A very promising piezoelectric property of Ta{sub 2}O{sub 5} thin films. II: Birefringence and piezoelectricity

Journal Article · Mon Aug 15 00:00:00 EDT 2011 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2011.06.002· OSTI ID:21580224

Audier, M ^[1]; Chenevier, B; Roussel, H ^[1]; Vincent, L ^[2]; Pena, A ^[3]; Lintanf Salauen, A ^[4]

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1. Laboratoire des Materiaux et du Genie Physique, UMR CNRS 5628, Minatec - INP Grenoble, 3 parvis Louis Neel, BP 257, 38016 Grenoble Cedex 1 (France)
2. CIME Nanotech Minatec, Microsystemes et capteurs, F-38016 Grenoble Cedex 1 (France)
3. Institut Neel - CNRS/UJF, Dpt. Matiere Condensee, Materiaux et Fonctions, F-38042 Grenoble (France)
4. L2MA, CEA LETI D2NT, F-38054 Grenoble (France)

Birefringent and piezoelectric properties of Ta{sub 2}O{sub 5} ceramic thin films of monoclinic and trigonal structures were analyzed. The birefringence, observed by reflected polarized light microscopy, yields information on thin film microstructures, crystal shapes and sizes and on crystallographic orientations of grains of trigonal structure. Such an information was considered for investigating piezoelectric properties by laser Doppler vibrometry and by piezoresponse force microscopy. The vibration velocity was measured by applying an oscillating electric field between electrodes on both sides of a Ta{sub 2}O{sub 5} film deposited on a Si substrate which was pasted on an isolating mica sheet. In this case, it is shown that the vibration velocity results were not only from a converse piezoelectric effect, proportional to the voltage, but also from the Coulomb force, proportional to the square of the voltage. A huge piezoelectric strain effect, up to 7.6%, is found in the case of Ta{sub 2}O{sub 5} of trigonal structure. From an estimation of the electrical field through the Ta{sub 2}O{sub 5} thin film, this strain likely corresponds to a very high longitudinal coefficient d{sub 33} of several thousand picometers. Results obtained by piezoresponse force microscopy show that trigonal grains exhibit a polarization at zero field, which is probably due to stress caused expansion in the transition monoclinic-trigonal, presented in a previous article (part I). - Graphical abstract: Image of cross-polarized optical microscopy showing grains of trigonal structure embedded in the monoclinic phase (on the left); (a) mounting of the sample for Laser Doppler Vibrometry, sample constituted of several layers and its equivalent electrical circuit; (b) longitudinal displacements due to converse piezoelectric and Coulomb effects and corresponding piezoelectric strain-U{sub app.}. hystereses. Highlights: > A new Ta{sub 2}O{sub 5} trigonal phase is shown to be birefringent and piezoelectric. > This phase is related to a reversible transition with a monoclinic phase. > The piezoelectricity of this trigonal phase is of several thousands of pm/V. > It is compared to piezoelectricity of the monoclinic phase of several tens of pm/V.

• OSTI ID: 21580224
• Journal Information: Journal of Solid State Chemistry, Vol. 184, Issue 8; Other Information: DOI: 10.1016/j.jssc.2011.06.002; PII: S0022-4596(11)00313-6; Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
BIREFRINGENCE
CERAMICS
CRYSTALLOGRAPHY
ELECTRIC FIELDS
LAYERS
MICROSTRUCTURE
MONOCLINIC LATTICES
OPTICAL MICROSCOPY
PIEZOELECTRICITY
STRAINS
SUBSTRATES
TANTALUM OXIDES
THIN FILMS
CHALCOGENIDES
CRYSTAL LATTICES
CRYSTAL STRUCTURE
ELECTRICITY
FILMS
MICROSCOPY
OXIDES
OXYGEN COMPOUNDS
REFRACTION
REFRACTORY METAL COMPOUNDS
TANTALUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS