Preparation chimioue et structure cristalline des tellurites de sodium et d'argent: Na2TeO3, Ag2TeO3

Masse, René; Guitel, J. C.; Tordjman, I.

doi:10.1016/0025-5408(80)90048-3

Cited by 47 publications

(23 citation statements)

References 7 publications

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“…4 and Table 1) could be indexed on the basis of a tetragonal unit cell with a = 7.250 and c = 6.843 ~, while the data for the sample heated up to 626 K have been indexed for monoclinic unit cell with a = 7.00, b = 10.509 and c = 4.911 ~ and /~ = 91.50 ~ The unit cell dimensions determined from our experimental data for the heat-treated sample are in agreement with those reported by Masse et al for the high temperature phase [9]. Some additional lines have been observed in the present case, which, of course, could be indexed according to the monoclinic unit celt dimensions.…”

Section: Resultssupporting

confidence: 78%

Characterization and thermoanalytical investigations of silver tellurite

Sharma

Batra

1989

Journal of Thermal Analysis

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Silver tellurite, prepared by precipitation, crystallized in tetragonal form and DSC studies show that it undergoes phase transformations on heat-treatment in the temperatuae ranges 578-604 K and 695-717 K. X-ray diffractometry suggests that in the first transformation, which is irreversible, the tellurite transforms to monoclinic form. The second transformation is reversible and the high temperature phase reverts back to the monoclinic form on cooling. The reversible phase transformation could be ascertained by electrical resistivity and reflectance spectrum measurements. The kinetic parameters, computed from the DSC data, show that the energy of activation, entropy of activation and the frequency factor are high. This is attributed to the effectiveness of a large number of vibrations. Numerous tellurites have been described in the literature and these have been studied to understand their structure and other related properties [1][2][3][4][5]. Investigations on silver tellurite, prepared by precipitation, show that it undergoes phase transformations on heat-treatment [3]. However, there appear to be no papers on the characterisation of the phases formed and on the mechanism of these transformations. In the present investigation, silver tellurite, prepared by precipitation, has been subjected to thermogravimetric and differential scanning calorimetric analysis to ascertain thermal effects. Different phases have been identified by X-ray diffractometry and chemical analysis. Magnetic susceptibility and electrical resistivity, as functions of temperature, and room temperature reflectance spectra have been recorded to gain further information. From the thermal data, kinetic parameters have been computed.

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Section: Resultssupporting

confidence: 78%

Characterization and thermoanalytical investigations of silver tellurite

Sharma

Batra

1989

Journal of Thermal Analysis

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“…For the crystal structure of Na 2 TeO 3 Á5H 2 O, see: Philippot et al (1979). For crystal structure of anhydrous Na 2 SeO 3 and Na 2 TeO 3 , see: Wickleder (2002); Masse et al (1980). For the crystal structures of the isotypic series MgSO 3 Á6H 2 O, MgSeO 3 Á6H 2 O, MgTeO 3 Á6H 2 O, and Mg(HPO 3 )Á6H 2 O, see: ; ; Powell et al (1994).…”

Section: Related Literaturementioning

confidence: 99%

“…The crystal structure of anhydrous Na 2 SeO 3 is known (Wickleder, 2002). This monoclinic structure can be seen as a distorted NaCl lattice (Masse et al, 1980), where Se replacing one out of three Na is shifted along a body diagonal of the NaCl lattice so that it has only three facial instead of six octahedral Se-O bonds while two Na atoms maintain their octahedral NaO 6 coordination of the NaCl lattice. In reality the oxygen atoms are shifted more than Na and Se because they compensate arising voids and bond length differences between <Na-O> = 2.48 Å and <Se-O> = 1.70 Å.…”

Section: Tablementioning

confidence: 99%

Sodium selenite pentahydrate, Na₂SeO₃·5H₂O

Mereiter

2013

Acta Cryst E

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Key indicators: single-crystal X-ray study; T = 100 K; mean (Se-O) = 0.001 Å; R factor = 0.015; wR factor = 0.039; data-to-parameter ratio = 16.9.In the crystal structure of Na 2 SeO 3 Á5H 2 O [disodium selenate(IV) pentahydrate], two Se, two selenite O atoms and one water O atom are located on a mirror plane, and one water O atom is located on a twofold rotation axis. The coordination of one Na + cation is distorted trigonal bipyramidal, formed by three equatorial H 2 O ligands and two axial selenite O atoms. The other Na + cation has an octahedral coordination by six water molecules. The two independent SeO 3 groups form almost undistorted trigonal pyramids, with Se-O bond lengths in the range 1.6856 (7)-1.7202 (10) Å and O-Se-O angles in the range 101.98 (3)-103.11 (5) , and both are 2 -O:O-bonded to a pair of Na + cations. Hydrogen bonds involving all water molecules and selenite O atoms consolidate the crystal packing. Although anhydrous Na 2 SeO 3 and Na 2 TeO 3 are isotypic, the title compound is surprisingly not isotypic with Na 2 TeO 3 Á5H 2 O. In the tellurite hydrate, all Na + cations have an octahedral coordination and the TeO 3 groups are bonded to Na + only via one of their three O atoms.

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“…The former are found in pure crystalline -TeO2 [15], while the latter have an arrangement of atoms similar to that present in M2TeO3 crystals [16][17][18]. The change in the local environment of a Te atom from [TeO4E] to [TeO3E] provides an additional NBO in the network, and hence reduces the total number of unfavourable M-BO bonds needed to fulfil the bond requirements of the M + ions [19].…”

Section: Introductionmentioning

confidence: 98%

Alkali environments in tellurite glasses

Barney

Hannon

Holland

et al. 2015

Journal of Non-Crystalline Solids

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Neutron diffraction measurements are reported for five binary alkali tellurite glasses, xM2O·(100-x)TeO2 (containing 10 and 20 mol% K2O, 10 and 19 mol% Na2O, and 20 mol% 7 Li2O), together with 23 Na MAS NMR measurements for the sodium containing glasses.Differences between neutron correlation functions are used to extract information about the local environments of lithium and sodium. The Na-O bond length is 2.37(1) Å and the average Na-O coordination number, nNaO, decreases from 5.2(2) for x=10 mol% Na2O to 4.6(1) for x=19 mol% Na2O. The average Li-O coordination number, nLiO, is 3.9(1) for the glass with x=20 mol% Li2O and the Li-O bond length is 2.078(2) Å. As x increases from 10 to 19 mol% Na2O, the 23 Na MAS NMR peak moves downfield, confirming an earlier report of a correlation of peak position with sodium coordination number. The close agreement of the maximum in the Te-O bond distribution for sodium and potassium tellurite glasses of the same composition, coupled with the extraction of reasonable alkali coordination numbers using isostoichiometric differences, gives strong evidence that the tellurium environment in alkali tellurites is independent of the size of the modifier cation used.

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Preparation chimioue et structure cristalline des tellurites de sodium et d'argent: Na2TeO3, Ag2TeO3

Cited by 47 publications

References 7 publications

Characterization and thermoanalytical investigations of silver tellurite

Characterization and thermoanalytical investigations of silver tellurite

Sodium selenite pentahydrate, Na₂SeO₃·5H₂O

Alkali environments in tellurite glasses

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Preparation chimioue et structure cristalline des tellurites de sodium et d'argent: Na2TeO3, Ag2TeO3

Cited by 47 publications

References 7 publications

Characterization and thermoanalytical investigations of silver tellurite

Characterization and thermoanalytical investigations of silver tellurite

Sodium selenite pentahydrate, Na2SeO3·5H2O

Alkali environments in tellurite glasses

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Sodium selenite pentahydrate, Na₂SeO₃·5H₂O