Origin of High Q for Microwave Complex Perovskite

2009 ◽  
Vol 421-422 ◽  
pp. 77-80 ◽  
Author(s):  
Hitoshi Ohsato ◽  
Eiichi Koga ◽  
Isao Kagomiya ◽  
Kenichi Kakimoto
Keyword(s):  
High Density ◽  
Order Structure ◽  
High Symmetry ◽  
Complex Perovskite ◽  
High Q ◽  
Sintering Time ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Lower Temperature ◽  
Q Values

Origins of high Q are considered on intrinsic as high symmetry, ordering structure and high density crystal structure. It was concluded that the high symmetry brings high Q instead of ordering comparing some cases as follows: As if ordering ratio of Ba(Zn1/3Ta2/3)O3 (BZT) is high of about 80%, Q values are distributed from low to high Q. Disordered BZT ceramics with high density obtained for short sintering time by spark plasma sintering (SPS) showed high Q. Ba(Zn1/3Nb2/3)O3 (BZN) with order-disorder transition showed high Q at disorder form sintered over the transition temperature. And, the disordered BZN with high Q annealed at lower temperature changed to order structure without improvement of Q.

scholarly journals Spark Plasma Sintering of Lithium Aluminum Germanium Phosphate Solid Electrolyte and its Electrochemical Properties

Nanomaterials ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 1086 ◽  
Author(s):  
Hongzheng Zhu ◽  
Anil Prasad ◽  
Somi Doja ◽  
Lukas Bichler ◽  
Jian Liu
Keyword(s):  
Ionic Conductivity ◽  
Solid Electrolyte ◽  
Spark Plasma Sintering ◽  
Lithium Ion ◽  
High Density ◽  
Lithium Aluminum ◽  
Composite Electrodes ◽  
Sintering Time ◽  
Plasma Sintering ◽  
Spark Plasma

Sodium superionic conductor (NASICON)-type lithium aluminum germanium phosphate (LAGP) has attracted increasing attention as a solid electrolyte for all-solid-state lithium-ion batteries (ASSLIBs), due to the good ionic conductivity and highly stable interface with Li metal. However, it still remains challenging to achieve high density and good ionic conductivity in LAGP pellets by using conventional sintering methods, because they required high temperatures (>800 °C) and long sintering time (>6 h), which could cause the loss of lithium, the formation of impurity phases, and thus the reduction of ionic conductivity. Herein, we report the utilization of a spark plasma sintering (SPS) method to synthesize LAGP pellets with a density of 3.477 g cm−3, a relative high density up to 97.6%, and a good ionic conductivity of 3.29 × 10−4 S cm−1. In contrast to the dry-pressing process followed with high-temperature annealing, the optimized SPS process only required a low operating temperature of 650 °C and short sintering time of 10 min. Despite the least energy and short time consumption, the SPS approach could still achieve LAGP pellets with high density, little voids and cracks, intimate grain–grain boundary, and high ionic conductivity. These advantages suggest the great potential of SPS as a fabrication technique for preparing solid electrolytes and composite electrodes used in ASSLIBs.

Effects of Spark-Plasma Sintering on the Piezoelectric Properties of High-Density (1-x)(Na0.5K0.5)NbO3-xLiTaO3 Ceramics

2007 ◽  
Vol 51 (92) ◽  
pp. 810 ◽  
Author(s):  
Jiro Abe ◽  
Masafumi Kobune ◽  
Kazuya Kitada ◽  
Tetsuo Yazawa ◽  
Hiroshi Masumoto ◽  
...  
Keyword(s):  
Spark Plasma Sintering ◽  
Piezoelectric Properties ◽  
High Density ◽  
Plasma Sintering ◽  
Spark Plasma

Kinetics Model for the Initial Stage of Spark Plasma Sintering

2007 ◽  
Vol 336-338 ◽  
pp. 2366-2368 ◽  
Author(s):  
Ming Hao Fang ◽  
Wei Pan ◽  
Sui Lin Shi ◽  
Zhen Yi Fang
Keyword(s):  
Spark Plasma Sintering ◽  
Kinetics Model ◽  
Shrinkage Ratio ◽  
Sintering Kinetics ◽  
Sintering Time ◽  
Plasma Sintering ◽  
Initial Stage ◽  
Spark Plasma ◽  
Powder Particles ◽  
The Relationship

The sintering kinetics model of initial stage by spark plasma sintering (SPS) is discussed in this paper. During SPS, there are discharges among the powder particles. And the particles surface will be melted and form viscose flow. These phenomena accelerate the particles rearrangement and reduce the sintering time. The relationship between the shrinkage ratio of particles and the sintering time during the initial stages of sintering by SPS has been obtained. The results show that L/L0 is linear to the time.

Densification of Sr-Mg Doped SiAlONs with GPS and SPS

2007 ◽  
Vol 554 ◽  
pp. 95-100 ◽  
Author(s):  
S. Kurama ◽  
Mathias Herrmann
Keyword(s):  
Mechanical Properties ◽  
Sintering Temperature ◽  
Phase 1 ◽  
Densification Process ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Lower Temperature ◽  
The Stability ◽  
Thermal Stability Of ◽  
Mg Doped

At temperature above 1200°C, the thermal stability of α-SiAlON phases has been debated since 1992; however, it has been discussed if any α-SiAlON phase can be formed in Ce, La, Eu and Sr-doped SiAlON systems. In our previous studies it was shown that the use of Mg-Ce and Mg-Sr elements as dopants SiAlON compositions, in which all elements just have very low or no stability in the α-SiAlON structure, would promote the stability of Mg-Ce elements in the α- SiAlON phase [1, 2]. However, in Mg-Sr systems, it was obtained that Mg2+ is predominantly incorporated in α-SiAlON structure whereas Sr2+ mainly remains in the grain boundaries [2]. In this study, by applying spark plasma sintering (SPS) (at 1400-1700°C) and post-sintering thermal heat treatment (at 1500°C for 5 hrs and 1700°C for 2hrs) Mg or Mg-Sr doped SiAlON (50:50 mole ratios) ceramics were prepared. The results were compared with GPS sintered samples data. The effect of sintering temperature on densification process, phase transformation, microstructure and mechanical properties of samples were investigated. The results showed that by using SPS, Sr-Mg doped samples can be sintered at lower temperature (at 1600°C) than at GPS (at 1800°C) and it has no Sr-doped grain boundary phases.

The Effect of Sb Content on Spark Plasma Sintered High-Density Antimony-Doped Tin Oxide Ceramics

2011 ◽  
Vol 687 ◽  
pp. 204-208 ◽  
Author(s):  
Qi Zhong Li ◽  
Dong Ming Zhang ◽  
Guo Qiang Luo ◽  
Cheng Zhang Li ◽  
Qiang Shen ◽  
...  
Keyword(s):  
Spark Plasma Sintering ◽  
Tin Oxide ◽  
Sintering Temperature ◽  
Glass Melting ◽  
High Density ◽  
Oxide Ceramics ◽  
Sintering Aids ◽  
Maximum Value ◽  
Plasma Sintering ◽  
Spark Plasma

Spark plasma sintering (SPS) is a newly developed technique that enables poorly sinterable tin oxide powder to be fully densified. Sintering without sintering aids is of great importance when SnO2ceramics are used as electrodes in the glass melting industry and aluminum electrometallurgy. Dense and good-conductive Antimony-doped SnO2 ceramics can be achieved by SPS at a lower sintering temperature and in a shorter time. When the Sb2O3concentration is 1.0 mol%, the densities of the samples reach their maximum value, which is 98.2% of the theoretical value. When the content of Sb2O3was 2.44mol%, SnO2ceramics with densities 97.6% can be obtained at 800°C-1000°C, and the resistivity was about 5.19×10-2Ω.cm at the sintering temperature of 1000°C. Defined amount of Sb3+used in our research are beneficial to low the sintering temperature and promote the densification of SnO2ceramics

Preparation of BaTiO3/SrTiO3 composite dielectric ceramics with a flat temperature dependence of permittivity

2003 ◽  
Vol 18 (8) ◽  
pp. 1809-1815 ◽  
Author(s):  
Tomonari Takeuchi ◽  
Hiroyuki Kageyama
Keyword(s):  
Temperature Dependence ◽  
X Ray ◽  
Sintering Time ◽  
Plasma Sintering ◽  
Complete Solid Solution ◽  
Phase Transition Temperatures ◽  
Spark Plasma ◽  
Ray Density ◽  
Dielectric Ceramics ◽  
Permittivity Measurements

Composite dielectric ceramics of BaTiO3/SrTiO3 were prepared using the spark plasma sintering (SPS) method. Relatively dense (>92% of the theoretical x-ray density) composite ceramics were obtained for a relatively short sintering time (∼3 min). Such a short sintering time was advantageous in suppressing the formation of a complete solid solution (Ba, Sr)TiO3. Fixed-frequency (100 kHz), room-temperature permittivity measurements of the BaTiO3/SrTiO3 = 9/1 composites showed a flat temperature dependence within the range 30–110 °C. X-ray diffractometry measurements showed that the current SPS-BaTiO3/SrTiO3 composites consisted of BaTiO3 and small amounts of (Ba1−xSrx)TiO3 with various x values having different phase transition temperatures. Such multicomponent microstructures would be responsible for the flat temperature dependence of permittivity.

scholarly journals Effect of Alumina Dopant on Transparency of Tetragonal Zirconia

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Haibin Zhang ◽  
Zhipeng Li ◽  
Byung-Nam Kim ◽  
Koji Morita ◽  
Hidehiro Yoshida ◽  
...  
Keyword(s):  
High Pressure ◽  
Beneficial Effect ◽  
Spark Plasma Sintering ◽  
Tetragonal Zirconia ◽  
High Density ◽  
Starting Material ◽  
Plasma Sintering ◽  
Spark Plasma

Aiming to characterize the effect of alumina dopant on transparency, powders of yttria stabilized tetragonal zirconia doped with alumina (TZ-3Y-E) are used as starting material to fabricate transparent tetragonal ZrO2by high-pressure spark plasma sintering (HP-SPS). However, low transparency of the resultant TZ-3Y-E specimens does not suggest a beneficial effect of alumina dopant although nanometric grains and high density have been achieved. The mechanism is analyzed by comparing with the results of as-sintered yttria stabilized tetragonal zirconia without alumina dopant.

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