Structure of Carbonated Hydroxyapatite Based on Rietveld Method

2008 ◽  
Vol 368-372 ◽  
pp. 1187-1189
Author(s):  
Xu Ran ◽  
Jun Guo Ran ◽  
Li Gou ◽  
Ji Yong Chen ◽  
Jiao Min Luo
Keyword(s):  
Crystal Structure ◽  
Sintering Temperature ◽  
Rietveld Method ◽  
Rietveld Analysis ◽  
Structure Parameters ◽  
X Ray Diffraction ◽  
Carbonated Hydroxyapatite ◽  
X Ray ◽  
Quantitative Results ◽  
Distortion Index

The crystalline structures of B-type carbonated hydroxyapatite (CHA) powders sintered at 700, 900 and 1100°C, respectively, were studied by Rietveld analysis of powder X-ray diffraction (XRD) data. A series of structure parameters, including lattice parameters (a and c), bond length and the distortion index of PO4 tetrahedron (Dind) were calculated by Rietveld method to characterize the fine structure of CHA. The broadening effect of XRD reflections was separated to calculate the micro-strain and crystalline size. The results showed that CHA become more stable with the increase of sintering temperature, but the CO3 2- is almost lost at temperature of 1100°C. The quantitative results about crystal structure of CHA based on crystalline structure simulated by Rietveld method are obtained.

scholarly journals Phase Analysis of Bio-Based Derived Tricalcium Disilicate From 2CaO:1SiO2 By X-ray Diffraction

2021 ◽  
Vol 2129 (1) ◽  
pp. 012054
Author(s):  
Siti Nur Hazwani Yunus ◽  
Khor Shing Fhan ◽  
Banjuraizah Johar ◽  
Nur Maizatul Shima Adzali ◽  
Nur Hazlinda Jakfar ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Rice Husk ◽  
Single Phase ◽  
Sintering Temperature ◽  
Rietveld Analysis ◽  
Dicalcium Silicate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Complete Formation

Abstract In this paper, tricalcium disilicate was formed from dicalcium silicate compound powder, synthesised via a mechanochemical technique using a stoichiometric 2CaO:1SiO2. Compound CaO and SiO2 were derived from the bio-waste of eggshell and rice husk at the calcination temperature of 900°C and 800°C, respectively. The dicalcium disilicate powder was sintered for 2 hours at different temperatures ranging from 1150°C to 1350°C. Using X-ray diffraction with Rietveld analysis, it was found that the amount of tricalcium disilicate with monoclinic (beta) crystal structure increases on sintering temperature at the expense of dicalcium silicate. The complete formation of single-phase tricalcium disilicate began at a sintering temperature of 1300°C. The effect of sintering temperatures on the crystallisation and phase transition of dicalcium silicate is reported. The size of crystallites depends on the sintering temperature. The finding of this study rebound to the benefit of society by reducing the risk-off pollution cause by accessive redundant bio-waste eggshell and rice husk and also reduced the amount of CaO and SiO2 used in the fabrication of Ca3Si2O7.

X-ray powder diffraction data of LaNi0.5Ti0.45Co0.05O3, LaNi0.45Co0.05Ti0.5O3, and LaNi0.5Ti0.5O3 perovskites

2021 ◽  
pp. 1-6
Author(s):  
Mariana M. V. M. Souza ◽  
Alex Maza ◽  
Pablo V. Tuza
Keyword(s):  
Crystal Structure ◽  
Rietveld Method ◽  
Pechini Method ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Modified Pechini Method ◽  
Scanning Electron

In the present work, LaNi0.5Ti0.45Co0.05O3, LaNi0.45Co0.05Ti0.5O3, and LaNi0.5Ti0.5O3 perovskites were synthesized by the modified Pechini method. These materials were characterized using X-ray fluorescence, scanning electron microscopy, and powder X-ray diffraction coupled to the Rietveld method. The crystal structure of these materials is orthorhombic, with space group Pbnm (No 62). The unit-cell parameters are a = 5.535(5) Å, b = 5.527(3) Å, c = 7.819(7) Å, V = 239.2(3) Å3, for the LaNi0.5Ti0.45Co0.05O3, a = 5.538(6) Å, b = 5.528(4) Å, c = 7.825(10) Å, V = 239.5(4) Å3, for the LaNi0.45Co0.05Ti0.5O3, and a = 5.540(2) Å, b = 5.5334(15) Å, c = 7.834(3) Å, V = 240.2(1) Å3, for the LaNi0.5Ti0.5O3.

Study on the Properties of Doped La in BaBi4Ti4O15 Ceramic

2007 ◽  
Vol 26-28 ◽  
pp. 243-246
Author(s):  
Xing Hua Yang ◽  
Jin Liang Huang ◽  
Xiao Wang ◽  
Chun Wei Cui
Keyword(s):  
Crystal Structure ◽  
Grain Size ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Sintering Temperature ◽  
Solid Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lanthanum Content ◽  
Scanning Electron

BaBi4-xLaxTi4O15 (BBLT) ceramics were prepared by conventional solid phase sintering ceramics processing technology. The crystal structure and the microstructure were detected by X-ray diffraction (XRD) and scanning electron microscope (SEM). The XRD analyses show that La3+ ions doping did not change the crystal structure of BBT ceramics. The sintering temperature increased from 1120°C to 1150°C with increasing Lanthanum content from 0 to 0.5, but it widened the sintering temperature range from 20°C to 50°C and refined the grain size of the BBT ceramic. Additionally, polarization treatment was performed and finally piezoelectric property was measured. As a result, the piezoelectric constant d33 of the 0.1at.% doped BBLT ceramics reached its highest value about 22pc/N at polarizing electric field of 8kV/mm and polarizing temperature of 120°C for 30min.

Effect of Sintering Temperatures and Ba/Ti Ratio on Dielectric Properties of BaTiO3 Ceramic

2013 ◽  
Vol 750-752 ◽  
pp. 506-511
Author(s):  
Yuan Yuan Li ◽  
Gui Xia Dong ◽  
Bi Yan Zhu ◽  
Qiu Xiang Liu ◽  
Di Wu
Keyword(s):  
Crystal Structure ◽  
Dielectric Properties ◽  
Curie Temperature ◽  
Sintering Temperature ◽  
Solid Phase ◽  
Solid Phase Reaction ◽  
Phase Reaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Method Effect

As a research object, the samples with various Ba/Ti ratios (Ba/Ti=0.95~1.05) were synthesized by solid phase reaction method. Effect of sintering temperatures and Ba/Ti ratio on dielectric properties and crystal structure of BaTiO3ceramic were investigated. Crystal structure and crystal phase composition were investigated by scanning electron microscopy and X-ray diffraction. The dielectric properties were studied by Agilent 4294A at 1 kHz. The results show that the BaTiO3ceramic has high permittivity and dielectric loss at 1340°C. The permittivity of BaTiO3ceramic with Ba/Ti=0.95 change small as the sintering temperatures vary at 1320°C. With the increasing of Ba/Ti ratio, the Curie temperature first increases and then decreases as the sample sintering at 1320°C. When Ba/Ti=1, the Curie temperature increase with the sintering temperature increasing.

Effect of Iron Substitution on Structure and Optical Properties of Nanocrystalline CaTiO3

2008 ◽  
Vol 3 ◽  
pp. 123-128 ◽  
Author(s):  
A. Bandyopadhyay ◽  
S. Mondal ◽  
M. Pal ◽  
Umapada Pal ◽  
M. Pal
Keyword(s):  
Crystal Structure ◽  
Particle Size ◽  
Iron Concentration ◽  
Rietveld Analysis ◽  
Exothermic Peak ◽  
Optical And Electrical Properties ◽  
X Ray Diffraction ◽  
Chemical Route ◽  
X Ray ◽  
Soft Chemical Route

Nanocrystalline CaTiO3 powders doped with Fe2O3 have been prepared using a soft chemical route. Precipitation of CaTiO3 nanocrystals has been studied by monitoring the exothermic peak in their DSC spectra. The crystal growth temperature of the samples depends on the concentration of iron. Surface morphology, crystal structure, optical and electrical properties of the nanostructures are investigated. X-ray diffraction study shows that the as-prepared powders are amorphous in nature and CaTiO3 phase formation starts at around 500 0C. Rietveld analysis revealed that the particle size of iron substituted CaTiO3 is in nanometer range. Optical bandgap of the nanostructures varies from 4.3 to 3.7 eV for the variation of iron concentration from 0.05 to 0.2 mole %.

scholarly journals Study of selection and purification of Brazilian bentonite clay by elutriation: a XRF, SEM and Rietveld analysis

Cerâmica ◽  
2016 ◽  
Vol 62 (361) ◽  
pp. 1-8 ◽  
Author(s):  
J. L. Alves ◽  
A. E. Zanini ◽  
M. E. de Souza ◽  
M. L. F. Nascimento
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Rietveld Method ◽  
Bentonite Clay ◽  
Rietveld Analysis ◽  
Industrial Applications ◽  
X Ray Diffraction ◽  
X Ray ◽  
Almost All ◽  
Scanning Electron

Abstract Clays obtained from nature have a lot of impurities. Therefore, for best using of these materials, it is necessary its selection and purification. Thus, the aim of this work is to separate and to purify the smectite fractions using water as a solvent at a low flux mixed with a bentonite clay extracted from a mine in Vitória da Conquista - Bahia / Brazil. For this a separation method of fractions of expandable clays based on the Stokes' Law was applied - this process is called elutriation, in order to ensure and to expand possible industrial applications of this material. The samples were characterized by analysis of X-ray diffraction, X-ray fluorescence and scanning electron microscopy. The Rietveld method enabled the quantification of main phase minerals: montmorillonite, kaolinite, nontronite and quartz, reaching 85% in mass of montmorillonite phase at the end of the process. Results showed that the method used was efficient to remove almost all quartz, carbonates and organic matter from the sample. It was also observed a monomodal grain size distribution of elutriated materials with thinner grains, around (18.1 ± 1.8) μm at the end of the process. It has been concluded that the method developed and applied showed promising characters to be applied to elutriate kilograms of clays and could be used in industrial scale.

A semi-empirical asymmetry function for X-ray diffraction peak profiles

1995 ◽  
Vol 10 (3) ◽  
pp. 204-206 ◽  
Author(s):  
P. Riello ◽  
P. Canton ◽  
G. Fagherazzi
Keyword(s):  
Goodness Of Fit ◽  
Rietveld Method ◽  
Rietveld Analysis ◽  
Opening Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Asymmetry Function ◽  
The Asymmetry ◽  
Fit Index ◽  
Semi Empirical

A new semi-empirical approximation for the asymmetry function to be used in the X-ray Rietveld analysis has resulted in lower values of the so-called goodness-of-fit index, defined as S = Rwp/Rexp, where Rwp is the R-weighted pattern and Rexp is the R-expected [R. A. Young, The Rietveld Method (Oxford U.P., Oxford, 1993)], with respect to the corresponding values obtained with the classical approximation used by Rietveld in his fundamental paper. A comparing test of the two asymmetry functions was carried out for the cubic Y2O3 and for αAl2O3 using either pseudo-Voigt or Pearson VII symmetrical functions and two diffractometers. As in the case of the Rietveld approximation, the present one, which employs an exponential function, is optimized using only one fitting parameter. Experimentally, the asymmetry can be considerably diminished by using Soller slits with a small opening angle (≤2°).

Rietveld Studies on Silicon Substituted Hydroxyapatite

2006 ◽  
Vol 309-311 ◽  
pp. 113-116 ◽  
Author(s):  
Shuo Zou ◽  
Jie Huang ◽  
Serena Best ◽  
William Bonfield
Keyword(s):  
Silicon Content ◽  
Sintering Temperature ◽  
Silicon Concentration ◽  
Crystallographic Structure ◽  
X Ray Diffraction ◽  
Phase Purity ◽  
X Ray ◽  
Similar Dependence ◽  
Initial Silicon ◽  
Distortion Index

Silicon-substituted hydroxyapatite (SiHA) attracts particular interest due its enhanced bioactivity compared with pure hydroxyapatite. In this study we seek to clarify the effects on the lattice parameters of both composition and sintering temperature in experimentally-produced HA and 0.8wt% SiHA, 1.5wt% SiHA and 2.0wt% SiHA sintered at 800oC and 1200oC. X ray diffraction was used to determine the phase purity and crystallographic structure. We found that while the c parameter increased with increasing silicon concentration, the a parameter decreased with initial silicon incorporation then recovered with further increases in silicon incorporation. The calcium (2) channel expanded with silicon incorporation while tetrahedron distortion index (TDI) and the radius of the P channel showed a similar dependence on silicon content as the a parameter.

Crystal Structure Analysis in the Dehydrogenation Process of Mg(NH2)2-LiH System

2006 ◽  
Vol 971 ◽  
Author(s):  
Tatsuo Noritake ◽  
Masakazu Aoki ◽  
Shin-ichi Towata ◽  
Yuko Nakamori ◽  
Shin-ichi Orimo
Keyword(s):  
Crystal Structure ◽  
Rietveld Analysis ◽  
Crystal Structure Analysis ◽  
Diffraction Measurement ◽  
Hydrogen Storage Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure Changes ◽  
Li Ion ◽  
Cation Sites

ABSTRACTMg(NH2)2-LiH system which have the properties of reversible hydrogenation and dehydrogenation is one of the promising candidates for new hydrogen storage materials. For understanding of the reversible reaction mechanism, we investigated the crystal structure changes in 3Mg(NH2)2-12LiH system using the pressure-composition (p-c) isotherm measurement and synchrotron X-ray diffraction. The sample was prepared by the hydrogenation of Mg3N2 + 4Li3N. At the several dehydrogenation stages of the p-c isotherm measurement at temperature 523 K, the sample was taken out and X-ray diffraction measurement was performed. By the amount of desorbed hydrogen, the reaction was expressed as the following formula, Mg(NH2)2 + 4LiH → LixMg(NH2)2-x(NH)x + (4-x)LiH + xH2 (x = 0∼2). The crystal structures of LixMg(NH2)2-x(NH)x, similar to CaF2-type one, formed during the dehydrogenation reaction were determined by Rietveld analysis. As a result, it is considered that the dehydrogenation process might relate to the diffusion of Li+ ion in cation sites of Mg(NH2)2.

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