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The first silver bismuth borate, AgBi 2 B 5 O 11
Author(s) -
Volkov Sergey,
Charkin Dmitri,
Bubnova Rimma,
Povolotskiy Alexey,
Arsent'ev Maxim,
Krzhizhanovskay Maria,
Stefanovich Sergey,
Ugolkov Valery,
Kurilenko Ludmila
Publication year - 2019
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 17
ISSN - 2053-2296
DOI - 10.1107/s2053229619007605
Subject(s) - bismuth , crystallography , boron , single crystal , acentric factor , materials science , crystal structure , band gap , second harmonic generation , anisotropy , crystallization , analytical chemistry (journal) , chemistry , optics , physics , optoelectronics , organic chemistry , chromatography , metallurgy , laser
The first silver bismuth borate, AgBi 2 B 5 O 11 (silver dibismuth pentaborate), has been prepared via glass crystallization in the Ag 2 O–Bi 2 O 3 –B 2 O 3 system and characterized by single‐crystal X‐ray diffraction. Its structure is derived from that of centrosymmetric Bi 3 B 5 O 12 by ordered substitution of one Bi 3+ ion for Ag + , which results in the disappearance of the mirror plane and inversion centre. Second harmonic generation (SHG) measurements confirm the acentric crystal structure. It is formed by [Bi 2 B 5 O 11 ] ∞ layers stretched along c and comprised of vertex‐sharing B 5 O 10 and BiO 3 groups which incorporate the Ag + cations. The new compound was characterized by thermal analysis, high‐temperature powder X‐ray diffraction, and vibrational and UV–Vis–NIR (near infrared) spectroscopy. Its thermal expansion is strongly anisotropic due to the presence of rigid B 5 O 10 groups aligned in a parallel manner. The minimal value is observed along their axis [parallel to c , α c = 3.1 (1) × 10 −6 K −1 ], while maximal values are observed in the ab plane [α a = 20.4 (2) and α b = 7.8 (2) × 10 −6 K −1 ]. Upon heating, AgBi 2 B 5 O 11 starts to decay above 684 K due to partial reduction of silver; incongruent melting is observed at 861 K. According to density functional theory (DFT) band‐structure calculations, the new compound is a semiconductor with an indirect energy gap of 3.57 eV, which agrees with the experimental data (absorption onset at 380 nm).