研究目的
To understand the phase diagram of PbZr1-xTixO3 (PZT) materials, specifically investigating the existence of an additional phase transition in a PbZr0.87Ti0.13O3 single crystal using elastic property measurements.
研究成果
The research successfully grew a high-quality PbZr0.87Ti0.13O3 single crystal and confirmed an additional phase transition at around 180°C, likely of improper type related to octahedral tilting. The monoclinic Cm symmetry was found to better describe the structure at room temperature than rhombohedral symmetries, indicating a more complex phase diagram for PZT materials than previously thought.
研究不足
The study is limited by the difficulty in growing high-quality single crystals for PZT, potential domain effects in measurements, and the need for synchrotron or neutron scattering for deeper structural insights. The x-ray diffraction may not fully resolve oxygen positions due to absorption effects and local disorder.
1：Experimental Design and Method Selection:
The study used piezoelectric resonance measurements and Brillouin light scattering to investigate elastic properties at low and high frequencies, chosen for reliability in detecting phase transitions. X-ray diffraction was employed for structural analysis at room temperature.
2：Sample Selection and Data Sources:
A PbZr
3：87Ti13O3 single crystal was grown using the top-seeded solution growth technique, with edges <100> oriented in pseudo-cubic symmetry. Powder diffraction was performed on crushed crystal to avoid domain issues. List of Experimental Equipment and Materials:
Equipment included a PANalytical PW1050 diffractometer for X-ray diffraction, JSM-5410 Oxford Instruments SEM with EDS for chemical analysis, Hewlett-Packard 4192A impedance analyzer for dielectric and piezoelectric measurements, and a tandem multi-pass Fabry-Perot interferometer (TFP-1, JRS Co.) for Brillouin scattering with a diode-pumped solid-state laser (Excelsior 532-300, Spectra Physics) and cryostat (THMS-600, Linkam). Materials included the single crystal sample, silver paste for electrodes, and agate mortar for grinding.
4：Experimental Procedures and Operational Workflow:
The crystal was electroded with silver paste; dielectric permittivity was measured at 1MHz with heating/cooling cycles at 1K/min. Piezoelectric properties were measured in d31 and d33 configurations after poling under DC field. Brillouin spectra were measured in backscattering geometry with cooling cycles, using Voigt function fitting. X-ray diffraction involved step scanning from 7 to 135 degrees with refinement using Fullprof software. EDS analysis checked element distribution.
5：Data Analysis Methods:
Data were analyzed using the forced harmonic oscillator model for piezoelectric parameters, Rietveld refinement for structural data, and curve-fitting for Brillouin spectra. Statistical analysis included agreement factors in refinement.
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