High-Temperature Synchrotron X-Ray Powder Diffraction Study of the Orthorhombic–Tetragonal Phase Transition in La0.63(Ti0.92,Nb0.08)O3
✍ Scribed by Roushown Ali; Masatomo Yashima; Masahiko Tanaka; Hideki Yoshioka; Takeharu Mori; Satoshi Sasaki
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- English
- Weight
- 273 KB
- Volume
- 164
- Category
- Article
- ISSN
- 0022-4596
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✦ Synopsis
The crystal structure of La 0.63 (Ti 0.92 ,Nb 0.08 )O 3 has been re5ned by the Rietveld analysis of CuK X-ray powder di4raction data collected at 233C. This material was con5rmed to have an A-site de5cient orthorhombic perovskite-type structure with double ideal perovskite ABO 3 units along the c-axis (space group Pmmm, Z ؍ 2, a ؍ 3.86036(5) A > , b ؍ 3.87222(5) A > , c ؍ 7.82609(9) A > ). Lattice parameters of the same sample have been investigated in situ in the temperature range from 253C to 4963C by 1.37873(3) A > synchrotron X-ray powder di4raction. The synchrotron X-ray powder di4raction technique was found to be very powerful to determine precise lattice parameters around a phase transition temperature. This compound exhibited a reversible phase transition between the orthorhombic and tetragonal phases at around 3703C. (1) The lattice parameters increased continuously with temperature, while the b/a ratio decreased continuously with temperature and became unity at the orthor-hombic+tetragonal transition point. (2) No hysteresis was observed in the lattice parameter values between heating and cooling. These results of (1) and (2) suggest that the orthorhom-bic+tetragonal phase transition is continuous.
2002 Elsevier Science (USA)