Characterizations of piezoelectric GaPO4 single crystals grown by the flux method

Armand, P.; Beaurain, M.; Rufflé, Benoît; Ménaert, Bertrand; Balitsky, Denis; Clement, Simon G.; Papet, Philippe

doi:10.1016/j.jcrysgro.2007.11.049

Cited by 19 publications

(27 citation statements)

References 12 publications

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“…This exothermic feature corresponded to a total transformation of the β-cristobalite GaPO 4 phase into the α-quartz phase as confirmed by the X-ray powder pattern of the end product of the DSC analysis [44,46,89,90]. This was the first time that GaPO 4 had been found, after a DSC cycle, exclusively in the α-quartz modification after cooling from the β-cristobalite phase without annealing periods.…”

Section: Flux-grown α-Gaposupporting

confidence: 54%

“…The melting point of these molybdenum-based solvents are between 500 and 600 °C which allows α-GaPO 4 growth under the allotropic phase transition temperature [44,89]. [89,90].…”

Section: Flux-grown α-Gapomentioning

confidence: 99%

“…Only the three bands at 3167, 3290 and 3400 cm −1 were registered. The OH content was materials [44,46,[88][89][90]101]. Compared to the spectra of hydrothermally-grown GaPO 4 , they did not present the characteristic broad and intense absorption band from 3600 to 2500 cm −1 due to quite strong OH contamination estimated with the extinction coefficient α calculated at 3400 cm −1 from the expression α = 1/d[log(T 3800 /T 3400 )]-α 3400 * where d represents the sample thickness in cm, T represents the % IR transmission at respectively 3800 and 3400 cm −1 , and α 3400 * represents the absorption coefficient due to intrinsic lattice vibrations of α-GaPO 4 at 3400 cm −1 [65].…”

Section: Flux-grown α-Gapomentioning

confidence: 99%

“…Differential scanning calorimetric (DSC) experiments were done on flux-grown α-GaPO 4 single crystals crystallized via spontaneous nucleation in MoO 3 -based fluxes as Li 2 O:3MoO 3 and K 2 O:3MoO 3 [44,46,89,90,101]. On heating runs up to 1200 °C (2-10 °C · min −1 ) of α-GaPO 4 as-grown single crystals or powdered samples, only a sharp endothermic peak appeared in the 950-964 °C temperature range, Figure 3, caused by the structural transition from the α-quartz GaPO 4 phase to the β-cristobalite modification stable above 960-980 °C [40][41][42].…”

Section: Flux-grown α-Gapomentioning

confidence: 99%

“…Effectively, concerning the hydrothermally-grown α-GaPO 4 material grown at 300 °C (direct solubility), the successive cooling curve (−10 °C/min) from 1200 °C back to 20 °C, showed two main exothermic peaks [43,90]: one with an onset temperature of 910 °C due to a partial transformation of the β-cristobalite GaPO 4 phase in α-quartz phase and a second, close to 578 °C, attributed to the β-cristobalite/α-cristobalite transition [40][41][42].…”

Section: Flux-grown α-Gapomentioning

confidence: 99%

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

et al. 2014

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Using the slow-cooling method in selected MoO 3 -based fluxes, single-crystals of GeO 2 and GaPO 4 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 GaPO 4 and an absence of phase transition before melting for α-GeO 2 . 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-GaPO 4 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 e 11 from the C D 11 to C E 11 difference gave for the piezoelectric strain coefficient d 11 of flux-grown α-GeO 2 crystal a value of 5.7(2) pC/N, which is more than twice that of α-quartz. As the α-quartz structure of GeO 2 remained stable up to melting, a piezoelectric activity was observed up to 1000 °C.

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Section: Flux-grown α-Gaposupporting

confidence: 54%

“…The melting point of these molybdenum-based solvents are between 500 and 600 °C which allows α-GaPO 4 growth under the allotropic phase transition temperature [44,89]. [89,90].…”

Section: Flux-grown α-Gapomentioning

confidence: 99%