CaMgP2O7∶Ce3+,Mn2+荧光粉的制备及其发光性能

采用高温固相法制备CaMgP2O7∶Ce3+,Mn2+荧光粉,并对其发光性质进行探究.荧光粉CaMgP2O7∶Ce3+,Mn2+在328 nm、351 nm与587 nm的发射峰分别归属于Ce3+的5d→2FJ跃迂和Mn2的4T1 (4G)→6A1(6S)跃迁.Ce3+的掺杂有效地提高了Mn2+的发光强度,同时电荷补偿剂Li+与Na+的添加也提高了CaMgP2O7∶Ce3+,Mn2+荧光粉的发光强度,依据Dexter能量传递公式判断CaMgP2O7基质中Ce3+对Mn2+的能量传递属于电四极-电四极相互作用引起的共振能量传递.     

电沉积法制备Bi2S3薄膜研究

采用阴极恒电压法在ITO导电玻璃表面沉积了Bi2S3薄膜,利用X射线衍射(XRD)、原子力显微镜(AFM)对制备的薄膜进行了表征.研究了pH值、沉积时间、沉积液浓度等工艺因素对薄膜的影响.结果表明:电沉积制备Bi2S3薄膜的过程中,合适的Bi3+与S2O32-的浓度水平是至关重要的;在电沉积溶液pH=6.5,沉积时间为20 min,沉积电压为1 V,加入柠檬酸三钠作络合剂的情况下,得到沿(240)晶面生长良好的Bi2S3薄膜,薄膜组成均匀致密;增加沉积溶液pH值,薄膜的结晶程度逐渐提高,红外透过比提高.     

γ-Bi2Sn2O7的水热合成及其可见光区光电响应研究

本文采用水热法制备了γ-Bi2Sn2O7并研究了其在可见光区的光电响应.Bi2Sn2O7的晶体结构和光电响应特性分别用X射线衍射和表面光电压谱进行表征.研究结果表明,合成的Bi2Sn2O7呈现γ相立方结构,通过吸收光谱估算光学带隙为2.67eV,比α-Bi2O3(2.85eV)的光学带隙小.Bi2Sn2O7的光电响应相对于α-Bi2O3在可见光区展现出一定的优势,同时对外加电压有很强的响应.     

BBZS掺杂对BaO-Sm2O3-TiO2系微波介质陶瓷性能的影响

利用固相法制备BaO-Sm2O3-TiO2系微波介质陶瓷.通过复合添加氧化物ZnO、CuO和玻璃料Bi2O3-B2O3-ZnO-SiO2(BBZS),系统的烧结温度降至900℃.研究了玻璃料的添加量对介电性能的影响.按BaSm2Ti4O12+1wt;ZnO+1wt;CuO+xwt;BBZS(0相似文献   

红色荧光粉Bi2-xZnB2O7∶xEu3+的制备及发光特性

采用高温固相反应法合成了Bi2-xZnB2O7∶xEu3+(x=0.06,0.08,0.10,0.12,0.15)红色发光材料,并对其制备工艺及发光特性进行了研究.利用XRD和SEM等对粉体进行了结构、纯度和形貌表征,同时讨论了烧结温度对其发光性能的影响得出最佳的烧结温度为680℃.在激发波长为465 nm的条件下,材料的发射峰主要位于582nm、596 nm、617 nm、656 nm和704 nm处,分别归属于Eu3+的5D0→7FJ(J=0,1,2,3,4)电子跃迁,其中以在617nm处的Eu3+的5D0→7F2跃迁产生的电偶极跃迁发射为最强.研究了Eu3+离子掺杂浓度对Bi2ZnB2O7∶Eu3+发光性能的影响,结果随着Eu3+离子浓度的增大,样品的发光强度先增大后减小,最佳掺杂浓度为x=0.1.     

TiO2-CeO2对电极材料的制备及其应用

本文采用溶胶-凝胶法制备TiO2-CeO2复合薄膜以期用于电致变色器件作对电极.通过调节Ti与Ce的原子摩尔配比对成膜的质量进行了研究.运用X射线衍射(XRD)、扫描电子显微镜(SEM)、紫外-可见光吸收光谱(UV)、循环伏安法对制得的复合薄膜的晶体结构、表面形貌及循环特性进行了表征.结果表明,当Ti与Ce的原子摩尔比为1:1时,制得的复合薄膜表面平整、致密,呈非晶态结构;在离子注入-抽出过程中,薄膜具有较快的电化学响应和较高的电荷容量.将该复合薄膜用于全固态电致变色器件中作对电极,当负载电压为3.4 V时,器件在632.8 nm波长处的色调范围达到56.8;,获得了良好的变色性能.     

La、Nb掺杂对Bi4Ti3O12薄膜介电性能和C-V特性的影响

采用溶胶-凝胶工艺制备了Bi4-xLaxTi3O12和Bi4Ti3-yNbyO12铁电薄膜,研究了La、Nb掺杂对薄膜介电性能和C-V特性的影响.研究表明,在x<0.75、y<0.06范围内,随La、Nb掺杂量的增加, Bi4-xLaxTi3O12和Bi4Ti3-yNbyO12薄膜的介电常数和C-V特性曲线回滞窗口增大,介电损耗和漏电流密度减小.x>0.5时,Bi4-xLaxTi3O12薄膜可获得大于1.8 V的C-V回滞窗口,且经1010极化开关后其回滞窗口的减小未超过6;;而Nb掺杂对增大Bi4Ti3-yNbyO12薄膜C-V回滞窗口的作用更加明显,但经1010极化开关后,其回滞窗口的减小较为明显,并出现一定平移.     

Bi4Ti3O12铁电薄膜X射线光电子能谱研究

本文采用化学溶液沉积(CSD)工艺在Si(100)衬底上制备了Bi4Ti3O12铁电薄膜,这种薄膜的X射线衍射(XRD)结果显示其具有较好的结晶性.运用X射线光电能谱仪(XPS)对薄膜的结构进行了研究,分析结果表明,衬底中Si向镀在其上的Bi4Ti3O12膜层内扩散,影响扩散的主要因素是膜厚及退火温度.     

Ce3+,Eu2+共掺Ba3Si6O12N2荧光粉发光特性及能量传递研究

通过高温固相法制备了一系列Ce3+/Eu2+共掺杂的Ba3Si6O12N2,利用X射线衍射(XRD)研究了其晶体结构.研究表明,Ba3Si6O12N2∶ Ce3+,Eu2+荧光粉在338 nm光激发下可以发射525 nm的绿光,且具有较大的半峰宽.研究还发现,单掺Ce3的发射光谱和单掺Eu2+的发射光谱存在交叠,同时Ce3+的5d1最低能级能量低于Eu2+的4f65d1最低能级,这二者共同证实了可能存在Ce3+到Eu2+的能量转移现象.同时还研究了Ce3+浓度对Ba(2.7-y)Si6O12N2∶0.3Eu2+,yCe3+(0≤y≤0.1)系列荧光粉发光强度和波长的影响.热猝灭性能研究表明,Ce3+引入可显著影响体系的热猝灭性能.     

Bi3Ti4O12/α-Bi2O3/TiO2复合光催化剂的制备及其可见光催化活性研究

以工业二氧化钛(TiO2)、五水合硝酸铋(Bi(NO3)3·5H2O)为原料制备了Bi3Ti4O12/α-Bi2O3/TiO2复合光催化剂.采用X射线衍射(XRD)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)、傅里叶变换红外光谱(FT-IR)、紫外-可见吸收光谱(UV-Vis)、荧光光谱(PL)等表征方法对光催化剂结构进行分析,表明复合样品中形成了Bi3 Ti4 O12/α-Bi2 O3/TiO2异质结结构,其禁带宽度减小、吸收带边红移,光催化效率有明显提高.以亚甲基蓝为目标污染物评价其光催化活性,TiO2与Bi(NO3)3·5H2O质量比为1:2.5,煅烧温度为600℃,煅烧时间为5 h时,复合样品光催化活性最佳,在12 W LED灯下,180 min后对浓度为10 mg/L的亚甲基蓝溶液的去除率达96.8;.     

(C2N2H10)2Mg(HP2O7)2·2H2O synthesis and crystal structure

(C₂N₂H₁₀)₂Mg(HP₂O₇)₂·2H₂O, is a new inorganic organic hybrid structure. It has been synthetized using wet chemistry. Its crystal structure consists of cis- and trans-edge sharing [MgO₄(H₂O)₂] octahedra resulting in chains, which are linked via [HP₂O₇] units to form [Mg(HP₂O₇)₂(H₂O)₂]⁴⁻ layers. The Mg²⁺ cations and the ethylendiammonium cations are located on centers of inversion. The ethylendiammonium cations are alternately located in the interlayer space. The cohesion of the crystal is well ensured by coulombic interactions between anions and cations and by several hydrogen bonds. The diphosphate anion shows an eclipsed conformation.     

Crystal structure of Rb2[GeO2(OH)2]·2H2O

Single crystals of Rb₂[GeO₂(OH)₂] · 2H₂O are studied by X-ray diffraction. The crystals belong to the orthorhombic system, sp. gr. Pna2₁, a = 13.523(6) Å, b = 8.143(4) Å, c = 13.407(6) Å, Z = 8, R ₁ = 0.0506. In [GeO₂(OH)₂]^2? anions, the Ge-O distances (1.71–1.73(1) Å) are shorter than the Ge-OH distances (1.76–1.80(1) Å). Anions are linked to each other by pairs of hydrogen bonds to form infinite chains. The chains are linked by hydrogen bonds involving water molecules to form a 3D structure. The assignment of the bands in the IR spectrum of the compound under study is performed.     

通过SiO2涂层改善BaSi2O2N2∶Eu2荧光粉的热性能

本文研究了SiO2涂层对BaSi2O2N2∶ Eu2蓝绿色荧光粉发光性能和热性能的影响.采用溶胶-凝胶法制备了SiO2包覆的BaSi2O2N2∶Eu2+蓝绿色荧光粉.实验结果表明,最佳镀膜量为6wt;,当镀膜量大于此值时,荧光粉亮度迅速降低.涂覆SiO2后,在150℃下BaSi2O2 N2∶Eu2荧光粉的热猝灭性能提高了2.4;,在500℃热降解后荧光粉的发光性能提高了15;.SiO2涂层显著提高了BaSi2O2N2∶Eu2+荧光粉的热稳定性.SiO2涂层的作用机理是在荧光粉表面和氧化气氛之间形成阻挡层,保护Eu2的发光中心在热加热过程中不被氧化.     

Crystal structure of bis 4-benzyl piperidinium monohydrogenmonophosphate pentahydrate, [C6H5CH2CHCH2CH2NH2CH2CH2]2HPO4·5H2O

The salt bis 4-benzyl piperidinium monohydrogenmonophosphate pentahydrate is orthorhombic with the following unit cell dimensions: a = 11.235(2) Å, b = 27.924(6) Å, c = 9.321(4) Å space group Pca2₁ with Z = 4. The structure was solved by the Patterson method and refined to final R value of 0.049 for 1802 independent reflections. The flack parameter is 0.14 with an e.s.d. of 0.23. The structure consists of infinite parallel two-dimensional [110] planes built of mutually connected ions and water molecules by strong O—H,...,O and N—H,...,O hydrogen bonding. There are no contacts other than normal van der Waals interactions between the layers.     

Optical properties of the germanate melilites Sr2MgGe2O7, Sr2ZnGe2O7 and Ba2ZnGe2O7

Refractive indices and their dispersion in the wavelength range from 365 nm to 2325 nm and transmission ranges of the tetragonal melilite‐type germanates Sr₂MgGe₂O₇, Sr₂ZnGe₂O₇ and Ba₂ZnGe₂O₇ were determined. The uniaxial positive crystals Sr₂MgGe₂O₇ and Ba₂ZnGe₂O₇ both offer the possibility for phase matched second harmonic generation, a detailed analysis of phase matching conditions is given. The refractive indices of Sr₂ZnGe₂O₇ show an isoindex (isotropic) point at 467 nm. The investigation was performed on Czochralski grown large single crystals. The crystal structure of all three germanates were determined by means of X ‐ray diffraction. The results corroborate unmodulated melilite‐type structures at room temperature. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Identification of a new family of diphosphate compounds, AI2BII3(P2O7)2: Structures of Ag2Co3(P2O7)2, Ag2Mn3(P2O7)2, and Na2Cd3(P2O7)2

Syntheses and single-crystal X-ray structural results are reported for three new mixed diphosphates of the family A^I ₂B^II ₃(P₂O₇)₂; Ag₂Co₃(P₂O₇)₂ (I), Ag₂Mn₃(P₂O₇)₂ (II), and Na₂Cd₃(P₂O₇)₂ (III). All crystallize in the triclinic system, space group P1 bar: (I) a = 5.351(4), b = 6.375(4), c = 16.532(4) Å, = 80.83(6) = 81.45(4), = 72.87(5)°, V = 528.9(6) ų, Z = 2, D _calc = 4.649 mg/m³, R/Rw = 0.0428/0.0548 for 3949 obs. reflns; (II) a = 5.432(7), b = 6.619(6), c = 16.51(3) Å, = 80.78(8) = 82.43(9), = 72.82(7)°, V = 557.7(13) ų, Z = 2, D _calc = 4.338 mg/m³, R/Rw = 0.0679/0.1303 for 2100 obs. reflns and (III) a = 5.67(3), b = 7.08(4), c = 7.90(4) Å, = 77.0(2), = 82.5(2), = 67.8(2)°, V = 286(3) ų, Z = 2, D _calc = 4.249 mg/m³, R/Rw = 0.0307/0.0342 for 1945 obs. reflns. (I) and (II) are isostructural but (III) is of a different type. All three structures are characterized by layers of P₂O₇ groups alternating with layers of mixed metal atoms. Differences are seen in the conglomerate bonding patterns of B atoms and in the irregular geometry of Ag in (I) and (II) compared to the octahedral bonding seen for Na in (III). The differences in structure may be understood in terms of the ratios of the ionic radii of A and B atoms.     

Oxygen-conducting compounds with La2Mo2O9 structure in the ternary system La2Mo2O9-Sm2W2O9-Sm2Mo2O 9 + : Synthesis and properties

Polycrystalline samples in the ternary system La₂Mo₂O₉-Sm₂W₂O₉-Sm₂Mo₂O ₉ ⁺ were synthesized in air. The region of the existence of compounds with the lanthanum molybdate (La₂Mo₂O₉) structure in this system was determined. The polymorphism of the synthesized compounds was studied. Doping with samarium or with samarium and tungsten was shown to lead to the suppression of the transition between the monoclinic and cubic phases α → β and the appearance of the transition β _ms → β between two cubic phases. In samples with a high samarium content, the phase transition β _ms → β manifests itself as significant anomalies in the temperature dependences of the dielectric permeability and electric conductivity. An increase in the concentration of samarium in the samples leads to a substantial decrease in the conductivity compared with the nondoped compound La₂Mo₂O₉.     

Synthesis and characterization of (NH4)2CuBr2Cl2·2H2O crystals

Single crystals of a new compound, (NH₄)₂CuBr₂Cl₂.2H₂O, were grown from saturated aqueous solution at room temperature by slow evaporation method. The grown crystals were characterized through elemental, powder XRD, thermal and DSC analyses and FTIR and far IR spectra. The elemental analysis and the decomposition pattern formulated using the TG‐DTG studies confirm the stoichiometry of the compound. The crystallinity of the compound is confirmed from the powder XRD pattern. A preliminary single crystal X‐ray diffraction structural analysis reveals that the title compound belongs to the orthorhombic system with a = 7.7466 Å, b = 7.783 Å and c = 8.1211 Å. The low temperature DSC shows thermal anomalies at –161.1, –156.5, –152.4, –145.2, –134, –18.5, and 1.4°C during the heating run and at –4.3, –54.8, –66.1, –90.6, –109.7 and –147.2 °C during the cooling run. The thermal hysterses indicate first order phase transitions in the title compound at these temperatures. The FTIR spectra were used to assign the characteristic vibrational frequencies due to NH₄⁺, CuX₄^2– ions and other chemical bonds. The effect of substitution of two bromine atoms on the phase transitions of a closely related crystal, diammonium tetrachloro cuprate dihydrate is also discussed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

KBe2BO3F2和RbBe2BO3F2晶体中的孪晶缺陷

通过化学腐蚀和偏光显微镜,对KBe2BO3F2(KBBF)和RbBe2BO3F2 (RBBF)晶体中存在的一种条状孪晶缺陷进行了研究,观察了孪晶习性,探讨了其孪晶律,并结合晶体生长情况对该孪晶的形成原因进行了分析.