Flux-Grown Piezoelectric Materials: Application to α-Quartz Analogues

Crystals

Pascale Armand¹  Adrien Lignie²  Marion Beaurain² 

[1] Institut Charles Gerhardt Montpellier, UMR5253, CNRS-UM2-ENSCM-UM1, C2M, UMII, CC 1504, Place E. Bataillon, 34095 Montpellier Cedex 5, France;

关键词: single crystal;    GaPO₄;    GeO₂;    SiO₂;    raman;    infrared;    Brillouin;    growth from high temperature solution;    differential scanning calorimetry (DSC);    X-ray diffraction;   

DOI  :  10.3390/cryst4020168

来源: mdpi

【 摘 要 】

Using the slow-cooling method in selected MoO₃-based fluxes, single-crystals of GeO₂ and GaPO₄ materials with an α-quartz-like structure were grown at high temperatures (T ≥ 950 °C). These piezoelectric materials were obtained in millimeter-size as well-faceted, visually colorless and transparent crystals. Compared to crystals grown by hydrothermal methods, infrared and Raman measurements revealed flux-grown samples without significant hydroxyl group contamination and thermal analyses demonstrated a total reversibility of the α-quartz ↔ β-cristobalite phase transition for GaPO₄ and an absence of phase transition before melting for α-GeO₂. The elastic constants C_IJ (with I, J indices from 1 to 6) of these flux-grown piezoelectric crystals were experimentally determined at room and high temperatures. The ambient results for as-grown α-GaPO₄ were in good agreement with those obtained from hydrothermally-grown samples and the two longitudinal elastic constants measured versus temperature up to 850 °C showed a monotonous evolution. The extraction of the ambient piezoelectric stress contribution e₁₁ from the C^D₁₁ to C^E₁₁ difference gave for the piezoelectric strain coefficient d₁₁ of flux-grown α-GeO₂ crystal a value of 5.7(2) pC/N, which is more than twice that of α-quartz. As the α-quartz structure of GeO₂ remained stable up to melting, a piezoelectric activity was observed up to 1000 °C.

【 授权许可】

CC BY   
© 2014 by the authors; licensee MDPI, Basel, Switzerland.