Influence of Zn and Ni substitutions for Mg on dielectric properties of (Mg4-xMx)(Nb2−ySby)O9 (M=Zn and Ni) solid solutions

Improvements in the sintering behavior and microwave dielectric properties of Mg4Nb2O9 by adding Fe2O3

“…Several corundum-structured A 4 B 2 O 9 (A = Co and Mg, B = Nb and Ta) had been reported due to their excellent microwave dielectric properties [1,[9][10][11][12][13]. Among these materials, Mg 4 Nb 2 O 9 was investigated to possess a dielectric constant ε r of ∼12.4, a temperature coefficient of resonant frequency f of ∼−70 ppm/ • C and in particular, a high Q × f of ∼194,000 GHz [13].…”

“…Among these materials, Mg 4 Nb 2 O 9 was investigated to possess a dielectric constant ε r of ∼12.4, a temperature coefficient of resonant frequency f of ∼−70 ppm/ • C and in particular, a high Q × f of ∼194,000 GHz [13]. However, it also required a sintering temperature of as high as 1350-1400 • C/10 h. Obviously, the high sintering temperature of the ceramics will limit its applications for practical cases.…”

Dielectric properties and mixture behavior of Mg4Nb2O9–SrTiO3 ceramic system at microwave frequency

“…2. In comparison with that from references [12,16], the average grain size of the Mg 4 Nb 2 O 9 phase had a remarkable reduce with an increase in SrTiO 3 content. It indicates that rapid grain growth was hold back by an appropriate addition of SrTiO 3 , which has a much smaller grain size than that of Mg 4 Nb 2 O 9 .…”

“…Mg 4 Nb 2 O 9 has a corundum structure, which is a trigonal crystal system and space group of (P3cl) [9,10]. Many experiments have also been conducted to study the preparation and properties of Mg 4 Nb 2 O 9 -based ceramics [11][12][13][14]. Among them, Mg 4 Nb 2 O 9 possesses high dielectric constant ε r ∼ 12.9, high Q × f value ∼210,000 GHz (at 11.7 GHz) and negative f value −70 ppm/ • C [15].…”

Dielectric properties and crystal structure of (Mg_0.95Ni_0.05)₄(Nb_1&minus;<i>_x</i>Ta<i>_x</i>)₂O₉ ceramics

“…where the frequency f should be limited to the vicinity of the phonon engine frequencies, on the order of 10 12 Hz at room temperature, to make the estimation valid. However, a series of experiments evidenced that the extrapolation of Eq.…”