Synthesis, thermal, structural and electrical properties of vanadium-doped lithium-manganese-borate glass and nanocomposites

Abstract

A glassy sample with a nominal formula LiMn1 − 3x/2VxBO3 (where x = 0.05) was synthesised using the melt-quenching method. Material was characterised by differential thermal analysis (DTA), X-ray diffactometry (XRD) at room temperature and as a function of temperature (HT-XRD), X-ray photoelectron spectroscopy (XPS), impedance spectroscopy (IS) and scanning electron microscopy (SEM). Dependences of glass transition and crystallisation temperatures on the heating rate in DTA experiments were determined. The initial value of electrical conductivity of the glass was 1.4 × 10− 15 Scm− 1. It was significantly increased by a proper thermal nanocrystallisation. The maximum value was higher by 6 orders of magnitude and reached 2.6 × 10− 9 Scm− 1 at room temperature. Expected crystalline phases (i.e. monoclinic and hexagonal LiMnBO3) upon heating were identified and assigned to thermal events observed with DTA. Microstructure of nanocrystalline samples observed by SEM revealed nanocrystalline grains noticeably smaller than 100 nm. Results explaining nanocrystallisation process are coherent.