LiNi1/3Co1/3Mn1/3O2粉体的类共沉淀制备及性能

在含有Li+、Co2+、Ni2+、Mn2+离子的混合溶液中加入（NH4）2CO3作沉淀剂,通过一步共沉淀反应得到含有四种金属离子的混合沉淀前驱体。前驱体经烘干,研磨后在不同温度（700～1 000 ℃）及不同时间（6～24 h）条件下进行烧结,即得到LiNi1/3Co1/3Mn1/3O2粉体。分别通过X射线衍射（XRD）、扫描电镜（SEM）及循环伏安（CV）、交流阻抗对制备粉体的微结构进行表征和对样品的电化学性能进行测试。结果表明:获得的LiNi1/3Co1/3Mn1/3O2粉体为-NaFeO2层状结构,颗粒分布均匀,放电比电容高,阻抗小。其中在900 ℃下烧结12 h所得的LiNi1/3Co1/3Mn1/3O2粉体电化学性能最优。当电压窗口在（0～1.4）Vvs.SCE、扫描速度为5 mVs-1、电解液为1 molL-1 Li2SO4溶液时,其比容量可达399.46 Fg-1;并且其阻抗也最小。     

钇铝石榴石上Mn-Co-Ni-O薄膜的制备及其相关特性表征

利用化学溶液法在具有良好导热性和红外透过性的钇铝石榴石单晶衬底上成功制备了具有单一尖晶石相的Mn1.56Co0.96Ni0.48O4薄膜.傅里叶红外光谱测试表明薄膜在2.5~5μm波段具有明显的吸收带.通过研究其电阻-温度关系并利用最近邻跳跃模型进行拟合,得到薄膜的特征温度约为2 530 K,室温下的负电阻温度系数约为-3.66%K-1.     

磁控溅射制备Mn-Co-Ni-O热敏红外探测薄膜

尖晶石Mn-Co-Ni-O三元氧化物具有优良的负温度系数（NTC）,是一种制作热敏红外探测器较为理想的材料。采用射频磁控溅射法在非晶Al2O3衬底上制备了Mn1.56Co0.96Ni0.48O4（MCNO）多晶薄膜。使用能量色散X射线谱（EDS）对薄膜中金属元素组分进行了测量,分析得出薄膜中金属元素组分与靶材中的组分偏离在5%以内。对经过750℃空气中退火后的薄膜结构、电学和光学性质也进行了研究。实验结果表明:退火后薄膜具有单一立方尖晶石结构,且薄膜表面致密、均匀性好;薄膜的传导机制遵循小极子跃迁传导,在240~330K范围内符合VRH模型,其激活能和电阻温度系数（TCR）在室温下（300K）分别为0.297eV和-3.83%K-1;薄膜在紫外-可见波段具有较高的吸收率,间接带宽为0.61eV。     

锰钴镍氧浸没式探测器制备及性能

基于化学溶液法制备了尖晶石结构氧化物锰钴镍氧Mn1.56Co0.96Ni0.48O4(MCNO)薄膜材料,研究了其电学性质及红外器件的探测性能,包括器件的响应率,时间常数和探测率.制作了厚度为8μm的MCNO薄膜及红外热敏探测器件,测量了材料的阻值-温度曲线.制作了基于半球形锗透镜的浸没式MCNO薄膜探测器,具有时间常数较小(~18 ms),响应率高(~4.4×103V/W)和探测率高(~5×108cm·Hz0.5/W)的优点.     

Mn2.1Ni0.9O4热敏陶瓷的制备与复阻抗分析

采用传统固相反应法制备了Mn2.1Ni0.9O4热敏陶瓷,运用X射线衍射仪、直流阻温测试仪、交流阻抗技术对其结构和电学性能进行了测试,并对Mn2.1Ni0.9O4热敏陶瓷的微观导电机理进行了分析。结果表明:Mn2.1Ni0.9O4热敏陶瓷由立方尖晶石相和岩盐相NiO组成。其电阻主要来源于晶粒和晶界的贡献,在293~363 K测试温区内,其晶粒电阻和晶界电阻都表现出明显的NTC特性,且两者导电机理均符合小极化子跳跃电导模型,晶界电阻受岩盐相NiO的影响大于晶粒电阻。     

锂离子电池混合正极材料LiNi0.5Co0.2Mn0.3O2/LiFePO4电化学性能研究

采用湿法球磨制备了锂离子电池用混合正极材料LiNi0.5Co0.2Mn0.3O2/LiFePO4。通过X射线衍射(XRD)和扫描电镜(SEM)表征了材料的结构和形貌,采用恒流充放电测试、循环伏安测试(CV)和电化学阻抗谱测试(EIS)方法研究了混合正极材料LiNi0.5Co0.2Mn0.3O2/LiFePO4的电化学性能。结果表明：混合正极材料LiNi0.5Co0.2Mn0.3O2/LiFePO4的晶体结构完好,碳包覆的纳米LiFePO4颗粒较好地包覆在LiNi0.5Co0.2Mn0.3O2表面。含质量分数15% LiFePO4的混合正极材料LiNi0.5Co0.2Mn0.3O2/LiFePO4电化学性能优良,0.2C首次充放电比容量为181.40 mAh?g–1,首次充放电效率为90.79%;1.0C循环50次后放电比容量为169.89 mAh?g–1,容量保持率为97.80%;3.0C循环5次后的放电比容量为162.22 mAh?g–1,容量保持率仍有89.43%;60 ℃高温存储7 d后,容量保持率和容量恢复率分别为86.48%和97.32%。     

高反Al2O3/SiO2膜内超快激光预损伤动力学过程

利用紫外飞秒激光光谱技术研究了Al2O3/SiO2高反射膜内的超快载流子动力学。通过实验,发现该反射膜Al2O3层的载流子动力学在紫外反射膜的激光诱导损伤中起着至关重要的作用。通过泵浦-探测实验,发现紫外飞秒激光与光学薄膜作用后,光学薄膜反射率有所下降,且探测光反射率变化的峰值在约2.3 ps的时间内从417 nm左右转移到402 nm左右。为了更好的解释激光诱导载流子动力学,一个具体的理论模型被提出来,该模型指出导带自由电子弛豫过程中与晶格相互作用,产生距导带一个光子能量的中间缺陷态,其初始电子密度影响了材料损伤阈值高低。通过该理论模型得出的激光损伤阈值数据和实验数据吻合得很好。     

室温铁磁性Al2O3∶Mn的制备及性质

以Al2O3为衬底利用多能态离子注入法在离子注入设备上制备了一系列具有室温铁磁性的Al2O3:Mn样品.在Al2O3的X射线衍射峰附近发现新的衍射峰,该衍射峰既可能对应一种未知新相,也可能对应Al2O3:Mn固溶体.所有样品都具有磁滞现象和室温铁磁性.     

Mn1.56Co(0.96-x)Ni0.48CuxO4系列薄膜光电性质研究

用化学溶液沉积法,以Al2O3为衬底在750℃温度下制备了锰钴镍铜Mn1.56 Co(0.96_x) Ni0.48 CuxO4系列薄膜.制备温度低于传统烧结工艺需要的温度(1100℃).采用X射线衍射(XRD)对所制备材料的结晶性能进行测量.结果表明,在一定范围内随着铜组分的增加,材料的择优取向发生变化,结晶性能提高且保持立方尖晶石单相结构.根据Scherrer方程和XRD数据计算薄膜的晶粒尺寸,Cu含量的增加导致薄膜晶粒尺寸增大.扫描电镜(SEM)图验证了制备的薄膜材料均匀致密,无裂痕.测量材料的变温I-V特性,计算材料在295 K下负温度电阻系数α及其活化能和特征温度,当Cu含量低时材料的α值较大,随着Cu组分的增加,α由-4.12％下降到-3.29％.利用椭偏光谱仪(SE),拟合材料在近紫外-可见-近红外波段的消光系数,并初步指认消光系数峰.     

低损耗、高Q_m值Pb(Nb_(2/3)Mn_(1/3))O_3-Pb(Sb_(2/3)Mn_(1/3))O_3-PZT材料

研究了组分变化及掺杂对四元系 Pb( Nb2 /3Mn1 /3) O3- Pb( Sb2 /3Mn1 /3) O3- PZT压电材料性能的影响 ,发现 Zr/Ti比值在准同型相界附近该材料有最大的压电常数 d33,而机械品质因数 Qm 值较小 ;Zr/Ti比偏离该相界时则机械品质因数 Qm 升高 ,相应的压电常数 d33减小。通过改变 Pb( Nb2 /3Mn1 /3) O3、Pb( Sb2 /3Mn1 /3) O3两组分的含量及掺入 Sr、Ce等杂质 ,获得的材料介电损耗为 0 .14 % ,机械品质因数为 2 3 4 1,压电常数为 2 16p C/N。     

Preparation and characterization of Fe-doped Ni0.9Co0.8Mn1.3−xFexO4 (0 ≤ x ≤ 0.7) negative temperature coefficient ceramic materials

Based on spinel-type semiconducting electroceramics, negative temperature coefficient (NTC) thermistor materials, Ni_0.9Co_0.8Mn_1.3−xFe_xO₄ (0 ≤ x ≤ 0.7), with different compositions were synthesized by a co-precipitation method. The optimal pH value and the influence of Fe³⁺ doping during the synthesis processing were discussed. As-prepared Ni_0.9Co_0.8Mn_1.3−xFe_xO₄ materials were characterized by DT/TGA, XRD, FTIR, SEM, electrical measurement and impendance analysis. It was found that, as the Fe doping content in the Ni_0.9Co_0.8Mn_1.3−xFe_xO₄ samples increased, both the grain size and the density decreased. The as-sintered Ni_0.9Co_0.8Mn_1.3−xFe_xO₄ samples presented a single-phase cubic spinel structure. The impendance diagram indicated that the grain boundary resistance was dominant in the overall impendance of Ni_0.9Co_0.8Mn_1.3−xFe_xO₄ NTC ceramic materials. The value of ρ₂₅, B_25/50, slope and activation energy for the samples Ni_0.9Co_0.8Mn_1.3−xFe_xO₄ sintered at 1200 °C were in the range of 453.1-2411 Ω cm, 3103-3355 K, 3.27325-3.43149 and 0.28207-0.29325 eV, respectively. This suggests that the electrical properties can be adjusted to desired values by controlling the Fe³⁺ ion doping content.     

Study of thick film Ni(1−x)CoxMn2O4,(0?x?1) using overlay technique on thick film microstrip ring resonator

The effect of thick film Ni_(1−x)Co_xMn₂O₄ in-touch overlay on the X band resonance characteristics of thick film microstrip ring resonator is studied. The thick film overlay decreases the resonance frequency and increases the peak output. From the frequency shift the dielectric constant of the thick film Ni_(1−x)Co_xMn₂O₄ has been calculated. For the first time Ag thick film microstrip ring resonator has been used to study thick film Ni_(1−x)Co_xMn₂O₄ in the X band.     

A Novel Cathode Material with a Concentration‐Gradient for High‐Energy and Safe Lithium‐Ion Batteries

A high‐energy functional cathode material with an average composition of Li[Ni_0.72Co_0.18Mn_0.10]O₂, mainly comprising a core material Li[Ni_0.8Co_0.2]O₂ encapsulated completely within a stable manganese‐rich concentration‐gradient shell is successfully synthesized by a co‐precipitation process. The Li[Ni_0.72Co_0.18Mn_0.10]O₂ with a concentration‐gradient shell has a shell thickness of about 1 µm and an outer shell composition rich in manganese, Li[Ni_0.55Co_0.15Mn_0.30]O₂. The core material can deliver a very high capacity of over 200 mA h g^?1, while the manganese‐rich concentration‐gradient shell improves the cycling and thermal stability of the material. These improvements are caused by a gradual and continuous increase of the stable tetravalent Mn in the concentration‐gradient shell layer. The electrochemical and thermal properties of this cathode material are found to be far superior to those of the core Li[Ni_0.8Co_0.2]O₂ material alone. Electron microscopy also reveals that the original crystal structure of this material remains intact after cycling.     

Influence of the annealing temperature on the IR properties of SiO2 films grown from SiH4 + O2

Dispersion analysis was performed on low pressure chemically vapor deposited (LPCVD) SiO₂ films grown from SiH₄ + O₂ at 425 °C. The transmission spectra were analyzed using four Lorentz oscillators within the range 900–1400 cm⁻¹. It was found that the distribution of the SiOSi angles is a superposition of two Gaussians; one corresponding to bridges located in the bulk of the film and one corresponding to bridges located close to the boundaries of the film namely the interfaces of the films and the grain boundaries. The ratio between the bulk like SiOSi bridges over the boundary bridges was found equal to 0.61:1 indicating that films grown from SiH₄ + O₂ contain a higher number of boundary SiOSi bridges relative to those located in the bulk of the film. After annealing for 30 min at temperatures in the range from 550 to 950 °C, films were found to have a lower thickness. The calculated ratio of the two distributions after annealing have shown a clear reduction in the concentration of the boundary bridges as the temperature of annealing increases, in advance of the bridges located in the bulk of the film. For the film annealed at 950 °C for 30 min the ratio was found equal to 4.0:1 which is the same to that of thermally grown films at the same temperature.     

Manipulating the Electronic Structure of Li‐Rich Manganese‐Based Oxide Using Polyanions: Towards Better Electrochemical Performance

Lithium‐rich manganese‐based layered oxides show great potential as high‐capacity cathode materials for lithium ion batteries, but usually exhibit a poor cycle life, gradual voltage drop during cycling, and low thermal stability in the highly delithiated state. Herein, a strategy to promote the electrochemical performance of this material by manipulating the electronic structure through incorporation of boracic polyanions is developed. As‐prepared Li[Li_0.2Ni_0.13Co_0.13Mn_0.54](BO₄)_0.015(BO₃)_0.005O_1.925 shows a decreased M‐O covalency and a lowered O 2p band top compared with pristine Li[Li_0.2Ni_0.13Co_0.13Mn_0.54]O₂. As a result, the modified cathode exhibits a superior reversible capacity of 300 mA h g^?1 after 80 cycles, excellent cycling stability with a capacity retention of 89% within 300 cycles, higher thermal stability, and enhanced redox couple potentials. The improvements are correlated to the enhanced oxygen stability that originates from the tuned electronic structure. This facile strategy may further be extended to other high capacity electrode systems.     

Lattice strains and magnetic properties evolution of Ni doped rod-like cobalt–manganese ferrite

Co_0.5Mn_0.5–xNi_xFe₂O₄ (0.0≤x≤0.3) precursor is obtained by solvothermal method at 160 °C in glycol–water. Cubic Co_0.5Mn_0.5–xNi_xFe₂O₄ is obtained by calcining the precursor from 600 °C to 800 °C in air. The precursor and its calcined products are characterized by thermogravimetry and differential scanning calorimetry, X-ray powder diffraction, scanning electron microscopy, and vibrating sample magnetometer. A high-crystallized rod-like Co_0.5Mn_0.5–xNi_xFe₂O₄ with a cubic structure is obtained when the precursor is calcined at 800 °C in air for 2 h. Lattice parameters decrease with the increase of Ni²⁺ addition amount. The magnetic properties of Co_0.5Mn_0.5–xNi_xFe₂O₄ depend on Ni²⁺ doped amount and calcination temperature. Co_0.5Mn_0.3Ni_0.2Fe₂O₄ obtained at 800 °C has the highest specific saturation magnetization value, 63.51 emu/g. However, Co_0.5Mn_0.3Ni_0.2Fe₂O₄ obtained at 600 °C has the highest coercivity value, 1204.02 Oe.     

水热法制备CoxMn1-xFe2O4纳米磁性粉体及磁性研究

用水热法成功合成了CoxMn1-xFe2O4纳米磁性颗粒粉体。样品物相用X射线衍射仪表征,形貌通过透射电镜(TEM)观测。CoxMn1-xFe2O4纳米粉体的平均尺寸和晶格常数从XRD计算得到,CoxMn1-xFe2O4纳米颗粒的晶格常数随着Co2+含量的增加而变小。所得样品的磁性用振动样品磁强计(VSM)测试,结果表明,所制备的CoxMn1-xFe2O4粉体在室温下的铁磁性、饱和磁化强度和矫顽力随着Co2+含量的增加而变大。     

The electronic structures and optical properties of BaTiO3 and SrTiO3 using first-principles calculations

The electronic-energy band structures and total density of states (TDOS) for bulk BaTiO₃ and SrTiO₃ were calculated by the first-principles calculations using density-functional theory and local-density approximation. The calculated band structure of BaTiO₃ and SrTiO₃ show the energy band gaps of 1.81 and 1.92 eV at the Γ point in the Brillouin zone, respectively. The optical properties of the both perovskites in the core-level spectra are investigated by the first principles under scissor approximation. The optical constants like refractive index and extinction coefficient of both BaTiO₃ and SrTiO₃ were derived from the calculated real and imaginary parts of the dielectric function. The calculated spectra were compared with the experimental results for BaTiO₃, SrTiO₃ in good agreement.     

Investigation of Ta2O5/SiO2/4H-SiC MIS capacitors

Tantalum pentoxide (Ta₂O₅) deposited by pulsed DC magnetron sputtering technique as the gate dielectric for 4H-SiC based metal-insulator-semiconductor (MIS) structure has been investigated. A rectifying current-voltage characteristic was observed, with the injection of current occurred when a positive DC bias was applied to the gate electrode with respect to the n type 4H-SiC substrate. This undesirable behavior is attributed to the relatively small band gap of Ta₂O₅ of around 4.3 eV, resulting in a small band offset between the 4H-SiC and Ta₂O₅. To overcome this problem, a thin thermal silicon oxide layer was introduced between Ta₂O₅ and 4H-SiC. This has substantially reduced the leakage current through the MIS structure. Further improvement was obtained by annealing the Ta₂O₅ at 900 °C in oxygen. The annealing has also reduced the effective charge in the dielectric film, as deduced from high frequency C-V measurements of the Ta₂O₅/SiO₂/4H-SiC capacitors.     

High-Temperature Thermoelectric Properties of Co4Sb12-Based Skutterudites with Multiple Filler Atoms: Ce0.1InxYbyCo4Sb12

Void-filling in the CoSb₃ skutterudite lattice with different kinds of heavy elements has proven to be an effective mechanism to enhance thermoelectric performance due primarily to a reduction in lattice thermal conductivity. Specifically, our findings on the series In _x Yb _y Co₄Sb₁₂ [0 ≤ (x, y) ≤ 0.2] have further motivated an attempt to form triple-filled skutterudites Ce_0.1In _x Yb _y Co₄Sb₁₂ with In and Yb concentrations [0 ≤ (x, y) ≤ 0.2] and with the Ce concentration held constant (Ce_0.1). All of these samples have been prepared via a simplified melting–annealing–sintering procedure and were first characterized by means of x-ray powder diffraction and scanning electron microscopy, followed by measurements of the Hall coefficient, electrical and thermal conductivities, and Seebeck coefficient. Our aim is to further elucidate the roles of the three elements (Ce, In, and Yb) in these materials. Compared with the addition of just In or Yb, we found that simultaneous addition of both In and Yb reduced the lattice thermal conductivity without significantly degrading the power factor. Further addition of the third element (Ce), along with In and Yb, also produced a similar result. However, we noticed that some of the In and Yb were also observed in the form of secondary phases (InSb and Yb₂O₃), not entering entirely as filler atoms. As a result of our investigation, several compositions achieved increased sustainability and enhanced thermoelectric performance, with maximum ZT values of about 1.3 to 1.4 obtained at around 800 K.