High dielectric permittivity and low loss of SrBi 4 Ti 4 O 15 with PbO and V 2 O 5 additions for RF and microwave applic
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High dielectric permittivity and low loss of SrBi4Ti4O15 with PbO and V2O5 additions for RF and microwave applications C. A. Rodrigues Jr. • J. M. S. Filho • P. M. O. Silva • M. A. S. Silva • C. C. M. Junqueira • A. S. B. Sombra
Received: 4 February 2013 / Accepted: 29 April 2013 Ó Springer Science+Business Media New York 2013
Abstract In this paper SrBi4Ti4O15 (SBTi), a perovskitetype ceramic, with cation deficit A5B4O15, was prepared by solid-state reaction method and PbO and V2O5 were added into SBTi (2, 5, 10 and 15 wt%). Samples were characterized through X-Ray Diffraction (XRD), Raman Spectroscopy and Scanning Electron Microscopy (SEM). Impedance Spectroscopy was carried out at room temperature. The analysis by XRD using the Rietveld refinement has confirmed the formation of single-phase compound with a crystalline tetragonal ˚ , b = 3.8408 A ˚ and c = 41.0959 A ˚ ). system (a = 3.8408 A A SEM shows globular grains (with addition of PbO) and crystal-shape ones (with additions of V2O5), from about 1 to 2 lm. The dielectric properties: dielectric permittivity (K0 ) and dielectric loss (tan d) were measured at room temperature over a range of 100 Hz–40 MHz by complex impedance spectroscopy and in the microwave (MW) frequency region were studied. The study showed that these properties are strongly dependent on frequency and on the added level of the impurity. All the samples were analyzed taking into account to possible applications in radio frequency (RF) and MW devices.
C. A. Rodrigues Jr. (&) J. M. S. Filho P. M. O. Silva Departamento de Engenharia de Teleinforma´tica, Centro de Tecnologia, Universidade Federal do Ceara´, Fortaleza, Ceara´ CEP: 60455-760, Brazil e-mail: [email protected] C. A. Rodrigues Jr. J. M. S. Filho P. M. O. Silva M. A. S. Silva A. S. B. Sombra Laborato´rio de Telecomunicac¸o˜es e Cieˆncia e Engenharia de Materiais (LOCEM), Universidade Federal do Ceara´, Fortaleza, Ceara´ CEP: 60455-760, Brazil C. C. M. Junqueira Instituto de Aerona´utica e Espac¸o IAE, Prac¸a Marechal Eduardo Gomes, 50, Vila das Aca´cias, Sa˜o Jose´ dos Campos, Sa˜o Paulo CEP 12228-904, Brazil
1 Introduction SrBi4Ti4O15 (SBTi) is one of the Aurivillius family members [1], which is called bismuth layer-structured ferroelectrics (BLSF), which have a natural superlattice structure along c axis consisting of two kinds of twodimensional nanolayers, defined as bismuth oxide (Bi2O2)2? sheet and a pseudoperovskite block generally described as (Am-1BmO3m?1)2-, where m is a number of BO6 octahedra in a perovskite block [2, 3]. SBTi has been extremely studied for many researchers for possible applications in piezoelectric devices and has potential use as a RF device because of the relative high Curie temperature (Tc = 520–620 °C), high dielectric breakdown strength, low dielectric loss, and high anisotropy [2, 3]. SBTi has a crystalline structure similar to Bi4Ti3O12 [BIT] which is another common ferroelectric structure [4]. This crystalline structure can be considered a junction of layers of (Bi2O2)2? and a per
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