TY - JOUR
T1 - High-temperature electrical resistivity and loss tangent of langasite-family Ca3Nb(Ga,Al)3Si2O14 single crystals
AU - Karaki, Tomoaki
AU - Ito, Kiyoto
AU - Fujii, Tadashi
AU - Adachi, Masatoshi
AU - Ohashi, Yuji
AU - Kushibiki, Jun Ichi
AU - Yoshikawa, Akira
N1 - Funding Information:
The authors would like to thank Professor Z. G. Hu of East China Normal University, Professor W. X. Jia of Beijin University of Technology, and Professor Z. Y. Man of Shanghai Institute of Ceramics, Chinese Academy of Sciences for help in spectroscopic ellipsometry and dielectric measurements.
Publisher Copyright:
© 2018 The Japan Society of Applied Physics.
PY - 2018/11
Y1 - 2018/11
N2 - Langasite-family Ca3Nb(Ga1- x Al x )3Si2O14 (CNGAS) (x = 0-0.6) single crystals were grown by a Czochralski technique along the x-axis. When the Al substituent was 0.5, electrical resistivity was greatly improved to 1010 Ω cm at 500 °C, which was more than two orders of magnitude higher than that of Ca3NbGa3Si2O14 (CNGS). This value is the highest resistivity among members of the langasite family at present. However, the dielectric features associated with loss tangent jump at about 400 °C were not improved by the Al substituent. The bandgap E g was measured by spectroscopic ellipsometry, and E g was changed by both temperature and amount of Al substituent. Real and imaginary dielectric constants at a frequency from 0.1 to 20,000 Hz were measured from 150 to 600 °C. There was no marked difference between Cole-Cole plots of specimens with x = 0.1 and 0.5. Oxygen vacancies associated with Nb ions were discussed for DC conductivity and AC loss tangent.
AB - Langasite-family Ca3Nb(Ga1- x Al x )3Si2O14 (CNGAS) (x = 0-0.6) single crystals were grown by a Czochralski technique along the x-axis. When the Al substituent was 0.5, electrical resistivity was greatly improved to 1010 Ω cm at 500 °C, which was more than two orders of magnitude higher than that of Ca3NbGa3Si2O14 (CNGS). This value is the highest resistivity among members of the langasite family at present. However, the dielectric features associated with loss tangent jump at about 400 °C were not improved by the Al substituent. The bandgap E g was measured by spectroscopic ellipsometry, and E g was changed by both temperature and amount of Al substituent. Real and imaginary dielectric constants at a frequency from 0.1 to 20,000 Hz were measured from 150 to 600 °C. There was no marked difference between Cole-Cole plots of specimens with x = 0.1 and 0.5. Oxygen vacancies associated with Nb ions were discussed for DC conductivity and AC loss tangent.
UR - http://www.scopus.com/inward/record.url?scp=85057162428&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85057162428&partnerID=8YFLogxK
U2 - 10.7567/JJAP.57.11UD04
DO - 10.7567/JJAP.57.11UD04
M3 - Article
AN - SCOPUS:85057162428
VL - 57
JO - Japanese Journal of Applied Physics, Part 1: Regular Papers & Short Notes
JF - Japanese Journal of Applied Physics, Part 1: Regular Papers & Short Notes
SN - 0021-4922
IS - 11
M1 - 11UD04
ER -