The elastic and anelastic constants of a synthetic fluor-mica formed by glass-ceramic fabrication techniques

"A tetrasilicic fluor mica, K2Mg5Si8O20F4, was synthesized using glass forming techniques. Density changes, weight losses, and shrinkage, as well as elastic and anelastic properties, were measured on bars heat-treated at selected temperatures between 500°C and 1150°C to determine the characteristics of this material. Phase changes were followed by determining thermal expansion, logarithmic decrement, and modulus of elasticity from room temperature to 800°C.It was found that the elastic and anelastic constants decreased gradually with heat treatments from 600°C to 1000°C. This indicated progressively increased structural ordering. Heat treatments above 1000°C produced appreciable decreases in the elastic constants and equally appreciable increases in the anelastic constants. This was evidence of increasing mica or crystal growth. Determinations of the modulus of elasticity, logarithmic decrement, and thermal expansion from room temperature to 800°C showed the transformation from an amorphous to ordered structure to occur at 600°C. There was also an indication of ionic arrangement prior to the actual transformation"--Abstract, page ii.