Abstract
With a deep study of the metamaterial, its unit cells have been widely extended from metals to dielectrics. The dielectric based unit cells attract much attention because of the advantage of easy preparation, tunability, and higher frequency response, and so forth. Using the conventional solid state method, we prepared a kind of incipient ferroelectrics (calcium titanate, CaTiO3) with higher microwave permittivity and lower loss, which can be successfully used to construct metamaterials. The temperature and frequency dependence of dielectric constant are also measured under different sintering temperatures. The dielectric spectra showed a slight permittivity decrease with the increase of temperature and exhibited a loss of 0.0005, combined with a higher microwave dielectric constant of ~167 and quality factorQof 2049. Therefore, CaTiO3is a kind of versatile and potential metamaterial unit cell. The permittivity of CaTiO3at higher microwave frequency was also examined in the rectangular waveguide and we got the permittivity of 165, creating a new method to test permittivity at higher microwave frequency.
Highlights
Since increasing attention has been paid to metamaterials due to their novel physical behaviors and versatile applications, such as left-handed metamaterials (LHMs) using split ring resonators (SRRs) and metal wire arrays to produce negative effective permeability and negative permittivity, respectively [1, 2], more and more outstanding ceramic materials such as BaxSr1−xTiO3 (BST) are being developed and utilized to build some supernormal materials and structures, such as ferromagnetic/ferroelectric composite metamaterial (CMM) with BST rods [3], Mie resonance structures using dielectric BST particles [4, 5], the prism of negative refraction in BST columns [6], and artificial magnetic conductor with high dielectric BST arrays applied in antenna and radar [7], opening a better and more potential approach to construct various isotropic metamaterials, suitable for higher operating frequencies [4]
It has been proved that CaTiO3 sintered at 1350∘C has the same lattice structure as the unsintered ones (JCPDS number 42-0423, Pnma(62), a = 5.442 A, b = 7.642 A, c = 5.381 A ), while being different from the other ceramics sintered at 1250∘C, 1300∘C, and 1400∘C (JCPDS number 22-0153, Pnma(62), a = 5.440 A, b = 7.644 A, c = 5.381 A )
The alteration of lattice parameters would be probably related to the appearance of defects due to the distortion in the CaTiO3 lattice [13]
Summary
Since increasing attention has been paid to metamaterials due to their novel physical behaviors and versatile applications, such as left-handed metamaterials (LHMs) using split ring resonators (SRRs) and metal wire arrays to produce negative effective permeability and negative permittivity, respectively [1, 2], more and more outstanding ceramic materials such as BaxSr1−xTiO3 (BST) are being developed and utilized to build some supernormal materials and structures, such as ferromagnetic/ferroelectric composite metamaterial (CMM) with BST rods [3], Mie resonance structures using dielectric BST particles [4, 5], the prism of negative refraction in BST columns [6], and artificial magnetic conductor with high dielectric BST arrays applied in antenna and radar [7], opening a better and more potential approach to construct various isotropic metamaterials, suitable for higher operating frequencies [4]. BST has been successfully applied to construct metamaterials, its higher dielectric loss of 0.001 [8] limits its realization of further novel properties.
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