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Effects of aluminum substitution on the structure and electric properties of langasite family crystals
Author(s) -
Takeda Hiroaki,
Yamaura Junichi,
Nishida Takashi,
Hoshina Takuya,
Tsurumi Takaaki
Publication year - 2015
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.201500261
Subject(s) - materials science , piezoelectricity , substitution (logic) , crystallography , aluminium , electrical resistivity and conductivity , crystal structure , crystal (programming language) , tetrahedron , chemistry , metallurgy , composite material , programming language , engineering , computer science , electrical engineering
The effects of aluminum substitution on the structure and electric properties of langasite (La 3 Ga 5 SiO 14 ) family crystals are reported. The maximum Al content x of La 3 Ga 5‐x Al x SiO 14 (LGAS), La 3 Nb 0.5 Ga 5.5‐x Al x O 14 (LNGA), and La 3 Ta 0.5 Ga 5.5‐x Al x O 14 (LTGA) crystals grown by the conventional Czochralski technique are x = 0.9, 0.2, and 0.5, respectively. Single‐crystal X‐ray structural analysis reveals that Al atoms are distributed in all cation sites except for the decahedral one occupied by La, rather than favoring the smallest tetrahedral sites. The electrical properties of the Al‐substituted crystals were also compared with those of pure ones. Al substitution was found to affect the piezoelectric constant d 14 , but not d 11 . The LGAS and LTGA crystals exhibit higher electric resistivity ρ as a result of Al substitution. Among the Al‐substituted and pure crystals, the LTGA crystal featured the lowest temperature dependence of d 11 and highest ρ , making it the most suitable of the group for high‐temperature piezoelectric applications.