High pressure treated ZnO ceramics towards giant dielectric constants

Abstract

We first synthesized ZnO porous ceramics with a giant permittivity of 104 and low dielectric loss using a high pressure treating method.

Heat treatment of ZnO nanoparticles: new methods to achieve high-purity nanoparticles for high-voltage applications

“…17 A higher breakdown voltage of nanocomposites with ultra-low electrical conductivity was obtained by decreasing the particle size from mm to nm. [19][20][21][22][23][24][25][26][27][28][29] The grain boundaries in the varistors provide a high charge barrier compared to that of the conductive ZnO bulk grains, and hence the breakdown voltage depends on the number of grain boundaries per unit volume. [19][20][21][22][23][24][25][26][27][28][29] The grain boundaries in the varistors provide a high charge barrier compared to that of the conductive ZnO bulk grains, and hence the breakdown voltage depends on the number of grain boundaries per unit volume.…”

Origin of anomalous giant dielectric performance in novel perovskite: Bi0.5−xLaxNa0.5−xLixTi1−yMyO3 (M = Mg2+, Ga3+)

“…Materials with high ε ’ range from perovskite ferroelectrics, relaxors, binary oxides, and ionic conductors, in which the general characteristics are their high conductive grains. Both localized and delocalized conduction are bulk processes and give rise to the impressive geometric capacitance458910111213.…”

Effect of powder size on the microstructure and dielectric properties of ZnO ceramics

“…During sintering, the densification and coarsening of porous ceramics are controlled by the neck growth in the porous regions and boundary migration in the dense region [14]. The inner parts of ZnO agglomerates are dense due to HPT, and they are easily to form well dense structures with large grain sizes, while the pores between agglomerates are difficult to eliminate [11]. Moreover, it has been reported that the grain growth of ZnO at a relatively high temperature is controlled by the vaporization rate [15].…”

“…The powders were firstly high-pressure treated (HPT) at 4.4 GPa for 5 min as described elsewhere [11], then the ceramics were sintered at 1250 C for 2 h in a conventional electric furnace and then cooled down to room temperature in air. The bulk density was obtained using the Archimedes method.…”

“…Therefore, further investigations on the dielectric behaviors of ZnO ceramics are still needed. We reported earlier that CDC attributed to Maxwell-Wagner relaxation can be achieved in high pressure treated ZnO porous ceramics [11]. Although dielectric properties of ZnO have been investigated by many researchers, few of them studied the effects of powder size on microstructure and properties of ZnO ceramics.…”