Preparation and structure of BiCrTeO6: A new compound in Bi–Cr–Te–O system. Thermal expansion studies of Cr2TeO6, Bi2TeO6 and BiCrTeO6

• A new compound BiCrTeO6 in Bi–Cr–Te–O system was prepared and characterized.
• The crystal structure of BiCrTeO6 was determined by Rietveld refinement method.
• The structure of BiCrTeO6 shows an octahedral coordination for all the metal ions.
• The thermal expansion behavior of BiCrTeO6 from room temperature to 923 K showed a positive thermal expansion.
• The average volume thermal expansion coefficient for BiCrTeO6 is 16.0 × 10−6/K.

A new compound BiCrTeO6 in Bi–Cr–Te–O system was prepared by solid state reaction of Bi2O3, Cr2O3 and H6TeO6 in oxygen and characterized by X-ray diffraction (XRD) method. It could be indexed on a trigonal lattice, with the space group P-31c, unit cell parameters a = 5.16268(7) Å and c = 9.91861(17) Å. The crystal structure of BiCrTeO6 was determined by Rietveld refinement method using the powder XRD data. Structure shows that there is one distinct site for bismuth (Bi) atom, one chromium rich (Cr/Te = 68/32), and one tellurium rich (Te/Cr = 68/32) sites, and one distinct site for oxygen (O) atom in the unit cell. All cations in this structure show an octahedral coordination with oxygen atoms at the corners. The thermogravimetric analysis (TGA) of the compound in air shows that it is stable up to 1103 K and decomposes thereafter. The thermal expansion behavior of Cr2TeO6, Bi2TeO6 and BiCrTeO6 was studied using High Temperature X-ray diffraction (HTXRD) method from room temperature to 973, 873 and 923 K respectively under vacuum of 10−8 atmospheres. All the compounds showed positive thermal expansion with the average volume thermal expansion coefficients of 14.38 × 10−6/K, 22.0 × 10−6/K and 16.0 × 10−6/K respectively.

A new compound BiCrTeO6 in the Bi–Cr–Te–O system was prepared by solid state route and characterized by X-ray diffraction method. The crystal structure of BiCrTeO6 shows that there is one distinct site for bismuth (Bi) atom (pink color), one chromium rich (Cr/Te = 68/32) (blue/green color), one tellurium rich (Te/Cr = 68/32) sites (green/blue color), and one distinct site for oxygen (O) atom (red color) in the unit cell. All cations in this structure show an octahedral coordination with oxygen atoms at the corners. The thermogram (TG) of the compound in air shows that it is stable up to 1103 K and decomposes thereafter. The thermal expansion behaviour of BiCrTeO6 was studied using high temperature X-ray diffraction method from room temperature to 923 K under vacuum of 10−8 atmosphere and showed positive thermal expansion with the average volume thermal expansion coefficients of 16.0 × 10−6/K.Figure optionsDownload as PowerPoint slide