We have successfully grown bulk, single crystals of AlxGa1-xN with the Al content x ranging from 0.5 to 0.9. Samples were grown from Ga melt under high nitrogen pressure (up to 10 kbar) and at high temperature (up to 1800 degrees C) using a gas pressure system. The homogeneity and Al content of the crystals were investigated by X-ray diffraction and laser ablation mass spectrometry. On the basis of the high-pressure experiments, the corresponding pressure-temperature (p-T) phase diagram of Al-Ga-N was derived. The bandgap of the material was determined by the femtosecond two-photon absorption autocorrelation method and is equal to 5.81 +/- 0.01 eV for the Al0.86Ga0.14N crystals. (C) 2009 Elsevier B.V. All rights reserved.