Microwave Dielectric Properties of Sol-Gel Derived BaTi4O9 and Ba2Ti9O20:B2O3 Ceramics

Abstract

BaTi 4 O 9 and B 2 O 3 -doped Ba 2 Ti 9 O 20 ceramics powders have been prepared by a sol-gel route. The phase evolution, grain size and dielectric properties of the BaTi 4 O 9 and Ba 2 Ti 9 O 20 -based ceramics powders have been investigated. These results show that the BaTi 4 O 9 and 5 wt% B 2 O 3 -doped Ba 2 Ti 9 O 20 ceramics powders calcined at 800 • C for 2 h with the grain sizes of 30-80 and 50-200 nm, respectively. Monophase sample of BaTi 4 O 9 with orthorhombic symmetry could be obtained after the BaTi 4 O 9 precursor was calcined at 1200 • C for 2 h, whereas, monophase sample of 5 wt% B 2 O 3 -doped Ba 2 Ti 9 O 20 was obtained at 800 • C for 2 h. The BaTi 4 O 9 and Ba 2 Ti 9 O 20 : 5 wt% B 2 O 3 ceramics fabricated using the sol-gel powders were found to have microwave dielectric properties with ε r = 36.1, Q = 3220 at 5.31 GHz, and ε r = 34.5, Q = 2425 at 5.53 GHz, respectively. The effect of sintering temperatures on the microwave dielectric properties of the Ba 2 Ti 9 O 20 : 5 wt% B 2 O 3 ceramics was studied.

Barium nanotitanate microwave ceramics obtained by a chemical method

“…From Table I, it is observed that the electric permittivity (I» ranges from 35 to 41, the Q factor from 2950 to 3400, the temperature coefficient (Tf) from 6.2 to 10.2 ppmrC, and the overall tunable frequency range of 5.12-6.95 GHz. Some results are in agreement with those obtained by Tang [7], although their samples were sintered at quite higher temperatures (> 1200°C).…”

“…However, during the sintering treatment, reactions between the glass and ceramics may induce compositional changes and/or development of second phases due to local heterogeneities, 978-1-4799-1397-8/13/$31.00 ©2013 IEEE which may deteriorate the microwave dielectric properties [1][2][3][4]. To minimize these drawbacks several preparation methods have been used [4][5][6][7][8][9][10]. In this study a new approach for obtaining B20radded BTO nanopowder is considered by using a hybrid chemical and co-precipitation method.…”

Chemical Compositions and Crystallization Behavior of BaO-TiO₂-GeO₂ Glass

“…Therefore, optical transparency in the crystallized sample is most likely caused by smallness of crystallizing-BaTi 4 O 9 phase, which suppress the scattering of incident light. Furthermore, this glass-ceramics is considered to be a possible functional material, because the BaTi 4 O 9 possesses a photocatalytic activity and a high-Q dielectric which was reported 3220 [7,8]. Consequently, the transparent BaTi 4 O 9 -nanocrystallized glass obtained in this study has a great possibility for optically/dielectrically-functional material.…”

Microwave dielectric properties of Mg4Nb2O9 ceramics produced by hydrothermal synthesis

“…There have been relatively fewer investigations [8,9] of the chemical processing methods such as hydrothermal, sol-gel, and precipitation processes for producing ceramics for microwave applications. Most of the microwave dielectric materials are being produced by conventional solid-state reaction process.…”