Papers by Keyword: BST

Abstract: Barium strontium titanate (Ba_0.8Sr_0.2TiO₃) thin films have been prepared by pulsed laser deposition (PLD). The thin film of (Ba_0.8Sr_0.2TiO₃) was deposited on a silicon (Si) substrate with different deposition temperatures. The XRD pattern identifies these specimens as being of the tetragonal phase. As the deposition substrate temperature varied from 200 °C to 400 °C, the average crystal size of BST increased from 34 nm to 68 nm calculated by the XDR pattern. Field (FESEM) images have estimated the particle size of the film. The dielectric constant increased with increasing substrate temperature.

Abstract: Barium strontium titanate (BST), Ba_0.8Sr_0.2TiO₃ ceramic prepared using conventional solid-state reaction method has achieved a single phase at 1400 °C. The Ba_0.8Sr_0.2TiO₃ ceramic shows the highest dielectric constant and capacitance at 65°C about 4001 (10 Hz) and 2.92765 x10^-9 F, respectively. The conductivity of Ba_0.8Sr_0.2TiO₃ ceramic is in between the range of semi-insulator and insulator materials, and this composition also has exhibited the positive temperature coefficient resistivity (PTCR) properties jump of one order of magnitude from 2.06202 x 10⁷ Ω.cm to 3.00958 x 10^8­ Ω.cm measured at 1 kHz.

Abstract: Barium Strontium Titanate (Ba_xSr_1-xTiO₃) thin films have been synthesized for mole fraction 𝑥 = 0; 0.125; 0.25; 0.375; and 0.500 using Chemical Solution Deposition (CSD) method. The thin film was grown on p-type silicon (100) substrate using spin coating technique and annealed at 850 ^∘C for 8 hours with an increasing rate of 1.67 ^∘C/minute. The BST thin film was characterized using LCR meter to obtain data on frequency, charge, and electrical current. We also model the occurrence of vicinity magnetic induction around the thin film produced by the current flow in the BST thin film. The electrical and magnetic induction response of BST thin film with variation of mole fraction are presented here.

Abstract: 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.

Abstract: Barium strontium titanate (BST) materials with the chemical formula of Ba_xSr_1-xTiO₃ had successfully made ​​by solid state reaction method. The materials were made in the form of bulk. Ba mole composition was varied in the value of x = 0,5; 0,7; and 0,9. It was varied to study the influence on crystal structure and dielectric constant. The result of crystalline characterization performed by X-ray diffractometer instrument shows that changes in the composition of x causes a shift in the diffraction angle. The lattice parameter was obtained from the refinement with the GSAS software and calculation process. Lattice parameter of BST with a value of x = 0,5 and 0,7 are a = b = c, so that the crystal structure is cubic. While the BST with a value of x = 0,9 has lattice parameter a = b ≠ c, so that the crystal structure is tetragonal. Dielectric constant measurements performed at frequency of 1 KHz by RLC-meter instrument. The highest dielectric constant ​was ​obtained at 465 on Ba_0,9Sr_0,1TiO₃. The dielectric constant of cubic-crystal structured material is bigger than tetragonal-crystal structured material.

Abstract: This paper presents the relationship between spin coating speed, heat treatment time, and annealing temperature in response to the grain size in ferroelectric Barium Strontium Titanate (BST). Many fundamental issues such as heat conduction, contact deformation, mechanical stress, and friction can be explained and distinguished through the understanding of the grain size. The investigation was done using a full factorial design of experiment (DOE). Analysis was done quantitatively by plotting the main effects graphs. The results suggest that higher spin coating speed and the annealing temperature decreases the grain size while the heat treatment time is directly proportional to the value of grain size.

Abstract: A thick film array of high sensitive UFPA detector, with 16×16 units, is described in this paper. A micromachining capacitive pixel structure of infrared detector is provided, with the doped (Ba, Sr) TiO3 (BST) thick film as sensitive material. The key factors that affect the detector performance are described, and the basic physical and electrical parameters of ferroelectric materials that the detector needs are given. In addition, the heat insulation technique and the corresponding parameters are provided. The capacitance increment of pixel for this structure is approximately equal to that of infrared detector with equivalent sensitive area, and then the parasitic capacitance between the pixel and substrate electrode lead is reduced. It is easy to design the integrated circuit because the infrared detector with this structure needs only low precision for the circuit. This design idea for array structure of infrared matches the development trend of structure design of infrared focal plane pixel with large array, which paves the way to develop new UFPA detector.

Abstract: As a typical composite with perovskite structure, (Ba_1-xSr_x)TiO₃ (briefly named BST) shows many merits, This paper provides a new sol-gel method to prepare BST gel, and carry out a research and analysis on the thermal evolution of gel. The BST nanopowder is prepared by the heat treatment through the traditional sintering method and microwave sintering technique, respectively. The synthesis temperature of perovskite phase by sol-gel method decreases from 1380°C to 900°C, comparing with that by traditional solid-state reaction method. The XRD and SEM results show that microwave sintering technique can control effectively the grain growth size of BST ceramic, and the powder has the uniform chemical components and grain size of around 60nm. Furthermore, the grain size is reduced, the dielectric constant increased dramatically and the dispersivity reduced.

Abstract: The barium and strontium titanate (BST) ceramics have been used with great success as excellent dielectrics in the construction of high voltage (HV) commercial ceramic capacitors with reduced dimensions because of their high dielectric constant. However, the main point of this paper is to investigate other type of ceramic known as PZT (Lead Zirconate Titanate) normally used as piezoelectric sensors in industrial applications. The idea herein is to use the PZT ceramics as HV dielectrics for applications in high-energy storage systems by de-poling their piezoelectric properties in order to avoid dielectric damage and losses at high frequencies. For this, de-poled PZT-4 ceramic samples (30 mm × 2 mm) were submitted to HV tests, in which their dielectric breakdown strength and dielectric constant variation with the applied voltage were assessed. These results obtained confirmed the use of PZT in applications that require reasonable dielectric constant stability (< 15 %) with voltage and HV dielectric breakdown (40 kV/cm) for compact high-energy storage devices.

Abstract: This paper presents a new application of (Ba, Sr)TiO3(BST) and Pb(Zr, Ti)O3 (PZT) thin films in anti-fuse and their resulting anti-fuse behaviors. Compared with amorphous silicon, BST and PZT anti-fuses demonstrate distinct advantages: lower on-state resistance and lower breakdown electric field. With the sandwich-like structure of Pt/Ferroelectric Ceramics/Pt, the devices exhibit an apparent anti-fuse behavior. The resistivity of BST structure switches from 6.7 MΩ to 12.3 Ω at the average breakdown electric field of 0.3 MV/cm, while the PZT structure switches from 106 MΩ to 10.7 Ω at the average breakdown electric field of 1.3 MV/cm. Finally, the prospect of using BST and PZT is discussed and suggestions for their improvements are proposed.