Thermal behaviour of acidic salts of mixed tetravalent metals

The results of investigations on intercalated crystalline zirconium phosphate are described in the literature. The behaviour of crystalline phosphates containing both zirconium and titanium metal ions has not been investigated previously. Within these investigations, the thermal behaviour of such materials has been studied in the temperature interval 25–1000 °C by simultaneous recording of TG, DTG and DTA curves. The results are presented in this paper.

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Zusammenfassung Ergebnisse über Untersuchungen an in Schichten eingelagerten kristallinen Zirkoniumphosphat sind in der Literatur beschrieben. Das Verhalten kristalliner Phosphate, die sowohl Zirkoniumals auch Titanmetallionen enthalten, wurde bis jetzt nicht untersucht. Als Teil dieser Untersuchungen wurde das thermische Verhalten solcher Materialien im Temperaturbereich 25–1000 °C durch simultanes Registrieren der TG-, DTG- und DTA-Kurven näher bestimmt, dessen Ergebnisse hier dargelegt werden.

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. , . , , 25–1000°. .

     

Thermal behaviour of acidic salts of mixed tetravalent metals

The mixed metal phosphates were synthetized by the HF method, the resulting materials being crystalline. Thermal analysis revealed that they contain almost one mole of crystalline water per molecule unit. The mode of thermal decomposition of the samples was similar to those for crystalline phosphates containing only zirconium or titanium.

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Zusammenfassung Die Mischmetallphosphate wurden mit der HF-Methode hergestellt, wobei man kristalline Substanzen erhielt. Die Thermoanalyse zeigte, daß sie fast ein Molekül Kristallwasser pro Moleküleinheit besitzen. Die Art der thermischen Zersetzung der Proben ähnelt der Zersetzung von kristallinen Phosphaten von nur Zirkonium oder nur Titan.

     

Thermal behaviour of acidic salts of mixed tetravalent metals

Mixed zirconium-titanium phosphate samples were irradiated in a gamma-radiation facility with a Co-60 source. The adsorbed dose was 10⁶ Gy. At this dose, a change in thermal bahaviour was found only for the samples intercalated withn-butylamine orn-propylamine. Further, it was found that the titanium catalysed the decomposition and the loss of organic molecules.

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Zusammenfassung Gemischte Zirkonium-Titanphosphatproben wurden in einer Gammabestrahlungskammer mit einer Co-60-Quelle bestrahlt. Die adsorbierte Dosis betrug 10⁶ Gy. Bei dieser Dosis konnte eine Veränderung im thermischen Verhalten nur für Proben mit eingelagertemn-Butylamin odern-Propylamin festgestellt werden. Weiterhin wurde gefunden, daß Titan die Zersetzung und die Abgabe der organischen Moleküle katalysiert.

     

Thermal behaviour of mixed tetravalent metal salts

In contrast with the well-known zirconium and titanium phosphates, products containing these metal ions together are unknown. To investigate the thermal behaviour of such materials, samples were synthetized with various ratios of the two metal ions. The samples were identified by means of X-ray diffraction. Their thermal behaviour was investigated in the temperature interval 25–1000 °C via simultaneous TG, DTG and DTA measurements. The data obtained are presented in this paper.

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Zusammenfassung Im Gegensatz zu den wohlbekannten Zirkonium- und Titanphosphaten sind beide Metallionen gleichzeitig enthaltende Produkte unbekannt. Zur Untersuchung solcher Substanzen wurden Proben mit unterschiedlichen Mengen der beiden Metallionen gefertigt und mittels Röntgendiffraktion identifiziert. Die Proben wurden im Temperaturbereich 25–1000 °C mittels simultaner TG-, DTG- und DTA-Messungen untersucht. Die Ergebnisse werden in dieser Arbeit mitgeteilt.

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, . . - , , 25–1000°. .

     

Mixed insoluble acidic salts of tetravalent metals

Mixed amorphous glassy type hafnium-titanium phosphates have been prepared. The composition and ion exchange capacity of the samples were investigated before and after -irradiation. In addition, the effect of temperature on the ion exchange capacity of the samples was determined. Based on the data obtained, neither the composition nor the ion exchange behavior of the investigated materials was altered by the irradiation. An increased drying temperature led to a decrease in the ion exchange capacity of the samples.     

Mixed insoluble acidic salts of tetravalent metals

Solid amorphous Zr-, Ti- and Zr_xTi_(1–x) phosphates (where x=0.10, 0.33, 0.66, and 0.90) in various sodium forms were contacted with an excess of solid oxalic acid dihydrate to its molten state for a given time. The oxalic acid was removed by extraction and the residue was washed with redistilled water. As a result of this, crystalline forms of Zr-, Ti-, and Zr_xTi_(1–x) phosphates were obtained. Using various sodium forms of the initial samples, higher rate of crystallisation resulted than that found in case of hydrogen forms of initial samples.     

Mixed insoluble acidic salts of tetravalent metals

Mixed amorphous, glassy type, zirconium-titanium arsenate (ZrTiAs) and hafniumtitanium arsenate (HfTiAs) have been prepared. The composition and exchange capacity of the prepared samples were investigated in comparison with pure zirconium, titanium and hafnium arsenates, respectively. For the samples the Zr_xTi_(1-x)(HAsO₄)₂·2H₂O and the Hf_xTi_(1-x)(HAsO₄)₂·2H₂O compositions (where 0<x<1) were found. The exchange capacity values were found less than those for pure arsenates, but they do not change their values under the effect of high dose of gamma-radiation.     

Mixed insoluble acidic salts of tetravalent metals IV. Crystalline mixed zirconium — Titanium phosphates

Mixed crystalline alpha zirconium — titanium phosphates with variable zirconium to titanium ratios have been prepared both by the well known gel reflux method and a modified HF method. Chemical analysis, X-ray, i.r. and thermal analysis were used to characterize the materials. Exchange capacities for these ion-exchangers have been evaluated by pH-titration combined with radioisotope tract technique for Na⁺, K⁺, Rb⁺ and Cs⁺.     

Mixed insoluble acidic salts of tetravalent metals VI. Crystalline mixed zirconium-titanium arsenate and hafnium-titanium arsenate

Mixed crystalline zirconium-titanium arsenates Zr_xTi(_1–x) (HAsO₄)₂·H₂O and harnium-titanium arsenates Hf_xTi(_1–x) (HAsO₄)₂ H₂O (where x=0–1) of various compositions with different Zr/Ti or Hf/Ti ratios have been prepared. The compounds have been characterized by X-ray, thermal analysis, chemical analysis, and pH-titrations. For powder X-rays, the compounds appear to be homogeneous crystalline materials with structures similar to -ZrP, -TiP or -ZrTiP. The thermograms show a loss of approximately two moles of H₂O, followed by a small loss of O₂ with probable formation of ZrO₂, As₂O₃, HfO₂, As₂O₃, ZrO₂, As₂O₅, HfO₂, As₂O₅ from which As₂O₃ and As₂O₅ are practically sublimed in two steps. The exchange capacities at r.t. are generally similar to -ZrP and -TiP but are found to be much lower in value.     

Thermal behaviour of mixed Sn and Ge phosphates

Pure and mixed Ge and Sn hydrogenphosphates, prepared either by refluxing in 8M H₃PO₄ or by hydrothermal treatment at 180° or 300°C, have been characterized in terms of chemical composition and thermal behaviour and also tested as catalysts in the 1-butene isomerization, in order to correlate acidic properties with preparation method. Solid solutions for every composition in this system are formed only when using the refluxing method, as proved by X-ray and TG-DTA data. The hydrothermal treatments are strongly influenced by the hydrolysability of the Ge phosphate: in almost all the samples, where Ge was present, GeOHPO₄ was identified on TG-DTA curves by the endothermic H₂O weight loss at 700°–800°C. The acidic properties of the various materials decrease as GeOHPO₄ content increases.     

Mixed insoluble acidic salts of tetravalent metals V. Effect of gamma radiation and drying temperature on granular mixed zirconium-titanium phosphates

Solid ZrOCl₂·8H₂O was added in a slow stream to a solution of phosphoric acid or to a solution of TiCl₄ in phosphoric acid to obtain granules of amorphous Zr(HPO₄)₂·nH₂O or Zr_xTi(_1–x) (HPO₄)₂·nH₂O(where x=0.95–0.80). Half of each product had been soaked in ethanol to produce alcohol solvated materials. It was found that the particle size of the resulting materials is very similar to that of ZrOCl₂·8H₂O, in such a way that it may be controlled indirectly. These materials are suitable for ion-exchange column operations. The relatively high gamma radiation doses of⁶⁰Co source did not alter its exchange properties. pH-titrations were performed by an automatic titrimeter and the exchange capacities of alkali metal ions were determined by isotopic tracer technique. Effect of drying temperature on the ion exchange properties of Na⁺, K⁺ and Cs⁺ on the granular materials have been studied. Other characterizations were made by usual chemical analysis and thermography.     

Thermal behaviour of mixed long-chain alkylammonium tetrachlorozincates

Mixed crystals of composition (n-C_mH_2m+1NH₃)_2xm(n-C_nH_2n+1 · NH₃)_2?2xm ZnCl₄ (m= 12; n=14, 16, 18) are formed upon annealing mechanical mixtures of layer compounds (n-C_nH_2n+1NH₃)₂ZnCl₄, through solid state diffusion of the n-alkylammonium cations. From a common high temperature monophasic modification, in which the polymethylenic chains are conformationally molten, different modifications are obtained on cooling [depending on the (n ? m) value] in which chain crystallinity is developed. The structure of such modifications is speculated on the grounds of DSC and preliminary X-ray diffractometric and IR data, and compared with that of similar previously characterized systems.     

Thermal behaviour of the precursors of ruthenia-titania based mixed oxides

Summary Studies on ruthenia-titania based materials have been attractive because of their catalytic properties as well as due to the possibility of solid solution formation. Samples of pure ruthenia and ruthenia containing various amounts of titania (10-70 mol%) were investigated during heating of their hydroxide precursors from 20 to 800°C in air using emanation thermal analysis (ETA), thermogravimetry (TG), and differential thermal analysis (DTA). The resulting mixed oxide type materials were characterized by X-ray diffraction (XRD), which indicate the presence of three ruthenia-titania phases. The onset temperature of the crystallization of materials was identified by ETA results, whereas DTA effects characterized the crystallization in bulk of the samples. A good agreement was found between the ETA results and other characterization techniques used. ETA results, indicating the microstructural changes in surface and subsurface of ruthenia-titania based catalytic materials, can be used for optimization of their synthesis protocols to achieve the better physical properties.     

Thermal behaviour of new biological active cadmium mixed ligands complexes

This paper reports the investigation on the thermal stability of new complexes with mixed ligands of the type [Cd(NN)(C₃H₃O₂)₂(H₂O)_m]·nH₂O [(1) NN: 1,10-phenantroline, m = 1, n = 0; (2) NN: 2,2′-bipyridine, m = 0, n = 1.5 and (C₃H₃O₂): acrylate anion]. The IR data indicate a bidentate coordination mode for both heterocyclic amine and acrylate. The in vitro qualitative and quantitative antimicrobial activity assays showed that the complexes exhibited variable antimicrobial activity against planktonic as well as biofilm embedded Gram-negative (Escherichia coli, Klebsiella sp., Proteus sp., Salmonella sp., Shigella sp., Acinetobacter boumani, Pseudomonas aeruginosa), Gram-positive (Bacillus subtilis, Staphylococcus aureus) and fungal (Candida albicans) strains, reference and isolated ones from the hospital environment. The thermal behaviour steps were investigated in synthetic air flow. The thermal transformations are complex processes according to TG and DTA curves including dehydration, amine as well as acrylate thermolysis. The final products of decomposition are the most stable metal oxides.     

Thermal behaviour of solid complexes of phenoxyalkanoic acids and divalent metals

Solid cadmium and mercury(II) phenoxyacetates were prepared and investigated by DSC and TG techniques. The cadmium salt decomposed in two steps with the loss of 1.5 water molecules at first and the successive formation of CdCO₃ as final product. _deh H ^* associated with the loss of one water molecule was compared with the corresponding values obtained for other phenoxyacetates previously studied and the obtained results were discussed. Anhydrous mercury(II) phenoxyacetate gave, on heating, HgCO₃ which successively decomposed with the formation of gaseous products and a little amount of solid residue.Authors thank the Italian M.U.R.S.T. for financial support.     

Thermal behaviour of solid complexes of phenoxyalkanoic acids and divalent metals

Two solid copper(II) phenoxyacetates (anhydrous and dihydrate) were prepared and investigated by DSC and TG techniques. The results obtained indicated that the water molecules of the dihydrate compounds were weakly and differently bonded; also, both anhydrous and dihydrate compound decomposed with formation of CuO as final product, but by different steps. Some thermodynamic parameters associated with the observed thermal processes were evaluated and the results obtained were discussed and interpreted.     

Thermal behaviour of solid complexes of phenoxyalkanoic acids and divalent metals

Solid Co(II) and Ni(II) phenoxyacetates were studied by DSC and TG techniques. The results showed that they were dihydrate and tetrahydrate respectively in the solid state. No evidence of the location of water molecules in different coordination shells was obtained. Both compounds decomposed with the formation of oxide as final product; the corresponding activation energies suggested a stronger metal-carboxylate bond in the nickel salt.     

Thermal behaviour of thallium(I) fatty acid salts,II

The electrical conductivity (EC) changes of thallium(I) salts of fatty acids, which possess liquid crystalline phases, were investigated as a function of temperature. It was found that sharp EC jumps are associated with the phase transitions. The EC of the liquid crystalline phases depended not only on the temperature, the molecular weight and the geometry of the measuring cell, but also very sensitively on the heat treatment conditions which affect the relative magnitude of the EC in the mesophases.Study of these dependences revealed a memory effect. An explanation is given for this phenomenon.

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Zusammenfassung Die Änderungen der elektrischen Leitfähigkeit (EC) von Fettsäure-Thalium(I)-Salzen mit flüssig-kristallinen Phasen wurden als Funktion der Temperatur untersucht. Es wurde festgestellt, daß den Phasenübergängen scharfe EC-Sprünge entsprechen. Die EC der flüssig-kristallinen Phase hängt nicht nur von der Temperatur, dem Molekulargewicht und der Geometrie der Meßzelle ab, sondern auch — in sehr empfindlicher Weise — Phasen bestimmen.Die Untersuchung dieser Zusammenhänge führte zur Beobachtung eines »Memorieeffektes« Eine Erklärung dieser Erscheinung wird gegeben.

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Résumé On a étudié les variations de la conductibilité électrique (EC) des sels de thallium(I) des acides gras possédant des phases cristallines liquides, en fonction de la température. On a établi que les variations brusques d'EC correspondent aux transitions de phases. L'EC des phases cristallines liquides dépend non seulement de la température, de la masse molaire et de la géométrie de la cellule de mesure, mais aussi, et d'une manière très sensible, des conditions du traitement thermique qui affectent l'amplitude relative de l'EC dans les mésophases.Un «effet de mémoire» a été observé lors de l'étude de ces phénomènes, dont on donne une explication.

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