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Abstract

In this article, the effect of magnesium doping on the properties of bis(thiourea)zinc(II) chloride (BTZC) crystals has been described. The incorporation of Mg(II) into the crystal lattice was confirmed by energy dispersive X-ray spectroscopy and quantified by inductively coupled plasma technique. The powder X-ray diffraction and FT-IR spectral analyses indicate that the crystal undergoes considerable stress as result of doping. SEM studies of pure and doped samples indicate the formation of structural defect centers in BTZC crystals. The TG–DTA studies reveal the purity of the materials, and no decomposition is observed up to the melting point. Improved crystalline perfection by doping is observed by high-resolution X-ray diffraction. High transmittance is observed, and the cutoff λ is ~295 nm.

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Furopyridines and furopyridine-Ni(II) complexes

Synthesis, thermal and spectral characterization

Journal of Thermal Analysis and Calorimetry
Authors:
S. C. Mojumdar
,
J. Miklovič
,
A. Krutošíková
,
D. Valigura
, and
J. M. Stewart
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Journal of Thermal Analysis and Calorimetry
Authors:
S. Šnircová
,
E. Jóna
,
R. Janík
,
Ľ. Lajdová
,
S. Lendvayová
,
M. Loduhová
,
V. Šutinská
,
R. Durný
,
P. Lizák
, and
S. C. Mojumdar

Abstract

The influence of different steric properties of ethylenediamine (EDA), trimethylenediamine (TrMeEDA) and tetraethylenediamine (TeMeEDA) on the type of interactions with Co(II)-exchanged montmorillonite and thermal decomposition of these materials were studied. The results of X-ray diffraction (XRD), thermogravimetry (TG), derivative thermogravimetry (DTG) and spectral analysis shows that the studied ethylenediamines are intercalated into the interlayer space of montmorillonite. Thermal decomposition at 20–500 °C of studied samples with EDA proceeds in three steps (the release of chemosorbed amines, coordinated EDA and dehydroxylation) while the sample with TrMeEDA and TeMeEDA in five steps (also release the protonated forms). The effect of different steric properties of individual diamines is evident.

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Thermal properties of oxide glasses

Part IV. Induction period of crystallization as a criterion of thermal stability of M2OSiO2 (M = Li, Na) glass systems against crystallization

Journal of Thermal Analysis and Calorimetry
Authors:
S. Lendvayová
,
K. Moricová
,
E. Jóna
,
J. Kraxner
,
M. Loduhová
,
V. Pavlík
,
J. Pagáčová
, and
S. C. Mojumdar

Abstract

A criterion based on the length of induction period of crystallization was used to evaluate the thermal stability of M2O·SiO2 (M = Li, Na) glasses against crystallization. It was founded out that the stability of studied glasses against crystallization is Li2O·SiO2 < Na2O·SiO2. The results coincide with the order determined by stability criteria based on temperatures and the values of activation energy. A criterion based on the length of induction period enables to discriminate among the thermal stabilities of the silicate glass systems.

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Thermal properties of solid complexes with biologically important heterocyclic ligands

Part IV. Thermal and spectral properties of 2-chloro- and 2-bromobenzoato Cu(II) complexes with nicotinamide and different bonded water molecules

Journal of Thermal Analysis and Calorimetry
Authors:
E. Jóna
,
L’. Lajdová
,
M. Loduhová
,
S. Lendvayová
,
V. Pavlík
,
J. Moncol’
,
P. Lizák
, and
S. C. Mojumdar

Abstract

Thermogravimetry (TG), derivative thermogravimetry (DTG) and infrared (IR) spectroscopy have been applied to the investigation of the thermal behaviour and structure of the compounds [Cu(2-Clbz)2(nia)2(H2O)2] (I), [Cu(2-Clbz)2(nia)2]·H2O (II), [Cu(2-Brbz)2(nia)2]·2H2O (III), [Cu(2-Brbz)2(nia)2(H2O)] (IV), where 2-Clbz and 2-Brbz = 2-chloro- and 2-bromobenzoate anions, nia = nicotinamide, H2O = water molecules. Thermal decomposition of all studied compounds proceeds in three steps. Heating the compounds first results in a release of non-coordinated and/or coordinated water molecules. The final product of thermal decomposition was CuO. The thermal stability of the complexes can be ordered in the sequence: I<IV<III<II. Nicotinamide is coordinated to Cu(II) through the nitrogen atom of the heterocyclic ring. IR data suggest the unidentate coordination of benzoate anions to Cu(II) in complexes I, IV and bidentate coordination in complexes II and III.

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Thermal properties of solid complexes with biologically important heterocyclic ligands

Part III. Thermal decomposition and infrared spectra of thiocyanato Mg(II) complexes with 2-hydroxypyridine, quinoline, and quinoxaline

Journal of Thermal Analysis and Calorimetry
Authors:
E. Jóna
,
L’. Lajdová
,
L’. Kvasnicová
,
S. Lendvayová
,
M. Pajtášová
,
D. Ondrušová
,
P. Lizák
, and
S. C. Mojumdar

Abstract

The thermal decomposition of the complexes Mg(SCN)2(2-OHpy)4·H2O(I), Mg(SCN)2(quin)4·2H2O(II) and Mg(SCN)(quinox)4·5H2O(III) (2-OHpy–2-hydroxypyridine, quin–quinoline, quinox–quinoxaline) has been investigated in static air atmosphere at 20–1000 °C by means of thermogravimetry (TG), differential thermal analysis (DTA), and infrared (IR) spectroscopy. The composition of the complexes had been identified by means of elemental analysis and complexometric titration. The possible scheme of destruction of the complexes is suggested. The final product of the thermal decomposition was MgS. IR data suggest that heterocyclic ligands were coordinated to Mg(II) through the nitrogen atom of their heterocyclic ring. Thiocyanate group is also coordinated through the nitrogen atom.

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Journal of Thermal Analysis and Calorimetry
Authors:
S. Ľalíková
,
M. Pajtášová
,
M. Chromčíková
,
M. Liška
,
V. Šutinská
,
M. Olšovský
,
D. Ondrušová
, and
S. C. Mojumdar

Abstract

This paper is devoted to the investigation of the properties of the natural rubber composites prepared using the cation exchanged-montmorillonite fillers. The characteristics of the montmorillonite fillers were studied by Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TG). These characterized fillers were used to preparation of the natural rubber composites, which were submitted to measurements of dynamic-mechanical thermal analysis (DMTA) and vulcanizing characteristics (M H, M L, t s, t c(90), R v) as well as physico-mechanical properties (tensile strength, modulus at 300 elongation—M 300, tensibility).

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Abstract

The influence of the 2-, 3-, and 4-OH phenols on the type of interaction with Co-exchanged montmorillonite and thermal properties of these materials were studied. The results of XRD, IR, and thermal (TG, DTG) analysis show that organic species are intercalated into the interlayer space of montmorillonite. Thermal decomposition in the temperature interval 20–700 °C of studied samples with 2- and 3-hydroxyphenol proceeds in three steps (the release of adsorbed H2O molecules, combustion/desorption of protonated hydroxy phenols and dehydroxylation), while the sample with 4-hydroxyphenol decompose in four steps (the new peak at ~222 °C corresponds to directly coordinated organic species). The effect of different position of the hydroxyl groups on the phenol ring on the thermal decomposition is evident.

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