K0．8 Fe1．7 SeS超导体内的畴区形貌及三维分布研究

本文利用高角环形暗场像（HAADF）和衍衬像研究了K0．8 Fe1．7 SeS超导样品的超导畴区形貌及三维分布。在[001]带轴下观察到两类形貌的超导畴区,一类畴区尺寸为1μm左右,另一类为由几十纳米大小的小畴区组成的阵列。选区电子衍射和电子能量损失谱结果表明母体区对应Fe空位有序,而超导畴区可能对应K空位有序。STEM-EDS元素Mapping表明超导畴区边缘处K元素含量较多,K0．8 Fe1．7 SeS超导样品中可能至少存在三个相,分别为：K空位有序超导相、畴区外部Fe空位有序基体相以及两种空位有序区的过渡相。在[100]带轴下观察到了超导畴区具有连通性,构建了K0．8 Fe1．7 SeS超导样品中超导畴区的三维分布图。     

La0．8Sr0．2Mn0．98-xFexNi0.02O3吸波性能研究

用溶胶-凝胶法制备了La0．8Sr0.2Mn0．98s-xFexNi0.02O3（x=0．08,0．10,0．12,0．14）粉晶,用矢量网络分析仪测量了样品在2～18GH：频段内的微波吸收特性曲线。研究结果表明,样品都有一个吸收峰,峰高及位置随x不同而异。其中,x=0．10,厚度1．80mm,吸收峰高达23dB,在2～18GHz频段吸收带宽6GHz（〉10dB）。掺杂Mn位,可以改变材料的电磁参数,改善材料的微波吸收性能。     

溶胶 凝胶法制备Sr2+取代Co2Z及性能研究

为了制备性能优良的Sr2+掺杂的Co2Z型六角钡铁氧体（Ba1.5Sr1.5Co2Fe24O41）,利用溶胶 凝胶自蔓延法,通过改变烧结温度制备了Co2Z钡铁氧体粉末,对其相成分、微观形貌和磁性能进行了研究。结果表明,采用溶胶 凝胶自蔓延法在1 200 ℃烧结时可制备较纯的Co2Z相,此时材料杂相最少,晶粒生长均匀,结构致密,起始磁导率为3.3,截止频率大于1.8 GHz,品质因数Q在1 GHz时为3.6。     

Mn^2＋掺杂NaFY4：Yb，Er晶体的形貌及发光性能研究

通过乙醇和油酸作为混合溶剂的溶剂热法合成了NaYF4：Yb,Er晶体。采用x射线衍射仪（XRD）,场发射扫描电镜（FESEM）以及光致发光检测（980nm激光源）和荧光光谱测试（Hitachi F-4500）,表征了Mn2＋离子掺杂量对NaYF4：Yb,Er晶体的显微结构、形貌和发光性能的影响。结果表明：少量5mol％Mn^2＋离子的掺入不会改变NaYF4：Yb,Er晶体的物相,当Mn2＋离子的掺杂量增大到10mol％～30mol％,样品出现NaMn3F10相,形貌也发生转变,从纳米棒变为纳米片。Mn^2＋离子的掺入,使得NaYF4：Yb,Er晶体的上转换荧光峰从在510nm～539nm和539nm～570nm这两个区间转换为635nm～690nm区间内,当掺杂浓度达到30 mol％时,上转换荧光峰全部转变为635nm～690nm区间内。     

AgIn共掺杂(AgIn)xPb1-2xTe化合物的合成及热电传输性能

用高温熔融法合成了Ag和In共掺的单相n型（AgIn）x Pb1-2x Te化合物,研究了（AgIn）掺杂量x对（AgIn）x Pb1-2x Te（x=0.01～0.05）物相组成及热电性能的影响.结果表明：掺杂量x≤0.04时得到单相四元化合物,x=0.05时样品中出现了组成为AgInTe2第二相;（AgIn）x Pb 1-2x Te化合物的Seebeck系数随着x增加而增大,电导率随着掺杂量x增加而降低;化合物的热导率随着掺杂量x增大而减小;当x=0.01时,（AgIn） x Pb1-2x Te化合物的热电性能指数值最大,在800K时达到1.1.     

AgIn共掺杂(AgIn)xPb1-2xTe化合物的合成及热电传输性能

用高温熔融法合成了Ag和In共掺的单相n型(AgIn)xPb1-2xTe化合物,研究了(AgIn)掺杂量x对(Ag-In)xPb1-2xTe(x=0.01～0.05)物相组成及热电性能的影响.结果表明:掺杂量x≤0.04时得到单相四元化合物,x=0.05时样品中出现了组成为AgInTe2第二相;(AgIn)xPb1-2xTe化合物的Seebeck系数随着x增加而增大,电导率随着掺杂量x增加而降低;化合物的热导率随着掺杂量x增大而减小;当x=0.01时,(AgIn)xPb1-2xTe化合物的热电性能指数值最大,在800K时达到1.1.     

非晶As2S3半导体薄膜在激光作用下的性能及结构研究

在激光辐照或退火作用下 ,As2 S3非晶半导体薄膜的光学吸收边出现红移现象 ,并且随着激光功率的增大和辐照时间的延长 ,红移值增大 ,并最后达到饱和。这种红移在先经过退火处理再激光辐照的薄膜中是可逆的。从扫描电镜的形貌图中也可以看出 ,经激光辐照后 ,薄膜表面有晶相出现 ,且随着激光功率的增加 ,晶相出现增多。As2 S3非晶半导体薄膜中光致效应的产生是由于光致结构变化所致 ,对其产生原因 ,进行了机理分析     

Sm~(3+)掺杂Co_(0．6)Zn_(0．4)Ni_(0．8)Fe_(1．2)O_4红外辐射陶瓷材料的研究

用常规固相合成法成功地制备出Sm3 掺杂Co0.6Zn0.4Ni0.8Fe1.2O4红外辐射陶瓷材料,并通过XRD、FT-IR和IRE-2型红外发射率测量仪测试了材料的微观结构,分析了材料的结构特征与红外辐射性能的关系,发现Sm3 的掺杂导致Sm3 以一定的配位形式进入Co0.6Zn0.4Ni0.8Fe1.2O4体系中,并形成了有限置换型固溶体结构.数据分析可知,Sm3 掺杂浓度对材料的红外辐射性能存在一定的影响,样品Sm0.1在全波段的积分发射率为0.74,而在>8μm波段的平均发射率最高值可达0.94.     

富锂材料Li1.2[Mn0.54Ni0.13Co0.13]O2的Mo掺杂及电化学性能研究

富锂锰基正极材料由于其高理论比容量和较高的工作电压深受人们的青睐,然而循环稳定性差、电压衰减严重和倍率性能差等一系列问题限制了其在锂离子电池中的商业应用。为了改善其电化学性能,利用共沉淀-煅烧法成功制备了不同摩尔量钼元素掺杂的富锂锰基正极材料Li_(1.2)[Mn_(0.54-)_xNi_(0.13)Co_(0.13)Mo_x]O_2(x=0,0.01,0.02,0.03,0.04)。钼元素主要取代富锂材料Li_(1.2)[Mn_(0.54)Ni_(0.13)Co_(0.13)]O_2结构中的锰位,由XRD衍射结果可知,钼元素的掺杂保持了材料本体的晶体结构。富锂材料经掺杂改性表现出优异的电化学性能,Li_(1.2)[Mn_(0.51)Ni_(0.13)Co_(0.13)Mo_(0.03)]O_2在0.5C倍率下循环100圈的放电比容量达到200.6 mAh/g,容量保持率为89.27%;Li_(1.2)[Mn_(0.52)Ni_(0.13)Co_(0.13)Mo_(0.02)]O_2的首圈库伦效率由74.41%提高到81.47%。这主要是由于钼的掺入抑制了晶格氧的脱出,提高了材料的结构稳定性。电化学阻抗测试也进一步表明钼掺杂可以有效提高材料的导电性和界面电化学反应活性。     

Influence of the oxidation temperature on the non-trigonal Ge dangling bonds at the (1 0 0)Ge/GeO2 interface

GeO₂ was proposed as valuable passivation layer at the surface with Ge to integrate oxide with high dielectric constant in Ge-based logic devices. Hence, the identification of the defects present at different Ge/GeO₂ interfaces becomes a mandatory issue to predict the electrical features of devices based on such materials. High sensitive electrically detected magnetic resonance measurements were performed to study the microstructure of defects occurring at such an interface. The influence of the oxidation temperature on the electrically active paramagnetic traps was investigated.     

Crystalline orientation dependence of electrical properties of Mn Germanide/Ge(1 1 1) and (0 0 1) Schottky contacts

We have investigated the crystalline orientation dependence of the electrical properties of Mn germanide/Ge(1 1 1) and (0 0 1) Schottky contacts. We prepared epitaxial and polycrystalline Mn₅Ge₃ layers on Ge(1 1 1) and (0 0 1) substrates, respectively. The Schottky barrier height (SBH) estimated from the current density-voltage characteristics for epitaxial Mn₅Ge₃/Ge(1 1 1) is as low as 0.30 eV, while the SBH of polycrystalline Mn₅Ge₃/Ge(0 0 1) is higher than 0.56 eV. On the other hand, the SBH estimated from capacitance-voltage characteristics are higher than 0.6 eV for both samples. The difference of these SBHs can be explained by the local carrier conduction through the small area with the low SBH regions in the epitaxial Mn₅Ge₃/Ge(1 1 1) contact. This result suggests the possibility that the lowering SBH takes place due to Fermi level depinning in epitaxial germanide/Ge(1 1 1) contacts.     

Fe/(Ga,Mn)As异质结的界面结构和磁性质

Fe/（Ga,Mn）As heterostructures were fabricated by all molecular-beam epitaxy.Double-crystal X-ray diffraction and high-resolution cross-sectional transmission electron micrographs show that the Fe layer has a well ordered crystal orientation and an abrupt interface.The different magnetic behavior between the Fe layer and（Ga, Mn）As layer is observed by superconducting quantum interference device magnetometry.X-ray photoelectron spectroscopy measurements indicate no Fe₂As and Fe-Ga-As compounds,i.e.,no dead magnetic layer at the interface, which strongly affects the magnetic proximity and the polarization of the Mn ion in a thin（Ga,Mn）As region near the interface of the Fe/（Ga,Mn）As heterostructure.     

Ge/Si量子点的生长研究进展

要有效应用SK模式生长的Ge量子点,必须实现Ge量子点的位置可控并且进一步缩小Ge量子点的尺寸.阐释了这方面的研究进展,特别对图形衬底生长Ge量子点,利用Si表面的自组织性在错切割的邻晶面衬底上生长有序Ge岛,表面杂质诱导成岛这三个方面的进展加以介绍分析.     

Epitaxial Ge layers on Si via GexSi1-xO2 reduction: The roles of the hydrogen partial pressure and the Ge content

The epitaxial growth of an epi-Ge layer via Ge_xSi_1-xO₂ reduction in hydrogen annealing is reported. Ge_xSi+_1-x alloys with x = 0.52 and 0.82 were first grown epitaxially on Si substrates. They were then oxidized in a wet ambient and subsequently annealed in 5% or 100% H₂. The reduction of Ge from its oxide state is observed in both samples with both ambients. However, an epitaxial Ge growth is only observed in the sample with x = 0.82 after the 5% H₂ annealing. The other three cases result in the formation of polycrystalline Ge. The roles of the hydrogen partial pressure and the Ge content are discussed and conditions under which this novel mode of solid-phase epitaxy can occur are explained.     

Structural and electrical properties of Er-doped HfO2 and of its interface with Ge (0 0 1)

Er-doped HfO₂ thin films with Er content ranging from 0% to 15% are deposited by atomic layer deposition on native oxide free Ge(001). The crystallographic phase is investigated by X-ray diffraction and is found to depend on the Er%. The cubic fluorite structure develops on Ge for Er% as low as 4% and is stable after annealing at 400 °C in N₂. Microstrain increases with increasing the Er content within the fluorite structure. Time of flight secondary ion mass and electron energy loss spectroscopy evidence a Ge diffusion from the substrate that results in the formation of a Ge-rich interfacial region which does not present a structural discontinuity with the oxide. The diffusion of Ge is enhanced by the annealing and causes a reordering of the crystal lattice. In annealed films the interface defect density measured by low temperature conductance measurements is found to decrease with decreasing the Er content.     

Fe-Cr-Si-B非晶磁粉芯的制备与磁性能研究

以水雾法制备的Fe-Cr-Si-B非晶合金粉末为原料制备了非晶磁粉芯,研究了退火温度和成型压力对磁粉芯性能的影响。结果表明:Fe-Cr-Si-B合金粉末具有较高的非晶化程度和良好的热稳定性;当退火温度低于非晶合金的起始晶化温度时,非晶磁粉芯的起始磁导率μi在440℃附近达到峰值44.7,对应的损耗则相对最低(260×10–3W/cm3,50 kHz);当成型压力由30 MPa增大到50 MPa时,磁粉芯的μi由38.6增大到46.4,其损耗则逐渐降低。     

Optical,electronic and magnetic properties of the dilute magnetic semiconductor Mn:CuInte2

CuInTe₂ and CuInSe₂ are direct bandgap ternary chalcopyrite (I-III-VI₂) semiconductors which are the simplest ternary analogs of the II-VI zincblende compounds. Some of the chalcopyrites exhibit nonlinear optical properties which make them good candidates for optical device technology. We have done preliminary studies on the influence of Mn²⁺ on the optical, transport and magnetic properties of CuInTe₂ in analog to previous stud-ies of Mn:CdTe etc. Bulk polycrystalline p-type samples, with up to 12% Mn substi-tution, have been examined with polarized light microscopy, x-ray energy dispersive analysis, optical spectrometry, van der Pauw technique and SQuID magnetometer mea-surements. From the metallurgical studies, Mn is found to substitute for Cu but not In. The bandgap of Mn:CuInTe₂ is larger than 0.92 eV. Most of our samples show phonon limited mobility, with the highest mobility occurring at ≈75K. Without Mn substitu-tion, CuInTe₂(Se₂) is diamagnetic. Samples with 3% Mn substitution in Cu sites are paramagnetic. At higher Mn concentration (3% < x < 12%), the (Cu_1-xMn_x)InTe₂ sam-ples show antiferromagnetic coupling and a measured effective magnetic moment up to ≈5.4 μB/Mn atom. Samples with attempted Mn substitution in In sites (from 3% to 9%) show anomalous magnetic behavior at low temperatures.     

钠米晶LaCo0.2Fe0.8O3的制备及湿敏特性研究

以La（NO3）3×6H2O，Fe（NO3）3×9H2O和Co（NO3）2×6H2O为原料，采用柠檬酸盐法合成LaCo0.2Fe0.8O3纳米晶，用DTA，TGA对原粉形成纳米晶过程进行分析，用XRD，SEM对纳米晶进行表征，并对其湿敏特性进行研究。结果表明，在600℃下焙烧使原粉形成了稳定的钙钛矿纳米晶。此材料在相对湿度大于54%RH时对湿度的变化有较高的灵敏度，掺杂适量无机盐可以改善材料的湿敏特性，使它在全程湿度范围内对湿度都有很好的响应。     

Mn^2＋掺杂CdWO4晶体的生长及光谱特性

采用坩埚下降法技术,选用CdO∶WO3∶MnO摩尔比为100∶100∶0.5的化学组分配比,在约60℃固液界面温度梯度与0.05 mm/h生长速度条件下,成功地生长出Φ25 mm×100 mm Mn^2＋掺杂CdWO4（Mn^2＋：CWO）单晶。观测了晶体未退火、经空气和O2退火处理后的的吸收、激发和发射光谱。结果表明...