Crystal structure and microwave dielectric properties of Mg2+-Si4+ co-modified yttrium aluminum garnet ceramics

Energetics of point defects in yttrium aluminum garnet doped with Mg and Si

“…It is in correspondence with the experiment [38], where the Y 3 Mg x Al 5−2x Si x O 12 : Ce ceramics with x = 0.5, 1, 2 was obtained. Similar results for undoped YAG were reported in [39], where ceramics Y 3 Mg x Al 5−2x Si x O 12 with x = 0.5, 1, 1.5, 2 were sintered and it was found that the samples were isostructural to YAG and were formed a single phase at x = 0.5, 1, 1.5.…”

Lattice evolution and microwave dielectric properties of La‐doped yttrium aluminum garnet ceramics

“…On the one hand, breakthroughs have been made in the microwave dielectric properties of novel garnet-based ceramics, for example, Sr 2 NaMg 2 V 3 O 12 8 with ε r = 11.7, Q × f of 37,950 GHz, and τ f value of −2.9 ppm/ • C; Ca 3 B 2 GeV 2 O 12 (B = Mg, Mn) 9 with ε r of 9.75 and 11.06, Q × f of 54,000 and 30,240 GHz, τ f of −61.2 and −66.4 ppm/ • C; A 3 Y 2 Ge 3 O 12 (A = Ca, Mg) 10 with ε r = 10.8 and 14.1, Q × f = 97,126 and 12,600 GHz, and τ f = −40.6 and 120.5 ppm/ • C; Sr 3 B 2 Ge 3 O 12 (B = Yb, Ho) 11 with ε r = 9.30 and 9.23, Q × f = 129,360 and 104,600 GHz, τ f = −42 and −26 ppm/ • C; Ca 3 MgBGe 3 O 12 (B = Zr, Sn) 12 ceramics with ε r = 10.80 and 9.68; Q × f = 79,600 and 83,400 GHz; and τ f = −66.8 and −57.9 ± 1 ppm/ • C. On the other hand, research studies on the modification of conventional yttrium aluminum garnets have also exhibited achievements. In 2016, Yu et al 13 reported the microwave dielectric properties of pure Y 3 Al 5 O 12 (YAG) transparent ceramics sintered at 1800 • C for 12 h: ε r = 10.8, Q × f = 213,400 GHz, and τ f = −30 ppm/ • C. In 2022, Wu et al 14 prepared Y 3 Mg 0.5 Al 4 Si 0.5 O 12 ceramics sintered at 1625 • C for 5 h by Mg 2+ and Si 4+ co-modifying and obtained excellent microwave dielectric properties with ε r = 10.56, Q × f = 67,571 GHz, and τ f = −35.23 ppm/ • C. However, due to the strict preparation process, the main research direction of ceramics in this system focuses on reducing the sintering temperature and improving the density of the ceramics, like adding sintering aid TEOS, 15 doping Nb 2 O 5 , 16 and adjusting the non-stoichiometry of YAG. 3 In fact, the ionic radius of Y 3+ ions is close to the ionic radii of rare-earth ions, providing the YAG ceramic with a wide range of ion substitution.…”

“…reported the microwave dielectric properties of pure Y 3 Al 5 O 12 (YAG) transparent ceramics sintered at 1800°C for 12 h: ε r = 10.8, Q × f = 213,400 GHz, and τ f = −30 ppm/°C. In 2022, Wu et al 14 . prepared Y 3 Mg 0.5 Al 4 Si 0.5 O 12 ceramics sintered at 1625°C for 5 h by Mg 2+ and Si 4+ co‐modifying and obtained excellent microwave dielectric properties with ε r = 10.56, Q × f = 67,571 GHz, and τ f = −35.23 ppm/°C.…”