Research and Development of Microwave Dielectric Ceramics for Wireless Communications

MICROSTRUCTURE, PHASE EVOLUTION, AND MICROWAVE DIELECTRIC PROPERTIES OF Li₂O AND Ga₂O ₃ DOPED ZINC ORTHOSILICATE

“…Microwave and millimeter-wave dielectric ceramics have been developed for a wide range of applications in telecommunication, such as cellular phone, wireless LAN, global position satellite (GPS), military radar system, intelligent transport system (ITS), and direct broadcast satellite [1,2]. Dielectric ceramics with low loss can be classified into three categories according to their applications.…”

Crystal structure of the Sr6Nb4ZrO18 slab perovskite-like compound

“…Recent studies in the field filed of microwave technology have an increased focus on the compounds of the AnBn-1O3n and AnBnO3n+1 families (A = Ba, Sr, Ca, Ln, Nd; B = Ti, Nb, Ta, Sn, Zr, W, Re, Al, Ga, Cr, Fe, Mg; n = 3 -7) with a slab perovskite-like structure (SPS) due to their excellent dielectric properties (such as high quality factors and high dielectric constants) [1][2][3][4][5][6][7][8][9][10][11][12]. In particular, as it is shown in [6][7][8][9][10][11], the dielectric constant (εr) range is from 26 to 48 while the quality factor (Q×f) is decreasing from 5600 to 51000 Ghz for the А6В5О18 five-layer ceramics (A = Ba, Sr, La; B = Nb, Ta, Ti, Zr, Mg, Zn; n = 5).…”

“…In particular, as it is shown in [6][7][8][9][10][11], the dielectric constant (εr) range is from 26 to 48 while the quality factor (Q×f) is decreasing from 5600 to 51000 Ghz for the А6В5О18 five-layer ceramics (A = Ba, Sr, La; B = Nb, Ta, Ti, Zr, Mg, Zn; n = 5). Besides, the temperature coefficient of the resonant frequency changes from -39 to +183 ppm/°C with the composition of these compounds.…”

“…Such a high value of the quality factor provides a narrow bandwidth, which ensures the selection of the frequency range desired while τf value close to zero is important to minimize the temperature fluctuations of resonant frequency [10]. The structural feature of the AnBn-1O3n slab perovskite-like compounds is another important factor along with the chemical composition that…”

“…has an effect on their properties [10]. However, it's worth to mention that among a number of strontium-containing five-layer compounds of the Sr6Nb4B IV O18-type (B IV = Ti, Sn, Zr), the crystal structures have been determined only for Sr6Nb4TiO18 and Sr6Nb4SnO18 [13,14].…”