Optimised phase compositions and improved microwave dielectric properties based on calcium tin silicates

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

“…In the CaO-SnO 2 -SiO 2 system, the single-phase CaSnSiO 5 ceramic exhibited a positive τ f value and was an effective compensator. 3 As shown in Figure 7C, the τ f variation tendency of CaSnSi y O 3+2y (0.1 ≤ y ≤ 1.0) ceramics was the same as that of CaSnSiO 5 phase content. The τ f values of CaSnSi y O 3+2y ceramics were mainly affected by CaSnSiO 5 phase content, and the near-zero τ f values of CaSnSi y O 3+2y ceramics were obtained at y = 0.5, 0.7, and 0.8.…”

“…With the increase in x, the average grain size of Ca 1+2x SnSi 2x O 3+6x ceramics decreased gradually; this condition was attributed to the small average grain size of Ca 3 SnSi 2 O 9 ceramic (approximately 2.1 μm). 3 As shown in Figure 3C, the grains were distinguished through EDS. The ratios of Ca:Sn:Si:O (Spot A) and Ca:Sn:O (Spot B) were approximately consistent with the composition of Ca 3 SnSi 2 O 9 and CaSnO 3 , and CaSnO 3 grains were observed at x = 0.9.…”

“…Microwave dielectric ceramics have played an important role in modern wireless communication systems, such as resonators, capacitors, and filters 1‐3 . 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.…”

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

“…To further examine the maximum solubility, content of the secondary phase, and lattice structure of Ca 1− x Sr x SnSiO 5 ceramics, Rietveld refinement was conducted. The refinement diffraction figure of CaSnSiO 5 ( x = 0) ceramic has been provided in our previous article, 8 and Figure 2 shows the refined diffraction figure of Ca 1− x Sr x SnSiO 5 ceramics ( x = 0.05, 0.1, and 0.15). The calculated refinement results agreed well with the measured diffraction profiles, and no secondary phase was observed in Figure 2.…”

“…2 The applications of low-permittivity CaSnSiO 5 microwave dielectric ceramic are attracting increased attention because of its large number of Si-O bonds and abnormally positive τ f value. 7,8 Silicates possess numerous Si-O bonds (approximately 55% covalent bonds) in their SiO 4 tetrahedrons and exhibit low permittivity (ε r < 15), 9 which can decrease signal transmission time. 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).…”