铁离子在Tl系1223超导相中的分布研究

对不同掺铁量的T1系1223相样品,测量了室温和77K的穆斯堡尔谱。根据铁可能具有的不同局域环境,按四套四极劈裂双峰进行拟合。发现室温下四套亚谱的同质异能移位均为0.25mm/s左右,表明铁在1223超导相中以高自旋Fe^3 形式存在。其四极劈裂分别为1.40mm/s,1.12mm/s,0.55mm/s和1.90mm/s左右。按照点电荷-有效价键模型,计算了铁处于不同局域位置时的核四极劈裂的大小。对铁所占晶位进行指认。     

TbFe10.5-xMnxMo1.5化合物的结构和磁性

用X射线和磁性测量研究了Mn替代Fe对TbFe10.5-xMnxMo1.5型金属间化合物的结构和磁性的影响。X射线衍射表明：TbFe10.5-xMnxMo1.5(x=1．5，2．0，3．0，4．0，5．0)化合物均为TnMn12型四方结构，晶格常数和单胞体积均随Mn含量增加而增大。磁性测量表明：TbFe10.5-xMnxMo1.5（x=1．5，2．0，3．0，4．0，5．0)化合物的居里温度和过渡金属次晶格磁矩随Mn含量的增加而逐渐降低；x=3．0化合物的热磁曲线上出现一个非零磁矩的类似补偿点；在4．5K温度下，化合物的饱和磁矩随Mn含量的增加而缓慢减小；x=3．0时达到最小值，然后又随Mn含量的增加而迅速增大。     

半导体金属氧化物的室温固相合成研究

以无机盐为原料,用室温固相化学反应直接合成了SnO2、In2O3、ZnO、Fe2O3等导体金属氧化物的纳米粉体,用X－射线衍射技术和透射电子显微镜对产物的物相和形貌进行了表征观察,结果表明,固相化学反应完全,所得产物为理论产物,且均为纳米粒子。     

两种TGS晶体在低温下的热电和介电性

测量了TGS、ATGSP两种晶体在室温至20K温度范围内的介电常数K_(22)和热电系数p_2。这两种参数都随温度降低而单调下降,不显示相变的迹象。在此范围内的任一温度,ATGSP的热电系数p_2和优值p_2/K_(22)均较TGS的大。优值p_2/K_(22)随温度下降而减小,与自发极化的温度特性不相一致。     

对-二苯氨基苯基硼酸的光谱及光物理行为研究

利用紫外可见吸收光谱和荧光光谱对新合成的化合物：对-二苯氨基苯基硼酸(DPBA，三苯胺衍生物)在不同极性介质中的光谱、光物理行为进行了研究，并利用Lippert-Mataga方程计算了该化合物基态和激发态偶极矩间的差值△μ=3．0D．实验结果表明，溶剂极性对DPBA的吸收光谱峰位和峰形产生相对较小的影响，而使DPBA荧光光谱发生较大的红移，荧光峰的半峰宽变宽且基态和激发态间的偶极矩差值△μ变大，表明了该化合物具有典型的分子内电荷转移(ICT)的特性．     

PbTiO3薄膜的热释电性和铁电性研究

采用Sol—Gel工艺制备了较大面积不裂的PbTiO_3薄膜,对样品做了不同烧结温度下的X射线衍射实验,经550℃保温30min的样品已形成了单一晶相的PbTiO_3多晶膜。对样品的热释电系数随温度、薄膜厚度和胶液浓度的变化关系研究,发现热释电系数随胶液浓度和薄膜厚度的增加而增大,最后达到饱和。样品的室温热释电系数为3.6×10~(-8)C/cm~2·K,介电常数为15～26,介电损耗为0.001—0.05,居里温度为515℃,自发极化强度和剩余极化强度分别为6.54μc/cm~2和3.37μc/cm~2,矫顽场强为54.8kV/cm。     

天然黑色电气石红外辐射特性研究

对新疆、内蒙古和云南等地的天然黑色电气石红外辐射特性进行了测试和分析，结果表明：不同产地和不同矿区的黑色电气石化学成分差异较大，其中氧化铁含量对红外辐射率具有明显影响，随氧化铁含量的增加，红外辐射率下降；天然黑色电气石在还原性气氛条件下进行热处理后，可具有比远红外陶瓷粉料更高的红外比辐射率值，其红外峰值辐照与维恩定律具有很好的对应关系，在室温下峰值辐射波长为9．5μm左右。研究认为，天然黑色电气石在保暖、保健等领域具有很高的实际应用价值。     

铁磁金属合金中的内磁场和磁矩

本文研究了若干晶态和非晶态铁磁金属合金中Fe原子的内磁场和磁矩,认为这些合金中存在两种不同的机制。类金属原子的键合效应和过渡金属原子的电子转移效应,它们导致Fe原子内磁场和磁矩明显降低。所得结果表明,虽然铁磁金属合金中Fe原子的内磁场和磁矩具有同样的变化趋势,但在一般情况下,两者之间不一定存在某种简单的正比关系或线性关系。     

Nanoindentation response analysis of TiN-Cu coating deposited by magnetron sputtering

To investigate the change of the mechanical properties of soft metals doped PVD(Physical Vapor Deposition)coatings after the migration of soft metal to the surface, TiN-Cu coating was deposited on Si(100) by magnetron sputtering. The microstructure and mechanical properties at room temperature and after vacuum heat treatment at 300 ℃ were investigated. The results showed that the grains were clustered and the microstructure was porous for TiN-Cu coating at room temperature, while many micro-and nano-sized Cu particles were observed on the surface after vacuum heat treatment at 300 ℃. The elastic properties of the TiN-Cu coating after vacuum heat treatment at 300℃ degraded compared with that at room temperature. The hardness and elasticity modulus of TiN-Cu coating kept constant(3.7 GPa and 125.0 GPa, respectively) with the increase of nano-indentation depth, while the hardness and elasticity modulus of TiN-Cu coating after vacuum heat treatment at 300 ℃ increased gradually.     

液晶彩色显示用正性黄、红色蔥醌型二色性染料的研究

合成了1,5-二羟基-2-对烷氧基苯基蒽醌和1,5-二羟基-3-对烷氧基苯基蒽醌型黄色正性的二色性染料8个。1-氨基4-羟基-2-苯硫基蒽醌及1-氨基-4-羟基-2-苄氧基蒽醌红色正性的二色性染料2个。测定了染料分子在液晶中的有序参数,用CAMTC-ppp程序,计算了染料的跃迁能及染料分子的基态和激发态的偶极矩,发现染料分子在液晶中有序参数与染料分子基态和激发态偶极矩之间夹角θ有密切的关系。     

过滤强化用极性硅盐粉末的鉴别优选

研究了来自新疆、河北、桂林三个产地的不同粒度提纯后极性硅盐粉末样品对空气过滤材料过滤性能影响，采用压电实验、热释电实验对各种极性硅盐粉末样品进行电极性表征鉴别优选.结果表明:桂林粒度0.074mm提纯品位最高的极性硅盐粉末自发极化性能最佳；将3种极性硅盐最高纯度的粉末分别附着滤料表面进行全尘效率实验，桂林粒度0.074mm提纯品位最高极性硅盐粉末对过滤效率提升最显著；采用Rietveld方法对极性硅盐粉末XRD图谱精修得到晶体结构，通过计算固有电偶极矩证明了极性硅盐自发极化产生的静电吸附作用是其提高滤料过滤性能的主要原因.     

Magnetic properties and giant magnetoresistance effect of nanometer Fe-In2O3 granular films

Nanometer ferromagnetic metal-semiconductor matrix Fe-In2O3 granular films are fabricated by the radio frequency sputtering. Magnetic properties and the giant magnetoresistance (GMR) effect of Fex(In2O3)1x granular film samples are studied. The result shows that the magne-toresistance (MR) ratio/0 value of the granular film samples with Fe volume fraction x = 35% is 4.5% at room temperature. The temperature dependence (T = 1.5-300 K) of the MR ratio /0 value of Fe0.35(In2O3)0.65 granular films shows that /0 value below 10 K increases rapidly with the decrease of the temperature, and when T = 2 K,/0 value is 85%. Through the study of the dependence of low field susceptibility on temperature and the hysteresis loops at different temperatures, it has been found that, when the temperature decreases to a critical point TP = 10 K, the change of the structure in Fe0.35(In2O3)0.65 granular films results in the transformation of state from ferromagnetic to spin-glass-like. The remarkable increase of the MR ratio ???/??0 value of Fe0.35(In2O3)0.65 granular films below 10 K seems to arise from the peculiar conducting mechanism of the granular film samples in the spin-glass-like state.     

团簇Co_2FeBP的磁性

对团簇Co2Fe BP中Co、Fe原子的平均磁矩进行研究分析,结果表明:Co、Fe原子的平均磁矩均小于其理论计算值和实验观测值,B、P原子的引入降低了Co、Fe的磁性;多重度对Co、Fe原子的平均磁矩影响较大,但对其改变量大致相同;随着各构型稳定性的降低,在单重态下,Co、Fe原子的平均磁矩出现振荡性变化,在三重态下,Co原子的平均磁矩呈振荡性,而Fe原子呈单峰状;Co原子的平均磁矩在不同多重度下均变化不大,这与文献报道相一致;构型4(3)的Co原子平均磁矩最大,构型3(3)的Fe原子平均磁矩最大。     

Orientation of molecular interface dipole on metal surface investigated by noncontact atomic force microscopy

We investigated the orientations of interface dipole moments of individual non-planar titanyl phthalocyanine(TiOPc)molecules on Cu(111)and Cu(100)substrates using scanning tunneling microscope(STM)and noncontact atomic force microscope(NC-AFM).The dipole moment orientations corresponding to two different configurations of individual TiOPc molecules were determined unambiguously.The correlation between the actual molecular structures and the corresponding STM topographies is proposed based on the sub-molecular resolution imaging and local contact potential difference(LCPD)measurements.Comparing with the pristine substrate,the LCPD shift due to the adsorption of non-planar molecule is dependent on the permanent molecular dipole,the charge transfer between the surface and the molecule,and the molecular configurations.This work would shed light on tailoring interfacial electronic properties and controlling local physical properties via polar molecule adsorption.     

Infinite-layer iron oxide with a square-planar coordination

Conventional high-temperature reactions limit the control of coordination polyhedra in transition-metal oxides to those obtainable within the bounds of known coordination geometries for a given transition metal. For example, iron atoms are almost exclusively coordinated by three-dimensional polyhedra such as tetrahedra and octahedra. However, recent works have shown that binary metal hydrides act as reducing agents at low temperatures, allowing access to unprecedented structures. Here we show the reaction of a perovskite SrFeO3 with CaH2 to yield SrFeO2, a new compound bearing a square-planar oxygen coordination around Fe2+. SrFeO2 is isostructural with 'infinite layer' cupric oxides, and exhibits a magnetic order far above room temperature in spite of the two-dimensional structure, indicating strong in-layer magnetic interactions due to strong Fe d to O p hybridization. Surprisingly, SrFeO2 remains free from the structural instability that might well be expected at low temperatures owing to twofold orbital degeneracy in the Fe2+ ground state with D(4h) point symmetry. The reduction and the oxidation between SrFeO2 and SrFeO3 proceed via the brownmillerite-type intermediate SrFeO2.5, and start at the relatively low temperature of approximately 400 K, making the material appealing for a variety of applications, including oxygen ion conduction, oxygen gas absorption and catalysis.     

二氧化硅气凝胶的性能受热过程的影响

成功地以水玻璃为硅源,经乙醇溶剂替换及六甲基二硅醚和盐酸的混合液对SiO₂湿凝胶表面基团改性后,常压干燥制备出低密度、高比表面积、超疏水、低热导率的高性能SiO₂气凝胶块体.SiO₂气凝胶在室温至400℃附近具有稳定的疏水性能,460℃附近气凝胶由疏水型完全转变成亲水型.重点研究了室温至400℃之间,SiO₂气凝胶的微观结构和物理性能受热处理过程的影响.SiO₂气凝胶即使经过400℃高温热处理后,仍能保持优异的疏水性能、较高的比表面积和较低的热导率等.     

蝎虎天体的射电辐射与寄主星系亮度的关系

选取了52个蝎虎天体,计算了它们的射电光度(包括核光度,延展光度及总光度)和寄主星系的绝对星等。分析各光度与亮度的相关知,其相关系数为0.008<|r|<0.154;当考虑射电谱指数的差异时,发现在不同的谱指数范围里,它们的相关系数为0.014<|r|<0.722。利用伽马射线多普勒因子(ΔT=6 h),计算了本征光度L c in和L t in,发现它们与寄主星系绝对星等相关的相关系数分别为0.093与?0.341。     

多铁材料BiNi_xFe_(1-x)O_3(x=0～0.5)磁性的第一性原理计算

采用基于密度泛函理论的第一性原理计算多铁材料BiNi_xFe_(1-x)O_3(x=0,0.125,0.167,0.25,0.5)各晶体结构的电子性质.能带结构、Mulliken电荷以及自旋磁矩等计算结果表明:由Ni离子部分替代掺杂Fe离子可使体系由反铁磁有序转变为局部亚铁磁有序,晶体总自旋磁矩随Ni离子浓度的增大而增大;Ni离子掺杂明显抑制了特定位置Fe离子的磁矩,这是由于Ni-eg轨道少数自旋方向的电子态被50%占据以及Ni离子与Fe离子之间的超交换作用所致.     

AIF分子外场效应的量子化学研究

选取密度泛函B3LYP方法和6—311＋＋g（d,P）基组对AlF分子在不同外电场（-0．015～0．015 a.u．）及没有外场下分子基态的稳定电子结构进行计算,研究了外电场对AlF分子基态总能量、键长、偶极矩、能隙、电荷分布及红外光谱等的影响．结果表明,随着Al→F方向外电场的增加,分子键长和偶极矩递减,原子电荷也递减,总能量升高,能隙增大,频率随Al→F方向外电场的增加而增加,其红外强度则递减;在外电场作用下,AlF基态分子势能曲线升高,离解能增大。     

Geomagnetic dipole strength and reversal rate over the past two million years

Independent records of relative magnetic palaeointensity from sediment cores in different areas of the world can be stacked together to extract the evolution of the geomagnetic dipole moment and thus provide information regarding the processes governing the geodynamo. So far, this procedure has been limited to the past 800,000 years (800 kyr; ref. 3), which does not include any geomagnetic reversals. Here we present a composite curve that shows the evolution of the dipole moment during the past two million years. This reconstruction is in good agreement with the absolute dipole moments derived from volcanic lavas, which were used for calibration. We show that, at least during this period, the time-averaged field was higher during periods without reversals but the amplitude of the short-term oscillations remained the same. As a consequence, few intervals of very low intensity, and thus fewer instabilities, are expected during periods with a strong average dipole moment, whereas more excursions and reversals are expected during periods of weak field intensity. We also observe that the axial dipole begins to decay 60-80 kyr before reversals, but rebuilds itself in the opposite direction in only a few thousand years.