| Synthesis of Norbergite Fe3BO6 of Single
Crystallites from a Borate Glass |
S. Ram*, K. Kumari and R. K. Kotnala**
Pages: 165-170
DOI : 10.1080/0371750X.2010.11090833 |
| Abstract |
| Iron oxyborate Fe3BO6 is one of the important ceramics of the norbergites useful for electrodes in lithium ion batteries, gas sensors and biological probes. A facile biofriendly method of rapid cooling of a borate glass-melt (starting composition 40Fe2O3-60 B2O3), after an isothermal heating for 30 min at ~1220°C in air, is explored in view of producing Fe3BO6 single crystallites. The method is feasible to scale-up for high yield. Scanning electron microscopic images of as-cooled rectangular bars or laminates of Fe3BO6 crystallites measure 1-2 m length, 0.5-1 m width and ~45 nm thickness. A single phase compound, Fe3BO6, as analyzed from the X-ray diffractogram, shows an orthorhombic crystal structure (Pnma space group), with lattice parameters a = 1.0048 nm, b = 0.8531 nm, c = 0.4466 nm, and density 4.76 g.cm–3. It is highly stable in air unless heating above 700°C. At room temperature these Fe3BO6 crystallites behave as the surface modified antiferromagnet, showing a nearly linearly increasing magnetization (i.e. a very small value of the order of a few 10–4 emu.g–1) against applied magnetic field and a peculiar open hysteresis loop with a huge coercivity ~2105 Oe. |
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