Abstract
The high-temperature phase of lanthanum germanate is useful due to its high oxide ion conductivity. While the transition from the high- to low-temperature phase could be suppressed by yttrium substitution in lanthanum sites, full stabilization of the high-temperature phase was difficult to achieve by yttrium substitution under conditions of different lanthanum-deficient compositions, as some X-ray diffraction (XRD) peaks were broadened after annealing at 873 K. With lattice constant analysis using the XRD peaks, the degree of lattice asymmetry for the low-temperature phase with triclinic lattice was found to decrease with increases in the deficiency of the lanthanum site and yttrium concentration. Formation of the low-temperature phase was difficult to detect even from Raman shift spectra. On the other hand, Raman shift spectra showed high sensitivity to detection of the La 2 GeO 5 impurity phase. The influence of the total conductivity on the phase transition showed different trends with increases in the lanthanum deficiency and yttrium concentration. With tuning of the composition, the highest conductivity was observed in La 8.51 Y 0.96 (GeO 4 ) 6 O 2.205 . This conductivity (6.12
| Original language | English |
|---|---|
| Pages (from-to) | 91-98 |
| Number of pages | 8 |
| Journal | Journal of the Ceramic Society of Japan |
| Volume | 126 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - 2018 Feb 1 |
| Externally published | Yes |
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Keywords
- Conductivity
- Lanthanum germanate
- Oxyapatite
- Phase transition
- Raman shift spectra
- Yttrium doping
ASJC Scopus subject areas
- Ceramics and Composites
- Chemistry(all)
- Condensed Matter Physics
- Materials Chemistry
Cite this
Stabilization of the high-temperature phase and total conductivity of yttrium-doped lanthanum germanate oxyapatite. / Kobayashi, Kiyoshi; Igarashi, Yukihito; Saito, Noriko; Higuchi, Tohru; Sakka, Yoshio; Suzuki, Tohru.
In: Journal of the Ceramic Society of Japan, Vol. 126, No. 2, 01.02.2018, p. 91-98.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Stabilization of the high-temperature phase and total conductivity of yttrium-doped lanthanum germanate oxyapatite
AU - Kobayashi, Kiyoshi
AU - Igarashi, Yukihito
AU - Saito, Noriko
AU - Higuchi, Tohru
AU - Sakka, Yoshio
AU - Suzuki, Tohru
PY - 2018/2/1
Y1 - 2018/2/1
N2 - The high-temperature phase of lanthanum germanate is useful due to its high oxide ion conductivity. While the transition from the high- to low-temperature phase could be suppressed by yttrium substitution in lanthanum sites, full stabilization of the high-temperature phase was difficult to achieve by yttrium substitution under conditions of different lanthanum-deficient compositions, as some X-ray diffraction (XRD) peaks were broadened after annealing at 873 K. With lattice constant analysis using the XRD peaks, the degree of lattice asymmetry for the low-temperature phase with triclinic lattice was found to decrease with increases in the deficiency of the lanthanum site and yttrium concentration. Formation of the low-temperature phase was difficult to detect even from Raman shift spectra. On the other hand, Raman shift spectra showed high sensitivity to detection of the La 2 GeO 5 impurity phase. The influence of the total conductivity on the phase transition showed different trends with increases in the lanthanum deficiency and yttrium concentration. With tuning of the composition, the highest conductivity was observed in La 8.51 Y 0.96 (GeO 4 ) 6 O 2.205 . This conductivity (6.12
AB - The high-temperature phase of lanthanum germanate is useful due to its high oxide ion conductivity. While the transition from the high- to low-temperature phase could be suppressed by yttrium substitution in lanthanum sites, full stabilization of the high-temperature phase was difficult to achieve by yttrium substitution under conditions of different lanthanum-deficient compositions, as some X-ray diffraction (XRD) peaks were broadened after annealing at 873 K. With lattice constant analysis using the XRD peaks, the degree of lattice asymmetry for the low-temperature phase with triclinic lattice was found to decrease with increases in the deficiency of the lanthanum site and yttrium concentration. Formation of the low-temperature phase was difficult to detect even from Raman shift spectra. On the other hand, Raman shift spectra showed high sensitivity to detection of the La 2 GeO 5 impurity phase. The influence of the total conductivity on the phase transition showed different trends with increases in the lanthanum deficiency and yttrium concentration. With tuning of the composition, the highest conductivity was observed in La 8.51 Y 0.96 (GeO 4 ) 6 O 2.205 . This conductivity (6.12
KW - Conductivity
KW - Lanthanum germanate
KW - Oxyapatite
KW - Phase transition
KW - Raman shift spectra
KW - Yttrium doping
UR - http://www.scopus.com/inward/record.url?scp=85041668421&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85041668421&partnerID=8YFLogxK
U2 - 10.2109/jcersj2.17198
DO - 10.2109/jcersj2.17198
M3 - Article
VL - 126
SP - 91
EP - 98
JO - Nippon Seramikkusu Kyokai Gakujutsu Ronbunshi/Journal of the Ceramic Society of Japan
JF - Nippon Seramikkusu Kyokai Gakujutsu Ronbunshi/Journal of the Ceramic Society of Japan
SN - 1882-0743
IS - 2
ER -