Title

High-Quality 2 Inch La3Ga5.5Ta0.5O 14 And Ca3Taga3Si2O14 Crystals For Oscillators And Resonators

Abstract

Ca3Ga2Ge4O14 (CGG)-type crystals have attracted much attention over the past years for their outstanding piezoelectric properties, superior to quartz, offering new possibilities in bulk (BAW) and surface acoustic wave (SAW) devices. Among them, most investigated are the isomorphs La3Ga5SiO14 (LGS), La3Ga5.5Nb0.5O14 (LGN), and La3Ga5.5Ta0.5O14 (LGT), so-called langasites, commonly denoted herein LGX (X = S, N, and T). Recently, the quaternary CGG isomorphs, Ca3TaGa3Si2O 14 (CTGS) and Ca3NbGa3Si2O 14 (CNGS) became of interest as they have an ordered crystal structure that may lead to a better consistency in acoustic properties and a higher Q than LGT. Today, the main limitation towards commercialization of any of these new piezoelectrics is the insufficient homogeneity of the crystals, which lead to non-reliable materials parameters measurements and a spread in device characteristics. We report on the growth of high-quality large-diameter 2" LGT and 1.5" CTGS crystals. The study of inherent and growth-induced crystal defects combined with systematic Czochralski growth process optimization have led to these colorless transparent crystals. The high-quality of the LGT crystals was confirmed by X-ray synchrotron topography. The LGT crystals were processed into Y-cut plano-convex resonators by MtronPTI (Orlando). The Q·f product was measured from fundamental to 9 th overtone. Values exceeding the limit of AT- and SC-cut quartz were obtained.

Publication Date

1-1-2005

Publication Title

Ceramic Engineering and Science Proceedings

Volume

26

Issue

5

Number of Pages

169-176

Document Type

Article; Proceedings Paper

Personal Identifier

scopus

DOI Link

https://doi.org/10.1002/9780470291252.ch18

Socpus ID

32044475174 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/32044475174

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