Abstract
The effects of Dy2O3 on the phase composition, microstructure, and the dielectric property, especially, dielectric constant, of AlN ceramics sintered at low-temperature (1650oC), were investigated systematically. X-ray diffraction (XRD) was employed to indentify the phase compositions of the ceramics during the sintering. Scanning electronic microscopy (SEM) was used to observe the microstructures of the AlN ceramics. The results show that the dielectric constant changes with the amount of Dy2O3. When the amount of Dy2O3 is less than 0.93 wt.%, the dielectric constant increases with the increased amount of Dy2O3. The dielectric constant of the AlN ceramics is higher than 200 when the amount of Dy2O3 is 0.93 wt.%. However, when the amount of Dy2O3 is more than 0.93 wt.%, the dielectric constant decreases with the increased amount of Dy2O3. The dielectric constant of the AlN ceramics with 1.87 wt.% Dy2O3 is only about 15, which closed to the theoretical value of pure AlN ceramics. The analysis illuminated that the grain phases changed from Al2O3-rich aluminate to AlDyO3 which existed at triple pockets with the increased amount of Dy2O3, the former can improve the dielectric constant greatly due to ion relaxation polarization.
Highlights
AlN has received growing interests in the electronics industry because of the need for smaller and more reliable integrated circuits and the need for higher voltage devices for power applications (Luo & Zhang, 2005)
The results show that the dielectric constant changes with the amount of Dy2O3
It can be observed that the water absorbability of all of the samples is less than 0.1% regardless of the amount of Dy2O3, which means that all the samples were almost fully densified
Summary
AlN has received growing interests in the electronics industry because of the need for smaller and more reliable integrated circuits and the need for higher voltage devices for power applications (Luo & Zhang, 2005). AlN ceramics are used as electronics materials because of its excellent properties, such as high resistivity, high thermal conductivity, low dielectric constant and thermal expansion coefficient close to that of silicon. When AlN ceramics were used as substrate and package materials for integrated circuits (ICs), dielectric loss and dielectric constant should be necessary low for the sake of shortening signal delay time. When multiple component additives were used for low-temperature sintering, the complicated microstructure of AlN ceramics was always unavoided. Under this condition, the dielectric constant and dielectric loss varied significantly. Vol 1, No 4; 2012 the dielectric loss, especially for high pure AlN ceramics (Kume & Yasuoka, 2005; Hagen & Yu, 2002), but less on dielectric constant. AlN with 0-1.87 wt.% Dy2O3 sintered at 1650oC were prepared, and the effects of Dy2O3 addition on the phase composition, microstructure and dielectric properties of AlN ceramics are investigated
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