Influence of alkali metal sodium doping on the properties of potassium hydrogen phthalate (KHP) crystals

The effect of doping sodium on the growth process and properties of potassium hydrogen phthalate (KHP) single crystals by slow evaporation solution growth technique has been investigated. Incorporation of sodium into the crystalline matrix even in the presence of low dopant concentration in aqueous growth medium is well confirmed by energy dispersive X-ray spectroscopy and quantified by atomic absorption spectroscopy and inductively coupled plasma emission spectrometer (ICP) techniques. The FT-IR spectral analysis confirms the slight distortion of the structure of the crystals as a result of doping. The TG-DTA studies reveal the purity of the material and no decomposition is observed up to the melting point. Low Na-doping (10 mol%) slightly increases the second harmonic generation efficiency, whereas heavy doping {[KHP]:[Na] = 1:1} results in significant enhancement. It has also been found that the doping results in morphological changes.     

Spectral and thermal characteristics of copper(II) carboxylates with fatty acid chains and their benzothiazole adducts

The carboxylato–Cu(II) complexes of type [Cu₂(RCOO)₄] and their benzothiazole adducts [Cu₂(RCOO)₄bt₂] (bt = benzothiazole, R = CH₃(CH₂) _n?2, n = 12, 14, 16, 18) form the main objectives of this study. The studied carboxylato–Cu(II) complexes are formed from dimeric units to polymeric chains (chromofor CuO₅). The structural changes are due to coordination of ligand (benzothiazole). The polymeric chains of carboxylato–Cu(II) complexes degraded to discrete centrosymetric tetracarboxylate-bridged dimmers (chromofor CuO₄N). These prepared compounds [Cu₂(RCOO)₄] and [Cu₂(RCOO)₄L₂] were submitted to measurements relating to spectral (IR, UV–Vis) and thermal properties (TG, DTA, DSC).     

Thermal stability of Li2O–SiO2–TiO2 gels evaluated by the induction period of crystallization

To evaluate the thermal stability of materials, various criteria have been used. Not only the simple parameters, as characteristic temperatures, but also the combined criteria E/RT _p , k _f (T) and criterion based on the length of induction period of crystallization have been taken into account. Four gels with the composition Li₂O–2SiO₂–nTiO₂ (n = 0.00, 0.03, 0.062, and 0.1) were prepared and the validity of the criteria was tested by applying them to these gels. The results indicate that thermal stability of the studied gels decrease with amount of TiO₂.     

Thermal properties of solid complexes with biologically important heterocyclic ligands

The stoichiometry of thermal decomposition of the complexes Ni(NCS)₂(fpy)₄ (I), Ni(NCS)₂(bfpy)₄ (II) and Ni(NCS)₂(CF₃Phfpy)₄ (III) (where fpy=furopyridine, bfpy=benzo-[2,3]furo[3,2-c]pyridine, CF₃Phfpy=2-(3-fluoromethylphenyl) furo[3,2-c]pyridine) have been investigated in nitrogen atmosphere from room temperature to 500°C by means of TG and DTG. The results revealed that release of the heterocyclic ligands occurs in two steps. IR data suggested that fpy, bfpy and CF₃Phfpy ligands were coordinated to Ni(II) through the N atom of the respective heterocyclic rings and same is the case with the anionic NCS group.     

Os(VIII) doping effects on the properties and crystalline perfection of potassium hydrogen phthalate (KHP) crystals

The effect of dopant, Os(VIII) on the growth process, crystalline perfection and properties of potassium hydrogen phthalate (KHP) single crystals grown by a slow evaporation solution growth technique has been investigated. The XRD analysis of black-colored doped specimen reveals slight structural changes as a result of doping. The SEM images exhibit defect centers and crystal voids. The complex formation of KHP with Os(VIII) is evidenced by the considerable shift in λ_max of the doped specimen and enhanced fluorescence intensity is observed by doping. Differential scanning calorimetry (DSC) and TG-DTA studies reveal the purity of the sample and no decomposition is observed up to the melting point. The high resolution X-ray diffraction (HRXRD) studies used to evaluate the crystalline perfection reveal some features on the capability of accommodating the dopant in the crystalline matrix. The diffraction curve (DC) patterns indicate that the high valence transition metal predominantly occupies the interstitial positions and the doping depresses the second harmonic generation (SHG) efficiency owing to the deterioration of crystalline perfection disturbing the charge transfer and nonlinearity.     

Thermal and spectral properties of halogenosalicylato-Cu(II) complexes

The paper presents the applicability of oxyreactive thermal analysis (OTA) for the investigation of different kinds of resins both natural (recent and fossil) and synthetic. For comparative reasons and a more precise interpretation, along with OTA infrared spectroscopy was used as a method commonly applied for the investigation of fossil resins. The results obtained prove that the OTA method may be very useful for diversification of different kinds of resins. The parameter most valuable for the preliminary characteristics of resins and the evaluation of their transformation was found to be the mass loss recorded on TG curves in three definite temperature ranges. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal properties,induction period,interfacial energy and nucleation parameters of solution grown benzophenone

The kinetic parameters (reaction order, n, activation energy, E, pre-exponential factor, A, constant rate, k) for the dehydration step due to elimination of osmotic water and hydrogen-bounded water with the carboxylic groups, and for the anhydrifying step owing to the dehydration of two neighboring (-COOH) groups, were determined under non-isothermal conditions for some carboxylic resins with acrylic-divinylbenzene (DVB) matrix. The kinetic parameters were evaluated by means of isoconversional methods from (TG/DTG) thermal analysis data. The results show a dependence of the apparent kinetic parameters on the cross-linking degree, granulation, gel/macroporous matrix nature, exchange capacity and heating rate.     

The Thermal Decomposition of Magnesium(II) Complexes with Acetic and Halogenacetic Acids

Thermogravimetry (TG), differential thermal analysis (DTA) and other analytical methods have been applied to the investigation of the thermal behaviour and structure of the compounds Mg(Ac)₂ × 2H₂ O(I), Mg(ClAc)₂ ×2H₂ O(II) and Mg(Cl₂ Ac)₂ ×H₂ O(III) (Ac =CH₃ COO⁻ , ClAc =ClCH2COO⁻ , Cl ₂ Ac =Cl₂ CHCOO⁻ ). The solid phased intermediate and resultant products of thermolysis had been identified. The possible scheme of destruction of the complexes is suggested. The halogenacetato magnesium complexes (II–III) are thermally more stable than the acetatomagnesium complex I. The final products of the decomposition of compounds were MgO. Infrared (IR) data suggest to a unidentate coordination of carboxylate ions to magnesium ions in complexes I–III. This revised version was published online in August 2006 with corrections to the Cover Date.