The influences of aluminum substitution for gallium in the langasite-type La3Nb0.5Ga5.5O14 (LNG) crystals on their growth and electric properties were investigated. Al-substituted LNG (La3Nb0.5Ga5.5-x,AlxO14; LNGAx) single crystals up to the solubility limit x = 0.2 have been grown by the conventional Czochralski technique. The electric properties of the LNGAx crystals were investigated and compared to those of LNG. With Al substitution, the piezoelectric constants, d(11) and d(14), were slightly higher. The LNGAx crystals showed a temperature dependence of d(11) similar to that of the LNG crystal. (c) 2007 Elsevier Ltd. All rights reserved.