Effect of Fe_2O_3 on non-isothermal crystallization of CaO-MgO-Al_2O_3-SiO_2 glass

The crystallization behavior and kinetics of CaO-MgO-Al2O3 SiO2（CMAS） glass with the Fe2O3 content ranging from zero to 5%were investigated by differential scanning calorimetry（DSC）.The structure and phase analyses were made by Fourier transform infrared spectroscopy（FT-IR） and X-ray diffraction（XRD）.The experiment results show that the endothermic peak temperature about 760℃ is associated with transition and the exothermic peak temperature about 1000℃ is associated with crystallization.The crystallization peak temperature decreases with increasing the Fe203 content.The crystallization mechanism is changed from two-dimensional crystallization to one-dimensional growth,and the intensity of diopside peaks becomes stronger gradually.There is a saltation for the crystallization temperature with the addition of 0.5%Fe2O3 due to the decomposition of Fe2O3.Si-O-Si,O-Si-O and T-O-T（T=Si,Fe,Al） linkages are observed in Fe2O3-CaO-MgO-Al2O3-SiO2 glass.

深红波段LiAlO_2:Fe^(3+)荧光粉发光性能的研究

用高温固相合成法制得Li Al O2:Fe3+,通过正交实验确定最佳含量和反应条件:1 mol体系中,n(Li)/n(Al)=0.93,n(Fe)=0.006 mol,并在1470℃下灼烧3h。XRD分析确证为四方晶系。在λem=743nm监测下,激发光谱峰为266nm;且在λex=266nm的激发下,发射光谱峰为743nm,色坐标x=0.7352,y=0.2648。

Growth and physical characterization of high resistivityFe:β-Ga2O3 crystals

High quality 0.02 mol%,0.05 mol%,and 0.08 mol%Fe:β-Ga2O3 single crystals were grown by the floating zone method.The crystal structure,optical,electrical,and thermal properties were measured and discussed.Fe:β-Ga2O3 single crystals showed transmittance of higher than 80%in the near infrared region.With the increase of the Fe doping concentration,the optical bandgaps reduced and room temperature resistivity increased.The resistivity of 0.08 mol%Fe:β-Ga2O3 crystal reached to 3.63×1011Ω·cm.The high resistivity Fe:β-Ga2O3 single crystals could be applied as the substrate for the high-power field effect transistors(FETs).

Crystal Structure of Natural Non-metamict Ti- and Fe^(2+)-rich Chevkinite-(Ce)

The crystal structure of non-metamict Ti- and Fe2+-rich chevkinite-(Ce) has been redetermined with the single -crystal sample collected from Bayan Obo, Inner Mongolia, China. The chemical formula of the sample is Ce4Fe2Ti3Si4O22. The crystals are monoclinic with the unit cell parameters a = 13.4656(15) ?, b = 5.7356(6) ?, c = 11.0977(12) ?, β= 100.636(2)o, V = 842.39 (16) ?3 and Z = 2. The structures of Ti- and Fe2+-rich chevkinite-(Ce) were refined with space groups P21/a and C2/m. Least-squares refinement results show that both structural models of Ti- and Fe2+-rich chevkinite-(Ce) are very good, R[F2>2σ(F2)] =0.027 with P21/a and R[F2>2σ(F2)] =0.021 with C2/m. In order to illustrate the relationship between the two space groups P21/a and C2/m, the distribution of diffraction intensities was inspected. Pseudo extinction was found, i.e., reflections with h+k=2n are systematically strong, while those with h+k=2n+1 are weak. By neglecting the systematically weak (h+k=2n+1) reflections the space group becomes C2/m. There is a mirror plane in the C2/m perpendicular to the b axis. However, oxygen atoms in the P21/a model are of a symmetrical relationship with the corresponding pseudo mirror plane. It is concluded that the crystal structure of non-metamict Ti- and Fe2+-rich chevkinite-(Ce) is a superstructure with the space group of P21/a, which is of pseudo symmetry corresponding to the space group C2/m.

SYNTHESIS,CHARACTERIZATION AND CRYSTAL STRUCTURES OF η~5-CH_3C_5H_4)M(CO)_2NO AND(η~5-CH_3C_5H_4)M(μ_3-NH)(μ_2-NO)(μ_2-CO)Fe_2(CO)_6(M=Mo or W)

Synthesis of complexes（η;-CH;C;H;）M（CO）;NO（M=Mo,I;M=W,II）and clusters（η;-CH;C;H;）M（μ;-NH）(μ;-NO) （μ;-CO）Fe;（CO）;（M=Mo,III:M=W,IV）,based on the reaction of （η;-C5;）M（CO）;Cl with Na[Fe（CO）;NO] at room tem-perature,have been demonstrated,The crystal structures of II and IV arealso presented.

Co Content Dependence of Crystal Structure and Specific Magnetization of Fe_(1-x)Co_x-SiO_2 Granules Prepared by Sol-Gel Method

The Co content dependence of crystal structure and specific magnetization of Fe1-xCox-SiO2granular solid prepared by the sol-gel method have been studied. It is found that the crystal structure, Iattice parameter and specific magnetization of the FeCo alloy particles depend on the Co content.

Synthesis and Crystal Structure of (SiCl_3)_2Fe(CO)_4

The compound （SiCl3）2Fe（CO）4 was synthesized and structurally characterized by X-ray single-crystal diffraction. It crystallizes in monoclinic, space group P2 1/n with α = 8.287（2）, b = 9.829（2）, c = 9.042（2） A, β = 96.19（3）°, V= 732.2（3） A^3, C4Cl6FeO4Si2, Mr = 436.77, Z = 2, Dc = 1.981 g/cm^3, F（000） = 424, μ（MoKα） = 2.282 mm^-1, the final R = 0.048 and wR = 0.164 for 1109 observed reflections （I 〉 2σ（I））. The crystal structure of （SiCl3）2Fe（CO）4 reveals that the Si（l）- Fe-Si（l）^a sequence is linear and perpendicular to the Fe（CO）4 cross-shaped plane.

Magnetic properties and crystallization kinetics of Zn_(0.5) Ni_(0.5) Fe_2O_4

Precursor of nanocrystalline Zno.sNio.sFe2O4 was obtained by grinding mixture of ZnSO4.7H2O, NiSO4.6H2O, FeSO4.7H2O, and Na2CO3.10H2O under the condition of suffactant polyethylene glycol （PEG）-400 being present at room temperature, washing the mixture with water to remove soluble inorganic salts and drying it at 373 K. The spinel Zn0.5Ni0.5Fe2O4 was obtained via calcining precursor above 773 K. The precursor and its calcined products were characterized by differential scanning calorimetry （DSC）, Fourier transform infrared （FF-IR）, X-ray diffraction （XRD）, and vibrating sample magnetometer （VSM）. The result showed that Zn0.sNio.sFe204 obtained at 1073 K had a saturation magnetization of 74 A.mLkg-1. Kinetics of the crystallization process of Zn0.5Ni0.5Fe2O4 was studied using DSC technique, and kinetic parameters were determined by Kissinger equation and Moynihan et al. equation. The value of the activation energy associated with the crystallization process of Zr0.5Ni0.5Fe2O4 is 220.89 kJ-mol-1. The average value of the Avrami exponent, n, is equal to 1.59±0.13, which suggests that crystallization process of Zn0.5Ni0.5Fe2O4 is the random nucleation and growth of nuclei reaction.

Investigation on Molecular and Crystal Structures of Metal Complexes with Aminopolycarboxylic Acids(Ⅰ)─Synthesis and Structure of Na_2[Fe~Ⅲ(ida)2]2·3H_2O

The crystal structure of the title complex salt has been determined by single-crystal X-ray structure analysis. The crystal data are as follows; Monoclinic, P21/c, a=15.6480(10)A,b=16.7870(10)A, c=10.347(2)A, β=90.790(10), V=2717.7(6)A3, Z=3, and R=0.0333 for 4789 unique reflections. The complex anion has a pseudo-octahedral structure distorted more than the CrⅢand CoⅢ analogs, in which cach iminodiacetato ligand (ida2-) is coordinated in a facial fashion with the two N atoms in a cis configuration, resulting in an unsyin-fac structure.

γ-LiAlO_2晶体的生长缺陷研究

γ LiAlO2 晶体是一种非常有前途的GaN衬底材料 ,本文利用化学腐蚀光学显微术和同步辐射X射线形貌术研究了LiAlO2 晶体的缺陷。结果表明 ,提拉法生长的γ LiAlO2 晶体中的缺陷主要为位错、包裹物和亚晶界。并发现在其 (10 0 )晶片上的腐蚀形貌两面有较大差异。

SiO_2-Al_2O_3-CaO-Fe_2O_3系微晶玻璃的晶化过程

利用差热分析 (DTA)、红外吸收光谱 (IR)、X射线衍射 (XRD)和扫描电镜 (SEM )等手段研究了SiO2 Al2 O3 CaO Fe2 O3系微晶玻璃晶化过程及其结晶动力学。结果表明 :SiO2 Al2 O3 CaO Fe2 O3系微晶玻璃晶化过程中 ,初晶相是钙铁透辉石 ,钙铝黄长石是中间过渡相且随晶化温度的提高而消失 ,最终晶相只有钙铁透辉石 ;晶体生长指数为 2 .9,属三维生长。玻璃网络中主要有SiO4,AlO4及Fe3+O4四面体结构单元 ,随核化时间延长及晶化温度提高 ,红外最强吸收带朝低波数方向移动 ,吸收带强度随晶化温度的提高而增大。

室温脉冲Fe^(2+):ZnSe中红外激光特性研究

处于3~5μm波段的激光源在遥感、环境保护、医疗、通信和红外对抗等民用和军用领域都有广阔的应用前景。Fe^(2+):ZnSe晶体由于在材料特性和光学特性等方面都具有明显优势,是3~5μm波段极具潜力的激光介质之一。在室温条件下利用自制非链式脉冲HF激光器作为泵浦光源,对晶体直径为10 mm,厚度1 mm,Fe^(2+)离子掺杂浓度为3×1019/cm3的Fe^(2+):ZnSe晶体进行了研究,获得了中心波长4 295 nm、最大输出能量78.8 mJ的中红外激光输出。输出激光能量相对于晶体吸收泵浦能量的转换效率为27.7%,斜率效率达28.8%。采用小角度(3°)斜入射的方案很好地解决了Fe^(2+):ZnSe激光器谐振腔镜镀膜问题。

CaO和YAG中掺杂Fe^(3+)、Mn^(2+)离子的零场分裂

本文采用Ｆｅ３＋和Ｍｎ２＋离子的ＳＣＦ－ｄ轨道理论，通过分析杂质离子引起晶体中局域结构的变化，研究了晶体ＣａＯ和ＹＡＧ中掺杂Ｆｅ３＋和Ｍｎ２＋离子的零场分裂立方分量ａ和三角分量，合理地解释了在同一种晶体中掺杂Ｆｅ３＋离子的零场分裂（ａ、｜Ｄ｜）比Ｍｎ２＋离子的大。

Nd(Fe_(1-x)Co_x)_(10)V_2的Mssbauer谱

通过X射线衍射、磁测量和M ssbauer谱等测试方法研究了Nd(Fe1-xCox) 10 V2 的结构和磁性。结果表明 :Nd(Fe1-xCox) 10 V2 (x =0 ,0 .0 5 ,0 .1,0 .15 ,0 .2 )化合物的晶体结构均为ThMn12 型结构 ;随着Co含量增大 ,晶格常数将单调减少 ,居里温度Tc 呈单调增大 ,饱和磁化强度Ms 逐渐增加。Co部分取代Nd(Fe1-xCox) 10 V2 中的Fe原子 ,将择优占据 8i铁晶位。

衬底材料LiGaO_2与LiAlO_2晶体的生长及缺陷分析

衬底材料ＬｉＧａＯ２与ＬｉＡｌＯ２晶体的生长及缺陷分析徐科徐军周永宗邓佩珍（中国科学院上海光学精密机械研究所，上海２０１８００）ＣｒｙｓｔａｌＧｒｏｗｔｈａｎｄＤｅｆｅｃｔｓｏｆＳｕｂｓｔｒａｔｅＭａｔｅｒｉａｌｓＬｉＧａＯ２ａｎｄＬｉＡｌＯ２ＸｕＫ...

LiAlO_2晶体的生长及完整性研究

ＬｉＡｌＯ２晶体的生长及完整性研究刘琳陈京兰刘海润（中国科学院物理研究所，北京１０００８０）ＣｒｙｓｔａｌＧｒｏｗｔｈａｎｄＩｍｐｅｒｆｅｃｔｉｏｎｏｆＬｉＡｌＯ２ＣｒｙｓｔａｌＬｉｕＬｉｎＣｈｅｎＪｉｎｇｌａｎＬｉｕＨａｉｒｕｎ（Ｉｎｓｔｉｔｕｔｅ...

Tb_2Fe_(17)和Tb_2(Fe,Si)_(17)磁性单晶的生长和相图

R2 Fe17(R为稀土 )是一大类稀土金属间化合物 ,具有硬磁特性。本工作生长了Tb2 Fe17和以Si部分替代Fe的Tb2 Fe17-xSix(x =1 ,2 ,3)的单晶 ,并研究了单晶的磁性和该化合物的相图。实验发现 ,该材料单晶生长的择优方向为其基本结构 ,六方Th2 Ni17的c轴方向 ,有Si替代和无Si替代均能同成分生长。这一结果与最新版本所载的Tb Fe二元相图中Tb2 Fe17为强烈的包晶反应是不一致的。为此做了Tb2 Fe17成分附近各种成分的差热分析。证明了这一化合物的同成分熔化性质 ,确定了其熔点和附近的一个共晶点 ,修正了以往的相图。物性研究发现 ,当Si替代Fe达到x =3时 ,化合物结构出现基本的Th2 Ni17和另一种三角结构Th2 Zn17的混合。化合物的居里温度随Si含量增加而上升。Si的替代产生了低温下c轴方向的矫顽力 ,认为是Si取代Fe位引起的能垒变化对磁畴的钉扎所致。在无Si替代的单晶样品中 ,难磁化的c轴样品出现一级磁化过程 (FOMP) ,其起始磁场为 2 .5T ,比以往报道的 3.5T降低很多 ,表明较高的完整性和较低的缺陷密度降低了磁畴的钉扎势垒。

Ba(ZnTi)_xFe_(12-2x)O_(19)铁氧体的磁特性

采用标准陶瓷工艺 ,并进行湿压磁场成型和氧气氛烧结 ,制备了高取向度、低介电损耗的各向异性 Ba(Zn Ti) x Fe12 - 2 x O19多晶六角铁氧体。根据分析 ,我们认为 M型六角钡铁氧体的六面体位 2 b位是一个特殊的四面体位 ,Zn2 +取代了 4f1和 2 b位上的 Fe3+,而 Ti4 +取代了1 2 k和 2 a位上的 Fe3+。

金属间化合物Nd(Fe_(1-x)Co_x)_(10)V_2的结构和磁性研究

通过 X射线衍射和磁测量等手段对金属间化合物 Nd(Fe1 - x Cox) 1 0 V2 的结构和磁性进行了研究。结果表明 ,金属间化合物 Nd(Fe1 - x Cox) 1 0 V2 (x=0 ,0 .0 5 ,0 .1,0 .15 ,0 .2 )的晶体结构均为 Th Mn1 2 型结构 ;随着 Co含量 x的增大 ,晶格常数 a、c和晶胞体积 V将单调减小 ,居里温度 Tc呈单调增大 ,饱和磁化强度 Ms逐渐增加。取向样品Nd Fe1 0 V2 的 X射线衍射和变温穆斯堡尔谱研究结果表明该化合物在 T=12 0 K条件下存在自旋重取向现象。

一步法快速合成Fe掺杂混晶TiO_(2)及其增强太阳光催化活性研究

基于半导体能带理论,设计并制备了不同浓度Fe掺杂的球形混晶TiO_(2)基光催化剂,利用X射线衍射、紫外-可见吸收光谱、X射线光电子能谱、扫描电镜、透射电镜、能谱分析、荧光光谱等测试方法对样品进行系统性表征,并以甲基橙(MO)溶液为目标污染物模拟印染废水,研究样品在太阳辐射下的光催化性能。结果表明:TiO_(2)具有锐钛矿/金红石/板钛矿三相混晶结构,Fe掺杂能明显促进锐钛矿向金红石转变,显著提高太阳光利用率和有效抑制光生载流子复合;2%Fe^(3+)/TiO_(2)的光催化活性表现最佳,其对MO的催化降解效率高达94.6%(120min),反应速率常数为23.22×10^(-3)min^(-1);活性组分猝灭实验证实h+氧化是降解MO的核心机制,·OH和·O_(2)^(-)则发挥次要作用。