OH impurities in GaPO4 crystals: correlation between infrared absorption and mass loss during thermal treatment

Jacobs, K.; Hofmann, P.; Klimm, D.

doi:10.1016/s0022-0248(01)02047-4

Cited by 11 publications

(11 citation statements)

References 4 publications

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“…The presence of OH-groups, which decrease the Q-factor of the resonators, is largely reported in the literature concerning the crystal growth of a-GaPO 4 by the hydrothermal method [1][2][3][4][5][6]. In a typical infrared spectrum of a GaPO 4 material containing significant OH-groups, a broad band between 2500 and 3600 cm À1 is observed.…”

Section: Resultsmentioning

confidence: 92%

“…In a typical infrared spectrum of a GaPO 4 material containing significant OH-groups, a broad band between 2500 and 3600 cm À1 is observed. This broad band is superimposed upon a sharp absorption band at 3508 cm À1 related to an isolated OH-group stretching band [4][5][6]. The 3169, 3292 and 3400 cm À1 bands are assigned to third overtone vibrations with an absorption respectively equal to 0.697, 0.285 and 0.078 cm À1 [4].…”

Section: Resultsmentioning

confidence: 95%

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Synthesis and characterization of α-GaPO4 single crystals grown by the flux method

Beaurain¹,

Armand²,

Papet³

2006

Journal of Crystal Growth

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Section: Resultsmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 95%

Synthesis and characterization of α-GaPO4 single crystals grown by the flux method

Beaurain¹,

Armand²,

Papet³

2006

Journal of Crystal Growth

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“…However, productivity and yield of growing GaPO 4 single crystals is rather low. Extremely anisotropic growth rates, twinning and the incorporation of OH-groups in the crystals are observed [23][24][25][26]. Due to those difficulties the availability of GaPO 4 is limited which prevents its large scale application.…”

Section: High-temperature Piezoelectric Materialsmentioning

confidence: 99%

High-temperature piezoelectric crystals and devices

Fritze

2011

J Electroceram

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Conventional piezoelectric materials such as quartz are widely used as high precision transducers and sensors based on bulk acoustic waves. However, their operation temperature is limited by the intrinsic materials properties to about 500 • C. High-temperature applications are feasible by applying materials that retain their piezoelectric properties up to higher temperatures. Here, langasite (La 3 Ga 5 SiO 14 ) and compounds of the langasite family are the most promising candidates, since they are shown to exhibit bulk acoustic waves up to at least 1400 • C. The mass sensitivity of langasite resonators at elevated temperatures is about as high as that of quartz at room temperature. Factors limiting potential use of those crystals include excessive conductive and viscous losses, deviations from stoichiometry and chemical instability. Therefore, the objective of this work is to identify the related microscopic mechanisms, to correlate electromechanical properties and defect chemistry and to improve the stability of the materials by e.g. appropriate dopants.Further application examples such as resonant gas sensors are given to demonstrate the capabilities of hightemperature stable piezoelectric materials. The electromechanical properties of langasite are determined and described by a one-dimensional physical model. Key properties relevant for stable operation of resonators are found to be shear modulus, density, electrical conductivity and effective viscosity. In order to quantify their impact on frequency and damping, a general-H. Fritze (B)

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“…The OH contamination of the crystalline lattice during crystallization via growth medium, which decreases the Q-factor of the resonators, has been largely reported in the literature concerning α-GaPO 4 grown by the hydrothermal method [43,52,53,55,57,68,71,99,100].…”

Section: Flux-grown α-Gapomentioning

confidence: 99%

“…However, for gallium orthophosphate material, it seems quite difficult to obtain very high quality crystals with these solution-based growth methods. The presence of twins, dislocations and/or a quite high level of hydroxyl group incorporated via the growth medium tend to deteriorate the piezoelectric properties especially at high temperatures as physical properties are very sensitive to material perfection [43,49,50,57,[63][64][65][66][67][68][69][70][71][72][73]. The OH impurities in α-GaPO 4 single crystals are responsible for the -milky‖ appearance of the samples when exposed to high temperature (600 °C).…”

Section: Introductionmentioning

confidence: 99%

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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OH impurities in GaPO4 crystals: correlation between infrared absorption and mass loss during thermal treatment

Cited by 11 publications

References 4 publications

Synthesis and characterization of α-GaPO4 single crystals grown by the flux method

Synthesis and characterization of α-GaPO4 single crystals grown by the flux method

High-temperature piezoelectric crystals and devices

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

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