Mechanical and Thermal Properties of Lead Borate Glasses Containing CaO and NaF

Glasses with the chemical composition 39PbO - 1NaF - (60-x){0.667B(2)O(3)_0.333Na(2)O }- x CaO (x = 0, 5, 10, 15, 20, and 25 mol %), were prepared by the usual melt quenching technique, and analyzed by using X-ray diffraction, density, differential thermal analysis (DTA), optical properties and mechanical properties. The structural variations due to the increase of the [BO4] at the expense of [BO3] structural units increase the ultrasonic velocity and the elastic moduli along with an increase of the density. The Makishima-Mackenzie model was applied successfully on the prepared glasses. The elastic moduli according to this model increase, which was due to the increase of CaO content. The increase of the glass transition temperature (T-g) according to DTA confirmed this behavior.