7 Li MAS-NMR and vibrational spectroscopic investigations of Li x V 2 O 5 (x=1.0, 1.2 and 1.4) M. Vijayakumar a , S. Selvasekarapandian a, * , Koichi Nakamura b , Tatsuo Kanashiro b , R. Kesavamoorthy c a Solid State and Radiation Physics Laboratory, Department of Physics, Bharathiar University, Coimbatore-641 046, Tamilnadu, India b Department of Physics, Faculty of Science, Tokushima University, 2-1 Minami Josanjima-Cho, Tokushima 770-8506, Japan c Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603 102, Tamilnadu, India Received 25 July 2003; received in revised form 25 November 2003; accepted 5 December 2003 Abstract The lithium vanadate Li x V 2 O 5 (x = 1.0, 1.2 and 1.4) has been prepared by solid state reaction method. The 7 Li MAS-NMR, Laser Raman and Fourier Transform Infrared (FTIR) spectroscopic analysis reveals the y-LiV 2 O 5 and g-LiV 2 O 5 phase formation. The 7 Li MAS-NMR spectrum shows the chemical shift around  1 and  10 ppm, which confirms the presence of g and y phases of lithium vanadate. The formation of y phase and g phase of LiV 2 O 5 has been detected by the presence of Raman peaks at 971 and 982 cm  1 . The phase transformation from y to g phases of LiV 2 O 5 with lithium incorporation has been identified. The reduction in the oxidation state of vanadium (V 5+ to V 4+ ) has been identified, due to lithium incorporation. This reduction affects the vanadium oxygen bonding nature and leads to the phase transformations. D 2004 Elsevier B.V. All rights reserved. PACS: 61.18.Fs; 78.30 Keywords: Lithium battery; 7 Li MAS-NMR spectra; FTIR analysis; Laser Raman Analysis; Ionic conductors 1. Introduction The growing desire for portable electronic devices and rechargeable power sources has fueled a strong interest in lithium batteries [1]. The development of high-performance lithium batteries is intimately linked to the availability of efficient electrode materials. The transition metal oxides are the most attractive electrode materials for batteries because of its layered structure which is useful for the intercalation [2,3]. The lithium vanadate LiV 2 O 5 attracts a great deal of attention because of its useful properties such as high conductivity of lithium ion to gain a high cathode utility of a cell and mixed conduction to increase the charge– discharge efficiency [4,5]. Different types of synthesis procedure are reported such as sol–gel method, xerogels, solid state reaction, electro- chemical insertion of lithium ions for the preparation of lithium vanadate LiV 2 O 5 [6–9]. However, each procedure yields different phases of lithium vanadate such as y, q, and g-LiV 2 O 5 depending upon the amount of lithium incorpo- rated. Pecquenard et al. [10] reported the identification of LiV 2 O 5 phases by EPR spectroscopy. The 7 Li MAS-NMR analysis is known to be an advanced technique, which gives the information about the local Li environment in Li ion conducting samples [10]. Recently, Fujiwara et al. [11,12] reported the 7 Li and 51 V NMR analysis of the lithium vanadate with multiple phases prepared by chemical inter- calation. The vibrational spectroscopic techniques Laser Raman and FTIR spectra are efficient tool to analyze various structures, and various phases of lithium vanadate have been identified by these methods by various research- ers [13,14]. However, these studies are reported for the chemically and electrochemically prepared LiV 2 O 5 . The 7 Li MAS-NMR and vibrational spectroscopic analysis of high temperature lithium vanadate is scarce. The high temperature preparation (solid state reaction) is a simple and cost-effective method. However, the lithium 0167-2738/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.ssi.2003.12.008 * Corresponding author. Tel.: +91-422-2422222x422; fax: +91-422- 2422387. E-mail address: sekarapandian@yahoo.com (S. Selvasekarapandian). www.elsevier.com/locate/ssi Solid State Ionics 167 (2004) 41 – 47