AlP-like Li3AlP2 crystallizes in an orthorhombic structure in contrast to cubic nitride semiconductors such as Li3AlN2 and Li3GaN2Li3AlP2 can be viewed as the zincblende-like (Li0.5Al0.5P)(-) lattice filled with He-like Li+ ions at the empty tetrahedral sites. Li3AlP2 is grown by direct reaction of Li, Al, and P in an evacuated quartz ampoule. A typical reaction temperature is 1073 K and the temperature is maintained for 100h. As-glown crystals, which are yellow in color, are confirmed to be a single phase of Li3AlP2 (space group: Ibca) with a = 11.43 angstrom, b = 11.93 angstrom, and c = 12.03 angstrom by a powder X-ray diffraction method. Twelve Raman peaks are observed, which are consistent with 12 Raman active modes (3A(g) + 3B(2g) + 3B(2g) + 3B(3g)) evaluated by a factor group analysis for Li3AlP2. The band gap of as-grown Li3AlP2 evaluated using photoacoustic spectroscopy is similar to 2.75 eV. The gap value is slightly larger than that of AlP (E-g = 2.43 ev), suggesting that the band gap of Li3AlP2 is essentially attributed to the six ionic Li-P bonds in the 1/8-sublattice as well as the Li-N bonds in the filled tetrahedral semiconductors Li3AlN2 and Li3GaN2. (C) 2007 Elsevier B.V. All rights reserved.