Abstract
We report aluminium substitution effect on structure and electric properties of langasite (La3Ga5SiO14) family crystals. Quasi-congruent melting composition of La3Ga5-xAlxSiO14 (LGAS), La3Nb0.5Ga5.5-xAlxO14 (LNGA), and La3Ta0.5Ga5.5-xAlxO14 (LTGA) crystals are x = 0.9, 0.2, and 0.5, respectively. A single-crystal x-ray structure analysis reveals that Al atoms are distributed in all cation sites except for the decahedral one occupied by La, by rather favoring the smallest tetrahedral one. The electrical properties of the Al-substituted crystals are compared with those of pure ones. By Al substitution, all langasite family crystals show higher piezoelectric constant d11 and higher electric resistivity ρ. Among them, the LTGA crystal with lower temperature dependence of d11 and highest ρ is a promising material for high temperature piezoelectric application.
Published Version
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