View More View Less
  • 1 Faculty of Chemistry and Chemical Engineering, University “Politehnica” Timisoara, P. Victoriei No. 2, 300006, Timisoara, Romania
  • 2 Research Center for Thermal Analysis in Environmental Problems, West University of Timisoara, Timisoara, Romania
  • 3 Faculty of Physics, West University of Timisoara, Bv. V. Parvan No. 4, 300223, Timisoara, Romania
Restricted access

Abstract

In this article, we present a new method for the obtaining of ZnCr2O4 and MgCr2O4 embedded in silica matrix. This method consists in the formation of Cr(III), Zn(II) and Cr(III), Mg(II) hydroxycarboxylate/carboxylate compounds, during the redox reaction between the nitrate ion and diol (1,3-propanediol), uniformly dispersed in the pores of hybrid gels. The thermal decomposition of these precursors leads to a mixture of corresponding metal oxides. The gels were synthesized starting from mixtures of Cr(NO3)3·9H2O, Zn(NO3)2·6H2O and Cr(NO3)3·9H2O, Mg(NO3)2·6H2O with tetraethyl orthosilicate and 1,3-propanediol for final compositions 50% ZnCr2O4/50% SiO2 and 50% MgCr2O4/50% SiO2. The obtained gels have been thermally treated at 140 °C, when the redox reaction nitrates-diol took place with formation of the precursors within the xerogels pores. The thermal decomposition of all precursors took place up to 300 °C, with formation of oxides mixtures (Cr2O3 + x and ZnO) and (Cr2O3 + x and MgO), respectively. At 400 °C, Cr2O3 + x turn to Cr2O3 which reacts with ZnO forming ZnCr2O4/SiO2. Starting with 400 °C, Cr2O3 reacts with MgO to an intermediary phase MgCrO4, which decomposes with the formation of MgCr2O4/SiO2. The formation of the precursors inside the silica matrix and the evolution of the crystalline phases were studied by thermal analysis, FT-IR spectrometry, XRD, and TEM.

  • 1. Morozova, LV, Popov, VP 2010 Synthesis and investigation of magnesium chromium spinel. Glass Phys Chem 36 1 8691 .

  • 2. Mančić, L, Marinković, ZV, Vulić, P, Milošević, O 2004 The synthesis-structure relationship in the ZnO-Cr2O3 system. Sci Sinter. 36:189196 .

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 3. Szczygiel, I, Winiarska, K 2011 Low-temperature synthesis and characterization of the Mn–Zn ferrite. J Therm Anal Calorim 104:577583 .

  • 4. Souaya, ER, Ismail, EH, Mohamed, AA, Milad, NE 2009 Preparation, characterization and thermal studies of some transition metal ternary complexes. J Therm Anal Calorim 95:253258 .

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 5. Suryanarayana, C, Grant Norton, M 1998 X-ray diffraction. A practical approach Plenum Press New York.

  • 6. Stefanescu, M, Sasca, V, Birzescu, M 2003 Thermal behaviour of the homopolynuclear glyoxylate complex combinations with Cu(II) and Cr(III). J Therm Anal Calorim 72 2 515524 .

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 7. Stefanescu, M, Sasca, V, Birzescu, M 1999 Studies on the thermal decompositions of heteropolynuclear glyoxylates of Cr(III) and Cu(II). J Therm Anal Calorim 56 2 569578 .

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 8. Stefanescu, M, Stoia, M, Stefanescu, O, Popa, A, Simon, M, Ionescu, C 2007 The interaction between teos and some polyols. Thermal analysis and FT-IR. J Therm Anal Calorim 88:1926 .

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 9. Stefanescu, M, Stoia, M, Stefanescu, O 2007 Thermal and FT-IR study of the hybrid ethylene–glycol–silica matrix. J Sol Gel Sci Techn. 41:7178 .

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 10. Brinker, CJ, Scherrer, GW 1990 Sol–gel science: the physics and chemistry of sol-gel Processing Academic Press New York.

  • 11. Stefanescu M . Consideration on the formation of the mixed oxides starting from substances with high reactivity. PhD Thesis, University of Timisoara, Romania, 1993.

    • Search Google Scholar
    • Export Citation
  • 12. Barbu, M, Stoia, M, Stefanescu, O, Stefanescu, M 2010 Thermal and FT-IR studies on the interaction between Cr(NO3)3·9H2O and some diols. Chem Bull. 55 69 180185.

    • Search Google Scholar
    • Export Citation
  • 13. Bernazzani, P, Sanchez, RF 2009 Structural and thermal behavior of polystyrene thin films using ATR–FTIR–NanoDSC measurements. J Therm Anal Calorim 96:727732 .

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 14. Purnendu, P, Manivannan, V 2008 Microwave metathetic approach for the synthesis and characterization of ZnCr2O4. J Eur Ceram Soc. 28:16651670 .

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 15. Pocol, V, Patron, L, Carp, O, Brezeanu, M, Segal, E, Stanica, N 1999 Some polynuclear coordination compounds precursor of chromites synthesis, physicochemical characterization and thermal stability. J Therm Anal Calorim 55:143154 .

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 16. Bielanski, A, Deren, J, Duczyminska, E 1962 Elektrische Leitfahigkeit von MgO–Cr2O3 Gemischen verschiedener Zusammensetzung und verschiedenen Sinterungsgrades. Z Anorg Allg Chim 316 1–2 7588 .

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 17. Rida, K, Benabbas, A, Bouremmad, F, Pen, MA, Martinez-Arias, A 2010 Influence of the synthesis method on structural properties and catalytic activity for oxidation of CO and C3H6 of pirochromite MgCr2O4. Appl Catal A 375:101106 .

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 18. Joint Committee on Powder Diffraction Standards-International Center for Diffraction Data. Swarthmore, 1993.

Monthly Content Usage

Abstract Views Full Text Views PDF Downloads
Oct 2020 3 0 0
Nov 2020 2 5 2
Dec 2020 4 0 0
Jan 2021 6 0 0
Feb 2021 5 0 0
Mar 2021 3 0 0
Apr 2021 1 0 0