退火温度对硅基铁电薄膜Bi_4Ti_3O_(12)晶相结构的影响

采用溶胶-凝胶(Sol-Gel)法制备铁电Bi4Ti3O12 (BIT)薄膜,研究退火温度对其微观特性的影响,以掌握制备工艺中最佳退火温度。研究表明,随着退火温度的增加,BIT薄膜的c轴取向生长更明显,晶粒尺寸增加,同时表面粗糙度增加;从退火750℃开始,晶粒开始呈棒状生长;当温度高于850℃时,薄膜的c轴生长取向增长趋势不再明显。退火时间对薄膜的相结构和生长取向没有明显影响。     

Bi_4Ti_3O_(12)陶瓷的制备及微观结构

以过量的Bi2O3和TiO2为组分,采用固相烧结法制备Bi4Ti3O12陶瓷。借助XRD和SEM分析相成分和微观结构。结果表明:经750℃/2h预烧后,合成粉体由Bi4Ti3O12、少量的Bi12TiO20和Ti5O9以及Bi2O3组成。成型烧结后,Bi12TiO20和Ti5O9的衍射峰消失,出现了Bi2Ti2O7的衍射峰。1000℃烧结后,Bi2Ti2O7的衍射峰消失,产物基本为Bi4Ti3O12相。SEM分析表明,温度低时,气孔较多,晶粒较细;温度升高后,晶粒长大,气孔减少;到1000℃时,气孔显著减少,晶粒尺寸约为2～5μm。     

La/Nb掺杂对Bi_4Ti_3O_(12)薄膜铁电性能和疲劳特性的影响

采用溶胶–凝胶工艺(sol–gel)在Pt/Ti/SiO2/p-Si衬底上分别制备Bi4–xLaxTi3O12和Bi4Ti3–yNbyO12铁电薄膜,研究La/Nb掺杂对Bi4Ti3O12薄膜铁电性能和疲劳特性的影响。结果表明:La/Nb掺杂均能有效改善Bi4Ti3O12薄膜的铁电性能和疲劳特性。当La摩尔(下同)掺量在0.5～0.75时,La掺杂对Bi4Ti3O12薄膜的性能改善作用最好,而且在明显提高薄膜铁电性能的同时,对薄膜疲劳特性的改善更加显著,薄膜经1010极化反转后,其剩余极化强度(Pr)仅下降5.1%。Nb掺杂对提高薄膜铁电性能的作用更加明显,Nb掺量为0.06时,Bi4Ti3–yNbyO12薄膜的Pr高达18.7μC/cm2,但Nb掺量不宜过多,当Nb掺量超过0.06以后,薄膜的铁电性能和疲劳特性均反而有所下降。     

溶剂热法制备多级纳米结构Bi_(4)Ti_(3)O_(12)及其光电性能研究

采用溶剂热法制备多级结构钛酸铋(Bi_(4)Ti_(3)O_(12))纳米材料,该材料由纳米片堆叠成层状,再自组装成5μm微米球状结构。表征该Bi_(4)Ti_(3)O_(12)纳米结构的光电性能,并与纳米片空心球结构Bi_(4)Ti_(3)O_(12)的光电性能进行对比。结果表明,该多级结构Bi_(4)Ti_(3)O_(12)的光电性能较纳米片空心球结构Bi_(4)Ti_(3)O_(12)提高了10倍。紫外-可见光吸收谱表明多级结构Bi_(4)Ti_(3)O_(12)的禁带宽度小于纳米片空心球结构Bi_(4)Ti_(3)O_(12)。多级结构Bi_(4)Ti_(3)O_(12)材料中纳米片暴露的晶面是影响材料光电性能的重要因素。     

制备工艺对溶胶-凝胶法制备BeFeO3薄膜的影响

利用溶胶-凝胶法在Pt/Ti/SiO2/Si基体上制备了BiFeO3薄膜,构架了Pt/BiFeO3/Pt电容器。对不同退火温度和保温时间制备薄膜的微观形貌和铁电性能做了研究。X射线衍射仪（XRD）结果显示,不同的退火温度和保温时间并没有改变BiFeO3（BFO）的钙钛矿结构,但温度的改变会产生不同的晶相。通过扫描电子显微镜（FE-SEM）可以观察到,随着烧结保温时间的延长,薄膜晶粒有减小的趋势。P-E曲线结果表明,BFO薄膜在外加电场较高时易击穿,难以得到清晰饱和的电滞回线。     

SrBi4Ti4O15薄膜的溶胶凝胶制备及其生长行为

以氯化锶、硝酸铋和钛酸丁酯为原料,柠檬酸为络合剂,配制了稳定的SrBi4Ti4O15（SBTi）前驱液.采用层层快速退火工艺,在Pt/Ti/SiO2/Si基片上制备了a轴取向增强的SBTi铁电薄膜,通过场发射扫描电镜、环境扫描电镜及X射线衍射等微观分析手段研究了保温时间和成膜次数对薄膜结晶性、微观结构和生长行为的影响.结果表明：层层快速退火工艺,可有效抑制焦绿石相的形成.随着退火时间的延长,薄膜的结晶性变好;但退火时间延长到30 min以上,薄膜的结晶性变差.由于SBTi晶体生长的各向异性及单层膜厚对晶体沿[119]方向生长的限制,随着涂覆次数的增加,SBTi薄膜（119）峰和（200）峰的强度逐渐增大,而（00l）峰的强度反而略有减少,从而使I（200）/I（119）、I（200）/I（0010）、I（119）/I（0010）逐渐增大.     

Al3+/Bi4Ti3O12薄膜的制备及其光催化性能表征

采用溶胶一凝胶法制备了掺 Al3+ 的Bi4 Ti3 O12 薄膜(Bl-xAlxTi3O12).采用分光光度法研究了薄膜对甲基橙溶液的降解,以及Al3+对薄膜的光催化效果影响.光催化结果表明,Al3+的掺杂量为 2atm% 时,薄膜的光催化效果最好,比未掺杂前提高 57.9%,且吸收边红移量为 36nm.     

硅酸铋(Bi4Si3O12)粉体制备的研究进展

Bi₄Si₃O₁₂晶体作为一种性能优异的新型闪烁体,在各个方面有着重要的作用,粉体制备有着重要的意义。本文综述了硅酸铋粉体的制备技术,有固相法、高能球磨法、溶胶-凝胶法、水热法和化学溶液分解法等,同时讨论了各个方法的优缺点,最后展望了硅酸铋粉体制备的未来发展趋势。     

Li_4Ti_(4.95)Nb_(0.05)O_(12)负极材料的制备及其电化学性能研究

采用二步固相法制备了Li_4Ti_(4.95)Nb_(0.05)O_(12)负极材料,扫描电镜、激光粒度分布仪、充放电测试和循环伏安等测试结果表明:合成的样品粒径分布均匀,Nb掺杂改性的Li_4Ti_5O_(12)具有优良的电化学性能,0.1 C、0.5 C、1 C和10 C首次放电比容量分别为174.1 m Ah/g、159.7 m Ah/g、147 m Ah/g和123.3 m Ah/g。10 C下,循环20次后容量保持为118.1 m Ah/g。     

Ce掺杂0.85Bi_4Ti_3O_(12)-0.15LiNbO_3铋层状铁电陶瓷的显微结构与性能(英文)

采用固相法制备CeO2掺杂改性0.85Bi4Ti3O12-0.15LiNbO3(BTO-LN)铋层状压电陶瓷。借助于X射线衍射和扫描电子显微镜研究了CeO2掺量与BTO-LN陶瓷晶体结构和电性能的关系。结果表明:所有陶瓷样品均为单一的正交相结构;随CeO2掺量的增加,陶瓷的晶粒尺寸变大,Curie温度TC由653℃下降到617℃;CeO2掺杂提高了样品的压电性能,压电常数d33随CeO2掺量的增加先增大后减小,相对介电常数εr表现出相反的变化趋势;当CeO2的掺入量为0.75%时,样品的电性能最佳,即d33=25pC/N,机械品质因数Qm=2 895,介电损耗tanδ=0.10%,TC=617℃。     

水热法制备钛酸铋粉体的研究

以TiCl4乙醇溶液和Bi（NO3）3·5H2O为原料．NaOH为矿化剂，其摩尔配比的关系为TiCl：Bi（NO3）3·5H2O：NaOH=0．1：0．75：1．5．用水热法合成钙钛矿结构的钛酸铋粉体。讨论了水热合成条件（前驱物和粉体处理、晶化时间、填充率）对钛酸铋粉体结构和形貌的影响。XRD、SEM分析表明，在240℃，晶化时间16h，填充比为60％的条件下，可制备平均晶粒粒径为9～12nm，团聚较轻，颗粒边界明显．球形的钛酸铋粉体。     

片状Bi4Ti3O12的合成及表征

采用熔盐法制备了Bi4Ti3O12粉体,研究了煅烧温度和盐的加入量对粉体显微形貌的影响.结果表明:Bi4Ti3O12晶粒呈较规则的薄片状四边形;烧温度的升高,晶粒尺寸显著增大,a-b面取向生长明显;盐与反应原料的质量比为1:1时,晶粒尺寸分布均匀,为6～8μm;晶粒生长遵循Ostwald熟化机理.     

钛酸铋陶瓷靶材的热压烧结

纯相、高致密度、结晶良好的陶瓷靶材是物理气相沉积薄膜的前提.采用热压烧结方法制备钛酸铋(Bi4Ti3O12)陶瓷靶材,重点研究了制备工艺对靶材的物相、微观结构和致密度的影响.以Bi2O3和TiO2微粉为原料,采用固相反应法,在800℃合成出纯相的Bi4Ti3O12粉体;加入过量3wt%的Bi2O3,可以有效防止烧结过程中因Bi挥发所产生的杂相,得到纯相的Bi4Ti3O12陶瓷;采用热压烧结方法,进一步实现了Bi4Ti3O12粉体的致密烧结,确定了适宜的制备条件为850℃,30MPa,2b,在该条件下制备的Bi4Ti3O12陶瓷致密度达到99%,晶粒呈片层状,大小约2-4μm,可满足靶材制备薄膜的需求.     

Effects of cerium on structures and electrical properties of (Nb,Ta) modified Bi4Ti3O12 piezoelectric ceramics

Bi₄Ti₃O₁₂ high-temperature piezoelectric ceramics composed of 0.03 mol (Nb, Ta)⁵⁺ substituting B site and x mol CeO₂ (x = 0–0.05, abbreviated as BCTNT100x) substituting A site were synthesized by the conventional solid-state reaction method. The effects of Ce additive on the structures and electrical properties of resulting Bi₄Ti₃O₁₂-based ceramics were systematically investigated. In-situ temperature-dependent X-ray diffraction (XRD) confirmed that the phase structure of BCTNT100x ceramics change from orthorhombic structure to tetragonal structure as temperature increased. The ceramics at Ce content x = 0.03 illustrated optimal performances with superior piezoelectric constant (d₃₃ = 36.5 pC/N), high Curie temperature (T_C = 649 °C), and large remanent polarization (2P_r = 21.6 μC/cm²). BCTNT3 ceramics also possessed high d₃₃ of 32.5 pC/N at an annealing temperature of 600°C, with electrical resistivity preserved at 10⁶ Ω cm at 500 °C. These results demonstrate that BCTNT100x ceramics can be used as high-temperature piezoelectric devices.     

Stabilizing temperature-capacitance dependence of (Sr,Pb, Bi)TiO3-Bi4Ti3O12 solutions for energy storage

(1-x)Sr_0.7Pb_0.15Bi_0.1TiO₃-xBi₄Ti₃O₁₂ ((1-x)SPBT-xBIT, x = 0-0.125) bulk ceramics were developed and calcined via the solid-state method, aimed at the application of pulsed power capacitors. The phase structures, temperature stability, hysteresis loop, and discharge properties were systematically investigated. Considering both the temperature stability and dielectric properties, 0.925SPBT-0.075BIT bulk ceramics with a capacitance variation satisfying the X7R specification were developed for pulsed power capacitors. The energy storage density was 0.252 J/cm³, and the ceramics showed high temperature stability at 80 kV/cm. The discharge current waveforms of the 0.925SPBT-0.075BIT ceramics were recorded. A high discharge power density of approximately 1.01 × 10⁸ W/kg with an 8 Ω load resistor and short discharge period of 84 ns were achieved at 50 kV/cm. The good temperature stability properties and high power density show that the 0.925SPBT-0.075BIT ceramics are well suited for pulsed power capacitors with a wide temperature range.     

Structural and electric properties of Ce-doped Na0.5Bi4.5Ti4O15 piezoceramics with high Curie temperatures

Na_0.5Bi_4.5-xCe_xTi₄O₁₅ (x = 0, 0.02, 0.04, 0.06, 0.08, 0.10) lead-free piezoelectric ceramics with high Curie temperatures are fabricated using the conventional solid-phase method. The effects of the Ce content on the phase structures, morphologies, and electrical properties of the Na_0.5Bi_4.5-xCe_xTi₄O₁₅ ceramics are systematically investigated. The appropriate content of Ce increases b/a and c/a and induces the distortion of the crystal structure. The increased b/a leads to a transverse asymmetry of the Na_0.5Bi_4.5-xCe_xTi₄O₁₅ ceramics, which facilitates the dipole flipping, thus enhancing the piezoelectric properties (d₃₃ = 20 pC/N). Although the improved c/a increases the degree of tetragonality of the Na_0.5Bi_4.5-xCe_xTi₄O₁₅ ceramic, which decreases the Curie temperature (T_C), the T_C values of all samples are higher than 600°C, considerably higher than the practical application temperature. The Ce doping significantly reduces the dielectric loss of the sample and increases its dielectric performance. The improvements in electric properties by the cerium doping can expand its use in high-temperature environments for oilfield logging, aerospace, and military applications.     

无定形TiO2合成尖晶石Li4Ti5O12的性能

用无定形TiO2与Li2CO3高温固相反应合成了性能良好的"零应变"电极材料Li4Ti5O12. XRD, SEM和激光粒度分析表明,产物结晶度好,无杂质相,为纯立方尖晶石相,Li4Ti5O12颗粒呈砾石状形貌,有团聚现象,平均粒度约2.66 μm. Li4Ti5O12电极具有较宽的充放电平台,循环性能稳定. 以0.1 C电流比率恒电流充放电,首次放电容量和循环容量分别达180和150 mA·h/g. 交流阻抗谱研究发现,Li4Ti5O12不同嵌锂程度下的电导率对其电极的电化学阻抗具有较大影响,电极的Warburg阻抗曲线斜率与其荷电状态相关.     

Mg2+和Sr2+掺杂对CaCu3Ti4O12陶瓷微观结构与介电性能的影响

采用固相反应法分别制备了Mg2+及Sr2+掺杂的Ca1-xMgxCu3Ti4O12和Ca1-xSrxCu3Ti4O12(x=0、0.1、0.2)陶瓷,利用XRD和SEM分别对陶瓷的物相结构和微观形貌进行了分析,并对其介电性能进行了测试.结果表明,Mg2+的掺杂易引起CaCu3Ti4O12(CCTO)化学计量比的偏失,同时陶瓷的致密化程度受到影响,介电常数也显著降低.而Sr2+的掺杂不仅对CCTO陶瓷物相结构影响不大,而且可以促进陶瓷晶粒的长大,并有效降低了CCTO陶瓷的烧结温度.当Sr2+掺杂量为0.2、测试频率在1 k-2.5kHz时,介电常数为104左右,介电损耗在0.05-0.1之间,介电综合性能比纯CCTO陶瓷有所提高.