Dielectric properties of glasses in the system TiO2-Na2O-SiO2

The incorporation of titanium oxide in glasses is widely practiced. From the more fundamental aspect the contribution of the titanium ion to the dielectric properties, particularly the dielectric constant, is of special interest. The dielectric constant of glasses in the TiO2-Na2O-SiO2 system has been measured up to 10¹⁰ cycles per second. These glasses have dielectric constants as high as 13 even at this high frequency. The polarisability of Ti⁺⁴ is small as may be seen by comparison of the molar refraction of Ti⁺⁴ (0.47 cm³) with that of Pb⁺⁴ (1.56 cm³) and Ba⁺² (3.9 cm³). Hence, the high dielectric constant of the TiO2 containing glasses cannot be attributed to the electronic polarization but must be attributed to ionic orientation of the Ti⁺⁴ ion.