The thermal conductivity, measured by the 3ω method, of amorphous films of Al₂P₁.₂O₆ (AlPO) deposited on Si substrates by an all-aqueous spin-coating technique is 0.93(3) Wm⁻¹K⁻¹. The thermal conductivity of a degenerately doped n-Si substrate is 85(5) Wm⁻¹K⁻¹ and of a more lightly doped p-Si substrate is 139(7) Wm⁻¹K⁻¹. The...