Abstract:The SiO₂-Li₂O-K₂O-B₂O₃ glasses doping La₂O₃ were prepared by traditional melting quenching method, using P₂O₅ and ZrO₂ as complex nucleating agent and Sb₂O₃ as clarifying agent. The effects of La₂O₃ content on the crystallization behavior, the crystalline phase and the mechanical properties of the glass-ceramics were investigated by using of DSC, XRD, SEM and mechanical property tester. The results show that, the change of La₂O₃ content mainly influences the exothermic peak temperature rather than the second exothermic peak temperature. When La₂O₃ content is lower than 0.40% (mole fraction), the doping content of La₂O₃ does not change the main crystal phase type in the glass-ceramics. However, when the La₂O₃ content increases to 0.80%, the La₂O₃ directly involves in the lattice construction of LaPO₄ micro-crystals. At the same time, La₂O₃ doping increases the precipitation temperature of Li₂Si₂O₅ phase. When the La₂O₃ content is 0.40%, the glass-ceramics has the highest bending strength and elastic modulus, which are 328 MPa and 143 GPa, respectively. When La₂O₃ content is lower than 0.40% and higher than 1.20%, the fracture toughness of the glass-ceramics changes slightly with increasing La₂O₃ content. However, when La₂O₃ content is 0.40%−1.20%, the fracture toughness increases obviously with increasing La₂O₃ content, the biggest fracture toughness of the glass-ceramics reaches up to 3.34 MPa·m^1/2.

Key words: La₂O₃; lithium disilicate; glass-ceramics; mechanical properties