Structure, microwave dielectric properties, and infrared reflectivity spectrum of olivine type Ca2GeO4 ceramic

Crystal structure, phase compositions, and microwave dielectric properties of malayaite‐type Ca1−xSrxSnSiO5 ceramics

“…τ f values linearly decreased with the increase in x. Generally, τ f values are determined by the temperature coefficient of the dielectric constant (τ ε ) in the single-phase area, and τ ε was calculated using Formulas (14) and (15). [30][31][32][33] where α is a constant of about 10 ppm/°C for ceramics, α m and V represent the polarizability and volume, respectively.…”

“…High Q × f values can improve frequency selectivity 14 and high bond relative covalency corresponds to a high Q × f value. 10,13 Moreover low-permittivity microwave dielectric ceramics with a positive temperature coefficient of resonant frequency (τ f ) based on the ε r -τ f relationship are rare.…”

“…Ternary silicate ceramics such as CaO–SnO 2 –SiO 2 , 10,11 CaO–ZrO 2 –SiO 2 , 12,13 CaO–HfO 2 –SiO 2 13 also have a high‐quality factor ( Q × f ). High Q × f values can improve frequency selectivity 14 and high bond relative covalency corresponds to a high Q × f value 10,13 . Moreover low‐permittivity microwave dielectric ceramics with a positive temperature coefficient of resonant frequency ( τ f ) based on the ε r ‒ τ f relationship are rare 15 .…”

Optimized sintering behavior and microwave dielectric properties of Ca1+2xSnSi2x+yO3+6x+2y by composition modulation

“…With the increase in communication frequency, microwave dielectric ceramics with low permittivity ( ε r < 15), high‐quality factor ( Q × f ), and near‐zero temperature coefficient of resonant frequency ( ‒ 10 ppm/°C ≤ τ f ≤ +10 ppm/°C) have attracted the attention of many researchers. Microwave dielectric ceramics with low ε r and high Q × f values mainly include: silicates, 2‐8 germanates, 9‐13 vanadates, 14‐18 and stannates 19‐25 . The Q × f value of stannates (Ca 2 SnO 4 19 and Li 2 O–MgO–SnO 2 24,25 ) exceed 100,000 GHz, and high Q × f value is necessary to improve frequency selectivity.…”

Structure, microwave dielectric performance, and infrared reflectivity spectrum of olivine‐type Mg2Ge0.98O4 ceramic

“…8 In the past several decades, orthorhombic olivine structure ceramics with a general formula A 2 BO 4 and some other low ε r compounds have been reported with excellent microwave dielectric properties as listed in Table 1. [9][10][11][12][13][14][15][16][17][18][19][20] The low ε r dielectric ceramics usually contain cations with relative low ionic polarizability, such as Al 3+ (0.79 Å 3 ), Ge 4+ (1.63 Å 3 ), Li + (1.20 Å 3 ), Sn 4+ (1.63 Å 3 ), and Si 4+ (0.87 Å 3 ), which form the [AO 6 ] octahedron and [BO 4 ] tetrahedron in the crystal structure. Some interesting phenomena are proposed in the A 2 BO 4 -type microwave dielectric material systems.…”