Glass Transition (Tg) and Dielectric Loss in Na2O-Bi2O3-TiO2-P2O5 GLASSES

Thermal and dielectric loss properties of Na₂O-Bi₂O₃-TiO₂-P₂O₅ phosphate glasses, have been studied by the differential scanning calorimetry (DSC) and electrical factor loss (tgi) measurements. The variation of tgi has been followed along two lines inside the quaternary systems Na₂O-Bi₂O₃-5TiO₂-P₂O₅ and Na₂O-5Bi₂O₃-TiO₂-P₂O₅. Experiments have been carried out from ambient temperature to 450°C and show a strong influence of sodium, bismuth and titanium ions on T_g and tgi.     

Glass Transition (T g ) and Dielectric Constant (e'r) of Li3PO4-Pb3(PO4)2-BiPO4 (Li2O-PbO-Bi2O3-P2O5) Glasses

Thermal and dielectric properties of heavy metal oxide glasses, Li₃PO₄-Pb₃(PO₄)₂-BiPO₄ (Li₂O-PbO-Bi₂O₃-P₂O₅), were studied from ambient temperature to 500°C by differential thermal analysis (DTA) and dielectric constant (?′_r) measurements. Experiment results show a strong influence of lithium, lead and bismuth ions on T _g and ?′_r.     

Glass forming regions and dielectric properties of Na2O-Bi2O3-TiO2-P2O5 glasses

The glass forming regions have been determined in the quaternary systems Na₂O-Bi₂O₃-0.05TiO₂-P₂O₅ and Na₂O-0.05Bi₂O₃-TiO₂-P₂O₅. The largest vitreous do main has been found in the diagram with 5mol% of titanium oxide TiO₂- The variation of dielectric constant has been followed along two lines inside the glass regions. e'_r increases with increasing amount of sodium oxide Na₂O and diminishes with increasing percentage of either Bi₂O₃ or TiO₂.     

Phase Transition in the Compound NH3(CH2)5NH3TlCl5

Penthylene diammonium pentachlorothallate(III) exhibits a phase transition at 316 K <artwork name="GPHT21157eu1"> This transition has been characterized by optical birefringence, dielectric measurements differential scanning calorimetry and spectroscopic measurements on polycrystalline samples. The space group and the cell parameters of phase I were determined by X-ray diffraction from single crystals. Phase I has space group P2₁2₁2₁, with Z = 4, a = 7.696(3), b = 13.2890(17) and c = 13.503(18) Å. The transition is both displacive and order-disorder involving mainly conformational changes of the organic chain [NH₃(CH₂)₅NH₃]²⁺ coupled with distortion of the TlCl₆ octahedra. This behaviour and the crystal dynamics will be discussed and compared with those found in the literature for homologous compounds.     

Pb(Sc_(1/2)Nb_(1/2))O_3中有序-无序转变和铁电相变的Raman光谱研究

采用wolframite前驱物法制备了Pb(Sc1/2Nb1/2)O3陶瓷。通过调节陶瓷烧结工艺,获得了三种具有不同B位离子有序度的PSN陶瓷。测量了三种陶瓷样品在室温至160°C范围内的Raman光谱随温度变化。结果表明,随着温度的升高,三种不同B位有序度的陶瓷样品中,Raman光谱中位于530 cm-1的F2g模的峰位和半峰宽分别在100°C,85°C和80°C发生了突变,表明陶瓷分别在100°C,85°C和80°C三个温度点发生了铁电-顺电相变。上述结论得到了介电温度谱测量数据的支持。     

CaO-B2O3-SiO2：Eu^2＋玻璃的合成及荧光光谱分析研究

在还原气氛中合成了CaO-B2O3-SiO2：Eu^2＋玻璃体系,研究了该玻璃体系中Eu^2＋的激发光谱和发射光谱,并归属了其相应的跃迁发射。研究了掺杂Eu^2＋浓度对其发光强度的影响,结果表明,Eu^2＋掺杂量在0.20%时发光强度达到最大值,在该玻璃体系中没有观察到浓度猝灭现象。研究了合成条件与Eu离子在玻璃中发光性质的关系,说明还原能力H2〉CO〉空气,空气几乎不具备还原能力。研究了玻璃中Eu^2＋的电子自旋共振谱（ESR）性质,证实了玻璃体系中Eu^2＋的存在,得到了玻璃体系中Eu^2＋的能级图。     

具有高机械强度的掺Er3+∶TeO2-Nb2O5玻璃的光谱性质研究

熔制了掺铒碲铌玻璃样品(100-XTeO2-XNb2O5(X=5,10,15,20 mol%),测试了其密度、折射率、转变温度、析晶温度、维氏机械强度、吸收光谱、荧光光谱、荧光寿命等参量。利用Judd-Ofelt和McCumber理论分别计算了铒离子强度参量Ωt (t=2, 4, 6)和受激发射截面σemi的大小,研究了掺铒碲铌玻璃样品光谱参量对Nb2O5成分的依赖性,并与典型的碲锌钠玻璃（75TeO2-20ZnO-5Na2O）在热学、机械强度、光谱性质和放大品行四个方面进行了比较.     

具有高机械强度的掺Er~(3 )∶TeO_2-Nb_2O_5玻璃的光谱性质研究

熔制了掺铒碲铌玻璃样品(100-X)TeO2-XNb2O5(X=5,10,15,20mol%),测试了其密度、折射率、转变温度、析晶温度、维氏机械强度、吸收光谱、荧光光谱、荧光寿命等参量。利用Judd-Ofelt和McCumber理论分别计算了铒离子强度参量Ωt(t=2,4,6)和受激发射截面σemi的大小,研究了掺铒碲铌玻璃样品光谱参量对Nb2O5成分的依赖性,并与典型的碲锌钠玻璃(75TeO2-20ZnO-5Na2O)在热学、机械强度、光谱性质和放大品行四个方面进行了比较.     

配合物57Fe(py)4(NCS)2的合成和穆斯堡尔谱研究

从含有57Fe(Ⅱ)的掺杂配合物中回收57Fe2O3,用N2H4*H2SO4为主还原剂将57Fe2O3还原为57Fe(Ⅱ),以保证57Fe具有较高的含量.最后合成配合物57Fe(py)4(NCS)2.并通过元素分析、红外光谱、穆斯堡尔谱等方法对其结构进行表征.     

Laser-diode-excited Blue Upconversion in Tm3+/Yb3+-codoped TeO2-Ga2O3-R2O (R=Li, Na, K) Glasses

This paper reports on intense blue upconversion in Tm³⁺/Yb³⁺ codoped TeO₂-Ga₂O₃-R₂O(R=Li, Na, K) glasses upon excitation with commercial available laser diode (LD). Effects of alkali ions on the Raman spectra, thermal stability and spectroscopic properties of the tellurite-gallium glasses have also been investigated. Energy transfer and the involved upconversion mechanisms have been discussed. Intense blue upconversion emission centered at 476 nm along with a weak red emission at 650 nm has been observed upon excitation of 977 nm LD, assigned to the transitions of , and and/or of Tm³⁺, respectively. The blue upconversion intensity has a cubelike dependence on incident pump laser power, indicating a three-photon process. However, a quadratic dependence of the 476 nm upconversion intensity on the incident pump laser power has been observed when samples under excitation of 808 nm LD due to a two-photon absorption process. Enhanced upconversion luminescence have been observed with replacing K⁺ for Na⁺ and Li⁺.     

A Ftir and Raman Spectral Study of the Preparation of Lead Titanate (PbTiO3) by a Sol-Gel Method

Lead Titanate (FT) materials were prepared by a sol-gel process in an air atmosphere using lead acetate and titanium propoxide in methoxyethanol as the precursor materials. FTIR and Raman spectroscopy were used to characterize the various structural changes that occurred during various stages of the preparation. A new crystalline lead titanate phase was detected by both Raman spectral and X-ray diffraction techniques when heating the gelled material at 430°C. In-situ Raman spectra were measured at high temperatures for the resulting sol-gel prepared PT material to investigate its phase-transition and soft-mode behavior.     

(ZnO)_(1-x-y)(P_2O_5)_x(B_2O_3)_y玻璃的环境稳定性和红外光致发光(英文)

Er3+掺杂的(ZnO)1-x-y(P2O5)x(B2O3)y玻璃具有优良的光学性质。沸水煮沸实验结果表明,该类玻璃具有较高的环境稳定性。与(Er2O3)z(ZnO)1-x-z(P2O5)x-z类玻璃相比,Er3+掺杂的该类玻璃在1.5μm峰值位置的光谱半峰全宽超过110 nm,而且具有较高的猝灭浓度。     

CH3CH2+O(3P)反应机理的理论研究

利用abinitio方法对CH3CH2+O(3P)反应进行了理论研究,在MP2/6311+G(d,p)水平上优化得到了反应途径上的反应物、中间体、过渡态和产物的几何构型和谐振频率,并在QCISD(T)/6311+G(d,p)水平上进行单点能计算.计算结果表明:CH2O+CH3、CH3CHO+H和CH2CH2+OH是主要反应产物,其中CH2O+CH3主要来自反应通道A1:(R)→IM1→TS3→(A),CH3CHO+H主要来自反应通道B1:(R)→IM1→TS4→(B),CH2CH2+OH主要来自直接抽提反应通道C1和C2:(R)→TS1(TS2)→(C).计算结果同时表明该反应生成CO的通道能垒是非常高的,CO应该不是主要产物.     

Effect of ZnO/CdO on the structure and electrical conductivity in Li2O·MO·Bi2O3·B2O3 glasses (M=Zn, Cd)

Studies of structural and electrical properties have been carried out on a number of glasses with wide ranging compositions in the glass systems Li₂O·MO·Bi₂O₃·B₂O₃ (where M=Zn or Cd), in order to understand the effect of transition metal (TM) ions on the structure of these glasses. The density and molar volume measurements have also been made to understand the structural changes occurring in these glasses. The dc conductivity measured in the temperature range 423-623 K obeys Arrhenius law. It increases with increase in Li₂O/MO ratio. The results of infrared spectra indicate that TM ions (Zn²⁺ or Cd²⁺) behave as network former in the present system. Boron exists in both tri- and tetra-hedral units in these glasses and no boroxol ring formation takes place in the glass structure. Values of theoretical optical basicity have also been reported.     

(Ta_2O_5)_(1-x)(TiO_2)_x陶瓷结构相变研究

采用固相反应技术制备了x分别为 0 0 5、0 0 8和 0 1 1的 (Ta2 O5) 1-x(TiO2 ) x 陶瓷 ;在室温至 6 0 0℃范围内 ,测量了这些陶瓷样品的拉曼光谱随温度的变化。随着温度的升高 ,拉曼光谱中位于 35～38cm- 1的最低频移的声子模发生软化 ,并随之发生结构相变。拉曼光谱和实验结果都表明 :组分x分别为0 0 5、0 0 8和 0 1 1的 (Ta2 O5) 1-x(TiO2 ) x 陶瓷分别在 36 0、4 5 0和 5 4 0℃发生了由三斜至单斜相的结构相变。上述结论得到了 (Ta2 O5) 0 92 (TiO2 ) 0 0 8单晶热膨胀系数测量数据的支持。     

The Mössbauer spectrum of synthetic hureaulite: Fe5 2+(H2O)4(PO4H)2(PO4)2

The crystal structure of synthetic ferrous hureaulite, Fe₅ ²⁺ (H₂O)₄(PO₄H)₂(PO₄)₂, was refined from single-crystal X-ray data. It is monoclinic, space group C2/c, with a=17.487(4), b=9.017(2), c=9.338(2) Å, β=96.27(3)°, V=1463.6(6) Å³, Z=4 and D _calc=3.327 g/cm³. This end member of the hureaulite series was crystallized under distinctly acidic conditions, by a method that gives perfect crystals, large enough for X-ray single crystal studies. The main feature of the hureaulite structure is that it has an equal number of normal (PO₄)³⁺ and acid (PO₄H)²⁺ tetradentate groups. These are centered on Fe²⁺ atoms and share corners with edge-linked octahedra, forming pentamer units. The five Fe²⁺ atoms are distributed on three distinct sites in these units. This can be directly observed in the Mössbauer spectrum at 295 K, which contains three doublets whose relative intensities correspond to the 1:2:2 distributions of crystallographic sites.     

硝酸溴与三重态氧原子反应机理的密度泛函研究

用密度泛函理论方法 (B3LYP) ,在 6 311+G(d ,p)水平上对硝酸溴与三重态氧原子的反应进行了研究 ,计算了反应中各驻点物种的平衡构型、振动频率、总能量和零点能 (ZPE) .对计算得到各可能反应途径的过渡态经内禀反应坐标分析加以了证实 ,对反应途径中的键长和能量的变化作了IRC解析 .在B3LYP优化的基础上利用了耦合簇理论方法 (CCSD(T) )在 6 311+G(d ,p)水平上对各驻点物种的单点能进行了修正 .研究表明 ,存在三种可能的反应途径 ,其产物分别为 :cis BrONO和 3 O2 、trans BrONO和 3 O2 以及BrOO和NO2 .其中第三个通道由于活化能垒较低 ,是主要反应 .     

SiH3+O(3P)反应机理的理论研究

利用abinitio方法对SiH3+O(3P)反应进行了理论研究,在MP2/6-311+G(d,p)水平上优化得到了反应途径上的反应物、中间体、过渡态和产物的几何构型,并在QCISD(T)/6-311+G(d,p)水平上进行单点能计算.计算结果表明,SiH3+O(3P)→IM1→TS3→IM2→TS8→HOSi+H2为主反应通道,其他可能存在的次要产物有HSiOH+H、H2SiO+H和HSiO+H2.HOSi、HSiO和HSiOH(cis)还可能进一步解离生成SiO.另外,计算结果对SiH4+O(3P)反应机理中存在的争议给出了可能的解释,认为Withnall等人在实验中观察到的产物HSiOH、H2SiO和SiO并不是SiH4+O(3P)反应的直接产物,而是来自副反应SiH3+O(3P).     

Sb_xBi_(2-x)Ti_4O_(11)体系的拉曼光谱及软模行为研究

本文合成出了系列样品Sb_xBi_(2-x)Ti_4O_(11),得到了它们在常温常压下的拉曼光谱。实验结果发现:体系在x=0.4和1.2处经历了两次相转变,且相变与“软模”随Sb~(+3)的浓度变化有关。     

Mechanism of heterogeneous mercury oxidation by HCl on V2O5(001) surface

The selective catalytic reduction (SCR) system for NO_X removal in coal-fired power plants has a promoting effect on the oxidation and removal of elemental mercury. In this study, basic mechanism of mercury oxidation by V₂O₅-based SCR catalyst is investigated via density functional theory method and the periodic slab models. Calculations are conducted to determine the adsorption energies and geometries of Hg⁰, HgCl, HgCl₂ and HCl on V₂O₅(001) surface, and to reveal the energy profile of oxidation reaction and the structures of relative transition states and intermediates. The results indicate that HCl can significantly promote Hg⁰ oxidation on V₂O₅(001) surface, by forming an intermediate HgCl-surface which is important for Hg⁰ oxidation. The Hg⁰ oxidation goes through Hg⁰ → HgCl → HgCl₂, and the two stages of the reaction follow Eley–Rideal mechanism and Langmuir-Hinshelwood mechanism, respectively. The formation of HgCl₂ is the rate-determining step due to its high energy barrier. Three detailed reaction pathways are obtained, and the related energy profiles and structures are analyzed in detail. The Hg⁰ oxidation reaction can take place through all three pathways even if differences exist in each other, while pathways I and II have relatively low energy barriers.