Synthesis and Characterization of Pt/ZnMgO/Si₂O₃ Coatings by Laser Molecular Beam Epitaxy Deposition

The surfaces of PGS piezoelectric crystal,a surface acoustic wave(SAW) sensor material,were modified with Pt/ZnMgO/Si₂O₍3)tri-layered coatings,synthesized by laser molecular beam epitaxy(L-MBE) deposition.The influence of the Si₂O₍3)particle-size on the microstructures and operation stability at~1000℃ of SAW sensors was investigated with scanning electron microscopy and X-ray diffraction.The preliminary results show that the Si₂O₃ particle-size had a major impact.Specifically,as the Si₂O₃ particle-size increased to 60μm,the "rapid conductivity-decrease temperature" increased to 1150℃,450℃ higher than that of the control sample; at sizes larger than 90μm,the decreased conductivity(at above 1000℃) remained roughly unchanged; the Pt grain-size decreased,because of the formation of voids and Si₂O₃-induced prevention of Pt-recrystallization and growth.Besides,the 200 μm-Si₂O₃ particles resulted in a decrease of grain-size,an increase of voids/pores density and the improvements of flatness and compactness of Pt-layer.