scholarly journals Characterization and Electrical Properties of [C6H9N2]2CuCl4 Compound

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
M. Hamdi ◽  
A. Oueslati ◽  
I. Chaabane ◽  
F. Hlel
Keyword(s):  
Small Polaron ◽  
Equivalent Circuit Model ◽  
Scanning Calorimetry ◽  
Bulk Resistance ◽  
X Ray ◽  
Compound C ◽  
Vibrational Study ◽  
Primary Mechanism ◽  
Constant Phase Elements ◽  
Alternative Current

We report measurements of X-ray powder diffraction, vibrational study, the differential scanning calorimetry (DSC), and the electric properties of a made-up [C6H9N2]2CuCl4 sample. The alternative current (ac) conductivity of the compound [C6H9N2]2CuCl4 has been measured in the temperature range 356–398 K and the frequency range 209 Hz–5 MHz. The Cole-Cole (the imaginer part (Z′′) versus real part (Z′) of impedance complex) plots are well fitted to an equivalent circuit model which consists of a parallel combination of a bulk resistance (R) and constant phase elements (CPE). The single semicircle indicates only one primary mechanism for the electrical conduction within [C6H9N2]2CuCl4. The variation of the value of these elements with temperatures confirmed the result detected by DSC and dielectric measurements. Thus the conduction in the material is probably due to a hopping or a small polaron tunneling process.

scholarly journals Impedance and modulus studies of Na0.9Ba0.1Nb0.9(Sn0.5Ti0.5)0.1O3 ceramic

2021 ◽  
pp. 2150013
Author(s):  
A. Oueslati ◽  
A. Aydi
Keyword(s):  
Single Phase ◽  
Equivalent Circuit Model ◽  
X Ray Diffraction ◽  
Solid State Reaction Technique ◽  
Bulk Resistance ◽  
X Ray ◽  
Arrhenius Relation ◽  
Nyquist Plots ◽  
Constant Phase Elements ◽  
Modulus Studies

Polycrystalline Na[Formula: see text]Ba[Formula: see text]Nb[Formula: see text](Sn[Formula: see text]Ti[Formula: see text]O3is prepared by the solid-state reaction technique. The formation of single-phase material was confirmed by an X-ray diffraction study and it was found to be a tetragonal phase at room temperature. Nyquist plots ([Formula: see text]ˆ2 versus [Formula: see text] show that the conductivity behavior is accurately represented by an equivalent circuit model which consists of a parallel combination of bulk resistance and constant phase elements (CPE). The frequency dependence of the conductivity is interpreted in terms of Jonscher’s law. The conductivity [Formula: see text] follows the Arrhenius relation. The modulus plots can be characterized by the empirical Kohlrausch–Williams–Watts (KWW), [Formula: see text] = exp([Formula: see text]/[Formula: see text] function and the value of the stretched exponent ([Formula: see text] is found to be almost independent of temperature. The near value of activation energies obtained from the analyses of modulus and conductivity data confirms that the transport is through an ion hopping mechanism dominated by the motion of the (O[Formula: see text] ions in the structure of the investigated material.

scholarly journals IMPEDANCE SPECTROSCOPY STUDY OF BIS(2-AMINO-6-METHYLPYRIDINIUM) TETRACHLORIDOZINCATE

2012 ◽  
Vol 02 (04) ◽  
pp. 1250025 ◽  
Author(s):  
A. OUESLATI ◽  
M. HAMDI ◽  
I. CHAABANE ◽  
F. HLEL ◽  
M. GARGOURI
Keyword(s):  
Activation Energy ◽  
Complex Impedance ◽  
Bulk Resistance ◽  
Electrical Equivalent Circuit ◽  
Compound C ◽  
Dielectric Data ◽  
Impedance Spectroscopy Study ◽  
Different Temperatures ◽  
Constant Phase Elements ◽  
Modified Power Law

The complex impedance of the bis(2-amino-6-methylpyridine) tetrachloridozincate compound (C6H9N2)2ZnCl4 has been investigated in the temperature range 313–403 K and in the frequency range 200 Hz–5 MHz. The impedance plots show semicircle arcs at different temperatures and an electrical equivalent circuit has been proposed to explain the impedance results. The circuits consist of the parallel combination of bulk resistance Rp and constant phase elements (CPE). The bulk resistance of the material decreases with rise in temperature. dc conduction activation energies are estimated from Arrhenius plots. The frequency-dependent conductivity data are fitted in the modified power law: σ ac (ω) = σ dc + A1ωs1 + A2ωs2. Dielectric data were analyzed using complex electrical modulus M* at various temperatures. The modulus plot can be characterized by full width at half height or by β values of Kohlrausch–William–Watts (KWW) function. Activation energy of hopping is almost close to the activation energy of conduction suggesting a hopping transport mechanism.

scholarly journals Structural, Thermal behaviour and Vibrational study of a new Cesium- Ammonium Dihydrogen Phosphate–Arsenate: Cs0.55(NH4)0.45H2(PO4)0.39(AsO4)0.61

2014 ◽  
Vol 10 (7) ◽  
pp. 2944-2954 ◽  
Author(s):  
Samia CHAUCHENE ◽  
Khaled JAOUADI ◽  
Tahar MHIRI
Keyword(s):  
Title Compound ◽  
Room Temperature ◽  
Structural Disorder ◽  
Dihydrogen Phosphate ◽  
Scanning Calorimetry ◽  
Two Phase ◽  
X Ray ◽  
Vibrational Study ◽  
Acidic Proton ◽  
Dynamical Disorder

Mixed crystals Cs0.55(NH4)0.45H2(PO4)0.39(AsO4)0.61 (CADPA) of the two antiferroelectric NH4H2PO4 (ADP) and NH4H2AsO4 (ADA) and of the two ferroelectric CsH2PO4 (CDP) and CsH2AsO4 (CDA) have been prepared by slow evaporation from aqueous solution at room temperature. The structural properties of the crystal were characterized by X-ray single analysis (performed at room temperature), which revealed that (CADPA) crystallizes in space group I42d with lattice parameters: a = 7.6473(1) Å, c = 7.6803(1) Å and Z = 4. The title compound is isostructural with the tetragonal phases of (ADP) and (ADA). This structure is characterized by two kinds of disorder: a statical or dynamical disorder of the acidic proton in the O–H…O hydrogen bond and another one which is connected with a reorientational motion of NH4+ ions. Broader peaks in the IR spectrum confirm a structural disorder in this material. Thermal analysis of the (CADPA) were characterized by differential scanning calorimetry (DSC), showed that the title compound undergo two phase transitions at T = 204 K and T = 407 K.

scholarly journals Impedance Spectroscopy, Electrical Relaxation and Ac Conductivity Studies of an Organic-Inorganic Hybrid Compound: C12H14N2CuCl4

2009 ◽  
Vol 5 (3) ◽  
pp. 741-752 ◽  
Author(s):  
W. Wamani ◽  
R. Elwej ◽  
T. Mhiri ◽  
Mohamed Belhouchet
Keyword(s):  
Ac Conductivity ◽  
Arrhenius Equation ◽  
Constant Phase Element ◽  
Equivalent Circuit Model ◽  
Relaxation Model ◽  
Frequency Range ◽  
Scanning Calorimetry ◽  
Bulk Resistance ◽  
Hybrid Compound ◽  
Translation Motion

The AC conductivity of the compound, C12H14N2CuCl4, in the temperature and frequency range from 373 to 423 K and 209 Hz – 5 MHz, respectively, is reported. The differential scanning calorimetry and thermogravimetric analysis indicate the presence of a phase transition at 400 K. The Z’ and Z’’ vs. frequency plots are found to be well fit by using the equivalent circuit model. The circuits consist of a parallel combination of bulk resistance Rp and constant phase element. Besides, the analysis of the experimental data based on the jump relaxation model shows that the translation motion of the charge carrier and reorientation hopping between the equivalent sites of the metal chloride anion and the cation groups are responsible for the observed AC conductivity in the temperature regions I (373–400 K) and II (400–423 K). The frequency dependence of the conductivity which follows the Arrhenius equation is interpreted in terms of Jonscher's law: σ (ω) = σdc +A ω S. 

Electron microscopy of crystalline structure in thermotropic random copolymers

1991 ◽  
Vol 49 ◽  
pp. 1054-1055
Author(s):  
Afzana Anwer ◽  
S. Eilidh Bedford ◽  
Richard J. Spontak ◽  
Alan H. Windle
Keyword(s):  
Electron Microscopy ◽  
Crystalline Structure ◽  
Liquid Crystalline ◽  
Elevated Temperatures ◽  
Random Copolymers ◽  
Molecular Characteristics ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Identical Monomer ◽  
Periodic Layer

Random copolyesters composed of wholly aromatic monomers such as p-oxybenzoate (B) and 2,6-oxynaphthoate (N) are known to exhibit liquid crystalline characteristics at elevated temperatures and over a broad composition range. Previous studies employing techniques such as X-ray diffractometry (XRD) and differential scanning calorimetry (DSC) have conclusively proven that these thermotropic copolymers can possess a significant crystalline fraction, depending on molecular characteristics and processing history, despite the fact that the copolymer chains possess random intramolecular sequencing. Consequently, the nature of the crystalline structure that develops when these materials are processed in their mesophases and subsequently annealed has recently received considerable attention. A model that has been consistent with all experimental observations involves the Non-Periodic Layer (NPL) crystallite, which occurs when identical monomer sequences enter into register between adjacent chains. The objective of this work is to employ electron microscopy to identify and characterize these crystallites.

Studies on the Preparation, Characterization and Solubility of -Cyclodextrin-Roxythromycin Inclusion Complexes

2009 ◽  
Vol 2 (2) ◽  
pp. 523-530
Author(s):  
D. Nagasamy Venkatesh ◽  
S. Karthick ◽  
M. Umesh ◽  
G. Vivek ◽  
R.M. Valliappan ◽  
...  
Keyword(s):  
Dissolution Rate ◽  
Inclusion Complexes ◽  
Phase Solubility ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Ir Studies ◽  
Poorly Soluble ◽  
Poorly Soluble Drug

Roxythromycin/ β-cyclodextrin (Roxy/ β-CD) dispersions were prepared with a view to study the influence of β-CD on the solubility and dissolution rate of this poorly soluble drug. Phase-solubility profile indicated that the solubility of roxythromycin was significantly increased in the presence of β-cyclodextrin and was classified as AL-type, indicating the 1:1 stoichiometric inclusion complexes. Physical characterization of the prepared systems was carried out by differential scanning calorimetry (DSC), X-ray diffraction studies (XRD) and IR studies. Solid state characterization of the drug β-CD binary system using XRD, FTIR and DSC revealed distinct loss of drug crystallinity in the formulation, ostensibly accounting for enhancement of dissolution rate.

Thermal Behaviour of Candesartan Active substance and in pharmaceutical compounds

2017 ◽  
Vol 68 (8) ◽  
pp. 1895-1902
Author(s):  
Ioana Cristina Tita ◽  
Eleonora Marian ◽  
Bogdan Tita ◽  
Claudia Crina Toma ◽  
Laura Vicas
Keyword(s):  
Thermal Behaviour ◽  
Active Substance ◽  
Pharmaceutical Research ◽  
Pharmaceutical Product ◽  
Nitrogen Atmosphere ◽  
Pure Substance ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Ft Ir

Thermal analysis is one of the most frequently used instrumental techniques in the pharmaceutical research, for the thermal characterization of different materials from solids to semi-solids, which are of pharmaceutical relevance. In this paper, simultaneous thermogravimetry/derivative thermogravimetry (TG/DTG) and differential scanning calorimetry (DSC) were used for characterization of the thermal behaviour of candesartan cilexetil � active substance (C-AS) under dynamic nitrogen atmosphere and nonisothermal conditions, in comparison with pharmaceutical product containing the corresponding active substance. It was observed that the commercial samples showed a different thermal profile than the standard sample, caused by the presence of excipients in the pharmaceutical product and to possible interaction of these with the active substance. The Fourier transformed infrared spectroscopy (FT-IR) and X-ray powder diffraction (XRPD) were used as complementary techniques adequately implement and assist in interpretation of the thermal results. The main conclusion of this comparative study was that the TG/DTG and DSC curves, together with the FT-IR spectra, respectively X-ray difractograms constitute believe data for the discrimination between the pure substance and pharmaceutical forms.

Crystal Transition and Drug-excipient Compatibility of Clarithromycin in Sustained Release Tablets

2020 ◽  
Vol 16 (7) ◽  
pp. 950-959
Author(s):  
Yu Li ◽  
Xiangwen Kong ◽  
Fan Hu
Keyword(s):  
Sustained Release ◽  
Powder Diffraction ◽  
Magnesium Stearate ◽  
Influential Factor ◽  
High Concentration ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Sustained Release Tablets ◽  
Crystal Transition ◽  
Excipient Compatibility

Background: Clarithromycin is widely used for infections of helicobacter pylori. Clarithromycin belongs to polymorphic drug. Crystalline state changes of clarithromycin in sustained release tablets were found. Objective: The aim of this study was to find the influential factor of the crystal transition of clarithromycin in preparation process of sustained-release tablets and to investigate the possible interactions between the clarithromycin and pharmaceutical excipients. Methods and Results: The crystal transition of active pharmaceuticals ingredients from form II to form I in portion in clarithromycin sustained release tablets were confirmed by x-ray powder diffraction. The techniques including differential scanning calorimetry and infrared spectroscopy, x-ray powder diffraction were used for assessing the compatibility between clarithromycin and several excipients as magnesium stearate, lactose, sodium carboxymethyl cellulose, polyvinyl-pyrrolidone K-30 and microcrystalline cellulose. All of these methods showed compatibilities between clarithromycin and the selected excipients. Alcohol prescription simulation was also done, which showed incompatibility between clarithromycin and concentration alcohol. Conclusion: It was confirmed that the reason for the incompatibility of clarithromycin with high concentration of alcohol was crystal transition.

scholarly journals Is Micro X-ray Computer Tomography a Suitable Non-Destructive Method for the Characterisation of Dental Materials?

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1271
Author(s):  
Andreas Koenig ◽  
Leonie Schmohl ◽  
Johannes Scheffler ◽  
Florian Fuchs ◽  
Michaela Schulz-Siegmund ◽  
...  
Keyword(s):  
Flexural Strength ◽  
Computer Tomography ◽  
Mechanical Performance ◽  
Dental Materials ◽  
Three Dimensional ◽  
X Rays ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Multiple Measurements ◽  
High Doses

The aim of the study was to investigate the effect of X-rays used in micro X-ray computer tomography (µXCT) on the mechanical performance and microstructure of a variety of dental materials. Standardised bending beams (2 × 2 × 25 mm3) were forwarded to irradiation with an industrial tomograph. Using three-dimensional datasets, the porosity of the materials was quantified and flexural strength was investigated prior to and after irradiation. The thermal properties of irradiated and unirradiated materials were analysed and compared by means of differential scanning calorimetry (DSC). Single µXCT measurements led to a significant decrease in flexural strength of polycarbonate with acrylnitril-butadien-styrol (PC-ABS). No significant influence in flexural strength was identified for resin-based composites (RBCs), poly(methyl methacrylate) (PMMA), and zinc phosphate cement (HAR) after a single irradiation by measurement. However, DSC results suggest that changes in the microstructure of PMMA are possible with increasing radiation doses (multiple measurements, longer measurements, higher output power from the X-ray tube). In summary, it must be assumed that X-ray radiation during µXCT measurement at high doses can lead to changes in the structure and properties of certain polymers.

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