Thermal expansion of AlN, sapphire, and silicon

Thermal expansion coefficients of high-purity AlN, sapphire, and silicon were calculated from the data obtained with precision high-temperature x-ray lattice parameter measurements. The mean thermal expansion coefficients obtained in the range 20–800°C are α⊥ = 5.3 × 10−6/°C and α∥ = 4.2 × 10−6/°C for AlN, α⊥ = 7.3 × 10−6/°C and α∥ = 8.1 × 10−6/°C for α-Al2O3, and α = 3.6 × 10−6/°C for Si.