Microwave dielectric properties of MO–La₂O₃–TiO₂ (M = Ca, Sr, Ba) ceramics

Abstract

9 O 31 , were prepared through the solid-state ceramic route. The phases and structure of the ceramics were analyzed through x-ray diffraction and scanning electron microscopy. The microwave dielectric properties of the ceramics were studied using a network analyzer. The investigated ceramics show high ⑀ r in the range 42 to 54, high quality factors with Q × f in the range 16,222 to 50,215 GHz, and low f in the range −25 to +6 ppm/°C. These high dielectric constant materials with high Q × f up to 50,215 GHz are suitable for applications where narrow bandwidth and extremely low insertion loss is necessary, especially at frequencies around 1.9 GHz.

Raman spectroscopy and microwave dielectric properties of Sn substituted SrLa4Ti5O17 ceramics

“…For commercial applications, any material used as a dielectric resonator must have ε r > 24, Q u f o > 30,000 GHz and |τ f | 3 ppm/°C [1]. For certain applications, such as antennas, the requirements for low τ f and high Q u f o are flexible but ε r is generally required to be as high as possible to miniaturize the device so that it might be incorporated into a handset [2]. Recently, layered perovskites with a general formula A n B n O 3n+2 (where A and B are cations) have received much attention due to their high dielectric performance and applications in patch antennas.…”

“…Recently, layered perovskites with a general formula A n B n O 3n+2 (where A and B are cations) have received much attention due to their high dielectric performance and applications in patch antennas. Jawahar et al [2] reported CaLa 4 Ti 5 O 17 with ε r = 53, * E-mail: drmanan82@yahoo.com τ f = −20 ppm/°C and Q u f o = 17359 GHz that was sintered at 1625°C. The microwave dielectric properties of CaLa 4 Ti 5 O 17 ceramics were improved by substituting Ca 2+ ions with Zn 2+ ions [4].…”

Structure and microwave dielectric properties of Ca0.66La0.387Ti0.88O3 ceramics

“…Iqbal et al [4] processed CaLa 4 Ti 5 O 17 which crystallized into an orthorhombic symmetry and exhibited e r * 52.7, Q 9 f o * 12,700 GHz and s f * -37 9 10 -6 /°C. CaLa 8 Ti 9 O 31 was also reported to crystallize into an orthorhombic symmetry and was reported to exhibit e r * 54.9, Q 9 f o * 19,300 GHz and s f * -6 9 10 -6 /°C [5]. Similarly, e r * 41, Q 9 f o * 50,246 GHz and s f * -25.5 9 10 -6 /°C were reported for CaLa 4 Ti 4-O 17 which crystallized into a hexagonal symmetry [6].…”

Microwave dielectric properties of La5(Ti4B)O17 and Nd5(Ti4B)O17 (B = Cr, Fe) ceramics

“…For example, for application as dielectrically loaded antennae cores, a dielectric materials must exhibit 20 B e r B 85, Q 9 f o [ 5,000 GHz, and s f = ± 10 ppm/ o C [9]. CaLa 4 Ti 5 O 17 is an A 5 B 5 O 17 type compound and has been reported to exhibit a high e r and Q 9 f o but its -ve s f is too high for commercial applications [10]. In this system, Sr was partially substituted for Ca in Ca 1-x Sr x La 4 Ti 5 O 17 and temperature stability was achieved at x = 0.4.…”

“…In this system, Sr was partially substituted for Ca in Ca 1-x Sr x La 4 Ti 5 O 17 and temperature stability was achieved at x = 0.4. The resulting compound was reported to exhibit e r = 53.7, Q 9 f o = 11,532 GHz and s f = -1.8 ppm/ o C [10]. Zhao et al [11] were heated at 300°C to remove hydroxides and moisture before weighing to ensure correct stoichiometry.…”