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 La2GeO5 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 La8.51Y0.96(GeO4)6O2.205. This conductivity (6.12
Original language | English |
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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 |
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