium in the synthetic apatite has been associated with biomineralization process and osteoporosis therapy in human and animals. Magnesium easily replaces calcium in the apatite lattice and influences or controls the hydroxyapatite crystallization processes. In this work, Mg-substituted calcium deficient apatite, with Mg/Ca ratio = 0.1, 0.15 and 0.2 were synthesized by precipitation method. Then, sintered at 1000 oC and compared with a commercial product labeled as tricalcium phosphate sintered at the 1000 oC. The sintered products showed tricalcium phosphate (β-TCP) structure. The Mg2+ substitution in the Ca(4) and Ca(5) sites of β-TCP and the lattice parameter changes were estimated using the Rietveld method. Using this method, the formulas Ca2.73(Mg0.27)(PO4)2, Ca2.71(Mg0.29)(PO4)2 and Ca2.70(Mg0.23Mg0.07)(PO4)2 were calculated for the samples with Mg/Ca ratio = 0.1, 0.15 and 0.2 respectively.

scholarly journals Structural Properties Analysis of Mg-β-TCP by X-ray Powder Diffraction with the Rietveld Refinement

2020 ◽  
Vol 9 (4) ◽  
pp. 1562-1568
Keyword(s):  
Powder Diffraction ◽  
Rietveld Method ◽  
Quantitative Phase Analysis ◽  
Structural Refinement ◽  
Osteoporosis Therapy ◽  
X Ray ◽  
Cell Parameters ◽  
Biomineralization Process ◽  
Resultant Powder ◽  
Rapid Reaction

The incorporation of magnesium in the synthetic apatite has been associated with the biomineralization process and osteoporosis therapy in humans and animals. β-tricalcium phosphate (β-TCP) is one of the most common bioceramics widely applied in bone cement and implants. In this work, Ca-deficient apatite (CDA) with a theoretical 0.08 Mg/(Ca+Mg) ratio was synthesized by the rapid reaction between Ca(OH)2, MgCl2.6H2O and H3PO4 at 40°C and the resultant powder calcined at 650 °C for 10h. X-ray powder diffraction analysis (XRD), in combination with the Rietveld method (Fullprof-suite), was employed for quantitative phase analysis and structural refinement. The results of XRD indicate that magnesium can substitute for calcium into a β-TCP structure inducing a reduction of the cell parameters and the compound crystallizes in the rhombohedral R3c structure, with the following unit cell constants: a = b = 10.3560 Å, c = 37.1718 Å, and cell volume V = 3452.44. The analysis indicated that the substitution of Mg2+ on the M(4) and M(5) sites were, approximately, 2.61 and 6.97 mol%, corresponding to the Ca2.72(MgIV0.07, MgV0.21)(PO4)2 stoichiometric formula and 0.09 Mg/(Ca+Mg) ratio.

Rietveld refinement of ternary compound Gd117Fe52Ge112

2007 ◽  
Vol 22 (4) ◽  
pp. 312-315 ◽  
Author(s):  
Wei He ◽  
Jiliang Zhang ◽  
Lingmin Zeng
Keyword(s):  
Rietveld Refinement ◽  
Ternary Compound ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Figure Of Merit ◽  
Rietveld Method ◽  
Lattice Parameter ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
X Ray

A new ternary compound Gd117Fe52Ge112 has been successfully synthesized and studied by means of X-ray powder diffraction technique. Gd117Fe52Ge112 crystallizes in a cubic Tb117Fe52Ge112-type structure with space group Fm3m(#225) and lattice parameter a=28.7680(1) Å. Crystal structure of Gd117Fe52Ge112 has been successfully refined using the Rietveld method from X-ray diffraction data. The R-factors for the Rietveld refinement are Rp=0.099 and Rwp=0.128. X-ray powder diffraction data with the figure of merit F30 of 80.4(30) are also reported.

Synthesis of Si-Substituted β-Tricalcium Phosphate Ceramics with Controlled Composition

2008 ◽  
Vol 396-398 ◽  
pp. 165-168 ◽  
Author(s):  
M.Kamal Mekki-Berrada ◽  
Chantal Damia ◽  
Eric Champion
Keyword(s):  
Rietveld Refinement ◽  
Tricalcium Phosphate ◽  
Single Phase ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Maturation Time ◽  
X Ray ◽  
Lattice Volume ◽  
Wet Precipitation ◽  
Si Content

Pure b-tricalcium phosphate (bTCP) and Si-substituted b-tricalcium phosphate powders with compositions ranging from x = 0.01 to 0.20 were synthesized using a wet precipitation method. The results showed that the addition of Si decreased the maturation time of single-phase Si-substituted bTCP. For longer maturation time, other phases were observed such as hydroxyapatite (HA) and a-tricalcium phosphate (aTCP). The Si incorporation was confirmed by X-ray diffraction with Rietveld refinement, indicating an increase of the lattice volume from 3524.88 Å3 for pure bTCP to 3527.41 Å3 with increasing Si content.

Quantitative powder diffraction phase analysis with a combination of the Rietveld method and the addition method

2002 ◽  
Vol 17 (4) ◽  
pp. 287-289 ◽  
Author(s):  
T. Balić-Žunić
Keyword(s):  
Rietveld Refinement ◽  
Phase Analysis ◽  
Amorphous Phase ◽  
Powder Diffraction ◽  
Rietveld Method ◽  
Original Sample ◽  
Addition Method ◽  
Original Mixture ◽  
The Absolute ◽  
New Variables

The Rietveld method can be combined with the addition method to determine the absolute quantities of the phases treated by Rietveld refinement plus the quantity of phase(s) not treated by it (amorphous or unobserved). If q is the added proportion of a defined phase already present in the sample, and a1 and a2 its relative proportions as determined by Rietveld refinement prior and after the addition, the proportion of the amorphous (untreated) phase(s) in the original sample is calculated as xo=[a2−(1−q)a1−q]/(1−q)(a2−a1). The absolute quantities of the phases treated by Rietveld refinement are then determined by a correction for the content of the amorphous phase(s), or they can be calculated directly from specific equations. The advantage of the method is that no new variables are introduced in the refinement when the added standard already is a part of the original mixture.

Rietveld refinement of the solid-solution series: (Cu,Mg)SO4·H2O

1995 ◽  
Vol 10 (3) ◽  
pp. 189-194 ◽  
Author(s):  
C. L. Lengauer ◽  
G. Giester
Keyword(s):  
Solid Solution ◽  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Rietveld Method ◽  
Structure Refinement ◽  
Solid Solution Series ◽  
Cation Site ◽  
Tg Analysis ◽  
X Ray ◽  
Solution Series

The kieserite-type solid-solution series of synthetic (Cu,Mg)SO4·H2O was investigated by TG-analysis and X-ray powder diffraction using the Rietveld method. Representatives with Cu≥20 mol% are triclinic distorted () analogous to the poitevinite (Cu,Fe)SO4·H2O compounds. Cation site ordering with preference of Cu for the more distorted M1 site was additionally proven by the structure refinement.

Rietveld Refinement of the BaTiO3 from X-Ray Powder Diffraction

2009 ◽  
Vol 79-82 ◽  
pp. 593-596
Author(s):  
Feng Sun ◽  
Yan Sheng Yin
Keyword(s):  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Rietveld Method ◽  
Structural Parameters ◽  
Ferroelectric Ceramic ◽  
Powder Diffraction Data ◽  
Ceramic Powders ◽  
Space Group ◽  
X Ray

The ferroelectric ceramic BaTiO3 was synthesized at 1000 °C for 5 h. The structure of the system under study was refined on the basis of X-ray powder diffraction data using the Rietveld method. The system crystallizes in the space group P4mm（99）. The refinement of instrumental and structural parameters led to reliable values for the Rp, Rwp and Rexp.We use the TOPAS software of Bruker AXS to refine this ceramic powders and show its conformation

scholarly journals Crystallographic, Energy Gap, Photoluminescence and Photo-Catalytic Investigation of Cu Doped Cd0.9Zn0.1S Nanostructures by Co-Precipitation Method

2021 ◽  
Author(s):  
P. Raju ◽  
Joseph Prince Jesuraj ◽  
S. Muthukumaran
Keyword(s):  
Crystallite Size ◽  
Energy Gap ◽  
Wavelength Region ◽  
Lattice Parameter ◽  
Precipitation Method ◽  
Optical Absorbance ◽  
Stability Measurement ◽  
Cubic Structure ◽  
The Stability ◽  
Co Precipitation

Abstract The controlled synthesis of Cd0.9Zn0.1S, Cd0.89Zn0.1Cu0.01S and Cd0.87Zn0.1Cu0.03S nanostructures by simple chemical co-precipitation technique was reported. The XRD investigation confirmed the basic CdS cubic structure on Zn-doped CdS and also Zn, Cu dual doped CdS with no secondary/impurity related phases. No modification in cubic structure was detected during the addition of Zn/Cu into CdS. The reduction of crystallite size from 63 Å to 40 Å and the changes in lattice parameter confirmed the incorporation of Cu into Cd0.9Zn0.1S and generation of Cu related defects. The shift of absorption edge along upper wavelength region and elevated absorption intensity by Cu doping can be accredited to the collective consequence of quantization and the generation of defect associated states. The enhanced optical absorbance and the reduced energy gap recommended that Cd0.87Zn0.1Cu0.03S nanostructure is useful to enhance the efficiency of opto-electronic devices. The presence of Cd-S / Zn-Cd-S /Zn/Cu-Cd-S chemical bonding were confirmed by Fourier transform infrared investigation. The elevated green emissions by Cu incorporation was explained by decrease of crystallite size and creation of more defects. Zn, Cu dual doped CdS nanostructures are recognized as the possible and also efficient photo-catalyst for the removal dyes like methylene blue. The enhanced photo-catalytic behaviour of Zn, Cu dual doped CdS is the collective consequences of high density electron-hole pairs creation, enhanced absorbance in the visible wavelength, surface area enhancement, reduced energy gap and the formation of novel defect associated states. The stability measurement signified that Cu doped Cd0.9Zn0.1S exhibits superior dye removal ability and better stability even after 6 repetitive runs with limited photo-corrosion.

scholarly journals Synthesis of Tricalcium Phosphate From Eggshells with Precipitation Method

2020 ◽  
Vol 1569 ◽  
pp. 042057
Author(s):  
S Sani ◽  
S Muljani ◽  
D Astuti ◽  
R Mardayana ◽  
V D Alfiyani
Keyword(s):  
Tricalcium Phosphate ◽  
Precipitation Method

EFFECT OF SURFACTANTS ON THE SIZE, COLOR, PHOTOLUMINESCENCE AND RESISTIVITY OF INDIUM TIN OXIDE NANOPARTICLES PREPARED BY CO-PRECIPITATION METHOD

2012 ◽  
Vol 19 (05) ◽  
pp. 1250054 ◽  
Author(s):  
AYYOOB JAFARI ◽  
YADOLAH GANJKHANLOU ◽  
MAHMOOD KAZEMZAD ◽  
HAMZEH GHORBANI
Keyword(s):  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Lattice Parameter ◽  
Precipitation Method ◽  
Tin Oxide Nanoparticles ◽  
Xrd Patterns ◽  
Ito Nanoparticles ◽  
Xrd Techniques ◽  
Co Precipitation ◽  
Triton X

Indium tin oxide (ITO) nanoparticles were synthesized by co-precipitation method using ammonia as a precipitator in absence/presence of various surfactants (LABS and Triton X-100). The synthesized nanoparticles were investigated by scanning electron microscopy, resistance measurement, photoluminescence (PL) spectroscopy and X-ray diffractometry (XRD) techniques. The XRD patterns of nanoparticles were also studied by Rietveld refinement method for calculation of crystallite size, micro-strain and lattice parameter. The results indicate that by application of LABS and Triton X-100 as surfactant the particle size was increased. Two luminescence bands were observed in PL spectra of ITO nanoparticles with the excitation energy lower than their band gaps. It was found that the ratios of luminescence bands have relation with resistances and colors of ITO nanoparticles. In addition, the band structure of ITO nanoparticles was described considering the obtained results.

XRD characterization of highly dispersed metal catalysts on carbon support

1993 ◽  
Vol 8 (8) ◽  
pp. 1829-1835 ◽  
Author(s):  
Paolo Scardi ◽  
Pier Luigi Antonucci
Keyword(s):  
Particle Size ◽  
Supported Catalysts ◽  
Profile Analysis ◽  
Rietveld Method ◽  
Carbon Support ◽  
Lattice Parameter ◽  
Microstructural Parameters ◽  
Transmission Electron ◽  
Supported Pt Catalysts ◽  
Highly Dispersed

Carbon-supported Pt catalysts were prepared from H2PtCl6 or K2PtCl6 aqueous solutions. Particle size and structure after several thermal activation treatments were studied by X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and Cyclic Voltammetry (CV), and the results of the three techniques were compared. As the catalysts were highly dispersed on an amorphous support, a conventional XRD profile analysis for crystallite size determination could not be performed properly, because of the strong overlapping between the broad Pt peaks superposed to the halos of the amorphous phase. Thus, a new procedure of whole XRD pattern fitting, based on the Rietveld method, was used to have reliable data of Pt particle size (surface area) and lattice parameter. All structural and microstructural parameters were refined within the same procedure, also considering the transparency of the carbon supported catalysts and minimizing the effect of the amorphous background. The method can also take into account the presence of bimodal particle size distributions, which is difficult to study by CV or TEM.

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