Structural analysis and properties of thermally stable Ba8Mg(Nb6−xSbx)O24 microwave ceramics

Shift–Twin Option in Eight-Layer Hexagonal Perovskite Niobates Ba8MNb6O24

“…The XRD patterns of the shifted and twinned perovskite display similar reflection positions, but different relative intensities, especially I Ba 8 MgNb 6 O 24 was first reported by Suresh et al to adopt an eight-layer twinned structure. 19 The synthesis of Ba 8 MgNb 6 O 24 was also attempted in this study, of which the XRD pattern is similar to that in the work by Suresh et al 19 However, careful analysis of XRD data indicate that this composition formed in mixtures containing Ba 5 Nb 4 O 15 hexagonal perovskite and Ba 3 MgNb 2 O 9 cubic perovskite phases when the samples were fired at different temperatures within 1200−1500 °C (Figure S3), instead of an eight-layer hexagonal phase. The sample melted when the temperature went above 1500 °C.…”

Fabrication of nanopowders by high energy ball milling and low temperature sintering of Mg2SiO4 microwave dielectrics

“…These applications demand microwave substrate materials with high quality factor (Q × f) to achieve high selectivity, low dielectric constant (ε r ) to reduce the delay time of electronic signal, and nearly zero temperature coefficient of resonant frequency ( f ) for frequency stability. Promising candidates include as Mg 2 SiO 4 (Q × f = 40,000-240,000 GHz, ε r = 6-7, f = −60 ppm/ • C) [1,2], Al 2 O 3 (Q × f = 680,000 GHz, ε r = 10, [3,19], Mg 2 SnO 4 (Q × f = 55,100 GHz, ε r = 8.41, f = −62 ppm/ • C) [11], Ba(Zn 1/3 Ta 2/3 )O 3 (Q × f = 120 THz) [23], Li 2 MgTi 3 O 8 (Q × f = 36,200 GHz, ε r = 26, f = −2 ppm/ • C) [24] and other microwave dielectrics materials [25][26][27][28][29][30][31][32][33]. Among these materials, forsterite Mg 2 SiO 4 has attracted a great attention with low dielectric constant and loss tangent.…”

Synthesis, characterization and thermal stability of a crystalline niobium oxysulfate

“…Niobium compounds cover a large class of diverse materials whose applications include: catalysts [13][14][15], photoluminescence [16], microwave dielectric ceramics [17][18][19][20][21][22][23][24][25]. However, only limited work focused on the structure of Nb 2 O 4 (SO 4 ) [26].…”