The Influence of Doped MgF2 on the Dielectric Properties of Barium Strontium Titanate Ceramics

2011 ◽  
Vol 687 ◽  
pp. 427-432
Author(s):  
Shan Shan Liu ◽  
Yu Zhen Zhao ◽  
Xi Lin Wang ◽  
He Ping Zhou

Barium-strontium titanate Ba1-xSrxTiO3[0≤x≤1] has been investigated for tunable microwave application due to their high permittivity, low losses and high tunability. The influence of MgF2additives on the dielectric performance of Ba0.6Sr0.4TiO3(BSTO) were investigated in this paper. MgF2doped BSTO ceramics were prepared using the conventional mixed oxide techniques. The phase structure, microstructure and dielectric properties of MgF2doped BSTO ceramics were studied. The XRD patterns showed that all the samples exhibit a perovskite phase. A secondary phase of MgO was observed with excessive MgF2additives. The grain size of MgF2doped BSTO ceramics was slightly increased with the increasing of MgF2additives, while the distributed porosity was concentrated to get larger. The relative permittivity, dielectric loss and tunability were decreased accordingly. The relative permittivity was reduced from 3717 (pure Ba0.6Sr0.4TiO3) to 680 (6 wt % MgF2doped BSTO), while the tunability changed from 51.7 % to 6.5 %. The dielectric losses were decreased from 0.004 to less than 0.001. The Curie temperature of MgF2doped BSTO was first decreased with the additives of MgF2(x<2 wt %) then remain the same with the rise of MgF2(2≤x≤6) content.

2017 ◽  
Vol 727 ◽  
pp. 942-946 ◽  
Author(s):  
Juan Li ◽  
Cong Chun Zhang ◽  
Yan Lei Wang ◽  
Yang Gao ◽  
Xiao Lin Zhao

Barium strontium titanate (BST) thin films with excellent dielectric properties are deposited by on-axis RF magnetron sputtering system. The effects of composition of the target and oxygen partial pressure on the microstructure of BST thin film have been investigated. The dielectric properties of the thin films are investigated. The results show that composition of BST thin film deposited with pure argon ambient by the target with 30atm% excess of Ba and Sr is stoichiometric. Perovskite phase can be observed in the thin film annealed in oxygen at 750 °C for 30 min. A metal-insulator-metal (MIM) capacitor is fabricated by microfabrication technique. The capacitance value at 2 GHz is 0.417 pF and 1.42 pF for 50 nm and 90 nm BST thin film respectively, and the leakage current density is 6×10-6 A/cm2 and 5.35×10-8 A/cm2 respectively.


Author(s):  
Kiflom Gebremedhn Kelele ◽  
Aschalew Tadesse ◽  
Tegene Desalegn ◽  
Suresh Ghotekar ◽  
Ruthramurthy Balachandran ◽  
...  

Abstract The ferroelectric barium strontium titanate (Ba1-xSrxTiO3) is a homogeneous solid solution prepared from the mixture of barium titanate (BaTiO3), strontium titanate (SrTiO3) and titanium (IV) isopropoxide. Barium strontium titanate (BST) nanomaterials with improved permittivity and dielectric properties due to their nano-properties have attracted great interest for extensive and versatile applications as super capacitors, dielectrics, ceramics and catalysts. Introduction of metal ion dopants into the parent system of BST significantly alters its structural, morphological, electrical, optical and dielectric characteristics. This review is aimed at addressing synthesis, characterization methods, photocatalytic and electrical applications of metal ions doped BST nanomaterials. The effect of doping BST, through metal ions, on its properties and application with most probable reasons have been thoroughly discussed.


2021 ◽  
pp. 2150030
Author(s):  
Hanting Dong ◽  
Liang Ke ◽  
Xiangjun Hui ◽  
Jiangfeng Mao ◽  
Haiqing Du ◽  
...  

Effects of thermal misfit strains on dielectric features for sandwich structural barium strontium titanate (BST) thin films on metal plates were investigated via a modified thermodynamic model. When TEC of substrates is closer to that of BST, larger permittivity and tunability can be received. The tendency of permittivities and tunabilities of such films as a function of TEC of substrates agrees with that of single compositional BST films and compositionally graded BST multilayer films. The highest tunability reaches 60% at the biasing field of 300 kV/cm when the films are onto Ti metal. Moreover, Ba[Formula: see text]Sr[Formula: see text]TiO3/Ba[Formula: see text]Sr[Formula: see text]TiO3/Ba[Formula: see text]Sr[Formula: see text]TiO3 structure can obtain higher tunability than Ba[Formula: see text]Sr[Formula: see text]TiO3/Ba[Formula: see text]Sr[Formula: see text]TiO3/Ba[Formula: see text]Sr[Formula: see text]TiO3 structure, while Ba[Formula: see text]Sr[Formula: see text]TiO3/Ba[Formula: see text]Sr[Formula: see text]TiO3/Ba[Formula: see text]Sr[Formula: see text]TiO3 films show better compatible composition range for relatively larger tunability. Dielectric properties of sandwich-like BST films in some references can also be analyzed based on our calculated results.


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