Ionic to Electronic Conductivity Studies of Lithium-Borate Ruby-Glass-Ceramics Containing Gold Nano Particles

Abstract

Glass-ceramics containing Au nanoparticles have been synthesized in the glass composition 30Li2O-70B2O3 with HAuCl4.3H2O as dopant. The characteristic ruby colour has been observed which is attributed to the surface Plasmon resonance of the Au nanoparticles, uniformly embedded in the glass matrix. The imparted red colour due to the presence of gold nanoparticles has been confirmed by studying the optical absorption spectra using UV-VIS spectrometer in the visible range (400–1000 nm) which show a characteristic absorption peak at ∼560 nm. In order to check the crystallization/ amorphous nature, the samples were powdered and characterized using X-ray diffraction (XRD). The microstructural modifications in the samples due to the addition of Au have been recorded using scanning electron microscopy (SEM). Further, the electron spin resonance (ESR) studies reveal that the electronic state of gold is either Au0 or Au+. AC conductivity studies have been performed at room temperature over a frequency range 100 to 10 MHz. The ac conductivity data is fitted by Almond-West law with power exponent ‘s’. The dc conductivity is found to be increasing with the increase of temperature for a typical ruby glass, but almost constant with dopant concentration.