光学浮区法生长掺锡氧化镓单晶及性能研究

作为垂直结构的GaN基LED新型衬底材料,β-Ga2 O3单晶已经引起了人们的广泛关注.β-Ga2O3单晶的导电性是通过掺杂来实现的,Sn4掺入是其中一种很好提高-Ga2O3导电性的方法.利用光学浮区法生长了尺寸为5×20 mm2,掺杂浓度为10;的掺锡氧化镓单晶(Sn∶ β-Ga2O3),并对Sn∶ β-Ga2O3单晶的缺陷密度、导电和荧光光谱特性进行了研究.结果表明:实验制得Sn∶β-Ga2O3样品的线缺陷约为6.51×105/cm2,掺入Sn4+杂质后β-Ga2 O3的电导率增加,样品的最高电导率为2.210 S/cm,同时Sn4+的掺入会抑制β-Ga2O3的红绿光发射.     

PZT基反铁电材料研究进展

在综述Pb(Zr,Ti)O3(PZT)基反铁电材料的研制与性能研究进展的基础上,重点探讨了PZT95/5反铁电材料和在PZT基础上掺杂改性的Pb(Zr,Sn,Ti)O3(PZST),(Pb,La)(Zr,Sn,Ti)O3 (PLZST)反铁电材料.总结了利用La3+、Nb4+、Hf4+、Sr2+、Ba2+和Nd3+等离子对富锆PZT以及PZST粉体、陶瓷以及薄膜材料的掺杂取代改性研究.讨论了各类PZT基反铁电材料的铁电(FE)-反铁电(AFE)相变机理以及其场致应变性能.展望了PZT基反铁电材料今后研究与应用的发展方向.     

过渡层（SiO2,TiO2）对F掺杂SnO2薄膜的光电性能影响研究

采用喷雾热解法分别在普通钠钙玻璃、含Si O2过渡层与Ti O2过渡层的玻璃上制备了F掺杂Sn O2薄膜,比较了不同过渡层上生长的F掺杂Sn O2薄膜的表面形貌特点,分析了过渡层对F掺杂Sn O2膜层的光电性能的影响。结果表明,过渡层种类对F掺杂Sn O2薄膜各项性能影响很大,在Si O2薄膜过渡层上制备的F掺杂Sn O2薄膜晶粒最小且表面致密,在Ti O2过渡层制备的F掺杂Sn O2薄膜晶粒最大,在玻璃上生长的F掺杂Sn O2薄膜较为疏松,以Si O2为过渡层制备的F掺杂Sn O2薄膜光电性能最佳,其平均可见光透过率为82.9%,电阻率为5.33×10-4Ω·cm,适合喷雾热解法制备性能优良的玻璃基F掺杂Sn O2薄膜。     

Y,Fe共掺杂SrTiO3混合导体材料电阻抗行为研究

采用溶胶-凝胶法制备了单一立方相钙钛矿结构的Y0.06Sr0.94Ti1-xFexO3-δ(x=0.2,0.3,0.4,0.5)混合导体材料,采用交流阻抗法分析了电子-离子总阻抗的Nyquist图,离子阻抗的Nyquist图和Z~lgf频谱图的特性。结果表明,试样以电子电导为主,阻抗随着Fe掺杂量的增大而逐渐减小;从离子阻抗的Z~lgf频谱可以看出,试样离子传导在晶界有一个弛豫过程,Fe的掺杂降低了Y0.06Sr0.94Ti1-xFexO3-δ的弛豫活化能。试样的总电导率和离子电导率都随着Fe的掺杂量的增大而增大,Y0.06Sr0.94Ti0.5Fe0.5O3-δ的总电导率和离子电导率分别为0.088~0.15 S·cm-1和0.00023~0.029 S·cm-1。     

类钙钛矿Pr1.3Sr0.7Ni0.7-xCu0.3FexO4+δ材料的制备与传导性能研究

以硝酸盐和氧化物为原料,通过甘氨酸-硝酸盐法(GNP)合成出Pr1.3Sr07Ni0.7-xCu0.3FexO4+δ(x=0,0.025,0.05,0.1) (PSNCF)粉体,经压制成形、烧结后得到烧结体样品.采用X射线衍射仪对煅烧后粉体的物相进行分析,利用扫描电子显微镜和能谱仪对样品的微观组织和元素分布进行了表征,采用四端子法和阻塞电极法测量了不同Fe掺杂量烧结体样品的电导率,并对材料的透氧性能进行了测试.实验结果表明,前驱体粉末在1000℃煅烧5h后得到具有四方相的PSNCF粉体.烧结体试样在300 ～ 950℃间的总电导率均在200 S·cm-1以上,且随Fe掺杂含量的增加有所下降;其中,Pr1.3 Sr0.7 Ni0.65 Cu0.3 Fe0.05 O4+δ样品的氧离子电导率在950℃时最大达到0.194 S ·cm-1.另外,随Fe掺杂量增加,PSNCF材料的透氧率增大,950℃下,Fe掺杂量为0.05时(厚1 mm,40;O2-60;N2),透氧率达0.034 mL·cm-2·min-1,为未掺杂样品的3倍.     

La掺杂BaTiO3材料的制备和电性能表征

采用溶胶-凝胶法制备了La掺杂BaTiO3(LBT)材料,通过对其进行X射线衍射、扫描电子显微镜及电导率的研究来讨论La掺杂含量对BaTiO3材料的电性能的影响.结果表明:900℃煅烧LaxBa1-xTiO3(x=0～0.4)粉末能获得单一的钙钛矿结构;La掺杂能明显提高BaTiO3的电导率,当x=0.2时,La02Ba08TiO3(LBT20)材料与Gd掺杂氧化铈Ce0.8Gd0.2O1.9电解质材料具有良好的化学相容性;且LBT20的电导率最大,在800℃还原条件下的电导率大约为0.15 S/cm,是在相同条件下测得的BaTiO3电导率的4倍多,表明LBT20可以作为一种潜在的直接在碳氢燃料下工作的中温固体氧化物燃料电池的阳极材料,但是它的电导率还需进一步提高.     

Ti4+掺杂对磷酸钒锂材料结构和电化学性能的影响

分别采用溶胶-凝胶法和高温固相法制备锂离子电池正极材料Li3V1.93 Ti0 05(PO4) 3/C,研究Ti4+掺杂对Li3 V2(PO4)3材料结构、形貌和电化学性能的影响.结果表明:利用溶胶-凝胶法和高温固相法均得到单斜晶系结构,且无杂相存在,少量Ti4掺杂并未影响材料的结构形貌,但显著改善了电化学性能.溶胶-凝胶法掺杂Ti4+试样在0.2C和12 C放电比容量分别为129 mAh·g-1和102 mAh·g-1,明显高于高温固相法掺杂Ti4+试样,且循环性能良好.研究表明利用溶胶-凝胶法掺杂是一种改善离子掺杂效果的有效路径.     

CeO2基固体氧化物燃料电池连接体薄膜的双层共烧制备研究

为了改善CeO2基SOFC阳极与LaCrO3基连接材料的共烧匹配性能,本研究将少量CeO2粉体添加到La0.7Ca0.3CrO3-δ连接材料中作为烧结助剂.相关性能测试表明CeO2的引入可以显著提高La0.7Ca0.3 CrO3-δ在空气条件下的烧结和电导性能,完全可以满足中温SOFC连接材料的性能要求.以NiO/SDC(质量比6∶4)为阳极支撑体,采用浆料浸渍涂膜工艺制备La0.7Ca0.3CrO3-δ +2; CeO2(质量比)连接体湿膜,1400℃空气条件下双层共烧,成功获得致密连接体薄膜.     

Ce0.8Sm0.2O2-δ-Ca3Co2O6-δ双相材料的制备及其透氧性能研究

采用共沉淀法和柠檬酸络合法分别制备了Ce0.8Sm0.2O2-δ和Ca3Co2O6-δ粉体,随后通过固相烧结法获得了致密Ce0.8Sm0.2O2-δ-Ca3Co2O6-δ双相透氧膜材料.分别通过X射线衍射(XRD)和场发射扫描电子显微镜(FESEM)对样品的晶体结构和形貌进行了表征.系统研究了双相比例对样品的热膨胀系数、电子电导率和透氧率的影响.实验结果表明该双相材料具有优异的化学稳定性,1150 ℃烧结6 h可以获得致密双相膜.双相膜具有较低的热膨胀系数,为13.47×10-6 ~14.23×10-6 K-1,接近电解质的热膨胀系数值.当离子导电相添加量由40wt;增加到80wt;,双相膜的电导率随之降低,而透氧率随之增大,950 ℃时,质量比为8∶2的Ce0.8Sm0.2O2-δ-Ca3Co2O6-δ双相膜的透氧率达到了2.80×10-7 mol·cm-2·s-1,表明该材料可以作为一种新型双相透氧膜材料用于氧分离.     

Sr掺杂对Ca3Co4O9基材料热电性能的影响

采用溶胶-凝胶法,结合常压烧结工艺制备了Ca3-xSrxCo4O9(x=0～0.5)热电陶瓷材料,并对材料的热电性能进行了测试。结果表明,Sr掺杂对Ca3Co4O9基材料的热电性能有较大影响。随着掺杂量的增加,电导率逐渐增大,Seebeck系数略有减小。Sr掺杂能显著降低热导率,而且随着掺杂量的增加,热导率的下降幅度逐渐增大。Sr掺杂显著改善Ca3Co4O9材料的热电性能,当掺杂量为0.5时获得最佳热电性能,573 K时Z值达1.07×10-4 K-1。     

(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.     

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.     

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.     

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)     

Structure of {Pb[S2CN(C2H5)2]2(1,10-phenanthroline)}2

Lead (II) nitrate reacts with 1,10-phenanthroline and sodium diethyldithiocarbamate in water to produce yellow bisdiethyldithiocarbamata 1,10-phenanthroline lead(II). Crystals from water are triclinic, space group $P\bar 1$ (#2),a=10.53(2) Å,b=11.050(12)Å,c=24.74 (3) Å, α=94.71 (9)⁰, β=98.15(11)^o, γ=114.11(9)^o,V=2569(6) ų,Z=2. Each lead atom has approximate pentagonal pyramid coordination geometry through the nitrogens of a phenathroline and sulfurs of two dithiocarbamates. Additionally, complexes form loose dimers in which lead atoms are weakly coordinated to a sulfur in an adjacent complex. IR and proton nmr spectrum of the complex are consistent with the solid state structure.     

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.