Dielectric and structural investigation of alkali triborate glasses

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Dielectric data are provided for M 2O·3B 2O 3 glasses (M=Li, Na, K, Rb, Cs) over a broad frequency (5 Hz–2 MHz) and temperature ranges (400–600 K). Activation energies for ionic transport and the parameters of a KWW analysis are presented. The Kohlrausch–Williams–Watts (KWW) exponent, β, increases with alkali cation size. The mid- and far-infrared glass spectra suggest that from Li to Cs both the B–O and M–O bonding changes. The relative intensity of the high frequency far-infrared cation motion band was found to scale linearly with β. Also, β depends linearly on the activation energy, E σ , the microscopic barrier, E α , the interionic distance, d M–M, and the decoupling index at T g. Data available on triborate and trisilicate glasses show that a simple master correlation exists between β and T/ T g over the 0.45 < β < 0.75 and 0.35 < T/ T g < 0.9 ranges.