Influence of amide content on the crystal structure of chitin

Holzforschung ◽  
2006 ◽  
Vol 60 (5) ◽  
pp. 480-484 ◽  
Author(s):  
Hiroshi Tamura ◽  
Makoto Sawada ◽  
Hideaki Nagahama ◽  
Taiichi Higuchi ◽  
Seiichi Tokura
Keyword(s):  
Crystalline Structure ◽  
X Ray Diffraction ◽  
Chloride Dihydrate ◽  
Structure Changes ◽  
Degree Of Acetylation ◽  
Calcium Chloride Dihydrate ◽  
Xrd Patterns ◽  
Chitin And Chitosan ◽  
Amide Content ◽  
Poor Solvent

Abstract The crystalline structure of chitin and chitosan was investigated by X-ray diffraction (XRD). Chitosan filaments were prepared using a saturated solution of calcium chloride dihydrate in methanol (CaCl2-MeOH) as a mild solvent and the study focused on the interaction between the degree of acetylation (DA) and crystallinity. There were pronounced differences in the XRD patterns for specimens with DA values between 44.2% and 52.2%. We suggest that the crystalline structure changes from an anhydrous-type chitosan to an α-chitin type without any additives. CaCl2-MeOH is a good solvent for chitin and a poor solvent for chitosan and we found that it can regulate the distribution of N-acetyl glucosamine and glucosamine between amorphous and crystalline regions.

Sinjarite, a new mineral from Iraq

1980 ◽  
Vol 43 (329) ◽  
pp. 643-645 ◽  
Author(s):  
Zeki A. Aljubouri ◽  
Salim M. Aldabbagh
Keyword(s):  
Calcium Chloride ◽  
New Mineral ◽  
X Ray Diffraction ◽  
X Ray ◽  
Chloride Dihydrate ◽  
Wet Chemical ◽  
Calcium Chloride Dihydrate

SummaryA hygroscopic, soft, pink mineral was discovered in Sinjar town, west of Mosul city. Wet chemical and X-ray diffraction analyses proved that the mineral has a composition of calcium chloride dihydrate CaCl2·2H2O, which has not been known in nature before. It is therefore a new mineral, and is named sinjarite after its locality.

Structural and Spectroscopic Characterization of ZrO2:Eu3+ Nanoparticles

2008 ◽  
Vol 8 (12) ◽  
pp. 6431-6436 ◽  
Author(s):  
P. Salas ◽  
N. Nava ◽  
C. Ángeles-Chavez ◽  
E. De la Rosa ◽  
L. A. Díaz-Torres
Keyword(s):  
Raman Spectroscopy ◽  
Crystalline Structure ◽  
Sol Gel ◽  
Tetragonal Zirconia ◽  
Fluorescence Emission ◽  
Spectroscopic Characterization ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Xrd Patterns

ZrO2:Eu3+ nanocrystals were prepared by the sol–gel technique. The structural and luminescence properties of europium doped zirconia with 0.5 to 2 mol% were studied by Mössbauer spectroscopy, Raman spectroscopy, X-ray diffraction (XRD), High Resolution Transmission Electron Microscopy (HRTEM) and photoluminescence (PL) under UV excitation. Structural characterization shows a crystallite size between 16 to 55 nm and monoclinic and tetragonal zirconia phases as the main crystalline structure. XRD patterns shown that the content of the active ions stabilizes the tetragonal structure of ZrO2 at 1000 °C, being 100% for 2 mol% Eu2O3 doped sample. Such results are in agreement with HRTEM and Raman spectroscopy. The Mössbauer spectra of the ZrO2:Eu3+ samples show a single peak near zero velocity which is attributed to Eu+3. Luminescence characterization shows the typical emission band centered at 595 and 611 nm. Change in the structure of such band was observed and explained in terms of crystalline phase change. The dependence between the fluorescence emission and the crystalline structure is discussed.

Structural and Magnetic Hysteresis Properties of Co-Zr Substituted Hexagonal Barium Ferrites

2015 ◽  
Vol 7 (1) ◽  
pp. 1346-1351
Author(s):  
Ch.Gopal Reddy ◽  
Ch. Venkateshwarlu ◽  
P. Vijaya Bhasker Reddy
Keyword(s):  
Magnetic Properties ◽  
Single Phase ◽  
Magnetic Hysteresis ◽  
Grain Morphology ◽  
Hexagonal Structure ◽  
Ion Composition ◽  
X Ray Diffraction ◽  
Ceramic Method ◽  
Barium Ferrites ◽  
Xrd Patterns

Co-Zr substituted M-type hexagonal barium ferrites, with chemical formula BaCoxZrxFe12-2xO19 (where x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0), have been synthesized by double sintering ceramic method. The crystallographic properties, grain morphology and magnetic properties of these ferrites have been investigated by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometer (VSM). The XRD patterns confirm the single phase with hexagonal structure of prepared ferrites. The magnetic properties have been investigated as a function of Co and Zr ion composition at an applied field in the range of 20 KOe. These studies indicate that the saturation magnetization (Ms) in the samples increases initially up to the Co-Zr composition of x=0.6 and decreases thereafter. On the other hand, the coercivity (Hc) and Remanent magnetization (Mr) are found to decrease continuously with increasing Co-Zr content. This property is most useful in permanent magnetic recording. The observed results are explained on the basis of site occupation of Co and Zr ions in the samples.

Study of the multiplet nature in shpol'skii effect: Host n-heptane crystalline structure by X-ray diffraction and guest coronene position by ESR

1977 ◽  
Vol 22 (2) ◽  
pp. 207-214 ◽  
Author(s):  
A.M. Merle ◽  
M. Lamotte ◽  
S. Risemberg ◽  
C. Hauw ◽  
J. Gaultier ◽  
...  
Keyword(s):  
Crystalline Structure ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals Influence of Li2CO3 addition on electrical and magnetic properties of Ni0.6Mg0.4Fe2O4

2020 ◽  
Vol 10 (03) ◽  
pp. 2050003
Author(s):  
M. R. Hassan ◽  
M. T. Islam ◽  
M. N. I. Khan
Keyword(s):  
Magnetic Properties ◽  
Single Phase ◽  
Low Frequency ◽  
Solid State Reaction Method ◽  
Charge Carriers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electrical And Magnetic Properties ◽  
Frequency Regime ◽  
Xrd Patterns

In this research, influence of adding Li2CO3 (at 0%, 2%, 4%, 6%) on electrical and magnetic properties of [Formula: see text][Formula: see text]Fe2O4 (with 60% Ni and 40% Mg) ferrite has been studied. The samples are prepared by solid state reaction method and sintered at 1300∘C for 6[Formula: see text]h. X-ray diffraction (XRD) patterns show the samples belong to single-phase cubic structure without any impurity phase. The magnetic properties (saturation magnetization and coercivity) of the samples have been investigated by VSM and found that the higher concentration of Li2CO3 reduces the hysteresis loss. DC resistivity increases with Li2CO3 contents whereas it decreases initially and then becomes constant at lower value with temperature which indicates that the studied samples are semiconductor. The dielectric dispersion occurs at a low-frequency regime and the loss peaks are formed in a higher frequency regime, which are due to the presence of resonance between applied frequency and hopping frequency of charge carriers. Notably, the loss peaks are shifted to the lower frequency with Li2CO3 additions.

Phase diagram of betaine calcium chloride dihydrate in an applied electric field

1991 ◽  
Vol 44 (1) ◽  
pp. 374-377 ◽  
Author(s):  
Ian Folkins ◽  
M. B. Walker ◽  
Z. Y. Chen
Keyword(s):  
Phase Diagram ◽  
Electric Field ◽  
Calcium Chloride ◽  
Applied Electric Field ◽  
Chloride Dihydrate ◽  
Calcium Chloride Dihydrate

Determination of crystallinity of Chinese handmade papers by means of X-ray diffraction

2020 ◽  
Vol 41 (2) ◽  
pp. 69-86
Author(s):  
Peng Liu ◽  
Hongbin Zhang ◽  
Sinong Wang ◽  
Hui Yu ◽  
Bingjie Lu ◽  
...  
Keyword(s):  
Negative Influence ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
X Ray ◽  
Eulaliopsis Binata ◽  
Different Types ◽  
Powder Samples ◽  
Xrd Patterns ◽  
Xrd Method

AbstractThe crystallinity indices (CrI) of Chinese handmade papers were investigated using the X-ray diffraction (XRD) method. Four Chinese handmade papers, Yingchun, Zhuma, Yuanshu and Longxucao papers were used as model substrates of mulberry bark, ramie, bamboo and Eulaliopsis binata papers, respectively. Two forms of the paper samples, paper sheets and their comminuted powders, were used in this study. The results showed that their XRD patterns belong to the cellulose-I type and Iβ dominates the cellulose microstructure of these paper samples. Moreover, it was found that the microstructures and CrIs of cellulose of these papers were changed by the grinding treatment. This work suggested that the sheet form of the handmade papers is suitable to determine CrI by XRD, despite the contribution of non-cellulosic components in the papers. The order of CrIs for these paper sheet samples was Yingchun, Zhuma, Longxucao and Yuanshu papers. Besides CrIs, differences in cross-sectional areas of the crystalline zone of cellulose can be used for comparing different types of handmade papers. It was also found that the CrIs and crystallite size of paper cellulose varied between the sheet samples and the powder samples, illustrating that the pulverisation has a negative influence on the microstructure of the handmade papers.

2D X-ray diffraction and molecular modelling of the crystalline structure of polyesters under uniaxial stress

2021 ◽  
pp. 096739112199822
Author(s):  
Ahmed I Abou-Kandil ◽  
Gerhard Goldbeck
Keyword(s):  
Crystalline Structure ◽  
Molecular Modelling ◽  
Three Dimensional ◽  
Uniaxial Stress ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wide Range ◽  
Modelling Techniques ◽  
Diffraction Patterns

Studying the crystalline structure of uniaxially and biaxially drawn polyesters is of great importance due to their wide range of applications. In this study, we shed some light on the behaviour of PET and PEN under uniaxial stress using experimental and molecular modelling techniques. Comparing experiment with modelling provides insights into polymer crystallisation with extended chains. Experimental x-ray diffraction patterns are reproduced by means of models of chains sliding along the c-axis leading to some loss of three-dimensional order, i.e. moving away from the condition of perfect register of the fully extended chains in triclinic crystals of both PET and PEN. This will help us understand the mechanism of polymer crystallisation under uniaxial stress and the appearance of mesophases in some cases as discussed herein.

A Fast Synthesis and Sintering of Mg2Si1−xSnx (0≤x≤1.0) Solid Solutions by Microwave Irradiation

2011 ◽  
Vol 197-198 ◽  
pp. 417-420 ◽  
Author(s):  
Shu Cai Zhou ◽  
Chen Guang Bai ◽  
Chun Lin Fu
Keyword(s):  
Microwave Irradiation ◽  
Solid Solutions ◽  
Microwave Assisted Synthesis ◽  
Green Density ◽  
X Ray Diffraction ◽  
Power Setting ◽  
Xrd Patterns ◽  
Heating Behavior ◽  
Fast Synthesis ◽  
Lower Heating

In order to reduce the oxidizing and volatilizing caused by Mg element in the traditional methods for synthesizing Mg2Sil-xSnxsolid solutions, Mg2Sil-xSnxsolid solutions have been prepared by Microwave-assisted Synthesis techniques. The heating behavior of Mg, Si and Sn fixed powder was investigated under microwave irradiation. X-ray diffraction (XRD) was used to characterize the powders. The results suggest that the temperature-rising rate is also dependent on the initial green density and higher green density provides lower heating rate while power setting are fixed. XRD patterns show that Mg2Sil-xSnxsolid solutions have been well formed under microwave irradiation.

Microstructure Characterization of Metal Mixed Oxides

MRS Advances ◽  
2017 ◽  
Vol 2 (64) ◽  
pp. 4025-4030 ◽  
Author(s):  
T. Kryshtab ◽  
H. A. Calderon ◽  
A. Kryvko
Keyword(s):  
Mixed Oxides ◽  
Profile Analysis ◽  
Atomic Resolution ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Reconstruction Procedure ◽  
Transmission Electron ◽  
Xrd Patterns ◽  
Co Precipitation

ABSTRACTThe microstructure of Ni-Mg-Al mixed oxides obtained by thermal decomposition of hydrotalcite-like compounds synthesized by a co-precipitation method has been studied by using X-ray diffraction (XRD) and atomic resolution transmission electron microscopy (TEM). XRD patterns revealed the formation of NixMg1-xO (x=0÷1), α-Al2O3 and traces of MgAl2O4 and NiAl2O4 phases. The peaks profile analysis indicated a small grain size, microdeformations and partial overlapping of peaks due to phases with different, but similar interplanar spacings. The microdeformations point out the presence of dislocations and the peaks shift associated with the presence of excess vacancies. The use of atomic resolution TEM made it possible to identify the phases, directly observe dislocations and demonstrate the vacancies excess. Atomic resolution TEM is achieved by applying an Exit Wave Reconstruction procedure with 40 low dose images taken at different defocus. The current results suggest that vacancies of metals are predominant in MgO (NiO) crystals and that vacancies of Oxygen are predominant in Al2O3 crystals.

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