Sintering behavior, crystal structure and microwave dielectric properties of (1−x)Nd[(Zn0.7Co0.3)0.5Ti0.5]O3– x(Na0.5Nd0.5)TiO3 ceramics

2017 ◽  
Vol 726 ◽  
pp. 261-268 ◽  
Author(s):  
Jiamao Li ◽  
Lichun Yao ◽  
Tai Qiu ◽  
Songlin Ran ◽  
Chuangang Fan
2017 ◽  
Vol 726 ◽  
pp. 220-224
Author(s):  
Gan Wang ◽  
Juan Jiang ◽  
Zhan Ming Dou ◽  
Fan Fan Ning ◽  
Er Tian Zhang ◽  
...  

A low temperature sintering method was used to avoid the relatively high sintering temperatures typically required to prepare 0.67CaTiO3-0.33LaAlO3 (CTLA) ceramics. 0.67CaTiO3-0.33LaAlO3 ceramics doped with Li2O-B2O3-SiO2 (LBS) were prepared by a conventional two-step solid-state reaction process. The sintering behavior, crystal structure, surface morphology, and microwave dielectric proprieties of the prepared ceramics were studied. As the small amount of LBS content increased, the small amount of liquid phase formed in an amorphous state around the surface of the grain boundaries. With the increase the content of LBS glass, the quality factor (Q×f) value decreased. CTLA+0.05 wt.% LBS ceramics sintered at 1320°C for 4h exhibited the optimal microwave dielectric properties of dielectric permittivity (εr) = 45.02, quality factor (Q×f) = 37400 GHz, and temperature coefficient of resonant frequency (τf) = 9.84 ppm/°C. .


Author(s):  
Changzhi Yin ◽  
Zezong Yu ◽  
Longlong Shu ◽  
Laijun Liu ◽  
Yan Chen ◽  
...  

AbstractA melilite Ba2CuGe2O7 ceramic was characterized by low sintering temperature and moderate microwave dielectric properties. Sintered at 960 °C, the Ba2CuGe2O7 ceramic had a high relative density 97%, a low relative permittivity (εr) 9.43, a quality factor (Q×f) of 20,000 GHz, and a temperature coefficient of resonance frequency (τf) −76 ppm/°C. To get a deep understanding of the relationship between composition, structure, and dielectric performances, magnesium substitution for copper in Ba2CuGe2O7 was conducted. Influences of magnesium doping on the sintering behavior, crystal structure, and microwave dielectric properties were studied. Mg doping in Ba2CuGe2O7 caused negligible changes in the macroscopic crystal structure, grain morphology, and size distribution, while induced visible variation in the local structure as revealed by Raman analysis. Microwave dielectric properties exhibit a remarkable dependence on composition. On increasing the magnesium content, the relative permittivity featured a continuous decrease, while both the quality factor and the temperature coefficient of resonance frequency increased monotonously. Such variations in dielectric performances were clarified in terms of the polarizability, packing fraction, and band valence theory.


2020 ◽  
Author(s):  
Changzhi Yin ◽  
Zezong Yu ◽  
Longlong Shu ◽  
Laijun Liu ◽  
Yan Chen ◽  
...  

Abstract A melilite Ba2CuGe2O7 ceramic was characterized with low sintering temperature and moderate microwave dielectric properties. Sintered at 960 oC, the Ba2CuGe2O7 ceramic had a high relative density 97%, a low relative permittivity 9.43, and a quality factor of 20,000 GHz. To get a deep understanding of the relationship between composition, structure, and dielectric performances, magnesium substitution for copper in Ba2CuGe2O7 was conducted. Influences of magnesium doping on the sintering behavior, crystal structure, and microwave dielectric properties were studied. Mg doping in Ba2CuGe2O7 caused negligible changes in the macroscopic crystal structure, grain morphology, and size distribution, while induced visible variation in the local structure as revealed by Raman analysis. Microwave dielectric properties exhibit a remarkable dependence on composition. On increasing the magnesium content, the dielectric constant (εr) featured a continuous decrease, while both the quality factor (Q × f) and the temperature coefficient of resonance frequency (τf) increased monotonously. Such variations in dielectric performances were clarified in terms of the polarizability, packing fraction, and band valence theory.


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