Structure of bismuth tellurite and bismuth niobium tellurite glasses and Bi2Te4O11 anti-glass by high energy X-ray diffraction. Issue 22 (2nd April 2020)

• Record Type: Journal Article
• Authors: Gupta, Nupur; Khanna, Atul; Hirdesh, ; Dippel, Ann-Christin; Gutowski, Olof
• Is Part Of: RSC advances. Volume 10:Issue 22(2020)
• Page Start: 13237
• Page End: 13251
• Publication Date: 2020-04-02
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/d0ra01422b
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : Te–O, Bi–O and Nb–O bond lengths, co-ordinations in bismuth tellurite, bismuth niobium tellurite glasses and Bi2 Te4 O11 anti-glass by HEXRD, RMC and Riteveld analysis. Abstract : Glass and anti-glass samples of bismuth tellurite ( x Bi2 O3 –(100 − x )TeO2 ) and bismuth niobium tellurite ( x Bi2 O3 – x Nb2 O5 –(100 − 2 x )TeO2 ) systems were prepared by melt-quenching. The bismuth tellurite system forms glasses at low Bi2 O3 concentration of 3 to 7 mol%. At 20 mol% Bi2 O3, the glass forming ability of the Bi2 O3 –TeO2 system decreases drastically and the anti-glass phase of monoclinic Bi2 Te4 O11 is produced. Structures of glass and the anti-glass Bi2 Te4 O11 samples were studied by high-energy X-ray diffraction, reverse Monte Carlo simulations and Rietveld Fullprof refinement. All glasses have short short-range disorder due to the existence of at least three types of Te–O bonds of lengths: 1.90, 2.25 and 2.59 Å, besides a variety of Bi–O and Nb–O bond-lengths. The medium-range order in glasses is also disturbed due to the distribution of Te–Te pair distances. The average Te–O co-ordination ( N Te–O ) in the glass network decreases with an increase in Bi2 O3 and Nb2 O5 mol% and is in the range: 4.17 to 3.56. The anti-glass Bi2 Te4 O11 has a long-range order of cations but it has vibrational disorder and it exhibits sharp X-ray reflections but broad vibrational bands similar to that in glasses. Anti-glass Bi2 Te4 O11 has an N Te–O of 2.96 and is significantly lower than in glass samples.