以LiCoO2为阴极的全固态薄膜锂电池的研究

采用射频磁控溅射技术制备了非晶态和不同取向的多晶LiCoO2薄膜,利用XRD和SEM研究了不同温度退火后LiCoO2薄膜的结构和形貌.以具有不同结构的LiCoO2薄膜为阴极、含氮磷酸锂薄膜为电解质以及金属锂薄膜为阳极,成功地制备了电化学性能不同的全固态薄膜锂电池.由电化学研究结果表明,LiCoO2薄膜的结构和多晶取向决定了薄膜电池的电化学性能.采用具有一定取向的多晶LiCoO2薄膜制备的全固态薄膜锂电池具有最佳的性能,稳定放电容量达到55.4μAh/cm2μm,充放电循环次数超过450次.     

退火对Mn和N共掺杂的Zno0.88Mn0.12O:N薄膜特性的影响

以NH3为掺N源,采用电子柬反应蒸发技术生长了Mn和N共掺杂的Zno0.88Mn0.12O:N薄膜,生长温度为300℃,然后在02气氛中400℃退火0.5 h.X射线衍射测量表明,Zno0.88Mn0.12O(Mn掺杂)薄膜或Zno0.88Mn0.12O:N(Mn和N共掺杂)薄膜仍具有单一晶相纤锌矿结构,未检测到杂质相.与不掺N的Zno0.88Mn0.12O薄膜相比,Zno0.88Mn0.12O:N薄膜的(002)晶面衍射峰向小角度方向偏移且半高宽变宽.Hall效应测量结果显示,Zno0.88Mn0.12O:N薄膜由退火前的n型导电转变为退火后的P型导电.室温磁特性测量结果表明,虽然原生Zno0.88Mn0.12O:N薄膜呈铁磁性,但其饱和磁化强度M.折算到每个Mn2 仅为约0.20μB,且稳定性不理想,在大气中放置30 d后M.降低到原来的3%左右.退火处理不仅使Zno0.88Mn0.12O:N薄膜的室温M.增大到每个Mn2 约为0.70μB,且在大气中放置30 d后其M.几乎不变.分析了Zno0.88Mn0.12O:N薄膜的铁磁性起源及退火导致其铁磁性增强并稳定的机理.     

重电子金属CeCu5.8 M0.2(M=Ni,Zn,Cd) 低温物性的比较

研究了不同元素等量掺杂下重电子金属CeCu5.8M0.2(M=Ni,Zn,Cd)低温电阻、比热容和磁化率随温度的变化关系.分析讨论了掺杂元素M(M=Ni,Zn,Cd)的磁性、价态及原子尺寸对近藤温度Tk、相干温度(即电阻极大值的温度TRmax)、每个Ce离子在较高温度时的平均磁矩μB以及在温度降低时被传导电子自旋屏蔽过程的影响.     

磁控溅射法制备β型Fe3Si8M系三元薄膜

二元β-FeSi2是-种非常有潜力的环境友好型半导体，但由于是线性化合物，所以很难制备较高质量的β单相．本文从β-FeSi2相的基本团簇出发，利用“团簇＋连接原子”结构模型，设计制备了Fe3SisM（M=B，Cr，Ni，Co）系三元薄膜．研究了Fe3Si8M系三元薄膜的结构、成分和光电特性．结果表明，溅射态薄膜都为非晶态，经850℃／4h退火后可全部转换为晶态，引入的第三组元M不同会影响退火后的相转变和结晶质量，Cr和B为第三组元时可实现单-β相，Co作为第三组元时，薄膜以Ⅸ相为主表现为金属特性．B，Cr和Ni作为第三组元的样品中半导体性质都有不同程度的体现，但相比较而言，Fe2．7Si8480．9薄膜的半导体性能最为明显，其电阻率为0．17Ω．cm、载流子浓度为2．8×10^20cm^-3、迁移率为0．13cm2／V．S，带隙宽度约为0．65eV．所以引入合适的第三组元可以扩展序相相区，并实现晶态三元β型硅化物薄膜与二元β-FeSi2薄膜的半导体性能相近．     

结合静电喷雾技术与浸渍法制备的固体氧化物燃料电池阴极

使用浸渍法制备具有纳米催化粒子的固体氧化物燃料电池电极可以提高电池性能。结合静电喷雾技术以及浸渍法制备的Sm0.2Ce0.8O2-δ（SDC）La0.6Sr0.4Co0.2Fe0.8O3-δ（LSCF）浸渍阴极。对于静电喷雾技术中沉积温度对于薄膜形貌的影响做了讨论。阻抗谱研究表明,以300℃下沉积制得的薄膜为骨架的阴极具有最小的极化阻抗,在650、700、750、800℃分别为0.484、0.077、0.034、0.022Ω.cm2。以这种电极为阴极并以稳定的氧化锆为电解质的单电池在750℃时最大功率密度为254mW/cm。     

掺Mo对NiSi薄膜热稳定性的改善

报导了在镍薄膜中掺入少量Mo提高了镍硅化物的热稳定性.结果表明，经650— 800℃快速热 退火形成的Ni(Mo)Si硅化物薄膜电阻值较低，约为2．4(Ω／□).XRD分析表明薄膜中只存在 NiSi相，而没有NiSi₂生成.由吉布斯自由能理论分析表明在Ni薄膜中掺人5．9 ％Mo对改善 Ni硅化物热稳定性起到至关重要的作用.经650—800℃快速热退火后的 Ni(Mo)Si／Si肖特基 二极管电学特性良好，势垒高度Φ_B为0．64—0．66eV，理想因子接近于1，更 进一步证明掺少量的Mo能够改善NiSi薄膜的热稳定性. 关键词： 镍硅化物 快速热退火 x射线衍射分析 卢瑟福背散射     

电子束退火法制备Li-N共掺杂多晶ZnO薄膜

为研究电子束退火对Li-N共掺杂Zn O薄膜性能的影响,首先利用溶胶-凝胶旋涂法在p型Si(111)衬底上制备Li-N共掺杂的Zn O前驱膜,然后用电子束对前驱膜进行退火。退火时,电子束加速电压10 k V,退火时间5 min,聚焦束流123 m A,束流为0.7~1.9 m A,最后得到Li-N共掺杂的Zn O薄膜。XRD谱分析表明,当束流高于1.5 m A之后,薄膜为六方Zn O和立方Zn O的混合多晶薄膜,且有金属Zn生成,导致薄膜有较强的绿光发射。SEM图片分析显示,薄膜的晶粒尺寸随束流增加而增大,当束流高于1.5 m A后,晶粒尺寸变化不大,约为60 nm。光致发光(PL)谱和激光拉曼谱的分析结果证实Li、N元素已掺入Zn O晶格中,PL谱中观察到Li元素掺杂引起的紫光发射,拉曼散射光谱中观察到N替代O位的缺陷振动模式。     

Zr掺杂TiO_2薄膜的光学性能和光催化性能

为了研究TiO2禁带宽度和光吸收系数对其光催化性能的影响,利用电子束沉积方法在玻璃基底上制备了TiO2薄膜及Zr掺杂TiO2薄膜。采用拉曼光谱仪和分光光度计对膜的结构和吸收光谱进行了表征。研究结果表明:当退火温度为773K时,沉积得到的TiO2薄膜为锐钛矿结构薄膜;掺杂使TiO2禁带宽度变窄,吸收波长红移,在350~450nm附近光吸收系数增大,增强了TiO2的光催化活性。     

La,Nb共掺杂BiFeO_3薄膜中的光致应变效应及应力调控

本文利用反射式飞秒抽运-探测技术,系统研究了飞秒激光诱导La和Nb共掺杂的铁酸铋(Bi0.8La0.2Fe0.99Nb0.01O3)薄膜中纵向声学声子的动力学过程,声学声子的产生源于光致应变效应.实验发现不同的衬底(ZrO2和PbMg1/3Nb2/3-PbTiO3)可以调制外延生长的Bi0.8La0.2Fe0.99Nb0.01O3薄膜的面外弹性系数C⊥.此外,通过对压电晶体衬底PbMg1/3Nb2/3-PbTiO3外加电压,实现了对薄膜应力的调制.     

(111)择优取向的Pb(Zr0.52Ti0.48)O3铁电薄膜的制备及研究

选用不同浓度的Pb(Zr0.52Ti0.48)O3溶胶,用Sol-gel法在Pt/Ti/SiO2/Si基片上沉积一层厚度不同的Pb(Zr0.52Ti0.48)O3(PZT52)过渡层,经400℃烘烤、550℃退火等程序后,再用Sol-gel法在PZT52过渡层上沉积Pb(Zr0.52Ti0.48)O3薄膜.XRD分析表明,有PZT52过渡层的Pb(Zr0.52Ti0.48)O3薄膜具有(111)择优取向的钙钛矿结构,且随着过渡层厚度的增加,Pb(Zr0.52Ti0.48)O3薄膜的(111)择优取向程度越高.SEM分析表明,当PZT52过渡层的厚度达到14nm以上,Pb(Zr0.52Ti0.48)O3薄膜结晶程度得到明显改善,平均晶粒尺寸大大增加.介电、铁电性能测试表明,与没有过渡层的Pb(Zr0.52Ti0.48)O3薄膜相比,有PZT52过渡层的Pb(Zr0.52Ti0.48)O3薄膜具有较大的介电常数和剩余极化强度,而介电损耗则较小.     

铁掺杂四方、三方两相共存PZN-PZT陶瓷的Raman散射分析

Raman散射常用于研究温度变化时铁电体的各种相变,如铁电-顺电相变等,但是,利用Raman散射研究掺杂诱导的相变并不常见。本文采用Raman散射研究了铁掺杂Pb(Zn1/3Nb2/3)0.2(Zr0.5Ti0.5)0.8O3(PZN-PZT)铁电陶瓷中三方-四方共存现象。通过分析四方相E(3TO)和A1(3TO)模式与三方相Rl模式,确定了铁掺杂对PZN-PZT陶瓷中三方-四方共存结构的影响。这一结果,得到了XRD相分析的验证。因此,通过对Raman散射中三方-四方振动模式的分析,可以表征掺杂诱导的PZT基陶瓷中三方-四方相结构变化趋势。     

New conducting thin films derived from M(dimt)2 salts (M=Ni(II), Pd(II)) by using poly counter cations

Two kinds of new M(dmit)₂ salts (M=Ni and Pd, (dmit=1,3-dithole-2-thione-4,5-dithiolate)) containing poly(4-vinyl-N-octanylpyridinium) (PVOP) as counter cations were synthesized. Semiconducting thin films derived from these salts were prepared by electrochemical deposition method. The Ni(dmit)₂ film shows an extremely smooth and uniform surface. The film-forming property of the Ni(dmit)₂ salt has been improved significantly by using PVOP as counter cation.     

Fe掺杂对溶胶凝胶法制备的ZnO: Ni薄膜结构及发光特性的影响

采用溶胶凝胶法在玻璃基片上制备了ZnO及Ni, Fe共掺杂的Zn_0.95-xNi_0.05Fe_xO (x=0, 0.005, 0.01, 0.03, 0.05) 薄膜. 通过扫描电镜(SEM) 和X射线衍射(XRD) 研究了薄膜样品的表面形貌和晶体结构. 结果表明所有样品都具有(002) 择优取向, Fe掺杂导致ZnO: Ni薄膜的晶体质量变差, 晶粒尺寸减小, 但适当的Fe掺杂有利于获得致密、 均匀的薄膜. XPS测试结果表明样品中Ni离子的价态为+2价, Fe离子的价态为+2价和+3价.室温光致发光(PL) 测量表明, 所有样品均观察到较强的紫外发光峰, 蓝光双峰和绿光发光峰. ZnO: Ni薄膜的发光强度可以通过Fe掺杂进行有效调节. 进而我们讨论了Ni, Fe共掺杂ZnO样品的发光机理.     

A strategy to improve the electrochemical performance of Ni-rich positive electrodes: Na/F-co-doped LiNi_(0.6)Mn_(0.2)Co_(0.2)O_2

Ni-rich layered lithium transition metal oxides LiNi_xMn_yCo_zO_2(1-y-z ≥ 0.6) are promising candidates for cathode materials, but their practical applications are hindered by high-voltage instability and fast capacity fading. Using density functional theory calculations, we demonstrate that Na-, F-doping, and Na/F-co-doping can stabilize the structure and result into a higher open circuit voltage than pristine LiNi_(0.6)Mn_(0.2)Co_(0.2)O_2(NMC622) during the charging process, which may attain greater discharge capacity. F doping may inhibit the diffusion of Li ions at the beginning and end of charging; Na doping may improve Li ion diffusion due to the increase in Li layer spacing, consistent with prior experiments. Na/F-codoping into NMC622 promotes rate performance and reduces irreversible phase transitions for two reasons:(i) a synergistic effect between Na and F can effectively restrain the Ni/Li mixing and then enhances the mobility of Li ions and(ii) Ni/Li mixing hinders the Ni ions to migrate into Li layers and thus, stabilizes the structure. This study proposes that a layer cathode material with high electrochemical performance can be achieved via rational dopant modification, which is a promising strategy for designing efficient Li ion batteries.     

Nickel-induced microwheel-like surface morphological evolution of ZnO thin films by spray pyrolysis

Nickel?Czinc oxide (Ni?CZnO) thin films were deposited onto glass and tin-doped indium oxide-coated glass substrates by using a pneumatic spray pyrolysis technique at 450?°C from aqueous solutions of zinc acetate and nickel acetate precursors. The effect of nickel doping on structural, morphological and optical properties of the ZnO thin films has been studied. The X-ray diffraction patterns confirmed the polycrystalline nature of the films having hexagonal crystal structure. Ni?CZnO films with appropriate nickel doping revealed the occurrence of novel wheel-like surface morphology. The absorption edge of the Ni?CZnO films showed a red shift, meaning that the optical band gap energy decreases as the nickel doping concentration increases. A growth model is developed and proposed for the novel wheel-like morphology. All the thin films exhibited room-temperature photoluminescence. Pure ZnO and Ni?CZnO thin films were tested for their photoelectrochemical performance in 0.5 M Na₂SO₄ electrolyte solution. The values of fill factor and open circuit voltage were improved for the Ni?CZnO thin films.     

X-ray absorption near edge structure and crystallographic studies of the mixed valence oxide SrRu0.8Ni0.2O3

Neutron diffraction methods are used to refine the structure of SrRu(0.8)Ni(0.2)O(3) at room temperature and 4 K. X-ray absorption measurements at the Ru L-edge demonstrate that partial oxidation of the Ru(4+) to Ru(5+) occurs upon introducing Ni into the SrRuO(3) structure to form SrRu(0.8)Ni(0.2)O(3). Whilst the diffraction measurements show that SrRu(0.8)Ni(0.2)O(3) is isostructural with SrRuO(3), the Ni doped compound exhibits an unusual first order orthorhombic-cubic phase transition near 670 K as revealed by x-ray diffraction. The Curie temperature in SrRu(0.8)Ni(0.2)O(3) is lower than that found in SrRuO(3) as a consequence of local distortions reducing the p-d hybridization.     

Effect of MoO3 surface coating on electrochemical performances of LiNi0.8Co0.1Mn0.1O2 cathode

In this paper, we synthesize the MoO 3 modified LiNi 0.8 Co 0.1 Mn 0.1 O 2 cathode (denoted as M-NCM81) and compare with pristine LiNi 0.8 Co 0.1 Mn 0.1 O 2 cathode (denoted as P-NCM81). The M-NCM81 cathode delivers good cation ordering and typical spherical form. The M-NCM81 cathode shows initial discharge capacity of 203.8 mAh g −1 at 0.1 C, capacity retention of 79.8% under the 5.0 C. In addition, the M-NCM81 cathode still retain a discharge capacity of 172.2 mAh g ⁻¹after 100 cycles. Such electrochemical performances are significantly improved compared to those of P-NCM81. It can be elucidated that MoO ₃ coating layer acts as a HF inhibitor/scavenger. The MoO ₃ modification plays an important role in inhibiting severe structural degradation, derived from a harmful side reaction with electrolyte. It effectively suppresses the increase in charge-transfer resistance, leading to superior electrochemical performances.     

Domain wall creep in epitaxial ferroelectric Pb(Zr(0.2)Ti(0.08)O(3) thin films

Ferroelectric switching and nanoscale domain dynamics were investigated using atomic force microscopy on monocrystalline Pb(Zr(0.2)Ti(0.8))O(3) thin films. Measurements of domain size versus writing time reveal a two-step domain growth mechanism, in which initial nucleation is followed by radial domain wall motion perpendicular to the polarization direction. The electric field dependence of the domain wall velocity demonstrates that domain wall motion in ferroelectric thin films is a creep process, with the critical exponent mu close to 1. The dimensionality of the films suggests that disorder is at the origin of the observed creep behavior.     

On the origin of the ferromagnetism in Zn0.8Mn0.2O having a higher Curie temperature than Zn0.8Co0.2O

Zn_0.8Co_0.2O and Zn_0.8Mn_0.2O films were deposited on substrates by a sol–gel technique. X-ray diffraction, field-emission scanning electron microscopy, photoluminescence, and ferromagnetism measurements were used to characterize these dilute magnetic semiconductors. It is shown that the ferromagnetic properties might be related to the formation of acceptor-like defects in the Zn_0.8Co_0.2O and Zn_0.8Mn_0.2O films. It is found that ferromagnetic Zn_0.8Mn_0.2O has a higher Curie temperature than Zn_0.8Co_0.2O. In addition, the higher ratio of grain-boundary area to grain volume of Zn_0.8Mn_0.2O than Zn_0.8Co_0.2O indicates that grain boundaries and related acceptors are the intrinsic origin for ferromagnetism.