Electronic structure and chemical bonding in bismuth sesquioxide polymorphs

Thermally stimulated luminescence of bismuth germanate ceramics with the benitoite, eulitine, and sillenite structures

“…Heptacoordinate Bi in Bi 12 GeO 20 also contains a closest trio of O atoms with bond lengths in the range 2.08-2.23 Å and a farther quartet with bond lengths 2.62-3.17 Å [21]. The calculated bond indices for the crystallographically nonequivalent Bi atoms in α-Bi 2 O 3 [18] also showed three strong Bi-O interactions. Thus, it is understandable that recombination processes with similar parameters occur in the structurally similar complexes.…”

“…The Bi 4 Ge 3 O 12 structure contains BiO 6 and GeO 4 complexes [2]; Bi 12 GeO 20 , BiO 2 and GeO 4 complexes [17]. The α-Bi 2 O 3 structure, which occurs in the prepared Bi 2 O 3 ceramics according to x-ray diffraction, contains BiO 5 and BiO 6 complexes [18]. However, the most detailed structural analysis [19] indicates that three O atoms, Bi partners, in the eulitine Bi 4 Ge 3 O 12 structure, form an equilateral triangle over which a Bi atom is located.…”

Luminescence centers in α-Bi2O3 ceramics

“…The bismuth-oxygen overlap integral as a function of Bi-O bond distance in Bi 2 O 3 has been published [6]. In particular, there are two types of Bi atoms in α-Bi 2 O 3 with a closest environment of 5-6 O atoms [6]. The calculated bond indices for crystallographically nonequivalent Bi atoms showed three strong Bi-O interactions.…”

“…According to the literature [16], the Bi 2 Ge 3 O 9 structure also contains two groups of bismuth ions with a ternary oxygen environment where the O atoms are located at different distances (2.743 and 2.141 A o ). The bismuth-oxygen overlap integral as a function of Bi-O bond distance in Bi 2 O 3 has been published [6]. In particular, there are two types of Bi atoms in α-Bi 2 O 3 with a closest environment of 5-6 O atoms [6].…”

“…The conductivity band in all studied compounds had a metallic character and consisted mainly of p-states of Bi whereas the top of the filled upper band was determined by uncompensated antibonding 6s-Bi and 2p-O [6,13]. Based on the structural chemical factors, bismuth complexes in an oxygen environment were identified in all compounds.…”