On the temperature coefficient of resonant frequency in microwave dielectrics

Citation
Im. Reaney et al., On the temperature coefficient of resonant frequency in microwave dielectrics, PHIL MAG A, 81(2), 2001, pp. 501-510
Citations number
16
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
PHILOSOPHICAL MAGAZINE A-PHYSICS OF CONDENSED MATTER STRUCTURE DEFECTS ANDMECHANICAL PROPERTIES
ISSN journal
1364-2804 → ACNP
Volume
81
Issue
2
Year of publication
2001
Pages
501 - 510
Database
ISI
SICI code
1364-2804(200102)81:2<501:OTTCOR>2.0.ZU;2-U
Abstract
Developing a material with a temperature coefficient of the resonant freque ncy (TCF) of zero is probably the most difficult aspect of research into mi crowave dielectric ceramics. There are a host of high-quality-factor (Q) hi gh-relative-permittivity (epsilon (r)) materials whose TCF is far too high to be usable, notably TiO2 (epsilon (r) = 104; Q = 14 000 at 3 GHz; TCF = 427 ppm K-1). The challenge is to find ways of tuning TCF while maintaining values of epsilon (r) and Q suitable for use in microwave components. This paper explains, in terms of octahedral tilting and epsilon (r) dilution, t he tunability of TCF or, more precisely, the temperature coefficient of eps ilon (r) in Ca and Sr titanate-based ceramics. Examples of the structural c hanges that occur during tuning are also shown.