Thermal expansion of lanthanum silicate oxyapatite (La{sub 9.33+2x}(SiO{sub 4}){sub 6}O{sub 2+3x}), lanthanum oxyorthosilicate (La{sub 2}SiO{sub 5}) and lanthanum sorosilicate (La{sub 2}Si{sub 2}O{sub 7})
- Department of Environmental and Materials Engineering, Nagoya Institute of Technology, Nagoya 466-8555 (Japan)
Four types of powder specimens of La{sub 9.33}(SiO{sub 4}){sub 6}O{sub 2} (space group P6{sub 3}/m and Z=1), La{sub 9.33+2x}(SiO{sub 4}){sub 6}O{sub 2+3x} with 0.06{<=}x{<=}0.13 (P6{sub 3}/m and Z=1), La{sub 2}SiO{sub 5} (P2{sub 1}/c and Z=4) and La{sub 2}Si{sub 2}O{sub 7} (P2{sub 1}/c and Z=4) were examined by high-temperature X-ray powder diffractometry to determine the changes in unit-cell dimensions up to 1473 K. The anisotropy of thermal expansion was demonstrated for the former two crystals to clarify the thermal behaviors of the highly c-axis-oriented polycrystals. With La{sub 9.33}(SiO{sub 4}){sub 6}O{sub 2}, the linear expansion coefficient of the a-axis ({alpha}{sub a}) was 4.8 Multiplication-Sign 10{sup -6} K{sup -1} and that of the c-axis ({alpha}{sub c}) was 1.8 Multiplication-Sign 10{sup -6} K{sup -1} in the temperature range from 298 to 1473 K. The {alpha}{sub a}- and {alpha}{sub c}-values of La{sub 9.33+2x}(SiO{sub 4}){sub 6}O{sub 2+3x} (0.06{<=}x{<=}0.13) were, respectively, 5.9 Multiplication-Sign 10{sup -6} K{sup -1} and 2.3 Multiplication-Sign 10{sup -6} K{sup -1}. The coefficients of mean linear thermal expansion were 4.9 Multiplication-Sign 10{sup -6} K{sup -1} for La{sub 2}SiO{sub 5} and 6.0 Multiplication-Sign 10{sup -6} K{sup -1} for La{sub 2}Si{sub 2}O{sub 7}, which describe the thermal expansion behaviors of the randomly grain-oriented polycrystalline materials. - Graphical abstarct: Temperature dependence of the coefficients of thermal expansion (CTE). The linear CTE along the a-axes for La{sub 9.33}(SiO{sub 4}){sub 6}O{sub 2} and La{sub 9.33+2x}(SiO{sub 4}){sub 6}O{sub 2+3x} with 0.06{<=}x{<=}0.13. The mean linear CTE for La{sub 2}SiO{sub 5} and La{sub 2}Si{sub 2}O{sub 7}. Highlights: Black-Right-Pointing-Pointer We examined the thermal expansion of La{sub 9.33+2x}(SiO{sub 4}){sub 6}O{sub 2+3x} (x=0 and 0.06{<=}x{<=}0.13), La{sub 2}SiO{sub 5} and La{sub 2}Si{sub 2}O{sub 7} Black-Right-Pointing-Pointer Unit-cell dimensions were determined up to 1473 K by high-temperature X-ray diffraction Black-Right-Pointing-Pointer Anisotropic expansion was clarified for La{sub 9.33+2x}(SiO{sub 4}){sub 6}O{sub 2+3x} (x=0 and 0.06{<=}x{<=}0.13) Black-Right-Pointing-Pointer Mean linear thermal expansion was determined for La{sub 2}SiO{sub 5} and La{sub 2}Si{sub 2}O{sub 7.}.
- OSTI ID:
- 22149842
- Journal Information:
- Journal of Solid State Chemistry, Vol. 194; Other Information: Copyright (c) 2012 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
Similar Records
Binary, ternary and quaternary silicates of CaO, BaO and ZnO in high thermal expansion seals for solid oxide fuel cells studied by high-temperature X-ray diffraction (HT-XRD)
Structure and high-temperature properties of the (Sr,Ca,Y)(Co, Mn)O{sub 3-y} perovskites - perspective cathode materials for IT-SOFC