Publication Date:
2013-04-26
Description:
SrLn 2 Al 2 O 7 (Ln = La, Nd, Sm) ceramics were proposed and investigated as new candidates for ultra-low loss microwave dielectric materials. These ceramics indicated the Ruddlesden–Popper structure of general formula A n +1 B n O 3 n +1 with n = 2, which was composed by n perovskite layers alternating with one rock-salt layer. Very high Qf value combined with a dielectric constant around 20 was obtained in the present ceramics, where the near-zero temperature coefficient of resonant frequency varied from negative to positive with changing Ln from La to Sm. The best combination of microwave dielectric characteristics was obtained as the following: ε r = 18.2, Qf = 71,680 GHz, and τ f = −22.1 ppm/°C for SrLa 2 Al 2 O 7 ; ε r = 20.5, Qf = 65,500 GHz, and τ f = −4.3 ppm/°C for SrNd 2 Al 2 O 7 ; and ε r = 21.6, Qf = 64,680 GHz, and τ f = +4.0 ppm/°C for SrSm 2 Al 2 O 7 .
Print ISSN:
1546-542X
Electronic ISSN:
1744-7402
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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