# Synthesis of non-stoichiometric $Bi_2O_{4-x}$ by oxidative precipitation

Prakash, AS and Shivakumara, C and Hegde, MS and Dupont, L and Tarascon, JM (2007) Synthesis of non-stoichiometric $Bi_2O_{4-x}$ by oxidative precipitation. In: Materials Research Bulletin, 42 (4). pp. 707-712.

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## Abstract

$Bi_2O_{4-x}$, a Bi mixed-valence phase was prepared at $95 ^0 C$, by a precipitation process, in a basic medium with a highly oxidizing $K_2S_2O_8/Na_2S_2O_8$. This phase has a low thermal stability as it decomposes below $400 ^0 C$ in a multiple step process by some $O_2$ losses prior to finally transforming into $\gamma-Bi_2O_3$. The as-prepared powders are 50–60 nm in size with a narrow size distribution. Optical spectra of $Bi_2O_{4-x}$ exhibit a broad absorption band with a band gap of $\sim 1.4 eV$ as compared to 2.61 eV for $Bi_2O_3$. The composition of this non-stoichiometric phase, which crystallizes in cubic fluorite related structure with a cell parameter of $5.538(3) \AA$, is $Bi_2O_{3.65 \pm 0.10}$.

Item Type: Journal Article Copyright of this article belongs to Elsevier. Inorganic compounds;Chemical synthesis;X-ray diffraction;Optical properties Division of Chemical Sciences > Solid State & Structural Chemistry Unit 30 May 2008 19 Sep 2010 04:45 http://eprints.iisc.ernet.in/id/eprint/14127