CaMgSi2O6:Eu的真空紫外光谱特性

采用高温固相反应利用原料CaCO3,MgO,SiO2和Eu2O3合成CaMgSi2O6:Eu3 样品,并研究了其结构特性、光谱特性.CaMgSi2O6:Eu3 属于单科晶系,基质掺入Eu离子后结构没有明显变化.CaMgSi2O6:Eu3 在147 nm真空紫外光激发下呈红色发射,发射主峰位于611 nm,是Eu3 的5D0→7F2跃迁的典型发射.当Eu3 的相对摩尔浓度在0.02到0.10 mol之间变化时,由相关数据可以发现有浓度猝灭现象发生.CaMgsi2O6:Eu2 在172 nm真空紫外光激发下呈蓝色发射,发射主峰位于452 nm,是Eu2 的5d→4f跃迁的典型发射.添加不同浓度的H3BO3后可大大提高样品的发光强度.     

Electrical and Thermal Transport Properties of n-type Bi6Cu2Se4O6 (2BiCuSeO + 2Bi2O2Se)

New thermoelectric materials, n-type Bi₆Cu₂Se₄O₆ oxyselenides, composed of well-known BiCuSeO and Bi₂O₂Se oxyselenides, are synthesized with a simple solid-state reaction. Electrical transport properties, microstructures, and elastic properties are investigated with an emphasis on thermal transport properties. Similar to Bi₂O₂Se, it is found that the halogen-doped Bi₆Cu₂Se₄O₆ possesses n-type conducting transports, which can be improved via Br/Cl doping. Compared with BiCuSeO and Bi₂O₂Se, an extremely low thermal conductivity can be observed in Bi₆Cu₂Se₄O₆. To reveal the origin of low thermal conductivity, elastic properties, sound velocity, Grüneisen parameter, and Debye temperature are evaluated. Importantly, the calculated phonon mean free path of Bi₆Cu₂Se₄O₆ is comparable to the interlayer distance for BiO─CuSe and BiO─Se layers, which is ascribed to the strong interlayer phonon scattering. Contributing from the outstanding low thermal conductivity and improved electrical transport properties, the maximum ZT ≈0.15 at 823 K and ≈0.11 at 873K are realized in n-type Bi₆Cu₂Se_3.2Br_0.8O₆ and Bi₆Cu₂Se_3.6Cl_0.4O₆, respectively, indicating the promising thermoelectric performance in n-type Bi₆Cu₂Se₄O₆ oxyselenides.     

Sr0.61Ba0.39Nb2O6薄膜的电光特性

用激光脉冲沉积(PLD)法在MgO(001)衬底上成功地生长、制备出了外延Sr_0.61Ba_0.39Nb₂O₆(SBN61)电光薄膜;通过SBN61电光薄膜椭偏光谱测量的分析研究,得到了SBN61电光薄膜的光学常数;通过电致双折射方法对生长在(001)MgO衬底上的SBN61薄膜的电光性能进行了测量研究,发现SBN61电光薄膜电致双折射的变化Δn与所加电场E成平方关系,其二次电光系数R=0.21×10^-16(m/V)²。     

Calculation and Comparison of Electronic,Vibrational, Polarization,and Magnetic Properties of Double Perovskites CaMnTi 2 O 6 and CaFeTi 2 O 6

Vibrational, polarization, magnetic, and electronic properties of double perovskites CaMnTi2O6 and CaFeTi2O6 with a rare type of “column” ordering of divalent metal cations have been calculated based on the density functional theory. Analysis of the crystal lattice dynamics for paraelectric phase P42/nmc of both compounds has revealed that ferroelectric instability exists only in CaMnTi2O6. It is found that the structure distortion of the paraphrase of CaMnTi2O6 in the eigenvector of the unstable polar mode leads to a structure with the P42/nmc space group. The calculated spontaneous polarization for the ferroelectric phase of CaMnTi2O6 is Ps = 25 μC/cm2. The spin-polarization calculations have shown that the ground state is ferromagnetic in the CaFeTi2O6 crystal and antiferromagnetic in the CaMnTi2O6 crystal. The exchange interaction constants have been calculated using the Heisenberg model and the mean field approximation; the phase transition temperature for each compound has been estimated.     

单斜辉石固溶体CaMgSi2O6-NaAlSi2O6的合成机理研究

 研究了压力和温度对单斜辉石的结晶和晶粒纤维编织的影响。在较低的晶化温度下压力对单斜辉石结晶的影响很明显，这种影响随温度升高而减弱。然而，压力对单斜辉石晶粒纤维编织的影响正相反，在相同的高温下，较高压力下晶化的单斜辉石晶粒纤维比较低压力下得到的晶粒纤维粗壮，而且编织紧密。     

Optical spectroscopy of MgNb2O6 and ZnNb2O6 doped with Ni2+

Published in Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 4, pp. 30–37, July–August, 1995.     

Study of Structural and Photoluminescent Properties of Ca8Eu2(PO4)6O2

In this work it is presented for the first time the nanostructured hydroxyapatites doped with 0.5, 1.0 and 2.0 wt% of Eu³⁺ prepared at room temperature by the mechanical alloying technique. X-ray diffraction powder (XRD), infrared (IR) and Raman scattering spectroscopy, scanning electron microscopy (SEM), microhardness measurements as well as luminescent data of Eu³⁺ were used to investigate the structural and optical properties of these nanomaterials. The electrical and dielectrical analyses were used with the intention of having a better comprehension about the electromagnetic fields in pure and doped hydroxyapatites.     

Characteristics of thermoradiative destruction of BaS2O6·2H2O

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 55, No. 4, pp. 613–618, October, 1991.     

间隙原子对ZnNb2O6光电特性影响的第一性原理研究

基于密度泛函理论第一性原理,研究Zn、Nb、O间隙原子对ZnNb2 O6体系光电特性的影响.分析显示:间隙原子对体系晶格畸变的影响与间隙原子几何尺寸有关.缺陷结构中,由于间隙原子电负性存在差异,也是产生晶格畸变的因素.光电特性分析显示:含有Zn、Nb间隙原子的体系表现为n型简并半导体.且Nbi表现出较强的介电效应,主要...     

理论研究V2O6-的结构和电子性质

采用自旋非限制密度泛函(B3LYP)方法研究了V2O6-的结构和电子性质,得到的基态和前人的理论计算结果不同．V2O6-阴离子是具有C2v对称性的双重基态,而以前Vyboishchikov等人得到的结果为D2h对称性双重基态．V2O6中性分了是具有D2h对称性的开壳层单重基态,它的能量和三重态的非常接近,而Vyboishchikov等人和Calatayud等人分别得到D2h对称性的闭壳层单重基态和Cs对称性的三重基态．从该基态结果出发计算出的电子分离能和实验上的PES谱相符,相反前人得到的电子分离能和实验相差较大．     

Optimizing conditions of fabrication and the properties of BaNb2O6-SrNb2O6 binary ceramics

Conditions for fabricating (Ba_0.5Sr_0.5)Nb₂O₆ ceramics are optimized. It is shown that materials synthesized at T = 1250°C and sintered at T = 1375–21400°C exhibit the best ceramic characteristics. The (Ba_0.5Sr_0.5)Nb₂O₆ solid solution is found to be a ferroelectric with a diffuse phase transition. The possibility of fabricating Ba_0.5Sr_0.5Nb₂O₆ thin films from ceramic targets prepared in the resulting optimum regimes is shown.     

Optical Properties of Li0.5Ln0.5Nb2O6 Compounds with REEs and Yttrium

By means of vibrational spectroscopy and crystal optic analysis, the symmetry of crystals with the structure of fersmite in the Li_0.5Ln_0.5Nb₂O₆ series, where Ln = Nd—Lu and Y, has been refined.     

Luminescence centers in Pb2Bi6O11 and Sn2Bi6O11 ceramics

We have studied the luminescence spectra and luminescence excitation spectra of Pb₂Bi₆O₁₁ and Sn₂Bi₆O₁₁ ceramics at 80 K. We have used the Alentsev-Fock to decompose the spectra into elementary components. We have established that the luminescence spectra of Pb₂Bi₆O₁₁ and Sn₂Bi₆O₁₁ ceramics contain three elementary bands each with maxima at 2.60, 2.32, 12.93 eV and 2.62, 2.30, 2.00 eV. Comparison of the data obtained with the results of a study of the luminescence spectra for a series of bismuth-containing oxide compounds suggest that luminescence of Pb₂Bi₆O₁₁ and Sn₂Bi₆O₁₁ is due to radiative processes in structural complexes containing a bismuth ion in a nearest-neighbor oxygen environment. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 5, pp. 597–600, September–October, 2006.     

Sr0.75Ba0.25Nb2O6薄膜的PLD制备及其光学性能研究

本文采用脉冲激光沉积(PLD)方法在熔石英衬底上制备了Sr0.75Ba0.25Nb2O6(SBN0.75)光波导薄膜,采用Hitachi U-3410紫外-可见分光光度计对SBN0.75薄膜的透射谱进行测量,编程计算得到了薄膜折射率色散关系,同时得到SBN0.75薄膜的厚度和光学带隙分别为647.0nm和3.97eV。采用Metricon 2010棱镜耦合仪测量得到SBN0.75光波导薄膜中能激发的TE模式有4个,TM模式有3个。波长在632.8nm处薄膜的折射率为2.2818。并利用透射谱计算得出的薄膜的折射率和厚度值,根据波导理论导光模本征值的有效折射率表达式,对SBN0.75薄膜中能激发的导光模个数及其对应有效折射率进行图解,其结果与棱镜耦合仪所测得的结果非常吻合。     

CsLiB6O10晶体光学参变振荡器的光学特性

根据三波耦合过程中的能量和动量守恒、晶体的塞耳迈耶尔色散方程,通过数值模拟计算了213nm作CLBO光学参变振荡抽运源时,分别得到了在Ⅰ类和Ⅱ类相位匹配时参量光调谐范围为237～289nm、807～2793nm和404～2800nm。获得了在Ⅰ类匹配时的单谐振或双谐振腔的CLBO光学参变振荡转换效率都大于同等条件下的BBO光学参变振荡,Ⅱ类匹配时,CLBO晶体的转换效率略小于BBO晶体,但是CLBO光学参变振荡转换效率的最大值较BBO光学参变振荡出现于更短的紫外波段。从理论上证明了CLBO晶体是优质的深紫外透光波段非线性光学晶体。     

Ionic conductivity of mixed K(NbW)O6 and KH2O(NbW)O6

The mixed oxides K(NbW)O₆ and KH₂O(NbW)O₆ were prepared by solid state reactions and characterized by X-Ray diffraction powder method, thermogravimetric analysis and differential scanning calorimetry. Electrical conductivity measurements were recorded between 190 and 508 K by the complex impedance method.