TY - JOUR
T1 - Synthesis, structure, and characterization of new low-firing microwave dielectric ceramics
T2 - (Ca1-3xBi2xΦx)MoO 4
AU - Guo, Jing
AU - Randall, Clive A.
AU - Zhang, Gaoqun
AU - Zhou, Di
AU - Chen, Yuyan
AU - Wang, Hong
PY - 2014/9/21
Y1 - 2014/9/21
N2 - A series of A-site deficient scheelite ceramics (Ca1-3xBi 2xΦx)MoO4 (x = 0.005, 0.015, 0.025, 0.035, 0.05, 0.1, 0.15, and 0.2, and Φ: A-site vacancy) were synthesized via the solid state reaction route. The structures were analyzed using a combination of X-ray diffraction and X-ray absorption fine structure spectroscopy (Mo K-edge and Bi L3-edge) to determine average and local structures. A series of defective scheelite (Ca1-3xBi2xΦx) MoO4 compositions can be formed as a solid solution, and local structures of Mo and Bi indicate that a MoO4 tetrahedron and a BiO8 polyhedron become more distorted with the x value. The large change in the Bi-O1 (the first shell) and Bi-O2 (the second shell) distances is an important insight into the nature of the defective structures. The statistical disorder of a Bi-O bond is one order of magnitude larger than that of a Mo-O bond. The microstructures and microwave dielectric properties were investigated by scanning electron microscopy and through network analyzer resonance studies. All the compositions can be sintered well below 900 °C. With slight Bi substitutions (x = 0.005 and 0.015), the samples exhibit improved Q × f values. At x = 0.15, temperature stable (TCF = -1.2 ppm per °C) low-firing (ST = 700 °C) microwave dielectric materials were obtained with a permittivity of 21.2 and a Q × f value of 29300 GHz. The factors affecting dielectric properties are associated with the local structures of Mo and Bi across the solid solution. This journal is
AB - A series of A-site deficient scheelite ceramics (Ca1-3xBi 2xΦx)MoO4 (x = 0.005, 0.015, 0.025, 0.035, 0.05, 0.1, 0.15, and 0.2, and Φ: A-site vacancy) were synthesized via the solid state reaction route. The structures were analyzed using a combination of X-ray diffraction and X-ray absorption fine structure spectroscopy (Mo K-edge and Bi L3-edge) to determine average and local structures. A series of defective scheelite (Ca1-3xBi2xΦx) MoO4 compositions can be formed as a solid solution, and local structures of Mo and Bi indicate that a MoO4 tetrahedron and a BiO8 polyhedron become more distorted with the x value. The large change in the Bi-O1 (the first shell) and Bi-O2 (the second shell) distances is an important insight into the nature of the defective structures. The statistical disorder of a Bi-O bond is one order of magnitude larger than that of a Mo-O bond. The microstructures and microwave dielectric properties were investigated by scanning electron microscopy and through network analyzer resonance studies. All the compositions can be sintered well below 900 °C. With slight Bi substitutions (x = 0.005 and 0.015), the samples exhibit improved Q × f values. At x = 0.15, temperature stable (TCF = -1.2 ppm per °C) low-firing (ST = 700 °C) microwave dielectric materials were obtained with a permittivity of 21.2 and a Q × f value of 29300 GHz. The factors affecting dielectric properties are associated with the local structures of Mo and Bi across the solid solution. This journal is
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U2 - 10.1039/c4tc00698d
DO - 10.1039/c4tc00698d
M3 - Article
AN - SCOPUS:84906086916
SN - 2050-7534
VL - 2
SP - 7364
EP - 7372
JO - Journal of Materials Chemistry C
JF - Journal of Materials Chemistry C
IS - 35
ER -