Glass-ceramics with LiFePO4 crystals and crystal line patterning in glass by YAG laser irradiation

New routes for fabrications of LiFePO4 crystals being a potential candidate for use as cathode materials for the next generation of rechargeable lithium ion batteries have been proposed. One is the crystallization of precursor LiFePO4 glasses using conventional heat treatments in an electric furnace and the other is the patterning of crystal lines with an assembly of LiFePO4 crystals at. the glass surface by irradiation of continuous wave Nd:YAG laser with a wavelength of lambda = 1064 nm. A glass with the composition of 26Li(2)O-43FeO-5Nb(2)O(5)-26P(2)O(5) (mol%) corresponding to a stoichiometric Li(Fe,Nb)PO4 crystal was prepared, and the formation of LiFePO4 crystals with an olivine structure was confirmed through a usual crystallization. Electrical conductivities at room temperature for the crystallized samples are less than 10(-9) Scm(-1), suggesting that Nb5+ ions are not incorporated into LiFePO4 crystals. Nd:YAG laser with powers of 70-100 mW and a scanning speed of 25 mu m/s was irradiated to the glasses, and the formation of LiFePO4 crystals was confirmed from X-ray diffraction (XRD) analyses and micro-Raman scattering spectra. XRD patterns suggest orientations of LiFePO4 crystals in the lines. (C) 2007 Elsevier B.V. All rights reserved.