Characterization and dielectric behavior of V2O5-doped 0.9Mg0.95Co0.05TiO3–0.1Ca0.6La0.8/3TiO3 ceramic system at microwave frequency

Abstract

a b s t r a c tThe microwave dielectric properties and the microstructures of Mg 0.95 Co 0.05 TiO 3 -Ca 0.6 La 0.8/3 TiO 3 ceramics, prepared by a mixed oxide route, have been investigated. With small amount of V 2 O 5 additions, the sintering temperatures of 0.9Mg 0.95 Co 0.05 TiO 3 -0.1Ca 0.6 La 0.8/3 TiO 3 ceramics can be lowered to 1250 • C. The microwave dielectric properties are found strongly correlated with the sintering temperature as well as the amount of V 2 O 5 additions. The Q × f value of 0.9Mg 0.95 Co 0.05 TiO 3 -0.1Ca 0.6 La 0.8/3 TiO 3 increased with increasing temperature to 1250 • C and decreased thereafter. The decrease in Q × f value was coincident with the abnormal grain growth. A maximum Q × f value of 58,000 (GHz) associated with a dielectric constant (ε r ) of 21.7 and a temperature coefficient ( f ) of −10 ppm/ • C, was achieved for 0.25 wt.% V 2 O 5 -doped samples at 1250 • C. Moreover, a cross-coupled compact hairpin filter with designed center frequency of 2.0 GHz is designed and fabricated using the proposed dielectric ceramic to study its performance. It also showed a substantial reduction in both insertion loss and size in comparison with other dielectrics FR4 and alumina.Crown

Dielectric Properties and Applications of Low‐Loss (1−x)(Mg0.95Ni0.05)2TiO4‐xSrTiO3 Ceramic System at Microwave Frequency

“…Research for new materials with such an optimum combination has been ongoing and reported in these few years. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Microwave dielectric properties of binary titanate ceramic Mg 2 TiO 4 has a spinel-type structure, belonging to the cubic space group Fd-3m (2 2 7). It exhibits a high dielectric constant e r $ 14, a high-quality factor Q9f $ 150,000 (GHz), and a temperature coefficient of resonant frequency s f $ À50 ppm/°C.…”

Effects of B 2 O 3 addition on sintering behavior and microwave dielectric properties of Mg 5 Nb 4 O 15 ceramics prepared by the sol–gel method

“…Until now, much attention has been paid to using various sintering aids such as LiF, Li 2 CO 3 , Sb 2 O 5 , V 2 O 5 and Fe 2 O 3 doping into the MN compounds [4][5][6][7][8][9] and B 2 O 3 is commonly recognized as a good additive of all sintering fluxes, which has been accomplished a substantial and reported by other papers elsewhere [10][11][12][13]. Meanwhile, to reduce the sintering temperature, many researches of the chemical methods have been developed as substitute for the conventional solid state reaction to producing ceramics.…”

Microwave Dielectric Properties of (1 − x)(Mg0.95Ni0.05)TiO3–x(Ca0.8Sr0.2)TiO3 Ceramic System With Near‐Zero Temperature Coefficient

“…In particular, size reduction is mainly a result from the use of high dielectric constant material as the wavelength (λ) in dielectrics is inversely proportional to according to the relation where λ o is the wavelength in vacuum. However, as the frequency of interest is extended from ISM (industrial, scientific, and medical) bands to millimeter wave range, materials with high dielectric constant tend to become a less of interest . Consequently, high quality factor together with low dielectric constant would play a more prominent role instead, as high quality factor can significantly reduce the dielectric loss, and low dielectric constant allows a fast time for electronic signal transition at ultra high frequencies.…”

“…Zero τ f value (temperature coefficient of resonant frequency) is also one of the major requirements for dielectric materials to allow a frequency‐stable passive component. The most convenient and promising way to achieve a zero τ f value is to combine two compounds having negative and positive τ f values to form a solid solution or mixed phases . However, high dielectric constant materials, in general, exhibit high dielectric loss (low Q × f value) and large positive τ f value, whereas low loss ceramics are usually accompanied by low ε r value and negative τ f value .…”