Enhanced energy storage and photoluminescence properties in ErBiO3-doped (Na0.5Bi0.5)TiO3-SrTiO3 ceramics

Journal of Materials Science - (1-x)(0.75Na0.5Bi0.5TiO3-0.25SrTiO3)-xErBiO3 (NBST-xEB, x?=?0–0.04) ceramics were fabricated through a solid state reaction method. Scanning...     

Enhanced energy-storage properties of lead-free Bi0.5Na0.5TiO3-based relaxor ferroelectric ceramics by tuning sintering temperature

Journal of Materials Science: Materials in Electronics - Ferroelectric is thought to be one of the most promising energy-storage materials due to its high polarization. However, large energy loss...     

Dielectric properties of La2O3-doped Ba0.8Sr0.2TiO3 ceramics

La₂O₃-doped Ba_0.8Sr_0.2TiO₃ dielectric ceramics were prepared by conventional solid state ceramic route. Scanning electron microscope was employed to observe the surface morphologies. The capacitance C and dielectric loss factor D of the samples were measured with automatic LCR Meter 4225 at 10 kHz respectively. The results show that: ε _r of the samples decreases and tgδ first decreases then increases with increasing amount of La₂O₃ doping. ε _r reaches better value, tgδ obtains the minimum value at 0.5 mol% La₂O₃. ε _r increases and tgδ decreases when sintering temperature increases. The samples doped with 0.5 mol% La₂O₃ sintered at 1,350 °C for 10 h exhibited attractive properties, including high relative dielectric constant (>4,000), low dielectric loss (16.8 × 10^?4), low temperature coefficient of relative dielectric constant(<±21 %) in the temperature range of +25 to +85 °C.     

Enhanced dielectric temperature stability and energy-storage properties of (Y0.5Nb0.5)4+ co-doped (Bi0.5Na0.5)0.94Ba0.06TiO3 lead-free relaxor ceramics

(Bi_0.5Na_0.5)_0.94Ba_0.06Ti_1?x(Y_0.5Nb_0.5)_xO₃ (abbreviated as BNTBT-100xYN) lead-free relaxor ceramics were designed and prepared using a traditional solid-state sintering technique. The influences of the introduction of (Y_0.5Nb_0.5)⁴⁺ complex ions for the dielectric properties and energy storage performances of BNTBT-100xYN ceramics were systematically studied. All samples exhibited a typical pseudo-cubic symmetry structure and obtained the dense microstructure with the uniform distribution of all elements. The ergodic relaxor behavior of all ceramics was observed and revealed a trend of increase as a function of composition. It accelerated the improvement of the temperature stability of the dielectric constant. All samples showed a single grain conduction mechanism and the activation energy decreased with the addition of composition. It is related to the generation of oxygen vacancies induced by the defect dipoles. BNTBT-6YN ceramic revealed excellent dielectric temperature stability within the temperature range from 87 to 479 °C and the loss tangent less than 0.05 between 25 °C and 474 °C. Besides, a high recoverable energy density of?~?0.91 J/cm³ with the corresponding efficiency of?~?78.5% at applied 115 kV/cm field was achieved for BNTBT-5YN ceramic. Hence, BNTBT-5YN and BNTBT-6YN ceramics will become one of the outstanding dielectric ceramics for the electronic components.

     

Structure and electrical properties of Bi0.5Na0.5TiO3-Y0.5Na0.5TiO3-BaTiO3 lead-free piezoelectric ceramics

New (1 – x ? y)Bi_0.5Na_0.5TiO₃-xY_0.5Na_0.5TiO₃-yBaTiO₃ lead-free ceramics have been prepared by a conventional ceramic fabrication technique, and their structure and electrical properties have been studied. A morphotropic phase boundary (MPB) of rhombohedral and tetragonal phases is formed at 0.04 < y < 0.10. As compared to pure Bi_0.5Na_0.5TiO₃ ceramic, the partial substitutions of Y³⁺ for Bi³⁺ and Ba²⁺ for (Bi_0.5Na_0.5)²⁺ in the A-sites of Bi_0.5Na_0.5TiO₃ lower effectively the coercive field E _c and increase the remanent polarization P _r of the ceramics. Because of low E _c, large P _r and the MPB, the ceramics with x = 0–0.02 and y = 0.06 exhibit the optimum piezoelectric properties: d ₃₃ = 155–159 pC/N and k _p = 28.8–36.7%. The temperature dependences of dielectric properties of the ceramics show relaxor-like behaviors. The ferroelectric properties at different temperature suggest that the ceramics may contain both the polar and non-polar regions near/above T _d.     

Enhanced room temperature multiferroic behaviour of Ni-doped Na0.5Bi0.5TiO3 ceramics

In this paper, room temperature multiferroic behaviour in Ni (Nickel)-doped NBT (Na_0.5Bi_0.5TiO₃) ceramics synthesized using solid state reaction technique have been investigated. Structural, dielectric, ferroelectric, magnetic and magneto-dielectric properties were consistently probed with the increment in transition metal doping. XRD peaks were indexed for the monoclinic Cc phase. SEM micrographs clearly depicted the reduction of grain size with addition of Ni content. Ferroelectric polarization (P) vs applied electric field (E) hysteresis curves shows an increase in lossy behaviour with an increase in Ni content. The room temperature magnetization (M) vs applied magnetic field (H) curves depict the weak ferromagnetic ordering on increasing the Ni doping. Enhanced magneto-dielectric change of 1.26% was observed in 25% Ni-doped NBT ceramic, which may be useful in the development of novel non-volatile lead-free multiferroic memory devices.

     

Optimization of energy-storage properties for lead-free relaxor-ferroelectric (1-x)Na0.5Bi0.5TiO3-xSr0.7Nd0.2TiO3 ceramics

Journal of Materials Science - Ferroelectrics are considered as the most promising energy-storage materials applied in advance power electronic devices due to excellent charge–discharge...     

脉冲激光沉积Ba0.5Sr0.5TiO3、Pb0.5Ba0.5TiO3和Pb0.5Sr0.5TiO3薄膜及其介电性质

采用脉冲激光沉积法,在Pt／Ti／SiO2／Si基底上分剐制备厚度为350nm的Ba0.5Sr0.5TiO3(BST)、Pb0.5Ba0.5TiO3(PBT)和Pb0.5Sr0.5TiO3(PST)薄膜并研究了它们的介电性质。XRD显示,在相同的制备条件下三者具有不同的择优取向,PST具有(110)择优取向,PBT具有(111)择优取向,而BST则是混合取向。SEM显示三者样品表面均匀致密,颗粒尺寸大约在50nm至150nm之间。PST与BST、PBT相比有更高的介电常数,在频率为10kHz时,分别为874、334和355,而损耗都较低,分别为0．0378、0．0316和0．0423,同时PST漏电流也是最小的。测量薄膜的C-V特性扣铁电性能表明室温下BST呈现的是顺电相,PST和PBT则呈铁电相。本文也测量了薄膜在不同频率下的介电温度特性,BST、PBT和PST均表现出频率弥散现象,即随着频率的降低．居里温度降低而介电常数会升高。并测得BST和PST的居里温度分剐为-75和150℃。而PBT的居里温度在250℃以上。本文研究表明：与BST相比较,PBT的介电常数与之相近,漏电流较大;而PST具有高介电常数,较小的漏电流和较大的电容-电压调谐度,在相关半导体器件中的应用将有很大的潜力。     

Piezoelectric properties in (K0.5Bi0.5)TiO3-(Na0.5Bi0.5)TiO3-BaTiO3 lead-free ceramics.

Lead-free piezoelectric ceramics with compositions around the morphotropic phase boundary (MPB) x(Na0.5Bi0.5)TiO3-y(K0.5Bi0.5)TiO3-zBaTiO3 [x + y + z = 1; y:z = 2:1] were synthesized using conventional, solid-state processing. Dielectric maximum temperatures of 280 degrees C and 262 degrees C were found for tetragonal 0.79(Na0.5Bi0.5)TiO3-0.14(K0.5Bi0.5)TiO3-0.07BaTiO3 (BNBK79) and MPB composition 0.88(Na0.5Bi0.5)TiO3-0.08(K0.5Bi0.5)TiO3-0.04BaTiO3 (BNBK88), with depolarization temperatures of 224 degrees C and 162 degrees C, respectively. Piezoelectric coefficients d33 were found to be 135 pC/N and 170 pC/N for BNBK79 and BNBK88, and the piezoelectric d31 was determined to be -37 pC/N and -51 pC/N, demonstrating strong anisotropy. Coercive field values were found to be 37 kV/cm and 29 kV/cm for BNBK79 and BNBK88, respectively. The remanent polarization of BNBK88 (approximately 40 microC/cm2) was larger than that of BNBK79 (approximately 29 microC/cm2). The piezoelectric, electromechanical, and high-field strain behaviors also were studied as a function of temperature and discussed.     

Successive relaxor ferroelectric behavior in La modified (Ba,Sr)TiO3 borosilicate glass ceramics

In the present investigation, we are reporting the successive ferroelectric relaxor behavior of (Ba,Sr)TiO₃ borosilicate glass ceramics. The ferroelectric relaxor nature of the present glass ceramics is attributed to structural phase transition from the rhombohedral to orthorhombic to tetragonal to cubic. A very high value of dielectric constant was found to be 89,684 at 100 Hz in glass ceramic sample 64[(Ba_0.7Sr_0.3)TiO₃]–30[2SiO₂–B₂O₃]–5[K₂O]–1[La₂O₃], BST5K1L0.3S831 and such large value may be due to space charge polarization in glassy matrix. The various contribution in polarization processes are confirmed by impedance spectroscopic analysis.     

Incipient piezoelectricity boosts large strain with excellent thermal stability in (Bi0.5Na0.5)TiO3-based ceramics

Journal of Materials Science: Materials in Electronics - Piezoactuators with high electric field-induced strain are critical devices widely used in electrical systems. However, ferroelectric...     

Ferroelectric, electromechanical, and dielectric properties of (Na0.5Bi0.5)0.94Ba0.06TiO3 co-doped MnO2 and La2O3 lead-free ceramics

The modified (Na_0.5Bi_0.5)_0.94Ba_0.03La_0.02Ti_0.995Mn_0.005O₃ lead-free ceramics were prepared using a traditional solid-state reaction process, and their structures were characterized by X-ray diffraction, scanning electron microscope, and Raman spectroscopy, respectively. A double-like P–E loop was discussed at the room temperature for the co-doped ceramics by reason of the appearance of the anti-ferroelectric. The ferroelectric hysteresis loop and field-induced strain were studied at different temperatures. A large strain (S ₃₃ = 0.33 %, E = 50 kV/cm at 120 °C) was observed due to the transformation between ferroelectric and anti-ferroelectric phase at the phase transition temperature. Also, the depolarization temperature (T _d) of the co-doped ceramics was determined from the pyroelectric current density versus temperature plots, which was consistent with the result from the position of dielectric loss’s peak as a function of temperature.     

高性能无铅压电陶瓷(Bi0.5Na0.5)0.94Ba0.06TiO3的制备与性能

采用企业的电子陶瓷工艺制备了(Bi0.5Na0.5)0.94Ba0.06TiO3(BNTBT-6)无铅压电陶瓷,研究了制备工艺对BNTBT-6陶瓷的晶相、微观结构与介电压电性能的影响.研究结果表明,烧结方式会对BNTBT-6陶瓷的晶相和性能产生一定的影响.电学性能研究结果表明,湿磨盖烧BNTBT-6陶瓷样品的压电性能优良,室温下陶瓷样品的压电常数d33达到195pC/N,机电耦合系数kp为35%,机械质量因子Qm达到130,介电损耗tgδ为0.025.     

脉冲激光沉积Bi0.5(Na0.7K0.1Li0.2)0.5TiO3无铅压电薄膜的研究

采用脉冲激光沉积制备了新型无铅压电Bi0.5(Na0.7K0.1Li0.2)0.5TiO3陶瓷薄膜,分别利用X射线衍射仪、X射线光电子谱、俄歇电子能谱、原子力显微镜及扫描电镜研究了该薄膜的晶体结构、组成成分及表面形貌.结果表明,薄膜基体温度和工作气压对所生长的薄膜影响较大;在SiO2/Si基片上制备Bi0.5(Na0.7K0.1Li0.2)0.5TiO3薄膜的最佳温度和氧气压力分别为600℃和13Pa;利用脉冲激光沉积的薄膜具有精细的表面结构.