混合阴离子磷酸盐RbCd6(P2O7)2P3O10的热学与光学特性研究

利用高温固态反应技术合成了一种新型磷酸盐RbCd6(P2 O7)2 P3O10,并用高温熔盐法自发结晶获得了其单晶.X射线单晶衍射分析表明,该物质结构中含有两种孤立的聚阴离子:P2O7二聚体与P3O10三聚体.两种不同的聚阴离子基元共存于一种结构中,在磷酸盐体系中很少见.这一发现不仅丰富了磷酸盐的结构化学,而且为混合阴离子材料的设计提供了新视角.此外,对该物质的热稳定性及光学性能进行了表征.     

HPO42-与H2PO4-在水热法制备CeO2纳米颗粒过程中的影响

以Ce(NO3)3·6H2O、Na5P3O10和Na3PO4·12H2O为原料,用水热法在180℃反应60h分别制备了CeO2纳米八面体和纳米棒,且对Na5P3O10与Na3PO4 · 12H2O系统同时调节pH =2时180℃反应12 h制备了纳米棒.通过XRD、FE-SEM、TEM等方法对CeO2纳米棒和纳米八面体进行了测试和分析.结果表明,对于Na5P3O10与Na3PO4·12H2O系统,初始时CeO2八面体与纳米棒共存,但随着水热时间的延长,Na5 P3O10系统中CeO2八面体成为主要产物,而在Na3PO4·12H2O系统中CeO2纳米棒成为主要产物.Na5P3O10水解产生的HPO42-是CeO2纳米八面体形成的主要原因,而Na3PO4·12H2O水解产生的H2PO4-是纳米棒形成的主要原因.     

不同离子掺杂的钛酸铋钠基陶瓷结构与性能表征

采用传统固相反应法制备了0.94(Na0.5 Bi0.) TiO3-0.06BaTiO3-3wt; Bi2 O3-xwt; Nd2O3(x=0,1.5)陶瓷.研究了Bi3+和Nd3+掺杂对0.94 (Na0.5 Bi05)TiO3-0.06BaTiO3陶瓷结构和电学性能的影响.结果表明,Bi2O3和Nd2O3掺杂不影响0.94(Na0.5 Bi0.5) TiO3-0.06BaTiO3的钙钛矿结构.3wt; Bi2O3添加使得铁电陶瓷0.94(Na0.5Bi05) TiO3-0.06BaTiO3转变为反铁电陶瓷.反铁电陶瓷0.94(Na0.5Bi0.5)TiO3-0.06BaTiO3-3wt; Bi2O3具有更高的相转变温度Tm(～320℃).Nd2O3添加不改变0.94(Na0.5 Bi0.5) TiO3-0.06BaTiO3-3wt; Bi2O3陶瓷的反铁电态,但增强了陶瓷的介电性能和弛豫性能.     

固化剂对磷酸盐粘结剂固化行为的影响研究

本文以H3PO4和Al(OH)3为原料制备磷酸铝粘结剂,探讨了不同固化剂ZnO、CuO、Cr2O3对其固化行为的影响.采用XRD、邵氏硬度仪、TG-DSC等分析手段研究了磷酸盐粘结剂的物相组成、硬度、吸湿率及其固化机理等.结果表明:当P/Al摩尔比为3∶1.3时,磷酸铝粘结剂的理论固化温度为262℃,固化后产物为AlH2P3O10·H2O.固化剂的加入可以有效地缩短固化时间和提高涂层性能,以CuO为最佳.当CuO添加量不低于8wt;时,磷酸盐粘结剂固化时间最短,为2.5 h;吸湿率最低,为4.21wt;.当CuO添加量为6wt;时,涂层硬度最大,为99.2 HA.其对应的理论固化温度为145℃,固化产物为Al4(PO4)3(OH)3·xH2O和少量的Cu4P2O9·H2O.     

Na3La2(BO3)3的晶体结构

以Na2CO3-H3BO3-NaF为助熔剂,使用顶部籽晶法生长出Na3La2(BO3)3透明单晶.测定了Na3La2(BO3)3的晶体结构,该晶体属正交晶系,空间群:mm2(No.38),晶胞参数为a＝0.51580(10)nm,b=1.1350(2)nm,c=0.73230(15)nm,α＝β＝γ＝90°,V＝0.42871(15)nm3,密度:.053g/cm3.晶体结构中的硼氧基团是平面的BO3基团,BO3基团相互独立,且与Na(1)O6、Na(2)O8、Na(3)O6和La(1)O9配位多面体连结形成三维网络骨架结构.讨论了Na3La2(BO3)3的晶体结构与倍频效应的关系.     

非线性光学晶体Na3La9O3(BO3)8的生长研究

以Na3CO3和H3BO3为助熔剂,Na3CO3和H3BO3摩尔比为7/6,熔质Na3La9O3(BO3)8和助熔剂摩尔比为1/10～1/14,采用顶部籽晶生长方法,生长Na3La9O3(BO3)8晶体,晶体尺寸为30×18×8mm3.本文讨论了籽晶方向对Na3La9O3(BO3)8晶体生长的影响,(100)方向比(001)方向更有利于晶体生长.     

拓扑化学法制备棒状(KxNa1-x)NbO3粉体

以Na2CO3、K2CO3、Nb2O5和KCl为原料,采用拓扑化学反应法合成出一维方向生长钙钛矿结构的棒状KxNa1-x NbO3 (KNN)粉体.首先采用熔盐法合成出棒状的前驱体K2Nb8O21晶体,系统研究了Nb2O5与KCl的起始质量比、合成温度对kNb8O21晶体显微结构和形貌的影响,研究发现当Nb2O5与KCl的质量比为3/8,850℃下保温3h可以获得长度为80～100 μm,直径为3～8 μm的棒状K2Nb8O21晶体,且晶体沿[100]方向生长;然后以棒状的前驱体K2Nb8O21为模板晶粒,采用拓扑化学反应法制备出棒状KNN晶体,研究了Na2 CO3的添加量、烧成温度和保温时间对棒状KNN晶体显微结构和形貌的影响.结果表明:添加过量10wt;的Na2CO3,在900℃下保温3h可以获得沿[001]方向生长的棒状KNN晶体,其中K/Na =47.31/52.69,接近1/1,其长度和宽度分别为30 ～ 50 μm和2～6 μm.     

承德某硬质伊利石除铁增白试验研究

以Na2S2O4为还原剂,六偏磷酸钠和EDTA为添加剂,对河北承德某硬质伊利石进行了除铁增白试验研究,考察了Na2S2O4用量、矿浆pH值、反应温度、添加剂用量等因素对除铁增白效果的影响,得出了还原-络合漂白优化工艺条件.硬质伊利石还原-络合漂白优化工艺条件为:矿浆浓度11;,Na2S2O4用量4;,(NaPO3)6用量0.2;,EDTA用量8;,pH =2.5,温度80℃,反应时间20 min.经还原-络合漂白后,硬质伊利石漂白产品中Fe2O3含量由1.14;降至0.70;,白度由79.3;提高至87.0;.     

Na3La9O3(BO3)8的晶体结构

以Na2CO3-H3BO3为助熔剂,用顶部籽晶法生长出Na3La9O3(BO3)8单晶.测定了Na3La9O3(BO3)8晶体结构,结果表明:该晶体属六方晶系,空间群:P62m,晶胞参数为a=b=0.89229(13)nm,c=O.87366(17)nm,α=β=90°,γ=120°,Z=1,V=0.60240(17)nm3,密度为5.066g/cm3.晶体结构中的硼氧基团是平面的BO3基团,BO3基团相互独立,通过与Na(1)O6、La(1)O9和La(2)O8的配位多面体连结形成层状结构,所有层平行于(001)面.描述了Na3La9O3(BO3)8晶体在非线性光学材料领域的应用前景.     

模拟熔融态黄磷炉渣制备微晶玻璃析晶规律研究

以SiO2-Al2O3、Na2O-SiO2-Al2O3 、K2O-SiO2-Al2O3、CaO-SiO2-Al2O3和MgO-SiO2-Al2O3五种混合辅料为研究对象,采用液-固混合法与热态黄磷炉渣进行高温混熔直接制CaO-Al2O3-SiO2系微晶玻璃.通过Factsage、差热分析和X射线衍射,并利用修正后的Johnson-Mehl-Avrami (JMA)方程,分析了不同辅料在高温下与热态黄磷炉渣混熔制备微晶玻璃的析晶规律.结果表明:混合辅料SiO2-Al2O3出现液相的最低温度为1595℃,而当加入碱金属或碱土金属作助熔剂时辅料的熔融液相温度均大幅降低.添加Na2O-SiO2-Al2O3辅料后制备出的微晶玻璃析晶活化能E为192.8718 kJ/mol,而添加K2O-SiO2-Al2O3辅料后其析晶活化能明显增加为306.4335 kJ/mol.当助熔剂为CaO和MgO时,其析晶活化能接近,分别为376.7427 kJ/mol和372.0462 kJ/mol.在五种混合辅料直接添加到热态黄磷炉渣制备微晶玻璃过程中,K2O-SiO2-Al2O3和CaO-SiO2-Al2O3辅料均出现目标主晶相为硅灰石(CaSiO3)的物相.综合考虑析晶活化能和物相组成,以K2O-SiO2-Al2O3为混合辅料直接加入热态黄磷炉渣制备出的微晶玻璃优于其它混合辅料的直接添加.     

Sol-gel synthesis and characterization of adsorbent and photoluminescent nanocomposites of starch and silica

Using sol-gel method, mesoporous and photoluminescent silica nanocomposites of soluble starch have been synthesized and characterized. Different ratios of H₂O, TEOS and EtOH were used at fixed template (soluble starch) and catalyst (NH₄OH) concentrations to obtain materials of different performances in terms of heavy metal binding from a solution which has been monitored using Cd(II) as representative divalent heavy metal ion. Optimum material was obtained when H₂O, TEOS and EtOH were used in 14:1:2 ratio. This sample was not only an efficient metal ion adsorbent but also had an intense luminescence in ultra-violet region and potentially may be used in silicon-based UV-emitting devices. Metal binding by the material was further enhanced after calcination (at 800 °C in air) while its luminescence had a multipeak profile in UV-visible region. In a batch adsorption study, calcined hybrid composite (0.25 g/L) could remove 98.5% Cd(II) from 100 mg/L Cd(II) solution in 2 h. The chemical, structural and textural characteristics of the synthesized materials have been investigated using Fourier Transform Infrared Spectroscopy (FTIR), X-rays Diffraction (XRD), Thermal Analysis (TGA/DTA), Photoluminescence (PL), Brunauer-Emmett-Teller Analysis (BET) and Scanning Electron Microscopy (SEM).     

Syntheses and structures of N-phenylmaleimidetriazoles and by-products

The syntheses, properties, and structures of N-phenylmaleimidetriazole derivatives are described. Intermediates and by-products are also discussed. 1b. a = 43.997(7) Å, 5.7610(9) Å, 8.245(1) Å, = 99.339(4), C₂/c; 2a. a = 13.646(4) Å, b = 7.744(2) Å, c = 10.612(3) Å, = 91.979(6), P2₁/c. 3a. a = 22.245(1) Å, b = 22.245(1) Å, 10.010(1) Å, P42/n. 3a. a = 11.727(2) Å, b = 14.075(3) Å, c = 16.080(3) Å, = 105.859(3), = 105.331(3), = 98.187(3), P-1. 3b. a = 8.561(3) Å, b = 14.755(5) Å, c = 22.771(7) Å, = 97.006(5), P2₁/c. 3c. a = 10.500(2) Å, b = 12.189(2) Å, c = 13.040(2) Å, = 109.091(3), = 106.089(3), = 101.022(3), P-1. 8a. a = 16.389(8) Å, b = 5.749(3) Å, c = 19.316(3) Å, = 97.467(9), P2₁/n. 8b. a = 5.822(2) Å, b = 10.114(3) Å, c = 16.705(4) Å, = 84.681(5), = 82.840(5), = 75.769(4), P-1. 9b. a = 11.251(1) Å, 13.335(3) Å, 13.376(3) Å, = 102.456(4), P2₁/n. 9c. a = 15.836(3) Å, b = 8.236(2) Å, c = 5.447(3) Å, = 92.551(3), P2₁/c. 10a. a = 13.177(2) Å, b = 14.597(2) Å, c = 5.5505(8) Å, = 110.979(2), Cc. 11a. a = 14.720(2) Å, b = 13.995(2) Å, c = 38.245(6) Å, = 94.430(3), P2₁/n. 12b. a = 15.067(5) Å, b = 20.378(6) Å, c = 8.669(5) Å, = 99.16(4), = 99.32(3), = 105.23(3), P-1. 13b. a = 8.2824(6) Å, b = 10.5245(7) Å, c = 15.518(1) Å, = 92.305(1), = 100.473(1), = 100.124(1), P-1. 15a. a = 15.357(3) Å, b = 7.778(2) Å, c = 22.957(2) Å, Pbca. 16b. a = 18.0384(4) Å, b = 12.474(3) Å, c = 20.078(5) Å, Pbca.     

Chemistry and Electrocrystallization of Organic Metals and Superconductors

Abstract

Considerable variation in the conditions of electrochemical crystal growth of TMTSF₂X (i.e., constant current versus constant potential, ambient versus inert atmosphere, etc.) and in the purity of the constituents (donor, electrolyte, solvent) does not significantly affect the unusual low-temperature properties of this class of materials. Our results suggest that the electrocrystallization procedure may be self-purifying by selecting for conducting crystal phases with constituents having specific oxidation potentials and solubility properties. However, doping solutions with structurally and chemically similar constituents (i.e., TMTTF, and IO^? ₄ in CIO^? ₄) leads to their incorporation in the crystal structure where they have a profound effect. Several mole percent of these dopants suppress superconductivity in the PF^? ₆ and CIO^? ₄ salts, and increase and broaden the metal-insulator phase transition.     

Structural and spectral studies of N-trans-cinnamylidene-m-toluidine and N-trans-cinnamylidene-m-chloroaniline

N-trans-cinnamylidene-m-toluidine (1) C₁₆H₁₅N, and N-trans-cinnamylidene-m-chloroaniline (2) C₁₅H₁₂NCl form isomorphous crystals which are monoclinic, space group P2_l/c, with unit cell dimensionsa=5.967(2),b=13.793(3),c=15.048(5) Å, =91.97(3)° anda=5.868(2),b=13.788(4),c=15.191(4) Å, =91.87(3)°, respectively. The single-crystal X-ray structure determinations of the title compounds revealtrans structures. Ring (A) C_10–15 and ring (B) C_1–6, are practically planar in both structures with dihedral angels of 61.3(3) and 63.6(2)°, respectively.¹H nmr, u.v. and i.r. spectra are also reported.     

Crystal structure and conformational analysis of N-formyl and N-nitroso derivatives of piperidinone

Single crystal X-ray studies for N-formyl-2,6-diortho chlorophenyl-3,5-dimethyl piperidin-4-one (FOCDMPO) and N-nitroso-2,6-di(3,4,5-trimethoxyphenyl)-3,5-dimethyl piperidin-4-one (NTMPO) are reported. Crystals of FOCDMPO and NTMPO belong to the monoclinic space groups P2₁/n and C2/c, respectively. FOCDMPO: a = 9.147(2), b = 14.586(3), c = 13.665(5) Å and = 101.68(2)° NTMPO: a = 38.52(2), b = 13.727(5), c = 9.564(3) Å and = 98.60(1)°. In both the structures, the piperidine ring adopts a boat conformation with slight distortion. In FOCDMPO, one of the phenyl and methyl groups are in axial positions while the other phenyl and methyl groups are in equatorial orientations. In NTMPO, the situation is reversed. The molecules are stabilized by weak intermolecular C—H ··· O interactions in addition to van der Waals forces.     

Surface topography and crystal and domain structures of films of ferroelectric copolymer of vinylidene difluoride and trifluoroethylene

The crystallization of a copolymer from a solution at room temperature is found to lead to the formation of a metastable structure, characterized by the coexistence of ferroelectric and paraelectric phases. The fraction of the latter decreases after annealing above the Curie point. Atomic force microscopy (AFM) has revealed a difference in the surface topographies between the films contacting with air and the films contacting with a glass substrate. The microstructure of copolymer chains has been investigated by ¹⁹F NMR spectroscopy. The chain fragments with “defect” attached monomeric units are ejected to the surface. The character of the ferroelectric domains formed during crystallization and their size distribution are analyzed.

     

Isothermal and Isochronal Studies of the Structural and Electrical Properties of CdTe

Cadmium telluride (CdTe) thin films were grown by thermal evaporation technique. The influence of post‐growth heat treatment, isothermal and isochronal, on the structural and electrical properties of these films were carried out. Multi phases were obtained as a function of the period and the value of annealing temperature. In isothermal annealing, the sheet resistance was dropped by many orders while in isochronal annealing it was increased fairly. A correlation between the temperature and the annealing time and the structural characteristics of these films was established in both type of annealing. The grain size and the sheet resistance were found greatly affected by the type of annealing as well as the temperature and the annealing time.     

Optical and structral properties of pure and Ce-doped nanocrystals of barium titanate

Nanocrystals barium titanate (nc-BT) and Ce-doped barium titanate were synthesized by an unusual hydrothermal process. X-ray diffraction and Raman spectroscopy were used to investigate their microstructures, as well as their lattice vibration and photoluminescence (PL) spectra. Particle sizes as small as 20 nm were measured by X-ray diffraction pattern via Scherer equation. The critical size relative to the cubic-tetragonal transition is about 48 nm in nc-BT below which ferroelectricity vanishes. The lattice parameter ratio c/a of is equal to 1.003, much smaller than 1.01 for that of the bulk crystal, leading to a weakening of ferroelectricity. Hydroxyl defects are observed in the Ce-doped nc-BT samples which show a vibrational band at 3300 em t. Good crystallization character and the lattice perfection were characterized by Raman spectra in the nanophase barium titanate. Strong PL spectra centered at 696 and 585 nm were observed in the pure and Ce-doped nc-BT, respectively. PL dependence on temperature and annealing time was examined. A molecule-like recombination and the charge transfer between Ce⁴⁺ and Ce ³⁺ are proposed to elucidate the luminescence process in the nc-BT and Cc-doped nc-BT system.     

Structure simulation and study of electronic and dielectric properties of two derivatives of benzamide

First-principles calculations based on density functional theory have been done on the chlorinated phenyl benzamides; 4-chloro-phenyl-benzamide – C13H10ClNO, and 2-chloro-3-chloro-phenyl-benzamide – C13H9Cl2NO. The triclinic structure of 4-chloro-phenyl-benzamide and orthorhombic structure of 2-chloro-3-chloro-phenyl-benzamide have been simulated and the structural parameters have been found out. Electron density of states has been computed in the materials using the electronic structure calculation code of Quantum-Espresso which gives a band gap of 0.74 eV in case of 4-chloro-phenyl-benzamide. This value is close to the value exhibited by semiconducting materials and photonic band gap materials. Band gap in case of 2-chloro-3-chloro-phenyl-benzamide comes out to be 3.08 eV. This value is in the range exhibited by NLO materials. Dielectric constant of the materials has been computed. The value of dielectric constant in 4-chloro-phenyl-benzamide comes out to be 2.78, 3.14, and 3.92 along X, Y, and Z axes, respectively, and the average value comes out to be 3.28. The value of dielectric constant in case of 2-chloro-3-chloro-phenyl-benzamide comes out to be 1.39, 1.53, and 1.34 along X, Y, and Z axes, respectively, and the average value comes out to be 1.42. Thus, additional chlorination is increasing the band gap and decreasing the dielectric constant in phenyl benzamide.     

Structures and properties of 1,4-dithiins and related molecules

A series of organosulfur compounds was characterized by NMR, IR, mass spectroscopy, cyclic voltammetry, and chemical analyses. The crystal structures of six compounds were determined: 1,3-dithioleno[4,5-e]naphtho[2,3-b]1,4-dithiin-2,5, 10-trione (1b), P , a = 7.665(4), b = 7.997(4), c = 11.443(5) Å, = 91.311(8), = 92.516(8), = 117.53(7)° 6,7-dimethylbenzo[1,2-b]1,3-dithioleno[4,5-e]1,4-dithiin-2,5,8-trione (2b), P2₁/m, a = 3.933(1), b = 12.864(2), c = 11.943(3) Å, = 99.161(4)° 6-phenyl-2-thioxo-6-hydrocyclopenta[2,1-b]1,3-dithioleno[4,5-e]1,4-dithiin-5,7-dione (3a), C2/c, a = 32.408(6), b = 3.8743(8), c = 27.123(5) Å, = 125.171(7)° 6-phenyl-1,3-dithioleno[4,5-e]3-pyrrolino[3,4-b]1,4-dithiin-5,7-trione (3b), P2₁/n, a = 7.9712(9), b = 6.1976(7), c = 55.978(6) Å, = 91.096(1)° 2,3,7,8-tetramethylthianthrene-1,4,6,9-tetraone (4), P2₁/c, a = 4.195(1), b = 17.924(5), c = 9.682(3) Å, = 98.509(5)° 3H,6H-1,4-oxathiino[6,5-2,1]naphtho[3,4-e]1,4-oxathiin-2,7-dione (5), P2₁/n, a = 9.3522(7), b = 7.8782(6), c = 17.118(1) Å, = 93.171(1)°. Several structures exhibited significant S—S intermolecular interactions, suggesting that the molecules might be precursors for preparing nonmetallic conductors.