Low temperature sintering of microwave magnetic garnet materials

The effect of TiO2 addition on the microstructure and magnetic properties of Bi-CVG material

“…The Bi-doped CVG material (Bi-CVG) with an optimized composition of (Bi 0.75 Ca 1.2 Y 1.05 )(V 0.6 Fe 4.4 )O 12 [4] was prepared by a conventional mixed oxide process. The material was synthesized using a mixture of 8.2 mol% Bi 2 O 3 , 26.2 mol% CaO, 11.0 mol% Y 2 O 3 , 6.5 mol% V 2 O 5 and 48.1 mol% Fe 2 O 3 powders, calcined at 1000 • C for 3 h. The calcined material was then pulverized in wet condition into a slurry with an average particle size of 10 m, filter pressed and molded into cylindrical specimens of 20 (ϕ) × 3 (t) mm using a pressing pressure of 1120 MPa.…”

“…Yttrium-iron garnet (YIG, Y 3 Fe 5 O 12 ) ceramic materials are widely used in the microwave devices such as circulators, oscillators and phase shifters, due to their superior magnetic properties at microwave frequencies [1][2][3][4][5]. A high density and a high saturation magnetization, as well as a uniform microstructure with a controlled grain size are all essential in these materials to minimize the energy loss at high frequencies [6].…”

“…A high density and a high saturation magnetization, as well as a uniform microstructure with a controlled grain size are all essential in these materials to minimize the energy loss at high frequencies [6]. However, in order to synthesize the YIG with a high enough density, a high sintering temperature of >1400 • C and a long soaking time of >6 h is required [4,6]. It has been reported that the sintering temperature required to obtain a density of >97% of the theoretical density, could be lowered from 1400 • C × 6 h for pure YIG, to 1280 • C × 6 h for a CaO-V 2 O 5 doped YIG, with a composition of (Ca 1 The effects of some other additives are still to be investigated in an attempt to further improve the density of YIG materials at still lower sintering temperatures.…”

Structure and Magnetic Properties ofY3−xErxFe5O12(x=0.2,1.0, and 2.0) Thin Films Prepared b

“…YIGs are also of scientific importance because of the wide variety of magnetic properties that can be obtained by substituting yttrium with a rare-earth (RE) metal [3][4][5][6][7][8][9]. Most of the previous studies have concentrated on the preparation of Biand Ce-doped YIG powders and films because of their high Faraday rotation coefficient [10][11][12][13][14][15][16][17]. Some studies have been carried out on Er-YIG powder nanoparticles [18][19][20][21][22][23][24][25][26][27].…”

Microstructure and densification mechanism of low temperature sintering Bi-Substituted yttrium iron garnet

“…Yttrium iron garnet (YIG) is an important material commonly used as circulators, oscillators and phase shifters for microwave applications, because it possesses small linewidth in ferromagnetic resonance, high DC resistance, low dielectric loss and controllable saturation magnetization in microwave region [1]. However, YIG garnet is hardly used in multilayer microwave components because its sintering temperature (>1350°C) is generally higher than the melting points of highly conductive metals like Ag-Pd alloy (1145°C) [2]. Previous investigations have shown that the Bi-substituted (YIG:Bi) powders can be prepared at a lower temperature (<1100°C), and the sintering temperature of relevant ceramics is much lower than that of pure YIG polycrystalline ceramics [3,4].…”