退火温度对Bi_4Ti_3O_(12)_Bi_3TiNbO_9复合薄膜铁电性能的影响

研究了退火工艺对溶胶-凝胶法Bi4Ti3O12_Bi3TiNbO9复合薄膜铁电性能的影响。结果表明,采用溶胶-凝胶工艺制备Bi4Ti3O12_Bi3TiNbO9复合薄膜,可将薄膜的剩余极化值Pr提高到19.8μC/cm2(而Bi4Ti3O12薄膜的Pr只有15μC/cm2);薄膜在650℃退火可获得最佳的铁电性能。     

LiFePO4/Li4Ti5O12锂离子电池的制备及研究

使用磷酸铁锂(LiFePO4)和钛酸锂(Li4Ti5O12)做正、负极活性材料,制备锂离子电池,并测试其性能。用三电极法考察不同配比时正负电极充放电电位的变化,并据此确定了电池中正负极的容量配比。性能测试结果表明,所制备的锂离子电池具有优异的循环稳定性,容量发挥好。正负极容量配比1.4时,18650圆柱电池负极钛酸锂的容量发挥为160mAh/g。     

铁电薄膜钛酸铋掺杂改善铁电性及疲劳特性的研究

分析了对铁电薄膜Bi4Ti3O12进行A位、B位掺杂时，Bi4Ti3O12铁电性及疲劳特性的改善及相应的理论解释，并指出Bi4Ti3O12值得进一步深入研究的领域。     

电极材料Li4Ti5O12制备方法研究进展

电极材料Li_4Ti_5O_(12)是一种具有零应变性质的负极材料,电化学性能十分优异,是锂离子电池负极材料的研究热点之一。制备Li_4Ti_5O_(12)材料的方法除了传统的高温固相合成法,还有溶胶-凝胶法、水热(溶剂热)法、高能球磨法、微波法和喷雾干燥法等。综述了近几年来Li_4Ti_5O_(12)制备方法的研究进展。     

电极材料Li4Ti5O12的研究进展

分析了钛酸锂(Li4Ti5O12)的晶体结构、嵌锂特性与电化学特性;介绍了目前制备Li4Ti5O12的几种方法,主要是固相法和溶胶-凝胶法;其改性方面的研究不但包括掺杂、包覆,还包括结构的改变.Li4Ti5O12作为零应变材料,具有优良的电化学性能,可用于提高其它电池材料的性能.最后提出了Li4Ti5O12今后的研究方向.     

钒掺杂对Li4Ti5O12性能的影响

采用固相反应法合成了锂离子电池负极材料Li4-xVxTi5O12(x=0,0.1,0.2),研究了钒掺杂对其晶格结构、相组成和颗粒形貌以及电化学性能的影响。结果表明:钒的掺杂增大了Li4-xVxTi5O12的晶胞参数,降低了晶格的规整度,增大了合成Li4-xVxTi5O12的颗粒度;同时随着钒掺杂量的增加,Li4-xVxTi5O12在高倍率下的循环稳定性增加,电极极化程度变小。Li4Ti5O12在3.0C下的比容量衰减迅速,但Li4-xVxTi5O12(x=0.1,0.2)在3.0C下仍保持很好的循环稳定性。钒的掺杂降低了Li4Ti5O12的比容量,这与钒在晶格中的存在形式以及掺杂试样较大的颗粒度有直接关系。     

铁电薄膜钛酸铋掺杂改善铁电性及疲劳特性的研究

分析了对铁电薄膜Bi4Ti3O12进行A位、B位掺杂时,Bi4Ti3O12铁电性及疲劳特性的改善及相应的理论解释,并指出Bi4Ti3O12值得进一步深入研究的领域。     

锂离子蓄电池负极材料Li4Ti5O12的研究进展

对Li4Ti5O12 的结构与电化学性能的关系、制备方法、掺杂改性研究现状等进行了介绍。锂离子蓄电池负极材料锂钛复合氧化物———Li4Ti5O12 相对于锂电极的电位为 1.5 5V ,理论容量为 175mAh/ g ,实验容量为 15 0～ 160mAh/ g。在Li 嵌入和脱出的过程中 ,其晶型不发生改变 ,有很小的收缩和膨胀 ,体积变化小于 1% ,被称为“零应变”材料。以该材料为负极的锂离子蓄电池具有很好的循环性能 ,同时相对于石墨等碳负极 ,安全性和可靠性也得以大大改善 ,具有应用在电动汽车、储能电池等方面的优良前景 ,在全固态锂离子蓄电池的研究中也大多采用该活性材料作为负极     

提高负极材料Li4Ti5O12倍率性能的进展

综述了近年来提高锂离子电池负极材料Li4Ti5O12倍率性能的进展。通过形貌控制和掺杂改性,可提高Li4Ti5O12的倍率性能。单晶、纳米粒径、球形及多孔结构,均可提高离子电导率;掺杂改性可提高电子电导率。     

Structural and Electrical Properties of Bi 3.25 La 0.75 Ti 3 O 12 and Bi 3.25 Pr 0.75 Ti 3 O 12 Thin Films for Memory Applications

In this work, Bi 3.25 La 0.75 Ti 3 O 12 (BLT) and Bi 3.25 Pr 0.75 Ti 3 O 12 (BPT) thin films were prepared by chemical solution deposition and characterized by X-ray diffraction, scanning electron microscope and electrical measurements. Layered perovskite BLT and BPT films can be achieved by 180 s annealing at a temperature as low as 650 C. Both BPT and BLT films are composed of closely packed spherical grains. BPT shows larger remnant polarization ( Pr ) and smaller coercive field. The Pr values of 700 C annealed BLT and BPT films are 18.3 w C/cm 2 and 20.5 w C/cm 2 , respectively, while BLT films show better-saturated hysteresis loops. The leakage current density of BPT films is significantly (about one order) lower than that of BLT. The dielectric properties of BLT and BPT films were measured and compared. Both films exhibit large dielectric constant and small loss tangent. Under bipolar switching cycles, BLT films showed little polarization reduction but a 30% polarization loss was observed for BPT films after 2 2 10 9 cycles.     

Ferroelectric Properties of Mo-Doped Bi4-XLaXTi3O12 Films

Mo-doped Bi_3.35La_0.75Ti₃O₁₂ (BLTM) films were deposited on Pt/Ti bottom electrodes by using a sol-gel method and crystallized at 700°C for 30 min in O₂ atmosphere. The ferroelectric properties were greatly improved by substituting B-site ions with Mo ions and the BLTM films showed strong preferred (117) orientation. Typical remanent polarization (2Pr) and coercive field (2Ec) values were 32.0 μC?cm^?2 and 158 kV?cm^?1, respectively. It was also found that the leakage current densities in the BLTM films were lower than those in Bi_3.35La_0.75Ti₃O₁₂ (BLT) films.     

Ferroelectric Properties of Bi3.25Nd0.75Ti3O12 Thin Films Prepared by MOD Process

Ferroelectric Bi_{4 – x}Nd_xTi₃O₁₂(BNdT) thin films with the composition (x = 0.75) were prepared on Pt/Ti/SiO₂/Si(100) substrate by metal-organic deposition. The films were annealed by various temperatures from 550 to 650C and then the electrical and structural characteristics were investigated for the application of FRAM. Electrical properties such as dielectric constant, 2Pr and capacitance were quite dependent on the thermal heat treatment. The measured 2Pr value on the BNdT capacitor annealed at 650C was 56 C/cm² at an applied voltage of 5 V. No fatigue was observed up to 8 × 10¹⁰ read/write switching cycles at a frequency of 1 MHz regardless of annealing temperatures.     

Ferroelectric Properties of (Bi, Sm)4Ti3O12 (BST) Thin Films Fabricated by a Metalorganic Solution Deposition Method

Ferroelectric properties of samarium substituted Bi₄Ti₃O₁₂ films, Bi_3.15Sm_0.85Ti₃O₁₂ (BST), were evaluated for use as lead-free thin film ferroelectrics for FeRAM applications. The BST films were fabricated on the Pt/Ti/SiO₂/Si(100) substrates by a metalorganic solution deposition method. The measured XRD patterns revealed that the BST films showed only a Bi₄Ti₃O₁₂-type phase with a random orientation. The BST film capacitors showed excellent ferroelectric properties. For the film capacitor annealed at 700C, 2P_r of 64.2 C/cm² and 2E_c of 101.7 kV/cm at applied electric field of 150 kV/cm were observed. The capacitor did not show any significant fatigue up to 1.5 × 10⁸ read/write switching cycles at a frequency of 1 MHz, which suggests that the samarium should be considered for a promising lanthanide elements to make a good thin ferroelectric film for memory applications.     

Excess Bismuth-Dependent Characteristics of Chemical Solution Deposited Bi3.15La0.85Ti3O12 Thin Films

The phase formation and electrical properties of (Bi_3.15La_0.85)Ti₃O₁₂ (BLT) thin films prepared by the chemical solution deposition method on Pt/Ti/SiO₂/Si substrates have been investigated. It was observed that the microstructure and electrical properties of BLT thin films dramatically varied with the excess Bi content. The crystallographic orientation of BLT films was varied with excess Bi content and the intermediate rapid thermal annealing (RTA) process. While BLT thin films prepared without intermediate RTA process have ?117? orientation irrespective of excess Bi content, BLT thin films with RTA process at 450°C have an orientation change with excess Bi content. The leakage current of BLT thin films slightly increased with increasing excess Bi content up to 6.5% and then considerably decreased in BLT film with 10% Bi, where was revealed to be almost stoichiometric composition.     

负极材料Li4Ti5O12在锂离子电池中应用的进展

介绍了Li4Ti5O12的结构和电化学性能,对该材料与LiFePO4、LiCoO2、LiMn2O4和Li2Co0.4FeMn3.2O8等正极材料的匹配情况进行了评述。Li4Ti5O12可与上述正极材料良好地匹配,组成不同电压的锂离子电池。以Li4Ti5O12作负极材料的锂离子电池比传统锂离子电池的快速充放电性能、循环性能更好,安全性能更高,但成本有待进一步降低。     

改善Li4Ti5O12倍率性能的研究进展

综述了提高Li4Ti5O12倍率性能的主要途径以及研究进展,并对今后的发展方向进行了展望.改性的有效途径主要有:溶胶-凝胶法合成纳米Li4Ti5O12提高离子导电能力;对Li4Ti5O12进行离子掺杂,提高电子导电能力;向Li4Ti5O12中引入高电子导电相(如金属,碳等),提高表面电子导电能力.