Zur thermischen Zersetzung des Hg2Cl2 und Hg2Br2

Thermical Decomposition of Hg₂Cl₂ and Hg₂Br₂ The thermical decomposition of Hg₂Cl₂ and Hg₂Br₂ was proved by total pressure measurements in a membrane manometer. The decomposition according to Hg₂X_2,s = Hg_,g + HgX_2,g and their thermodynamic data were confirmed.     

Zur Frage der Pb(II)-Komplexe im Gemischten System KCl-KJ

The absorption spectra of mixed solutions KCl-KI with lead admixture and of crystals of that system, as far as they make fast solutions were measured. From the absorption spectra it was derived that lead builds up mixed complexes in the mentioned system. With the growing relative abundance of iodide in the system the content of the iodide component in complexes increases faster than that one.

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Der Verfasser dankt herzlich Herrn Dr. A. Bohun für die Unterstützung bei dieser Arbeit und Frau L. Svárová für die Züchtung der Kristalle.     

Use of a summation technique for evaluation of the phase transition in lead germanate,Pb5Ge3O11

A computer technique is outlined to increase the signal: noise ratio of DSC results for transformations involving small changes of energy. The method is applied to determine the transformation temperature of the ferroelectric-paraelectric transformation of lead germanate, Pb₅Ge₃O₁₁, either pure or doped with Nd³⁺ or with Nd³⁺+K⁺.

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Zusammenfassung Eine Computermethode wird angegeben, die es erlaubt, das Signal: Rausch-Verhältnis bei DSC-Messungen von Umwandlungen mit geringer Energie zu erhöhen. Diese Methode wird verwendet, um die Temperatur der Umwandlung ferroelektrisch-paraelektrisch an Bleigermanat Pb₅Ge₃O₁₁, rein oder dotiert mit Nd³⁺ oder mit Nd³⁺ +K⁺, zu bestimmen.

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Thanks are due to Dr. H. D. Kürsten, who prepared the crystals.     

Zur Frage der Pb(Il)-Komplexe in den Alkalichloriden

The absorption of bivalent lead in solutions of alkali chlorides of different concentration was studied. The absorption bands that occur were ascribed to the complexes of lead with chlorine. The agreement between absorption bands in crystals doped with lead and in sufficiently concentrated solutions shows that lead in crystals of alkali chlorides forms an octahedral complex with six neighbouring atoms of chlorine.

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Die Verfasser sprechen Frau Z. Pecháková für ihre wirksame Hilfeleistung bei den Absorptionsmessungen ihren herzlichen Dank aus.     

Optische und elektrische Erscheinungen in kupferaktivierten Natriumchloridkristallen

NaCl crystals activated with copper were prepared either from the melt or from an aqueous solution. They were coloured either photochemically or additively. The absorption, luminescence and electron emission were then measured on such crystals. The experimental results show the cause of the different results obtained by different authors and what conclusions can be drawn for the elaboration of models of luminescent centres.