A new additive-free microwave dielectric ceramic system for LTCC applications: (1 − x)CaWO4 − x(Li0.5Sm0.5)WO4

Zero-Temperature Coefficient of Resonant Frequency in [(Mg0.6Zn0.4)0.95Co0.05]1.02TiO3.02-Ca0.6(La0.9Y0.1)0.2667TiO3 Ultra-Low-Loss Composite Dielectrics

“…The distinct electrical properties of ceramic dielectric resonators (DRs) have spurred a revolution in the wireless communications industry by minimizing the dimensions and cost of oscillator and filter components within the microwave circuit [1][2][3]. The integration of DRs enables the downsizing of microwave components, with requirements including a low dielectric loss, high permittivity, and a closee-zero τ f [4][5][6][7][8]. The product of the quality factor (Q) and the frequency (f), denoted as Q × f, exhibits an inverse relationship with the dielectric loss tangent (tanδ) in dielectric materials.…”

Microwave dielectric properties of tetragonal scheelite‐structured (NaY)1/2MoO4 ceramics

“…Thus, it is urgent to exploit microwave dielectric ceramic materials with appropriate permittivity (ε r ) to meet the requirements of equipment application, high quality factor (Q × f), nearzero temperature coefficient of resonant frequency (TCF) and low sintering temperature (S.T.). [8][9][10] In recent years, many Mo-based ABO 4 compounds with scheelite structure have received much interest because they have low S.T., high microwave dielectric properties, and high tolerance to structural adjustment, [11][12][13][14] such as (Na 0.5 Ln 0.5 )MoO 4 (where Ln is = Ce, La, or Nd), 15,16 (Li 0.5 Ln 0.5 )MoO 4 (where Ln = is Ce, Y, Sm, Nd, Gd, Er, or Yb), 17 (A 1/2 Bi 1/2 )MoO 4 (where A = is Rb, Na, Ag, K, or Li). 18 Mo-based ABO 4 ceramics have been reported with low or medium dielectric constants, and most of them could crystalize as tetragonal scheelite phase.…”

“…Thus, it is urgent to exploit microwave dielectric ceramic materials with appropriate permittivity (ε r ) to meet the requirements of equipment application, high quality factor (Q × f), near‐zero temperature coefficient of resonant frequency (TCF) and low sintering temperature (S.T.) 8–10 …”

Li2+xZrO3Fx (0 ≤ x ≤1.25): A new high‐Q × f and temperature‐stable microwave dielectric ceramic system for LTCC applications

“…For instance, although 0.9CaWO 4 –0.1Na 2 WO 4 ( ε r = 9.0, Q × f = 105660 GHz, and τ f = −35.4 ppm/°C), 15 Li 2 SrSiO 4 ( ε r = 7.4, Q × f = 100700 GHz, and τ f = −85.4 ppm/°C), 16 and Li 0.98 Mg 0.01 VO 3 ( ε r = 9.8, Q × f = 45600 GHz, and τ f = −45.0 ppm/°C) 17 all have relatively high‐ Q × f values, their τ f levels are not near zero. In contrast, near‐zero τ f levels were achieved in Ca 0.8 (Li 0.5 Nd 0.5 ) 0.2 WO 4 ( ε r = 11.7, Q × f = 36700 GHz, and τ f = 5.36 ppm/°C), 18 0.86CaWO 4 –0.14(Li 0.5 Sm 0.5 )WO 4 ( ε r = 10.8, Q × f = 28754 GHz, and τ f = −0.54 ppm/°C), 19 0.85CaMoO 4 –0.15(Li 0.5 Y 0.5 )WO 4 ( ε r = 11.1, Q × f = 30568 GHz, and τ f = −0.04 ppm/°C), 20 and Zn 0.85 (Li 0.5 Bi 0.5 ) 0.15 Mo 0.15 W 0.85 O 4 ( ε r = 18.937, Q × f = 20022 GHz, and τ f = −6.57 ppm/°C), 21 whereas the Q × f values of these LTCC materials are relatively low. This implies that it is not easy work to develop additive‐free LTCC materials with both a high‐ Q × f and a near‐zero τ f .…”