Abstract
We prepared (1−x)CaTiO3–xLaAlO3 (0 ≤ x ≤ 1) microwave dielectric ceramics using a conventional two-step solid-state reaction method, and investigated microwave dielectric properties of the ceramics in terms of A/B-site ionic-parameters. Ionic-parameters such as ionic polarizability, A-site bond valence, and ionic rattling were linked to the microwave dielectric properties. As the LaAlO3 content x in the (1−x)CaTiO3–xLaAlO3 ceramics increased from 0.3 to 0.7, the dielectric constant gradually decreased, which was attributed to the decrease of polarizability deviation and suppression of the cation rattling. The temperature coefficient of the resonant frequency decreased as the content of LaAlO3 increased because of the increase of A-site cation bond valence. The quality factor value (Q × f) increased as LaAlO3 content increased because of the enhancement of the order degree of B-site cation. A significant deterioration of the temperature coefficient of the resonant frequency and Q × f value was observed at the composition x = 0.5. These decreases were attributed to a phase transition from orthorhombic crystal (for x ≤ 0.5) to rhombohedral crystal (for x > 0.5).
Highlights
Modern wireless communication devices, such as filters, oscillators, and dielectric resonators, require microwave dielectric ceramics with appropriate dielectric constant ( r ≈45), high quality factor value (Q × f > 30 000 GHz), and near-zero temperature coefficient of resonant frequency ( f ≈ 0) [1,2,3]
Among CaTiO3–REAlO3 materials, CaTiO3–LaAlO3 stands out as a candidate with suitable microwave dielectric properties that could meet the need of microwave dielectric filters used in mobile communication base stations because of the good thermal stability of the ceramics [6,7] and the relatively low cost of the starting materials
Moon et al [8] and Hou et al [9] investigated the sintering behaviour and microwave dielectric properties of xCaTiO3–(1−x)LaAlO3 ceramics, and Khalyavin et al [10] studied the structure sequence transformation of xCaTiO3–(1−x)LaAlO3 ceramics. These studies focused on the direct relation between composition and microwave dielectric properties in this system
Summary
Modern wireless communication devices, such as filters, oscillators, and dielectric resonators, require microwave dielectric ceramics with appropriate dielectric constant ( r ≈45), high quality factor value (Q × f > 30 000 GHz), and near-zero temperature coefficient of resonant frequency ( f ≈ 0) [1,2,3]. Moon et al [8] and Hou et al [9] investigated the sintering behaviour and microwave dielectric properties of xCaTiO3–(1−x)LaAlO3 ceramics, and Khalyavin et al [10] studied the structure sequence transformation of xCaTiO3–(1−x)LaAlO3 ceramics. These studies focused on the direct relation between composition and microwave dielectric properties in this system. To understand the effect of composition on the microwave dielectric properties of (1−x)CaTiO3–xLaAlO3 ceramics and to tailor their microwave dielectric properties, the correlation between the microwave dielectric properties and ionic-parameters such as polarizability, cation rattling effect, bond valence, and the order degree of B-site cation must be understood. The relationship between the microwave dielectric properties and ionic-parameters was established, and the microwave dielectric properties of CTLA ceramics with 0.3 ≤ x ≤ 0.7 were discussed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
