Synchrotron White Beam X-Ray Topography Characterization of LGX and SXGS Bulk Single Crystals, Thin Films and Piezoelectric Devices
Final rept. 1 Jul 2001-31 Dec 2006
STATE UNIV OF NEW YORK AT STONY BROOK
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This project comprised a program of research aimed at applying the technique of Synchrotron White Beam X-ray Topography SWBXT, supplemented by the complementary technique of High Resolution Triple-Axis X-ray Diffraction HRTXD, to the determination of defect and general distortion distributions in novel LGX piezoelectric crystals with a view to enabling improvement in crystal quality and consequently in piezoelectric device performance. The LGX family of compounds, which includes langanite, LGS La3Ga5SiO14, and its isomorphs, langanite or LGN La3Ga5.5Nb0.5O14 and langatate or LGT La3Ga5.5Ta0.5O14, as well as several other variants, are of current interest for application as bulk wave resonators for precision oscillators, with all these materials exhibiting high piezoelectric coupling, low acoustic loss high Q and temperature compensation. However, the influence of crystal quality on piezoelectric properties, for example, on mode shapes dictates that high quality crystals are required for this technology to reach full potential. This requires collaboration between crystal growers and characterizers to gain an understanding of the defect content of the crystals and to enable optimization of growth parameters. To this end, detailed SWBXT studies will be carried out on 1 bulk LGX crystals grown using the Czochralski technique, 2 homo- and heteroepitaxial thin films of LGX, and 3 various LGX resonator structures including Surface Acoustic Wave SAW resonators. 4 Selected Quartz Resonators 5 SiC substratesepilayers.
- Electricity and Magnetism