Microwave Dielectric Properties of CaO-Li₂O-Ln₂O₃-TiO₂ Ceramics

Abstract

We have investigated the microwave dielectric properties of the Li2O-Ln2O3-TiO2 system and the CaO-Li2O-Ln2O3-TiO2 system (Ln: Lanthanide), both of which have a perovskite structure. The relationship between the kind of lanthanide element and dielectric properties at microwave frequencies was confirmed. It was also found that the ionic radius of lanthanide ions has a strong influence on the dielectric properties. Excellent dielectric properties of εr=110, f·Q value=4500 GHz and high temperature stability for the resonant frequency at 3 GHz were obtained with a composition of CaO:SrO:Li2O:Sm2O3:TiO2=15.0:1.0:9.0:12.0:63.0 (molar ratio). Also, band-pass filters made of this material were examined. The filters were greatly miniaturized to the size of about 2×5×4 mm3 (0.04 cm3).

Sintering and compositional effects on the microwave dielectric characteristics of Mg(Ta1−x Nb x )2O6 ceramics with 0.25 ≦ x ≦ 0.35

“…Kucheiko reported that zero t f value could be achieved in CaTiO 3 -Ca(Al 1/2 Ta 1/2 )O 3 system [3]. Chen et al reported that small t f value was achieved in CaO−Li 2 O−Sm 2 O 3 −TiO 2 (CLST) system [4], in which the Li 1/2 Sm 1/2 TiO 3 (e r =52, Q Â f ¼ 2; 280 GHz, and t f =−260 ppm/°C) and CaTiO 3 (e r =170, Q Â f ¼ 3; 600 GHz, and t f =800 ppm/°C) dielectrics were employed [5].…”

Dielectric Properties and Sintering Characteristics of CaTiO3-(Li1/2Nd1/2)TiO3 Ceramics

“…Hitherto, several materials with high dielectric constant have been reported and most of them are focused on plural elements system including TiO 2 , such as BaO-Nd 2 O 3 -TiO 2 -Ta 2 O 5 [1,2], BaO-Sm 2 O 3 -TiO 2 [3,4], CaO-Li 2 O-Ln 2 O 3 -TiO 2 [5][6][7][8][9], or (A +1 1/2 A +3 1/2 )TiO 3 system [10]. Among of these materials, compositions with perovskite structure based on (A +1 1/2 A +3 1/2 )TiO 3 system or CaTiO 3 system have superior microwave properties: ε = 81, Q f = 6150 GHz, τ f = +17 ppm/ • C for 0.6(Li 1/2 Sm 1/2 )TiO 3 -0.4(Na 1/2 Sm 1/2 )TiO 3 ceramics [10], ε = 110, Q f = 4500 GHz, τ f = +7 ppm/ • C for CaOSrO-Li 2 O-Ln 2 O 3 -TiO 2 (Ln = Sm, Nd) system [5], ε108,Q f = 17200 GHz in (Ca 1−x Nd 2x/3 )TiO 3 system [11] and 0.67Ca 2/5 Sm 2/5 TiO 3 -0.33Li 1/2 Sm 1/2 TiO 3 ceramics with ε = 95.5, Q f = 7200 GHz, τ f = 0 ppm/ • C [9]. CaTiO 3 and (A +1 1/2 A +3 1/2 )TiO 3 are promising materials with high dielectric constant and high Q f value.…”

Effects of La2O3-B2O3-ZnO additions on the low temperature sintering and microwave dielectric properties of (Ca0.61La0.26) TiO3ceramics

“…They reported that CaTiO 3 had a high permittivity, ε r =170, and a temperate dielectric losses, Q×f =3500 GHz, which provides a valuable reference for microwave components [9]. Then many studies about the advance of the microwave dielectric properties of CaTiO 3 -based ceramics have been conducted for the last 20 years [10][11][12][13]. Moreover, the substitution of Ca 2+ by other trivalent lanthanide ions, such as La 3+ , Sm 3+ and Nd 3+ , has also been investigated by several research groups.…”