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.