7446-07-3Relevant articles and documents
Structural and thermal studies on PuTe2O6
Krishnan,Mudher,Venugopal
, p. 114 - 118 (2000)
PuTe2O6 was synthesised by the solid state reaction route and characterized by X-ray diffraction and thermal methods. The structure of PuTe2O6 was derived by the Rietveld analysis of X-ray powder diffraction data in the monoclinic system with cell parameters a = 0.69937(1), b = 1.10014(2), c = 0.73404(2) nm, β = 107.98(2)°, Z = 4 in the space group P21/n. In the structure, each plutonium atom is coordinated to eight oxygen atoms. The structure is made up of zigzag strings of PuO8 distorted edge-sharing polyhedron parallel to the a axis. Tellurium atoms are coordinated to three oxygen atoms. PuTe2O6 melts at 1125 K incongruently and decomposes according to the reaction: PuTe2O6(s) → PuO2(s) + 2TeO2(g). The kinetics of decomposition under isothermal heating conditions in flowing air were studied to determine the rate constants, activation energy and reaction mechanism.
Engelbrecht, A.,Sladky, F.
, (1965)
Pashinkin, A. S.,Rabinovich, I. B.,Sheiman, M. S.,Nistratov, V. P.,Vorobjova, O. I.
, p. 43 - 48 (1985)
Gaitan, M.,Jerez, A.,Pico, C.,Veiga, M. L.
, p. 1069 - 1074 (1985)
Standard enthalpies of formation of tellurium compounds. I. Tellurium dioxide
Cordfunke, E. H. P.,Ouweltjes, W.,Prins, G.
, p. 369 - 376 (1987)
The enthalpy of formation of TeO2(s) has been obtained by solution calorimetry using two independent thermochemical cycles: the first, in -3 H2SO4 + 0.10 mol * dm-3 K2Cr2O7 + 0.010 mol * dm-3 MnSO4>(aq), based
Standard molar Gibbs energy of formation of Ba3Te2O9(s) by transpiration technique
Parida,Banerjee,Prasad,Singh,Venugopal
, p. 285 - 287 (2002)
The standard molar Gibbs energy of formation of barium tellurite, Ba3Te2O9(s), was determined by the transpiration technique using pure oxygen as the carrier gas in the temperature range from 1119 to 1280 K. The condensate
Thermodynamic stability of Sm2TeO6
Balakrishnan,Pankajavalli,Ananthasivan,Anthonysamy
, p. 80 - 85 (2008)
The vapour pressure of Sm2TeO6 was measured using a thermal analyser with a horizontal arm. This TG based transpiration technique, was validated by measuring the vapour pressure of pure TeO2(s). The temperature dependence of the latter was measured to be log p (Pa) = {14.2 - 13321/T (K)} (±0.03) in the range 884-987 K. These data yielded a Δ H298 ° value of 269.7 ± 0.6 kJ mol-1 for the enthalpy of sublimation (third-law method) of TeO2 which compared well with the data reported in the literature. The temperature dependence of the vapour pressure of TeO2 over the mixture Sm2TeO6(s) + Sm2O3(s) generated by the incongruent vapourisation reaction,Sm2TeO6(s) → Sm2O3(s) + TeO2(g) + 1/2O2(g)could be expressed aslog p (Pa) = { 18.56 - 25469 / T (K) } ± 0.06 (1374 - 1533 K). The standard Gibbs energy of formation of Sm2TeO6(s) was derived from the above vapour pressure data in conjunction with auxiliary data for the other coexisting phases. The temperature dependence of the Gibbs energy of formation of Sm2TeO6 over the temperature range 1374-1533 K could be represented asΔ Gf ° (S m2 Te O6) (kJ mo l- 1) = { - 2399.3 + 0.5714 T (K) } ± 5.8. The Gibbs energy of formation of Sm2TeO6(s) is being reported for the first time.
X-ray and thermal investigations of LaFeTeO6 and LaCrTeO6 compounds
Gupta, Neeraj K.,Roy,Joshi,Rama Rao,Krishnan,Singh Mudher
, p. 300 - 303 (2006)
LaFeTeO6 and LaCrTeO6 were prepared by the solid-state reaction of La2O3, M2O3 (M = Fe or Cr) and TeO2 in 1:1:2 molar ratio. The compounds were characterised by X-ray and thermogravimetric techniques. Thermal and X-ray studies indicated that LaFeTeO6 and LaCrTeO6 vapourize incongruently according to the reactions:{A formula is presented}{A formula is presented}X-ray diffraction data of both the compounds have been indexed on the hexagonal system. Vapour pressures of TeO2(g) over LaFeO3(s) and LaCrO3(s) were independently measured by employing the Knudsen effusion mass loss (KEML) technique. From the partial pressures of TeO2(g) measured, the standard Gibbs free energy of formation of (ΔfG°) LaFeTeO6(s) and LaCrTeO6(s) were obtained and could be represented by the following relations:{A formula is presented}.
New glasses within the Tl2O-Ag2O-TeO2 system: Thermal characteristics, Raman spectra and structural properties
Linda,Dutreilh-Colas,Hamani,Thomas,Mirgorodsky,Duclre,Masson,Loukil,Kabadou
, p. 1816 - 1824 (2010)
Within the Tl2O-Ag2O-TeO2 system, a large glass-forming domain was evidenced and is presented for the fist time. Densities, glass transition (Tg) and crystallization (Tc) temperatures of the relevant glasses were measured. A structural approach of these glasses as functions of the composition was performed using Raman scattering. The Raman spectra were analysed in terms of the structural modifications induced by the Tl2O and Ag2O modifiers. It has clearly evidenced a phase separation inherent in tellurite glasses with low valence cations (as Tl+ and Ag+). The glasses would be constituted of two phases only: one of pure TeO2 and one of pure ortho-tellurite M2TeO3 (M = Ag, Tl) with the statistically mixed Ag-Tl cationic composition.
Hartley, G. A. R.,Henry, T. H.,Whytlaw-Gray, R.
, p. 952 - 952 (1938)
Ag2Te2O7, a novel silver tellurate of Weberite structure type
Klein, Wilhelm,Curda, Jan,Peters, Eva-Maria,Jansen, Martin
, p. 1508 - 1513 (2006)
Ag2Te2O7 has been synthesized by solid state reaction of Ag2O and TeO2 under elevated oxygen pressure. The compound is diamagnetic and insulating, and decomposes at 560 °C in an Ar atmosphere into oxygen, Ag2TeO3 and TeO2. Ag2Te2O7 crystallizes orthorhombic in space group Imma with a = 7.266(2), b = 10.1430(9), c = 7.6021(17) A, V = 560.3(2) A3, Z = 4, 410 independent reflections, R1 = 4.65 %, wR2 = 11.13%. The crystal structure consists of a three-dimensional framework of TeO6 octahedra which are linked by common vertices. Voids of the framework accommodate silver atoms which are coordinated by eight oxygen atoms. The structure derives from that one of naturally occurring Weberite, Na2MgAlF7. The relationship to the pyrochlore structure type is discussed.
Marganian, V. M.,Whisenhunt, J. E.,Fanning, J. C.
, p. 3775 - 3781 (1969)
125Te and 129I Moessbauer Spectroscopic Studies of the Tetragonal and Orthorhombic Forms of Tellurium(IV) Oxide
Sakai, Hiroshi,Maeda, Yutaka
, p. 33 - 38 (1989)
125Te and 129I Moessbauer spectra have been measured for the tetragonal (α) and orthorhombic (β) forms of TeO2.The Moessbauer data show that there are no significant differences between the two modification in either the electronic structure or the chemic
New vanadium(IV) and titanium(IV) oxyfluorotellurates(IV): V 2Te2O7F2 and TiTeO3F 2
Laval, Jean Paul,Boukharrata, Nefla Jennene
, p. i1-i6 (2009)
Titanium(IV) tellurium(IV) trioxide difluoride, TiTeO3F2, and divanadium(IV) ditellurium(IV) heptaoxide difluoride, V2Te2O7F2, were characterized. The Te, Ti, one F and two O atoms are on g
Gospodinov, G. G.,Karaivanova, V. G.
, p. 197 - 202 (1991)
Study of the formation of bi2te4o11
Szaller,Poeppl,Lovas, Gy,Dodony
, p. 251 - 261 (1996)
The solid state reaction in a 1:4 mole ratio mixture of Bi2O3 and TeO2 and the polymorphic phase transition of Bi2Te4O11 have been investigated using differential scanning calorimetry (DSC), electron microprobe, X-ray powder diffraction (XPD), and selected area electron diffraction (SAED) analysis in the 25-730°C temperature range. Upon heating first a 8Bi2Te4O11 + 23TeO2 eutectic is formed, which melts at 598.9°C. In this melt the excess of Bi2O3 reacts further and the Bi2O3 + 4TeO2 = Bi2Te4O11 reaction takes place. The cubic modification is formed by fast crystallization of the Bi2Te4O11 melt. The structure of the cubic Bi2Te4O11 can be characterized by the lattice constant of a = 5.6397(5) A and space group Fm3m. The main product of a slow cooling is the same cubic polymorph although a subordinate formation of the monoclinic phase is also observed. The β-Bi2Te4O11 cubic phase undergoes a monotropic transformation into the α-Bi2Te4O11 monoclinic modification at temperatures higher than 400°C. The cubic → monoclinic transition is the result of an ordering in one set of {111} planes and the orthogonality of the cubic phase in the [110] projection changes to monoclinic symmetry. The melting enthalpies of the cubic β-phase and the monoclinic α-phase are 35.9 ± 3.3 J/g and 84.3 ± 4.3 J/g respectively.
Structural and thermochemical studies on Cr2TeO6 and Fe2TeO6
Krishnan,Singh Mudher,Rama Rao,Venugopal
, p. 264 - 268 (2001)
The crystal structure and measurement of the thermodynamic quantities of Cr2TeO6 and Fe2TeO6 prepared by the solid state reaction were studied. The crystal structure was derived from X-ray powder diffraction, wh
Room temperature gas sensing of p -type Te O2 nanowires
Liu, Zhifu,Yamazaki, Toshinai,Shen, Yanbai,Kikuta, Toshio,Nakatani, Noriyuki,Kawabata, Tokimasa
, (2007)
Tellurium dioxide (Te O2) nanowires with a tetragonal structure have been grown by thermally evaporating tellurium metal at 400 °C in air. The nanowires produced have diameters ranging from 30 to 200 nm and have lengths of several tens of micrometers. Gas sensors were fabricated using the obtained Te O2 nanowires. The sensing behavior to N O2, N H3, and H2 S gases at room temperature showed typical characteristics of a p -type semiconductor. The results demonstrate the potential to develop Te O2 nanowire based gas sensors with low power consumption.
Comparative study of bulk and supported V-Mo-Te-Nb-O mixed metal oxide catalysts for oxidative dehydrogenation of propane to propylene
Zhao, Zhen,Gao, Xingtao,Wachs, Israel E.
, p. 6333 - 6342 (2003)
Bulk V-Nb-O, Mo-Nb-O, Te-Nb-O, and V-Mo-Te-Nb-O mixed metal oxides were synthesized and characterized with Raman spectroscopy, XRD, and BET methods. The catalytic properties of these bulk mixed metal oxides were studied for the oxidative dehydrogenation (
TeO2-WO3 glasses: Infrared, XPS and XANES structural characterizations
Charton,Gengembre,Armand
, p. 175 - 183 (2002)
Transparent (1-x)TeO2-xWO3 glasses with 0≤x≤0.325 mol were synthesized by the fast quenching technique. Several complementary techniques as infrared, X-ray photoelectron and X-ray absorption spectroscopies were used to approach the s
Synthesis, structure, and characterization of novel two- and three-dimensional vanadates: Ba2.5(VO2) 3(SeO3)4·H2O and La(VO 2)3(TeO6)·3H2O
Sivakumar,Kang, Min Ok,Halasyamani, P. Shiv
, p. 3602 - 3605 (2006)
Two new vanadates, Ba2.5(VO2)3(SeO 3)4·H2O and La(VO2) 3(TeO6)·3H2O, have been synthesized by hydrothermal methods using BaCO3, Ba(OH)2·H 2O, La(NO3)3·6H2O, V 2O5, TeO2, and H2SeO3 as reagents. The structures were determined by single-crystal X-ray diffraction. Ba2.5(VO2)3(SeO3) 4·H2O exhibits a two-dimensional layered structure consisting of VO5 square pyramids and SeO3 polyhedra, whereas La(VO2)3(TeO6)·3H2O has a three-dimensional framework structure composed of VO4 tetrahedra and TeO6 octahedra. Infrared and Raman spectroscopy, UV-vis diffuse reflectance spectroscopy, and thermogravimetric analysis are also presented. Crystal data: Ba2.5(VO2)3-(SeO 3)4·H2O, trigonal, space group P3 (No. 147) with a = b = 12.8279(15) A, c = 7.2631(9) A, V = 1035.1(2) A3, and Z = 2; La(VO2)3(TeO 6)·3H2O, trigonal, space group R3c (No. 161) with a = b = 9.4577(16) A, c = 23.455(7) A, V = 1816.9(7) A3, and Z = 6.
New oxyfluoro-tellurates(IV): MTeO3F (M = FeIII, GaIII and CrIII)
Laval, Jean Paul,Jennene Boukharrata, Nefla,Thomas, Philippe
, p. i12-i14 (2008)
The crystal structures of the new isomorphous compounds iron(III) oxyfluoro-tellurate(IV), FeTeO3F, gallium(III) oxy-fluoro-tellurate(IV), GaTeO3F, and chromium(III) oxyfluoro-tellurate(IV), CrTeO3F, consist of zigzag chains of MO4F2 distorted octa-hedra alternately sharing O-O and F-F edges and connected via TeO3 trigonal pyramids. A full O/F anionic ordering is observed and the electronic lone pair of the TeIV cation is stereochemically active.
TeO2 nanoparticles synthesized by evaporation of tellurium in atmospheric microwave-plasma torch-flame
Cho, Soon Cheon,Hong, Yong Cheol,Uhm, Han Sup
, p. 214 - 218 (2006)
Tellurium dioxide (TeO2) nanoparticles were synthesized directly by evaporation of tellurium (Te) granules in an atmospheric microwave-plasma torch-flame with possibility for a direct continuous preparation and mass production of TeO2 nanoparticles. The mean size of the synthesized TeO2 particles was 108.2 nm observed from the TEM image and was 112.0 nm estimated by the Williamson-Hall plot using XRD data. The surface area and pore distribution properties of the particles were also analyzed by making use of a nitrogen adsorption apparatus.
Redman, M. J.,Harvey, W. W.
, p. 395 - 404 (1967)
Characterization of nanocrystalline bismuth telluride (Bi 2Te3) synthesized by a novel approach through aqueous precursor method
Dhak, Debasis,Pramanik, Panchanan
, p. 534 - 537 (2006)
Bi2Te3-based alloys are currently best-known, technologically important thermoelectric materials near room temperature. In this paper, nanocrystalline Bi2Te3 was synthesized by an aqueous solution technique based on the reaction between the aqueous solution of Bi-ethylenediamine tetraaceticacid (EDTA), TeO-EDTA, and NaBH4 at room temperature. NaBH4 was used as a reducing agent. TeO-EDTA was prepared from TeO2 after satisfactory purification. The sample purity was examined by selected area energy dispersive X-ray analysis. The products were characterized by X-ray diffraction and high-resolution transmission electron microscopy by which the particle morphologies and size were studied. The particle size ranges from 60 to 90 nm.
Synthesis and structure determination of In3TeO 3F7: An indium oxyfluorotellurate IV derived from W bronze structure with Te4+ in hexagonal tunnels
Jennene Boukharrata,Laval
, p. 1517 - 1522 (2011/03/16)
After InTeO3F and InTe2O5F recently described, a new compound In3TeO3F7 is characterized in the In-TeIV-O-F system. The crystal structure was determined by single X-ray diffraction and refined to R1 = 0.028. In3TeO3F7 crystallizes in orthorhombic space group Cmmm, a = 7.850(2) , b = 27.637(6) , c = 4.098(1) , V = 889.1(4) 3 and Z = 4. Its structure consists of the stacking, via vertices, of identical layers composed of InF6 and InO2F4 octahedra sharing corners and of InO4F3 pentagonal bipyramids sharing edges and vertices. The Te cations statistically occupy one or the other of two close sites located inside tunnels delimited by the In polyhedra and are bonded to F anions located in the same tunnels. The structure can be considered as an intergrowth of parallel strips of MIn3F 10 and hexagonal tungsten bronze (c)-types. It is compared to other structures such as the bronze Sb0.157WO3, TeMo 5O16 and Sb2Mo10O31, phases also comprising Te4+ or Sb3+ inside hexagonal tunnels. The electronic lone pair of Te4+ is stereochemically active and a perfect O/F ordering occurs on the anionic sites.