STRUCTURE-PROPERTY RELATIONSHIPS IN THE ELECTROSTRICTION RESPONSE OF LOW DIELECTRIC PERMITTIVITY SILICATE-GLASSES

Some of the polarization mechanisms that affect the dielectric and ele ctrostrictive responses of low dielectric permittivity glasses are exa mined in this work. Electrostriction is the basic electromechanical co upling mechanism in all insulators. It is defined as x(ij) = Q(ijk1)P( k)P(l), where x(ij) is the strain tensor, Q(ijk1) the electrostriction tensor, and P-k the induced polarization. The electrostriction consta nt Q(11) (in Voigt notation) for glasses containing sodium was found t o decrease with frequency in the range 0.1-10 kHz. Q(11) decreased wit h frequency from 0.95 to 0.55 m(4)/C-2 for sodium trisilicate glass an d from 0.6 to 0.45 m(4)/C-2 for sodium aluminosilicate glass. In contr ast, the Q(11) for two samples of silica glass remained nearly constan t at similar to 0.4 m(4)/C-2 in this frequency range. The role played by the Na+ ion and that of silicate coordination shells in effecting t he different electrostrictive responses of these glasses was analyzed. (C) 1998 Elsevier Science Ltd.