Crystalline microstructure of boehmites studied by multi-peak analysis of powder X-ray diffraction patterns

2017 ◽  
Vol 32 (S1) ◽  
pp. S87-S98 ◽  
Author(s):  
Pablo Pardo ◽  
Marek Andrzej Kojdecki ◽  
José Miguel Calatayud ◽  
José María Amigó ◽  
Javier Alarcón
Keyword(s):  
Hydrothermal Treatment ◽  
Treatment Time ◽  
Crystalline Lattice ◽  
X Ray Diffraction ◽  
Hydrothermal Aging ◽  
X Ray ◽  
Boehmite Nanoparticles ◽  
Diffraction Patterns ◽  
Crystalline Microstructure ◽  
Hydrothermal Treatment Time

Nanocrystalline boehmite (gamma-aluminium-oxyhydroxide) is a material of industrial importance, the functionality of which follows from its crystalline microstructure. A procedure for preparing boehmite nanoparticles, comprising the formation of a precipitate by the alkalization of an aqueous solution of aluminium nitrate and subsequent hydrothermal aging, was previously elaborated. The application of an additive (maltitol or tartaric acid) to control the sizes and shapes of crystallites in the produced polycrystalline powder of boehmite was developed. The aim of this work is a study of the effect of the hydrothermal treatment time on nanocrystalline characteristics of boehmite, both in absence and in presence of the additive. The obtained materials were investigated by using X-ray diffraction (XRD) as principal technique and additionally by scanning and transmission electron microscopy. The multi-peak analysis of powder XRD patterns was applied to determine the prevalent crystallite shape, volume-weighted crystallite size distribution, and second-order crystalline lattice strain distribution being principal quantitative characteristics of the crystalline microstructure. Based on these characteristics, three types of the microstructure correlated with the production procedures were observed and discussed in detail. The nanoparticles of boehmites were found to be monocrystalline grains with characteristic habits and sizes of order of ten nanometers weakly dependent on the hydrothermal treatment time.

Evaluation of Biocompatibility of Porous Hydroxyapatite Developed from Edible Cuttlefish Bone

2007 ◽  
Vol 361-363 ◽  
pp. 155-158 ◽  
Author(s):  
Jung Jae Kim ◽  
Hae Jung Kim ◽  
Kang Sik Lee
Keyword(s):  
Hydrothermal Treatment ◽  
X Ray Diffraction ◽  
Porous Hydroxyapatite ◽  
X Ray ◽  
In Vivo Test ◽  
Time Period ◽  
Calcium Source ◽  
Good Biocompatibility ◽  
Diffraction Patterns

A edible cuttlefish(Zoological name : Sepia esculenta) bone has a porous structure with all pores interconnected The purpose of this research is to develop porous hydroxyapatite prepared by hydrothermal treatment from cuttlefish bone and evaluate the biocompatibility using undecalcified materials through the in-vivo test of rabbits. In this study, the phase and substructure of a porous hydroxyapatite, prepared by hydrothermal treatment using edible cuttlefish bone as a calcium source, has been confirmed by X-ray diffractometer and scanning electronic microscope. After preparing the specimens with 5mm diameter and 7mm length, the specimens were implanted into the femoral condyles of rabbits. Each rabbits were sacrificed at each time period of 1, 2, 3, 4 weeks after operation, respectively and the stained section was examined by a transmission light microscope. The X-ray diffraction patterns of the edible cuttlefish bone was confirm for aragonite phase and of the sample after hydrothermal treatment showed mostly into hydroxyapatite phase. There was more bone density increase in porous HA rod around implant site than natural edible cuttlefish bone. Because the edible cuttlefish bone is a very pure and good calcium source, porous hydroxyapatite developed from this study is expected to be a biomaterial having a good biocompatibility to be used as a suitable bone substitute.

scholarly journals Crystalline Microstructure of Corundum Fillers Determined from Powder X-Ray Diffraction Patterns

2016 ◽  
Vol 130 (4) ◽  
pp. 1000-1003 ◽  
Author(s):  
M.A. Kojdecki ◽  
J. Bastida ◽  
F.J. De la Torre ◽  
P. Pardo ◽  
R. Ibáńez ◽  
...  
Keyword(s):  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Patterns ◽  
Crystalline Microstructure

Crystalline microstructure of sepiolite influenced by grinding

2005 ◽  
Vol 38 (6) ◽  
pp. 888-899 ◽  
Author(s):  
Marek Andrzej Kojdecki ◽  
Joaquín Bastida ◽  
Pablo Pardo ◽  
Pedro Amorós
Keyword(s):  
Specific Surface ◽  
Mean Value ◽  
Crystalline Lattice ◽  
Mean Deviation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystallite Shape ◽  
The Mean ◽  
Crystalline Microstructure ◽  
Grinding Time

The crystalline microstructure of ground sepiolite has been investigated. A reference sample of sepiolite and products of its comminution by dry grinding were studied through X-ray diffraction pattern analysis, specific surface measurements by nitrogen adsorption and complementary analysis of field emission scanning electron microscope images. A statistical model of polycrystals was applied to describe and determine the crystalline microstructure of the studied specimens. The model parameters characterizing the microstructure were prevalent crystallite shape, volume-weighted crystallite size distribution and second-order crystalline lattice strain distribution, and they were determined for each sample by modelling a selected part of the X-ray diffraction pattern and fitting the simulated pattern to a measured one. A strict correlation of microstructure parameters with grinding time and with specific surface magnitudes was observed. A parallelepiped with edge-length ratios almost independent of grinding time (for longer times) was found to be the predominant crystallite shape. The crystallite size distributions were found to be close to logarithmic normal ones, with the mean values decreasing with increasing grinding time and the standard-deviation-to-mean-value ratios approximately constant. The second-order crystalline lattice strain distributions were found to be close to some simple function with the mean value equal to zero, the mean deviation increasing with increasing grinding time and the standard-to-mean-deviation ratios approximately constant. It was demonstrated that the specific surface can be calculated on the basis of the microstructure characteristics. Some details of the relation between crystallites and crystalline grains were explained by comparing the results of analysesviaX-ray diffraction and scanning electron microscopy.

Luminescence Properties of ZnS:Cu,Tm Semiconductor Nanocrystals Synthesize by a Hydrothermal Process

2011 ◽  
Vol 415-417 ◽  
pp. 499-503
Author(s):  
Mei Xin ◽  
Dong Ping Liu ◽  
Nai Sen Yu ◽  
Xiao Hui Qi ◽  
Hui Li
Keyword(s):  
Hydrothermal Treatment ◽  
Emission Intensity ◽  
Treatment Time ◽  
Semiconductor Nanocrystals ◽  
Hydrothermal Process ◽  
Luminescence Properties ◽  
X Ray Diffraction ◽  
Pl Emission ◽  
Hydrothermal Approach ◽  
Hydrothermal Treatment Time

ZnS:Cu,Tm nanocrystal with 15nm cubic structures have been synthesized by hydrothermal approach at 200°C. The photoluminescence (PL) properties and the effect of hydrothermal treatment time on the structure, morphology and PL spectra of ZnS:Cu,Tm samples have been studied. The as-obtained samples have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and FT-IR spectra.The result indicated that the PL emission spectrum of codoped with Cu and Tm sample compares with undoped ZnS and doped with Cu alone samples has a significant changes, while the PL emission peak has red shift and PL emission intensity increased. The samples size and crystallization are increase with extending of the treatment time. However, when the hydrothermal treatment time is too long(>12h), the PL emission intensity of sample instead of decreased. Demonstrated changes in surface state of nanomaterials have a greater impact on its luminescence properties.

The Paracrystalline Nature of the Purple Membrane of Halobacterium halobium I. Lattice Distortions within the Membrane

1980 ◽  
Vol 35 (11-12) ◽  
pp. 1032-1035 ◽  
Author(s):  
E. Lopez Cabarcos ◽  
S. Fernandez Bermudez ◽  
F. J. Baltá Calleja
Keyword(s):  
Purple Membrane ◽  
Crystalline Lattice ◽  
Halobacterium Halobium ◽  
X Ray Diffraction ◽  
X Ray ◽  
Paracrystalline Structure ◽  
Lattice Distortions ◽  
Diffraction Patterns

Abstract X-Ray diffraction patterns from oriented purple membrane of Halobacterium halobium show that the packing of proteins within the membrane has a paracrystalline structure. The paracrystalline mean distance fluctuations, g, were found to be 1.5 (± 0.1)% for the (100) packing planes of the proteins. The corresponding paracrystallite sizes are of ~ 850 Å. It is suggested that para­ crystalline lattice distortions within the membrane may be explained by conformational singularities of the proteins or by an irregular packing of adjacent proteins and lipids.

Approximate Estimation of Contributions to Pure X-Ray Diffraction Line Profiles from Crystallite Shapes, Sizes and Strains by Analysing Peak Widths

2004 ◽  
Vol 443-444 ◽  
pp. 107-110 ◽  
Author(s):  
Marek Andrzej Kojdecki
Keyword(s):  
Size Distribution ◽  
Strain Distribution ◽  
Polycrystalline Material ◽  
Physical Reality ◽  
Diffraction Line ◽  
Crystalline Lattice ◽  
Line Profiles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystalline Microstructure

A polycrystalline material may be considered as a set of crystallites. Since the crystallites have rather regular shapes, the assumption about the same shape is not far from physical reality for most polycrystals, especially powders. Such a system may be characterised in a statistical manner by two functions, the crystallite size distribution and the crystalline lattice strain distribution (for some materials other lattice distortions inside the crystallites, like stacking faults or dislocations, are to be considered additionally). The crystalline microstructure can be determined by investigating an X-ray diffraction pattern, what should be based on comparing an experimental pattern with a simulated one, derived from an appropriate physical model. Pure X-ray diffraction line profiles, containing information about crystalline microstructure, can be extracted from experimental data. An important step in analysing them is the separation of contributions from crystallite shapes and sizes and from strains, enabling the proper determination of both distributions together with the estimation of prevalent crystallite shape. A model of polycrystalline material combined with a description of X-ray diffraction on it, making such an analysis possible, is presented in this article. An approximate formula for separating both effects is based on results of computer simulation of pure X-ray diffraction line profiles from different crystalline powders, done under simplifying assumptions that the crystallites are prismatic or spherical, the size distribution is logarithmic-normal and the second-order strain distribution is normal.

Evaluation of Freezing Methods by Low Temperature X-Ray Diffraction

1977 ◽  
Vol 35 ◽  
pp. 330-333
Author(s):  
T. Gulik-Krzywicki ◽  
M.J. Costello
Keyword(s):  
Biological Materials ◽  
Molecular Organization ◽  
X Ray Diffraction ◽  
Glass Capillary ◽  
X Ray ◽  
Rate Dependent ◽  
Before And After ◽  
Freeze Etching ◽  
Diffraction Patterns ◽  
Set Up

Freeze-etching electron microscopy is currently one of the best methods for studying molecular organization of biological materials. Its application, however, is still limited by our imprecise knowledge about the perturbations of the original organization which may occur during quenching and fracturing of the samples and during the replication of fractured surfaces. Although it is well known that the preservation of the molecular organization of biological materials is critically dependent on the rate of freezing of the samples, little information is presently available concerning the nature and the extent of freezing-rate dependent perturbations of the original organizations. In order to obtain this information, we have developed a method based on the comparison of x-ray diffraction patterns of samples before and after freezing, prior to fracturing and replication.Our experimental set-up is shown in Fig. 1. The sample to be quenched is placed on its holder which is then mounted on a small metal holder (O) fixed on a glass capillary (p), whose position is controlled by a micromanipulator.

Examination of Rabbit Fc Crystals

1968 ◽  
Vol 26 ◽  
pp. 140-141
Author(s):  
J. P. Robinson ◽  
P. G. Lenhert
Keyword(s):  
Molecular Weight ◽  
Flat Plate ◽  
Phosphate Buffer ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
X Ray ◽  
Neutral Ph ◽  
Small Crystals ◽  
Carbon Coated ◽  
Diffraction Patterns

Crystallographic studies of rabbit Fc using X-ray diffraction patterns were recently reported. The unit cell constants were reported to be a = 69. 2 A°, b = 73. 1 A°, c = 60. 6 A°, B = 104° 30', space group P21, monoclinic, volume of asymmetric unit V = 148, 000 A°3. The molecular weight of the fragment was determined to be 55, 000 ± 2000 which is in agreement with earlier determinations by other methods.Fc crystals were formed in water or dilute phosphate buffer at neutral pH. The resulting crystal was a flat plate as previously described. Preparations of small crystals were negatively stained by mixing the suspension with equal volumes of 2% silicotungstate at neutral pH. A drop of the mixture was placed on a carbon coated grid and allowed to stand for a few minutes. The excess liquid was removed and the grid was immediately put in the microscope.

Control of the phase composition of advanced calcium phosphates using an x-ray diffractometer with a curved position-sensitive detector

2020 ◽  
Vol 86 (6) ◽  
pp. 29-35
Author(s):  
V. P. Sirotinkin ◽  
O. V. Baranov ◽  
A. Yu. Fedotov ◽  
S. M. Barinov
Keyword(s):  
Phase Composition ◽  
Calcium Phosphates ◽  
Position Sensitive Detector ◽  
Sensitive Detector ◽  
X Ray Diffraction ◽  
X Ray ◽  
Impurity Phases ◽  
Position Sensitive ◽  
Diffraction Peaks ◽  
Diffraction Patterns

The results of studying the phase composition of advanced calcium phosphates Ca10(PO4)6(OH)2, β-Ca3(PO4)2, α-Ca3(PO4)2, CaHPO4 · 2H2O, Ca8(HPO4)2(PO4)4 · 5H2O using an x-ray diffractometer with a curved position-sensitive detector are presented. Optimal experimental conditions (angular positions of the x-ray tube and detector, size of the slits, exposure time) were determined with allowance for possible formation of the impurity phases during synthesis. The construction features of diffractometers with a position-sensitive detector affecting the profile characteristics of x-ray diffraction peaks are considered. The composition for calibration of the diffractometer (a mixture of sodium acetate and yttrium oxide) was determined. Theoretical x-ray diffraction patterns for corresponding calcium phosphates are constructed on the basis of the literature data. These x-ray diffraction patterns were used to determine the phase composition of the advanced calcium phosphates. The features of advanced calcium phosphates, which should be taken into account during the phase analysis, are indicated. The powder of high-temperature form of tricalcium phosphate strongly adsorbs water from the environment. A strong texture is observed on the x-ray diffraction spectra of dicalcium phosphate dihydrate. A rather specific x-ray diffraction pattern of octacalcium phosphate pentahydrate revealed the only one strong peak at small angles. In all cases, significant deviations are observed for the recorded angular positions and relative intensity of the diffraction peaks. The results of the study of experimentally obtained mixtures of calcium phosphate are presented. It is shown that the graphic comparison of experimental x-ray diffraction spectra and pre-recorded spectra of the reference calcium phosphates and possible impurity phases is the most effective method. In this case, there is no need for calibration. When using this method, the total time for analysis of one sample is no more than 10 min.

Infrared spectroscopic study of the YPO4-YCrO4 system

1985 ◽  
Vol 50 (10) ◽  
pp. 2139-2145
Author(s):  
Alexander Muck ◽  
Eva Šantavá ◽  
Bohumil Hájek
Keyword(s):  
Spectroscopic Study ◽  
Infrared Spectra ◽  
Point Of View ◽  
Mixed Crystals ◽  
Crystal Symmetry ◽  
Infrared Spectroscopic Study ◽  
X Ray Diffraction ◽  
X Ray ◽  
Infrared Spectroscopic ◽  
Diffraction Patterns

The infrared spectra and powder X-ray diffraction patterns of polycrystalline YPO4-YCrO4 samples are studied from the point of view of their crystal symmetry. Mixed crystals of the D4h19 symmetry are formed over the region of 0-30 mol.% YPO4 in YCrO4. The Td → D2d → D2 or C2v(GS eff) correlation is appropriate for both PO43- and CrO43- anions.

Sign in / Sign up

Export Citation Format

Share Document