Phase composition and crystal structure of alumina-zirconia ceramics with varying LaAl₁₁O₁₈ content

This study investigates the phase composition and structure of alumina-zirconia ceramics containing varying amounts of LaAl11O18 plates. The research addresses the significant influence of lanthanum hexaaluminate on the structural and physical properties of these ceramics, specifically focusing on its effects on crystal lattice parameters and phase volume content. Using synchrotron radiation and the Rietveld refinement method, the influence of lanthanum hexaaluminate content on the parameters of crystal lattices and phase content of the investigated materials were evaluated. Scanning electron microscopy was employed to analyze the grain size, morphology, and distribution within the material matrix. High-purity powders of α-Al2O3, 3Y-ZrO2, and La2O3 were used as initial materials. The materials were obtained by the pressureless sintering techniques in two hours at 1520 °C. A series of materials comprising 50 wt.% ZrO2 and varying percentage (0–15 wt.%) of LaAl11O18 was obtained. The coherent scattering regions of the alumina and zirconia matrix phases remained relatively unchanged in the composites. The coherent scattering regions of lanthanum hexaaluminate increased significantly with its concentration in the materials. The analysis revealed a decrease in alumina grain size with increasing LaAl11O18 content, while the size of the LaAl11O18 plates displayed a consistent increase. The best properties were observed for alumina-zirconia ceramics with the calculated content of lanthanum hexaaluminate of 12 wt.%. The relative density of this material is 95.3±0.3%, the hardness is 1490 Hv, and the indentation fracture resistance is 7.2±0.3 MPaThis study investigates the phase composition and structure of alumina-zirconia ceramics containing varying amounts of LaAl11O18 plates. The research addresses the significant influence of lanthanum hexaaluminate on the structural and physical properties of these ceramics, specifically focusing on its effects on crystal lattice parameters and phase volume content. Using synchrotron radiation and the Rietveld refinement method, the influence of lanthanum hexaaluminate content on the parameters of crystal lattices and phase content of the investigated materials were evaluated. Scanning electron microscopy was employed to analyze the grain size, morphology, and distribution within the material matrix. High-purity powders of α-Al2O3, 3Y-ZrO2, and La2O3 were used as initial materials. The materials were obtained by the pressureless sintering techniques in two hours at 1520 °C. A series of materials comprising 50 wt.% ZrO2 and varying percentage (0–15 wt.%) of LaAl11O18 was obtained. The coherent scattering regions of the alumina and zirconia matrix phases remained relatively unchanged in the composites. The coherent scattering regions of lanthanum hexaaluminate increased significantly with its concentration in the materials. The analysis revealed a decrease in alumina grain size with increasing LaAl11O18 content, while the size of the LaAl11O18 plates displayed a consistent increase. The best properties were observed for alumina-zirconia ceramics with the calculated content of lanthanum hexaaluminate of 12 wt.%. The relative density of this material is 95.3±0.3%, the hardness is 1490 Hv, and the indentation fracture resistance is 7.2±0.3 MPa.m1/2.