Crystalline phase evolution and thermal behavior of zirconia‐lanthanum aluminate ceramics produced by surface modification

Abstract

The purpose of the present work was to investigate the effect doping with lanthanum aluminate on the phase assemblage and thermal behavior of zirconia ceramics for biomedical applications. Four compositions were prepared by a surface modification route of either conventional tetragonal zirconia (3Y‐TZP) or high translucency cubic‐based zirconia (5Y‐PSZ) to reach a nominal composition of either 0.5 wt. % (3Y‐0.5LAO and 5Y‐0.5LAO) or 5 wt. % of lanthanum monoaluminate (3Y‐5LAO and 5Y‐5LAO). Undoped powders were used as controls. DTA and XRD analyses revealed that lanthanum dizirconate crystallized in the 934°C–936°C range, while lanthanum aluminate crystallized in the 1,056°C–1,063°C range in both types of zirconias doped at the 5% level. No second phase was found in compositions doped at the 0.5% level. The a lattice parameter and the amount of the cubic phase increased in both 3Y‐5LAO and 5Y‐5LAO. The microstructure of the compositions doped with 5% LAO was characterized by well distributed LAO twinned crystals and sparse needle‐shaped lanthanum hexaaluminate crystals. A bimodal grain size distribution was observed in 5Y‐doped compositions. This was attributed to abnormal grain growth of the cubic phase, and in line with aluminum segregation at grain boundaries and the presence of second‐phase LAO crystals.

La-Doped Alumina, Lanthanum Aluminate, Lanthanum Hexaaluminate, and Related Compounds: A Review Covering Synthesis, Structure, and Practical Importance

“…Depending on the synthesis method used, hexagonal and orthorhombic structures are occasionally reported . LMA has excellent chemical, thermal and mechanical stability (mp 2180 °C), and interesting optoelectronic and thermoelectric properties. ,, LMA has low toxicity, which makes it a promising component of dental implants . It is a wide-band gap perovskite that is of great interest as a dielectric with high relative permittivity ε r (ω).…”

“…176,230,233 LMA has low toxicity, which makes it a promising component of dental implants. 234 It is a wideband gap perovskite that is of great interest as a dielectric with high relative permittivity ε r (ω). Shen et al 232 reassessed the value of the band gap and the position of the La 4f states, which allowed them to recalculate the optical spectra.…”