Mechanism of the thermal decomposition of hydrophosphites of lithium,sodium and potassium

The thermal decomposition of some M ₂ ^I HPO₃ (M-Li, Na, K) phosphites under nitrogen atmosphere was investigated. A stepwise mechanism of thermal decomposition has been proposed.

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Zusammenfassung Es wurde die thermische Zersetzung von Phosphiten M ₂ ^I HPO₃ (M-Li, Na, K) in Stickstoffatmosphere untersucht. Die Schritte des Mechanismus der thermischen Zersetzung wurden vorgeschlagen.

     

Preparation and purification of Semi-Methylthymol Blue

A direct extractive method has been developed for preparation of pure Semi-Methylthymol Blue (SMTB) from a synthetic mixture containing ca. 30% of SMTB in presence of Thymol Blue (TB, ca. 45%), Methylthymol Blue (MTB, ca. 10%) and other components such as acetic acid and iminodiacetic acid (IDA). The method is based on the dependence of the extraction coefficients of the individual components on the pH of an aqueous phase in equilibrium with butanol phase. The separation of TB from the mixture is best at pH 9.5–10.5 and the separation of SMTB is best at pH 2.9–4.5. At pH 10.2 the ratio of the extraction coefficient of TB to that of SMTB is 213 and to that of MTB is 776. At pH 2.9 the ratio of the extraction coefficient of SMTB to that of MTB is ca. 20 and at pH 4.5 is ca. 100, but the absolute values of the extraction coefficient for SMTB are only 3.4 at pH 4.5 and ca. 10 at pH 2.9. This means the quantitative transfer of SMTB to the butanol phase is much easier at pH 2.9. Then a more complete separation of SMTB from the mixture with MTB can be achieved by stripping of the latter into a pH 4.5 aqueous medium. The method for obtaining of anhydrous SMTB is also given. About 70% of the original amount SMTB present can be obtained as the dry product (containing over 99% SMTB).     

Analysis of the steps of thermal decomposition of oxo-compounds of the dsp block elements

Analysis of thermal decomposition of manganates(VII) and chromates(VI) in terms of the Górski's morphological classification was used to distinguish typical steps of decomposition of oxides and oxo-salts of dsp block elements and to determine the effect of cationic counterions on decomposition of chromates(VI).

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Zusammenfassung Eine Analyse der thermischen Zersetzung von Manganaten(VII) und Chromaten(VI) der morphologischen Klassifizierung von Gorski wurde benutzt, um typische Schritte der Zersetzung von Oxiden und Oxosalzen der Elemente des dsp-Feldes zu unterscheiden und den Effekt der kationischen Gegenionen auf die Zersetzung von Chromaten(VI) zu bestimmen.

     

Solid phase reactivity of sodium oxosalts of manganese

The observed relationships are presented of the solid phase reactivity of the following salts: NaMnO₄, Na₂MnO₄, Na₃MnO₄, Na₄MnO₄, Na₂MnO₃, Na₂Mn₂O₅, Na₅MnO₄, Na₄Mn₂O₅, NaMnO₂, Na₄MnO₃, Na₂MnO₂ and Na₂Mn₂O₃.     

Stages of thermal decomposition of sodium oxo-salts of sulphur

Thermal behaviour of sodium oxo-salts of sulphur: Na₂SO₄, Na₂S₂O₇, Na₂S₂O₆, Na₂SO₃, Na₂S₂O₅, Na₂S₂O₄, Na₂S₂O₃, Na₂S₃O₆ and of sulphides Na₂S and Na₂S₂ was studied on heating up to 1000°C. The experiments were performed with anhydrous compounds obtained from commercial products by recrystallisation and dehydration. The stage mechanisms of decomposition of anionic sub-lattices of the salts have been proposed basing on the Górski’s morphological classification of simple species. The thermal stability and the stage decomposition mechanisms were correlated with the structure and the potential chemical properties of the salt anions. The thermal decomposition processes were studied by means of thermal analysis, and the decomposition products were identified by means of X-ray phase analysis.     

Chemical processes in kaolin sintered with NaH2PO4

The results of experiments on application of NaH₂PO₄ as a binding agent for ceramic kaolin samples were presented. The experiments were carried out at temperatures of 973, 1073 and 1173 K and NiO and CoO additives were used as tempering agents. The parameters of the obtained samples with NaH₂PO₄ were compared with the samples compressed with water only. The materials of 3-4 times higher bending strength, lower water absorption as well decreased open porosity were prepared during these experiments. The binding function of the NaH₂PO₄ additive relies on creation of some compounds in reaction between the products of its condensation and products of kaolin decomposition. Finally a ceramic material of prospective properties was created. This revised version was published online in July 2006 with corrections to the Cover Date.     

Mechanism of thermal decomposition of hydrogenphosphities

Evolution of hydrogen during thermal decomposition of some M^IIHPO₃ (M= Mg, Ca, Zn, Sr, Cd, Ba) phosphities under nitrogen atmosphere was investigated. Step mechanism of thermal decomposition has been proposed.

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Zusammenfassung Es wurde die Wasserstoffentwicklung während der thermischen Zersetzung einiger Phosphite M^II)HPO₃ (mitM=Mg, Ca, Zn, Sr, Cd, Ba) in einer Stickstoffatmosphäre untersucht. Es wurde ein schematischer Mechanismus für die thermische Zersetzungsreaktion gegeben.

     

Interface magnetic anisotropy in metallic superlattices

We have prepared Pd/M and Cu/M (M = Fe, Co, Ni) magnetic superlattices using a dc sputtering and standard UHV e-beam evaporation. Sample quality was confirmed by the intense satellite peaks in the θ−2θ X-ray diffraction patterns. For all the systems studied, torque measurements revealed positive intrinsic uniaxial anisotropy but less than 2πM²_s. Results showed that the main source of the interface anisotropy is Néel surface anisotropy.     

Simultaneous spectrophotometric determination of o-cresol red, semi-xylenol orange and xylenol orange

A direct simultaneous spectrophotometric method for the determination of o-Cresol Red (CR), Semi-Xylenol Orange (SXO) and Xylenol Orange (XO) in mixtures in the presence of other components usually found in commercial SXO and XO reagents is presented. The method of selecting the most advantageous conditions for the spectrophotometric determination of the three dyes in different mixtures is given.     

Optical and magneto-optical properties of Co/Pt multilayered films

Both experimental and computer-simulated magneto-optical (MO) and optical spectroscopies of Co/Pt multilayered films (MLF) with a nearly constant Pt sublayer thickness and variable Co sublayer thickness, as well as pure Co and Pt, and Co_0.51Pt_0.49 alloy films, have been performed in the energy range 1.1–4.7 eV. The simulations were achieved by solving the multireflection task for various models of the MLF. The comparison between experimental and computer-simulated optical properties of the Co/Pt MLF allowed us to evaluate the thickness of the interfacial regions with the alloyed components. The diagonal and off-diagonal components of the optical conductivity tensor were calculated not only for the pure Co and Co_0.51Pt_0.49 alloy films, and the whole Co/Pt MLF, but also for the spin-polarized Pt layers in the Co/Pt MLF.