Tantalum-Lanthanum Mixing Effect on Structural and Mechanical Properties of Aluminate Glasses

Abstract

Aluminate glasses are known for their superior mechanical and optical properties. Here, we investigated the tantalum (Ta)-lanthanum (La) mixing effect on structural and mechanical properties of these glasses. Using the aerodynamic levitation and laser melting technique, we prepared a series of aluminate glasses with the molar composition 54Al2O3·(46-x)La2O3·xTa2O5. The structural, thermal, and mechanical analyses revealed that substituting Ta for La strongly impacted the local Al environment in the glasses, thereby affecting their glass transition temperature, crystallization behavior, and mechanical properties. The Vickers microhardness (HV) varied non-monotonically with the molar ratio R (defined as Ta/(Ta+La) = x/46), reaching a maximum Hv value of 8.59 GPa at R = 0.8. This trend was explained in terms of both the average bonding energy and the density of rigid constraints. Moreover, the crack initiation resistance of the glasses increased as R rose. This work helps in designing highly crack resistant and hard oxide glasses.

Keywords: Aluminate glasses, Ta-La mixing effect, Aluminum coordination, Structure, Glass transition, Mechanical properties