In this paper, data on structural, optical, and electrical properties of bulk AlN are presented. It is shown that the polycrystalline AlN boules grown by PVT are of high purity. Single-crystalline areas exhibit high structural quality, but void formation occurs dependent on crystal orientation. Aluminum precipitation and nitrogen vacancy formation are observed in boules grown at high temperature. Results from optical absorption, FT-IR micro-spectroscopy and resistivity measurements are valuable for further optimization of bulk crystal growth of AlN.