Papers by Keyword: Strontium Barium Niobate

Abstract: Ferroelectric Sr_xBa_1−xNb₂O₆ (SBN) thin films are deposited on Al/Si (100) substrates by radio frequency magnetron sputtering at room temperature. The nanograin sizes of the SBN thin films were analized by scanning electron microscopy (SEM). X-ray diffraction reveals that all the SBN thin films show an amorphous structure because they were deposited at room temperature.The capacitive properties of the SBN thin films were measured using metal ferroelectric insulation semiconductor (MFIS) structures. The memory window of the MFIS structure was characterized with a capacitance-voltage (C-V) method.

Abstract: Single crystals of Sr_xBa_1-xNb₂O₆ (0.26 a parameter monotonically increases with increasing of temperature, while the c parameter decreases up to the phase transition temperature T_C, and the next it begins increasing slowly. It was ascertained that with the increase of the Sr concentration in the studied crystals the changes of the lattice parameters were observed. They can be described according to the following relations: a = - 2.418 • 10-5 x² + 1.050 • 10-3 x + 12.479 Å and c = - 0.0015 x + 4.0216 Å. Basing on the obtained results the character of the phase transition was able to do.

Abstract: The influences of BaF2 addition on phase composition, electrical property and energy storage density in strontium barium niobate based glass-ceramics prepared using melt-casting followed by controlled crystallization were investigated. The results indicate that adding 1wt% BaF2 improves the precipitation of Ba0.27Sr0.75Nb2O6 phase. However, the secondary phases, Ba3SrNb2O9 and BaBF5 are formed as the amount of BaF2 exceeds 3wt% when heated at 800°C/3h+900°C/3h in the glass-ceramics. The dielectric constant, microstructure, volume resistivity and breakdown strength are related to BaF2 content. The maximum breakdown strength (1450 kV/cm) and the energy storage density (5.1J/cm3) can be obtained in the glass-ceramic sample with 1wt% BaF2 addition, which would be suitable to be used as the dielectric materials for high energy storage capacitors.

Abstract: Strontium barium niobate-based glass-ceramics are prepared by melt-casting followed by controlled crystallization. Results show that Ba_0.25Sr_0.75Nb₂O₆ with tungsten bronze structure forms as the dielectric phases from the glass matrix at 800°C. However, a secondary phase NaSr_1.2Ba_0.8Nb₅O₁₅ occurrs when crystallization temperature exceeds 850°C. The glass-ceramics formed through controlled crystallization exhibit the excellent stability of the temperature and frequency dependence of dielectric properties. The breakdown strength increases with the crystallization temperature. The glass-ceramic material heated at 800°C/3h+950°C/3h shows a breakdown strength of 1400 kV/cm and its energy storage density can reach up to 4.0 J/cm3, which may be strong candidate for high energy density storage capacitors for portable or pulsed power applications.

Abstract: The high quality Sr0.61Ba0.39Nb2O6 (SBN61) single crystals without any striations were obtained by Czochralski pulling method. The temperature dependence of the lattice parameters of the investigated crystals was studied using a precision X-ray Bond's method. The angular precision of the goniometer 1 arcsine and metric value of Cu K1 (λ = 1.54059292Å) allowed to obtain high precision and accuracy of lattice parameter measurements. The received results allowed to determine the Curie temperature and character of the phase transition in this material. The lattice parameter a monotonically increases and shows hardly visible inflection point at TC when increasing the temperature. The temperature dependence of the lattice parameter c displays quite distinct temperature behaviour. Contrastingly, it decreases with increasing the temperature experiencing an evident anomaly in the vicinity of the structural phase transition point. Obtained value of the ferroelectric phase transition point is TC = 346 ± 3K.

Abstract: Single crystals of composition Sr0.61Ba0.39Nb2O6 (space group P4bm) were prepared using the Czochralski method. The Bond's method of the precise lattice parameter measurements was used to study structure of SBN 61 at room temperature. In this way lattice parameters a = b = 12.45676 ± 6*10-5Å and c = 3.93541 ± 5*10-5Å were determined.

Abstract: Pure Strontium barium niobate, Sr0.5Ba0.5Nb2O6 (SBN50), was synthesized successfully by spark plasma sintering from two mixtures: SrCO3/BaCO3/Nb2O5 mixtures and the mixtures calcined at 800oC. The phase identification of the SBN crystalline grains was evaluated by X-ray diffraction analysis, and the formation mechanism was discussion based on the XRD results at various temperatures. They are different when SrCO3/BaCO3/Nb2O5 powder mixtures and the mixtures calcined at 800oC was chosen as the raw materials.