New results on high perfection langasite crystals: studies of crystalline defects and mode shapes

Zarka, A.; Capelle, B.; Détaint, J.; Cochet-Muchy, D.

doi:10.1109/freq.1995.484064

Cited by 11 publications

(1 citation statement)

References 2 publications

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“…With increase of the electrode thickness maximum of energy changes position to the left side of the excitation area and the shape of the diffraction image changes from circular to ellipsoidal [15,16,17]. The shift of the maximum of energy to the left side of the excitation area can be due to the presence of defects like growth sectors boundaries.…”

Section: Measurements By X-ray Topographymentioning

confidence: 99%

Investigations on the langasite resonators by X-ray topography

Mateescu¹,

Capelle²,

Détaint³

et al.

IEEE International Frequency Control Sympposium and PDA Exhibition Jointly With the 17th European Frequency and Time Forum, 200

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In this paper the results of electrical measurements of the mass-loading influence on Y-cut langasite resonator parameters are compared with those obtained by X-ray topography analysis of the same resonators. Based on the Ballato's transmission-line analogs of the trapped-energy resonators vibrating in thickness-shear mode [1], the massloading effect on resonator characteristics was studied. The effective mass-loading, motional inductance and quality factor of langasite resonators were computed.Sawyer plan-parallel polished Y-cut langasite resonators with 14mm diameter, 5 MHz resonant frequency, Au electrodes of 7 mm diameters and various thickness were used in experiments.X-ray topography measurements were performed by conventional transmission Laue setting using the white beam synchrotron radiation on fundamental, third and fifth overtones. The results are in agreement with those obtained by electrical measurements.The comparison of X-ray diffraction topography images previously performed on AT-cut quartz resonators with X-ray topographs on langasite resonators pointed out that the Y-cut langasite resonators are less influenced by the mass-loading than the AT-cut quartz resonators.

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Section: Measurements By X-ray Topographymentioning

confidence: 99%

Investigations on the langasite resonators by X-ray topography

Mateescu¹,

Capelle²,

Détaint³

et al.

IEEE International Frequency Control Sympposium and PDA Exhibition Jointly With the 17th European Frequency and Time Forum, 200

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Langasite, langanite, and langatate bulk-wave Y-cut resonators

Smythe

Helmbold

Hague

et al. 2000

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Materials in the langasite family are of current interest for both bulk wave and surface wave devices. Piano-convex Y-cut bulk wave resonators have been built and tested on overtones 1 through 9 using LGS (langasite; La(3)Ga(5)SiO(14)), LGN (langanite; La(3)Ga(5.5)Nb(0.5)O(14)), and LGT (langatate; La(3)Ga(5.5)Ta(5.5)O(14)). Frequencies and motional inductances are compared with calculated values, with good agreement except for the motional inductance of LGT. For all three materials, frequency variation is an essentially parabolic function of temperature. For LGN and LGT, reported values of the Q-frequency product are significantly above the classical limit for AT-cut quartz. A maximum 4 f value of 25.6x10(6), where frequency is in megahertz;, was observed for an LGT resonator; for an unplated resonator, 29.2x10(6) was measured. Still higher values are believed possible.

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