Vaporisation et dissociation thermique des sulfures de phosphore P4S3, P4S7 et P4S10 a l'etat gazeux

Résumé Nous avons montré par spectrométrie Raman à chaud et mesure des tensions de vapeur que P₄S₃ se vaporise de façon congruente tandis que P₄S₇ et P₄S₁₀ se dissocient dès le début de leur vaporisation. P₄S₇ donne réversiblement P₄S₃ et soufre. P₄S₁₀ se dissocie irréversiblement en P₄S₇ et soufre. A l'état de vapeur non saturante, P₄S₃ se dissocie au-dessus de 600° avec formation de phosphore, de soufre et d'autres espèces non identifiées.Nous avons mesuré expérimentalement la capacité calorifique de P₄S₃ liquide, calculé celle de P₄S₃ gazeux et son entropie standard. Nous avons aussi estimé l'enthalpie standard de vaporisation de P₄S₃ à l'aide des mesures des tensions de vapeur saturante. Nous en avons déduit l'entropie standard de P₄S₃ liquide et son point d'ébullition.

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It is shown by Raman spectroscopy at high temperature and by vapor tensimetric measurements that the vaporisation of P₄S₃ is congruent, whereas P₄S₇ and P₄S₁₀ dissociate at the beginning of vaporisation. P₄S₇ gives P₄S₃ and sulfur reversibly. The dissociation of P₄S₁₀ into P₄S₇ and sulfur is irreversible. Above 600°, in non-saturated vapour the dissociation of P₄S₃ gives phosphorus, sulfur and some unidentified gaseous species. The heat capacity of liquid P₄S₃ has been measured. That of gaseous P₄S₃ and its standard entropy have been calculated. The vaporisation standard enthalpy of P₄S₃ has been estimated from the experimental results on the saturated vapour pressures. The standard entropy of liquid P₄S₃ and its boiling point have been derived from these data.

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Zusammenfassung Mittels Raman-Spektrometrie bei erhöhter Temperatur und durch Messung der Dampfdrucke wurde festgestellt, daß sich P₄S₃ verflüchtigt, während P₄S₇ und P₄S₁₀ mit Beginn der Verflüchtigung dissoziieren. P₄S₇ ergibt reversibel P₄S₃ und Schwefel. Im Zustand ungesättigten Dampfes dissoziiert P₄S₃ oberhalb von 600° unter Bildung von Phosphor, Schwefel und anderer nicht identifizierter Substanzen.Die Wärmekapazität von flüssigem P₄S₃ wurde gemessen, während die vom gasförmigem P₄S₃ sowie seine Standard-Entropie berechnet wurden. Die Standard-Enthalpie der Verflüchtigung des P₄S₃ wurde durch Messungen der Sättigungs-Dampfdrucke ermittelt. Daraus wurden die Standard-Entropie des flüssigen P₄S₃ sowie sein Siedepunkt berechnet.

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- - , P₄S₃ , P₄S₇ P₄S₁₀ . P₄S₇ P₄S₃ , P₄S₁₀ P₄S₇ . 600° P₄S₃ , . P₄S₃, P₄S₃ . P₄S₃. P₄S₃ .

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Nous remercions Monsieur Letoffe du laboratoire du Professeur J. Bousquet, INSA de Lyon, 20 Avenue Albert Einstein 401, 69621 Villeurbanne, qui a r6alis6 pour nous les déterminations expérimentales des capacités calorifiques de P₄S₈ liquide.     

Etude par diffraction de neutrons de la phase Sr0,5La1,5Li0,5Fe0,5O4

A neutron diffraction study has been carried out on Sr_0.5La_1.5Li_0.5Fe_0.5O₄ of K₂NiF₄-type derived structure and it has shown that iron in the tetravalent state has a high spin configuration (t³_2ge¹_g) and that the material has some stacking defects. At room temperature this compound shows an ordering between iron and lithium atoms leading to a nuclear cell a₀√2, a₀√2, c₀ (a₀ and c₀ are the parameters of the K₂NiF₄-type cell). At low temperature ($\text{T <}\text{T}{}_{\mathrm{<mtext>N</mtext>}}\text{2}$) the magnetic structure can be described as antiferromagnetic, corresponding likely to a colinear pattern with a propagation vector of 0.5 ($\text{2π}\text{a}{}_0$) along the [110] axis. At higher temperature ($\text{T}{}_{\mathrm{<mtext>N</mtext>}}\text{2}\text{< T < T}{}_{\mathrm{<mtext>N</mtext>}}$) helimagnetic structure is consistent with a propagation vector of 0.47 ($\text{2π}\text{a}{}_0$) [110].     

Le metaplombate et le triplombate de potassium

Two new potassium plumbates are prepared by action of anhydrous KOH on its melting point on PbO₂: the metaplumbate K₂PbO₃ and the triplumbate K₂Pb₃O₇. They are isostructural with previously studied K₂SnO₃ and K₂Sn₃O₇. Some properties of both compounds are given.     

Nombre de transport et conductivite cationique dans les oxydes de calcium et de strontium

The cationic transference numbers have been determined for alkaline earth oxides using sample linear expansion measurements coupled with coulometric titration.Single crystal CaO has been studied in the temperature range 1200–1450°C, under oxygen partial pressures varying from 1 to 10^?5 atm. Under air, t_Ca at 1300°C is close to 0.02.Polycrystalline samples of SrO, under air, were tested from 1100°C to 1350°C, and showed a t_Sr value of 0.012 at 1300°C.The total conductivity of CaO was measured to obtain a value for the cationic conductivity. This value is compared with the data obtained from the self diffusion coefficient of Ca in CaO.     

Structure Cristalline du Sulfure d'Étain(II) et de Thallium(I) Tl2Sn2S3

Crystal Structure of Tl₂Sn₂S₃ The compound Tl₂Sn₂S₃ had been prepared from SnS? Tl₂S mixtures. The cell is monoclinic, space group C2/c with a = 13.887(7), b = 7.742(4), c = 7.267(4) Å, β = 105.39(3)° and Z = 4. The structure was solved by the symbolic addition method and refined by least-squares to a final R = 0.086 for the 382 observed reflections. From this structure it is apparent that Tl₂Sn₂S₃ is of defect NaCl type with the thallium and tin atoms distributed over the cation positions, the sulfur atoms and vacancies over the anion positions. Tl and Sn atoms have four bonds to S atoms of 2.81–3.13 Å and 2.68–3.11 Å respectively. The thallium and tin lone pairs of electrons are stereochemically active.     

Spectres de vibration et champ de force de l'antimoniate et de l'arseniate de calcium CaSb2O6 et CaAs2O6

The i.r. and Raman spectra of the antimonate CaSb₂O₆ and arsenate CaAs₂O₆ belonging to the “PbSb₂O₆ type” structure are studied. A normal coordinate calculation permitted us to calculate and to compare their relative force fields. A comparison with results obtained for other antimony and arsenic oxides is presented.     

Etude par spectroscopie de vibration des hexahydroxodialuminate et digallate de potassium

Infrared and Raman spectra of K AlO₂, 1,5 H₂O and K GaO₂, 1,5 H₂O are interpreted on the basis of [Al₂O(OH)₆]²⁻ and [Ga₂O(OH)₆]²⁻ ions. They support a previous X-ray study on the potassium hexahydroxodialuminate. These ions are constituted by two MO₄ tetrahedra sharing one oxygen atom. Spectra show very little difference between the three external MO bonds and the internal one, around each metal atom. On the other hand, due to the presence of a cristallographic symmetry axis on the oxygen atom of the MOM bridge, the spectra of isotopic mixed crystals allow us to characterize only three OH (or OD) bonds of different lengths. The hydrogen bonds lengths obtained from the v(OH) frequencies agree very well with the observed external oxygen-hydrogen distances. The MO₄ tetrahedra of a M₂O₇ unit are slightly coupled and the study of MO₃ group frequencies shows that the MO bond strength increases when aluminium is replaced by gallium. This fact explains increase and decrease of bending and stretching OH vibrations.     

Dosage amperometrique rapide et directe de calcium et de magnesium dans l'eau,les ciments et le sol

An amperometric method for thé successive titration of calcium and magnesium with EGTA and EDTA respectively is proposed. The method is direct and rapid. Calcium and magnesium can be determined in waters (41.5 mg/l and 4.6 mg/l with a precision of ±1.15% and ±6.70%), in cements (66.7% CaO and 1.70% MgO with a precision of ±2% and ±8%), and in soils (16.5% CaCO₃ and 1.8% MgCO₃ with a precision of ±2.6% and ±5.5%). The results obtained are compared with those obtained by gravimetric or titrimctric methods.     

Etude des residus d'evaporation de solutions d'hydrogenocarbonates de calcium et de magnesium

Résumé Des résidus d'évaporation de solutions pures ou mixtes de Ca(HCO₃)₂ et Mg(HCO₃)₂ ont été étudiés par ATD (atmosphère N₂ ou CO₂), ATG, AGE, rayons X et analyse classique. La valeur du rapport atomique Ca/Mg a une influence considérable sur la manifestation des accidents thermiques compris entre 400 et 500°. Pour 1.2 3 est sous forme d'aragonite. Pour Ca/Mg > 1.25, la calcite se substitue progressivement à l'aragonite, mais pas totalement. L'étude se poursuit afin de dégager d'autres conclusions.

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Residues from the evaporation of pure or mixed solutions of Ca(HCO₃)₂ and Mg(HCO₃)₂ were subjected to investigation by DTA (N₂ or CO₂ atmosphere), TG, EGA, X-ray and classical chemical analysis. The Ca/Mg atomic ratio exerted a great effect on EGA and DTA peaks between 400 and 500°. Peak temperatures were the lowest when 1.2 < Ca/Mg < 1.33. When Ca/Mg < 1.25, CaCO₃ exists only as aragonite. When Ca/Mg > 1.25, calcite progressively replaces aragonite, but never entirely. Investigations are continuing.

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Zusammenfassung Die Verdampfungsrückstände reiner Lösungen bzw. Gemische von Ca(HCO₃)₂ und Mg(HCO₃)₂ wurden mittels DTA (in N₂- oder CO₂-Atmosphäre), TGA, EGA, Röntgenstrahlung und klassischer Analyse untersucht. Der Wert des Atomverhältnisses Ca/Mg hat einen bedeutenden Einfluß auf die thermischen Vorgänge zwischen 400° und 500°. Bei 1.2 < Ca/Mg < 1.33 werden die Spitzen in Richtung der niederen Temperaturen verschoben. Bei Ca/Mg < 1.25 befindet sich das CaCO₃ in der Aragonitform. Bei Ca/Mg > 1.25 wird Aragonit fortschreitend, jedoch nicht vollständig durch Calcit ersetzt. Die Versuche werden fortgesetzt, um weitere Aussagen zu ermöglichen.

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, C(₃)₂ Mg (₃)₂, ( N_{2 2}) , , () . Ca/Mg 400–500°. 1.2 < Ca/Mg < 1.33. Ca/Mg < 1,25, ₃ . Ca/Mg > 1.25, , . .

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Nos remerciements vont à Monsieur le Professeur A. Beugnies, pour nous avoir accordé Ja permission d'utiliser son installation de rayons X avec le concours de son personnel spécialisé.     

Comportement thermique des benzènesulfonates de lithium,sodium et potassium

Résumé Le comportement thermique des benzènesulfonates de lithium, sodium et potassium a été étudié par TG et ATD à l'air et sous atmosphère d'azote.Dans la zone de stabilité des sels anhydres, nous avons mis en évidence des transformations réversibles (changements de phase cristalline) dont certaines ont fait l'objet de mesures calorimétriques.L'étude des résidus solides de la décomposition a montré une proportion importante de sulfates dans les produits obtenus dans l'air, alors que sous azote, il s'agissait surtout de sulfures. Les sulfites ne se présentent qu'en très faible quantité dans les deux cas.

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The thermal behaviour of benzènesulphonates of lithium, sodium and potassium has been investigated by TG and DTA in air and in an atmosphere of nitrogen.We have shown in the stability interval of the anhydrous salts reversible transformations (phase transitions), some of which were quantitatively studied by calorimetry.The radiocristallographic study of the solid residues has shown an important proportion of sulphates in the residues in air and of sulphides in an inert atmosphere. The sulphites were found in very small quantity in both cases.

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Zusammenfassung Das thermische Verhalten der Benzolsulfonate von Lithium, Natrium und Kalium wurde durch TG und DTA in Luft und in Stickstoff untersucht.Im Stabilitätsbereich der wasserfreien Salze wurden reversible Umwandlungen (Phasenübergänge) nachgewiesen, von denen einige quantitativ durch Kalorimetrie untersucht wurden.Das radiokristallographische Studium der festen Rückstände zeigte, daß in Luft ein bedeutender Anteil der Rückstände aus Sulfaten und in inerter Atmosphäre aus Sulfiden besteht. Sulfite wurden in beiden Fällen in sehr geringen Mengen gefunden.

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Determination par calorimetrie de dissolution des enthalpies de formation de quelques silicates,aluminates et alumino-silicates de calcium

The enthalpies of formation of 13 calcium silicates, aluminates, alumino-silicates and ferro-alumino-silicates were measured by dissolution calorimetry with the help of a high-temperature Calvet calorimeter. Dissolution experiments were performed in a lead metaborate (2PbO?B₂O₃) baths at 1173 K. The synthesis of the samples was realized by melting together pure silica, alumina, ferric oxide and calcium carbonate in appropriate ratios. The samples obtained in this way were examined by X-ray diffraction and scanning electronic microscopy. The free lime content was also determined by chemical analysis. The enthalpy of formation of silicates and aluminates obeys two different linear relations with respect to the ratio Ca/X (X=Al or/and Si) except for Ca₁₂Al₁₄O₃₃ which does not exist in its pure form but has to be stabilized by anions as OH^? or Cl^?. The data corresponding to the two aluminosilicates are located between these lines. The enthalpy of formation of tricalcium silicate (Ca₃SiO₅ i.e. C₃S according to the Bogue terminology) from dicalcium silicate and lime could be calculated as ?6kJ·mol^?1. This reaction is the most important one in the industrial process of clinkerization.