Effects of impurities on dielectric properties of fluorozirconate glasses at microwave frequencies

The dielectric properties of fluorozirconate glasses doped with different impurities have been investigated in the frequency region of 3.0-12.5 GHz using a microwave network analyzer. For glasses containing oxide impurities such as PbO, SiO2, and TiO2, the position of the dielectric resonance, which is observed in the pure fluoride glass, shifts to higher frequencies. Amplitudes of the resonance peaks also become much smaller. The oxide impurities are observed to exist as large numbers of tiny precipitates in the glasses. When the glasses are doped with InF3, the position of the resonance peak shifts to a higher frequency but the amplitude of the peak remains unchanged. The InF3 may be substituted for AlF3 in the glasses. A higher half-resonance width is observed in the doped fluorozirconate glasses. The changes in the dielectric properties are attributed to the different behaviors of the impurities, which affect the structural interunit vibration in the fluoride glasses. (C) 1998 American Institute of Physics. [S0021-8979(98)04802-6].