The effect of filler on the temperature coefficient of the relative permittivity of PTFE/ceramic composites

2011 ◽  
Vol 406 (22) ◽  
pp. 4312-4316 ◽  
Author(s):  
S. Rajesh ◽  
K.P. Murali ◽  
H. Jantunen ◽  
R. Ratheesh
Keyword(s):  
Temperature Coefficient ◽  
Relative Permittivity ◽  
Ceramic Composites

HDPE Matrix Composites Filled With Ca4La6(SiO4)4(PO4)2O2 for Microwave Substrate Applications

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Dhanesh Thomas ◽  
Mailadil T. Sebastian
Keyword(s):  
Dielectric Loss ◽  
Relative Permittivity ◽  
Volume Fraction ◽  
Linear Thermal Expansion ◽  
Theoretical Models ◽  
Ceramic Composites ◽  
Filler Loading ◽  
Scanning Electron Micrographs ◽  
Melt Mixing ◽  
5 Ghz

Polymer–ceramic composites have been prepared by dispersing Ca4La6(SiO4)4(PO4)2O2 (CLSP) ceramic filler in high density polyethylene (HDPE) matrix through melt mixing. Scanning electron micrographs reveal the extent of filler dispersion. The dielectric properties at 1 MHz and 5 GHz have been investigated as a function of filler content. The relative permittivity increases with filler loading, maintaining a low dielectric loss. The composite with highest filler loading of 0.4 volume fraction shows a relative permittivity of 5.1 and dielectric loss of 2.3 × 10−3 at 5 GHz. Experimentally observed values of relative permittivity at 5 GHz have been compared with the values calculated using various theoretical models. Both the coefficient of linear thermal expansion and tensile strength have been observed to decrease with filler loading, reaching a minimum value of 117 ppm/ °C and 20.7 MPa, respectively, at 0.4 volume fraction of filler. The composite with maximum filler loading of 0.4 volume fraction shows the highest thermal conductivity (TC) and is 1.2 W m−1 K−1.

Low Dielectric Loss Polymer-Ceramic Composites for Wireless Temperature Sensation

2014 ◽  
Vol 602-603 ◽  
pp. 752-756 ◽  
Author(s):  
Li Zhang ◽  
Zhen Xing Yue ◽  
Long Tu Li
Keyword(s):  
Dielectric Loss ◽  
Relative Permittivity ◽  
High Density Polyethylene ◽  
Microstrip Antenna ◽  
Ceramic Composites ◽  
Processing Technique ◽  
Uhf Rfid ◽  
Temperature Sensation ◽  
Low Dielectric ◽  
Extrusion Processing

The low dielectric loss polymer-ceramic composites with high density polyethylene (HDPE) as matrix and BaO-Nd2O3-TiO2(BNT) as filter for wireless temperature sensation were prepared by an extrusion processing technique. For 30vol % ceramic loaded HDPE, as the ambient temperature increases from 30 to 100 °C, the relative permittivity and loss tangent of the composite vary from 6.25 to 6.09 and from 0.004 to 0.011 respectively, and the temperature coefficient of relative permittivity is -370ppm/°C. By using this composite as the patch microstrip antenna substrate, a simple UHF RFID temperature sensor antenna is fabricated and measured. The experimental results show that a 2MHz/10°C frequency increment can be obtained at 900 MHz in the temperature range from 25 to 100°C.

scholarly journals A low-firing melilite ceramic Ba2CuGe2O7 and compositional modulation on microwave dielectric properties through Mg substitution

2020 ◽  
Author(s):  
Changzhi Yin ◽  
Zezong Yu ◽  
Longlong Shu ◽  
Laijun Liu ◽  
Yan Chen ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Dielectric Properties ◽  
Resonance Frequency ◽  
Temperature Coefficient ◽  
Quality Factor ◽  
Relative Permittivity ◽  
Microwave Dielectric Properties ◽  
Sintering Behavior ◽  
Magnesium Doping ◽  
Microwave Dielectric

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.

Structure-dielectric property relationship in Nb-doped Ca4La2Ti5O17 ceramics

2016 ◽  
Vol 30 (18) ◽  
pp. 1650104 ◽  
Author(s):  
Raz Muhammad ◽  
Yaseen Iqbal
Keyword(s):  
Dielectric Property ◽  
Solid State ◽  
Resonance Frequency ◽  
Temperature Coefficient ◽  
Quality Factor ◽  
Mixed Oxide ◽  
Relative Permittivity ◽  
Property Relationship ◽  
Solid State Sintering

A number of compounds in the [Formula: see text] (x = 0–2) series were prepared through a mixed oxide solid-state sintering route. These compounds crystallized into orthorhombic (Pbnm) structure. The relative permittivity [Formula: see text] and temperature coefficient of resonance frequency [Formula: see text] depended on the polarizability of constituent cations while the quality factor [Formula: see text] was affected by ordering of cations. These compounds exhibited promising [Formula: see text] (74–90) and [Formula: see text] (10[Formula: see text]208–14[Formula: see text]116 GHz); however, the observed high [Formula: see text] (157–542 ppm/[Formula: see text]C) requires further investigations to tune it through zero.

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