X-ray diffraction study of p -(alkoxybenzylidene)- p ′-toluidines C5H11O-C6H4-CH=N-C6H4-CH3 and C8H17O-C6H4-CH=N-C6H4-CH3

The molecular and crystal structures of two p-(alkoxybenzylidene)-p′-toluidines C₅H₁₁O-C₆H₄-CH=N-C₆H₄-CH₃ (1) and C₈H₁₇O-C₆H₄-CH=N-C₆H₄-CH₃ (2), which form the nematic phase upon melting, is determined by X-ray diffraction. The geometry of the benzylideneaniline fragments in molecules 1 and 2 is actually identical. The crystal packings of 1 and 2 are characterized by the alternation of layers formed by loosely packed aliphatic fragments of molecules and layers of closely packed aromatic fragments. The packing in the aromatic regions of 1 follows the parquet pattern. The crystal packing of 2 has a stacking structure, which is formed by π-stacking dimers superimposed on one another. The formation of the mesogenic phase upon melting of crystals 1 is due to the disturbance of the structurality of loose aliphatic layers with retention of the structure of the aromatic regions, which are stabilized by the cooperative effect of weak directed C-H ··· π-system interactions. The mesogenic phase of crystals 2 is formed upon melting as a consequence of the retention of the structure of π-stacking dimers. Original Russian Text ? L.G. Kuz’mina, N.S. Kucherepa, M.N. Rodnikova, 2008, published in Kristallografiya, 2008, Vol. 53, No. 6, pp. 1079–1085.     

X-ray diffraction study of p -(alkoxybenzylidene)- p ′-toluidines C2H5O-C6H4-CH=N-C6H4-CH3 and C4H9O-C6H4-CH=N-C6H4-CH3

The molecular and crystal structures of two p-alkoxybenzylidene)-p′-toluidines C₂H₅O-C₆H₄-CH=N-C₆H₄-CH₃ (1) and C₄H₉O-C₆H₄-CH=N-C₆H₄-CH₃ (2) are determined by X-ray diffraction. Crystals 1 and 2 contain four and two crystallographically independent molecules, respectively. In 1, the geometry of the independent molecules is almost identical. In 2, the independent molecules differ in the conformation of the alkyl chain, which is disordered in one of them. An analysis of the crystal packing of 2 reveals the alternation of spacious layers formed by loosely packed aliphatic fragments of molecules and layers of closely packed aromatic fragments, which ensures the formation of the mesogenic phase in the course of melting of crystals 2. In crystal 1, loose aliphatic layers are absent. Original Russian Text ? L.G. Kuz’mina, N.S. Kucherepa, M.N. Rodnikova, 2008, published in Kristallografiya, 2008, Vol. 53, No. 6, pp. 1072–1078.     

Al2O3掺杂对Ca0.2Sr0.05Li0.375Sm0.375TiO3微波介电性能的影响

采用固相烧结法制备了掺杂Al2O3的Ca0.2Sr0.05Li0.375Sm0.375Ti O3微波介质陶瓷。研究了Al2O3掺杂对Ca0.2Sr0.05Li0.375Sm0.375Ti O3的助烧效果、物相结构、显微组织和微波介电性能的影响规律。结果表明:Al2O3的添加降低了Ca0.2Sr0.05Li0.375Sm0.375Ti O3陶瓷的烧成温度,但对物相基本无影响。此外,高含量Al2O3的添加能促进晶粒细化。此体系陶瓷的最佳介电性能为:Al2O3含量为0.9wt%且烧成温度为1250℃时,εr=110.8、Q·f=4159.6 GHzτf=49.4 ppm/℃。     

Bi4Si3O12-Bi4Ge3O12赝二元系统析晶行为及其晶体生长

本文采用固相合成方法制备了Bi4(GexSi1-x)3O12(BGSO)固溶体(x=0～0.4),研究了它的固溶特性和析晶行为。实验结果表明,不同组成混合料在900℃左右固相反应能生成BGSO纯相;XRD分析显示,在x=0～0.4区间内,Bi4Si3O12和Bi4Ge3O12可以完全互溶,其晶格常数随x的增加呈线性增长。采用坩埚下降法生长了x=0.15组成的BGSO混晶,获得了透明晶体,并测试了晶体的光学性能。     

Ba2Ti9O20-BaFe12O19复合陶瓷电磁性能的研究

本文采用流延成型法制备2-2型Ba2Ti9O20-BaFe12O19复合陶瓷。通过扫描电镜、能量散射光谱仪、X射线衍射、振动样品磁强计对复合陶瓷界面微观结构及磁、电性能进行了分析。结果表明:复合陶瓷的介电常数和介电损耗均大于单相Ba2Ti9O20,饱和磁化强度、剩余磁化强度均小于单相BaFe12O19,矫顽力大于单相BaFe12O19。随着烧结温度的升高,复合陶瓷的介电常数先增加后减小,介电损耗的变化则相反;饱和磁化强度、剩余磁化强度和矫顽力减小。在1180℃烧结4 h的复合陶瓷具有适合的磁、电性能:εr=115,tanδ=0.0054,Ms=21.9 A.m2/kg,Mr=12.5 A.m2/kg和Hc=63.0 kA/m。     

Invar effect in n-Nb2O5, αht-Nb2O5, and L-Nb2O5

An X-ray diffraction analysis of two commercial sets of niobium pentaoxide (Nb₂O₅) of Nbo-Pt grade has been performed. Each set reveals the coexistence of three modifications: n-Nb₂O₅, α_ht-Nb₂O₅, and L-Nb₂O₅. Anomalous behavior in the structural characteristics, with the occurrence of plateaus upon heating (the invar effect), is established for each phase. It is suggested that the coincidence of the temperature ranges with constant unit-cell parameters in Nb₂O₅ and complex Nb-containing oxides indicates the unified nature of the invar effect, which is related to the defect state of objects under study. Original Russian Text ? L.A. Reznichenko, V.V. Akhnazarova, L.A. Shilkina, O.N. Razumovskaya, S.I. Dudkina, 2009, published in Kristallografiya, 2009, Vol. 54, No. 3, pp. 517–526.     

Zn0.99Cu0.01Al2O4-SrTiO3微波陶瓷介电性能的研究

以分析纯Zn O、Cu O、Al2O3、Ti O2以及Sr CO3为原料,采用传统固相法制备了(1-x)Zn0.99Cu0.01Al2O4-x Sr Ti O3(ZCAST,x=0~0.045)微波介质陶瓷,利用X射线衍射仪、扫描电镜和网络分析仪对其结构、形貌和微波介电性能进行表征。研究了不同x值对ZCAST陶瓷相组成、显微结构以及微波介电性能的影响。结果表明,ZCAST陶瓷的体积密度、介电常数εr随着Sr Ti O3含量的增多而增大。当x=0.04具有最佳微波介电性能:介电常数εr=14.12,品质因数Q×f=28700 GHz,频率温度系数τf=-1.8×10-6/℃。     

Characterization and synthesis of Y0.9Ca0.1Ba1.8Sr0.2Cu3O7−δ via combining sol-gel and solid-state route

We applied the conventional sol-gel and solid-state reactions in this study to prepare double-substituted superconducting Y_0.9Ca_0.1Ba_1.8Sr_0.2Cu₃O_7−δ. The result and the effect of calcium and strontium doping on high-T_c compound Y-123 have been investigated. The precursor gel Ca-Ba-Sr-Cu-O was prepared by acetate-tartrate sol-gel route which involved hydrolysis and olation (polycondensation). Y_0.9Ca_0.1Ba_1.8Sr_0.2Cu₃O_7−δ was obtained by solid-state reaction between Y₂O₃ and Ca-Ba-Sr-Cu-O heated at 880 °C for 18 h with step cooling 50 °C/h until 450 °C. Without oxygen flow during the whole annealing process, the sample still showed good superconducting properties with T_c-zero close to 80 K. The presence of organic material in the sol-gel precursor Ca-Ba-Sr-Cu-O is nucleophile species, which is chemically reactive to Y₂O₃ during solid-state reaction thus enhance the diffusion rate. Moreover, -OH group in the precursor gel has ability to provide a sufficient amount of oxygen for the sample to stabilized the multicomponent superconductor.     

K0.5Na0.5NbO3掺杂对0.94Bi0.5Na0.5TiO3-0.06BaTiO3陶瓷储能性能的影响

采用传统固相反应法制备了K_0.5Na_0.5NbO₃(KNN)掺杂的无铅介电储能陶瓷BNT-BT-KNN,其组分配比为0.94Bi_0.5Na_0.5TiO₃-(0.06-x)BaTiO₃-xK_0.5Na_0.5NbO₃(BNT-BT+xKNN,x=0.00～0.04),并研究了KNN掺杂对BNT-BT基陶瓷材料晶相、微观结构、介电、铁电性能及储能的影响。结果表明：在1 150℃温度下烧成后的陶瓷样品具有纯的钙钛矿结构,且样品的晶粒均匀致密;介电温谱显示,添加KNN后的BNT-BT铁电陶瓷在T_m处的介电峰进一步宽化,表现出更好的温度稳定性和弛豫性;同时随着KNN掺杂量的增加,样品的电滞曲线(P-E曲线)逐渐由“宽胖型”向“细长型”转变,样品的剩余极化强度(P_r)逐渐降低,从而进一步提高了BNT-BT陶瓷的储能性能。在2 kV/mm的场...     

Synthesis and X-ray structural investigation of (C3N6H7)4(CN3H6)2[UO2(CrO4)4] · 4H2O and (H3O)6[UO2(CrO4)4]

Single crystals of the compounds (C₃N₆ H₇)₄(CN₃H₆)₂[UO₂(CrO₄)₄] · 4H₂O (I) and (H₃O)₆[UO₂(CrO₄)₄] (II) are synthesized, and their structures are investigated using X-ray diffraction. Compound I crystallizes in the triclinic system with the unit cell parameters a = 6.3951(8) ?, b = 10.8187(16) ?, c = 16.9709(18) ?, α = 93.674(4)°, β = 97.127(4)°, γ = 92.020(4)°, space group, P Z = 1, V = 1161.6(3) ?³, and R = 0.0470. Crystals of compound II belong to the monoclinic system with the unit cell parameters a = 14.3158(4) ?, b = 11.7477(3) ?, c = 13.1351(4) ?, β= 105.836(1)°, space group C2/c, Z = 4, V = 2125.2(1) ?³, and R = 0.0213. The uranium-containing structural units of crystals I and II are mononuclear anionic complexes of the composition [UO₂(CrO₄)₄]⁶⁻ with an island structure, which belong to the crystal-chemical group Am ₁⁴ (A = UO₂₊², M ¹ = CrO₂₋⁴) of the uranyl complexes. The [UO₂(CrO₄)₄]⁶⁻ anionic complexes are joined into a three-dimensional framework through the electrostatic interactions with outer-sphere cations and a system of hydrogen bonds. Original Russian Text ? L.B. Serezhkina, E.V. Peresypkina, A.V. Virovets, A.G. Verevkin, D.V. Pushkin, 2009, published in Kristallografiya, 2009, Vol. 54, No. 2, pp. 284–290.     

0.2wt% Bi2O3、CuO、B2O3对5Ca0.6La0.267TiO3-5Ca(Mg1/3Nb2/3)O3微波介质陶瓷的性能影响

采用传统的固相反应法,研究了三种烧结助剂Bi2O3、CuO、B2O3对5Ca0.6La0.267TiO3-5Ca(Mg1/3Nb2/3)O3微波介质陶瓷的烧结性能和介电性能的影响。实验结果表明,掺入0.2wt%的Bi2O3、CuO、B2O3产生了液相,有效地降低了体系的烧结温度。Bi2O3和CuO的加入没有改变烧结体的微观形貌,它们介电常数和品质因数随烧结温度的变化趋势和体积密度趋于一致,均在体积密度最大时最高。当温度大于1300℃时,加入0.2wt%B2O3试样有柱状晶体生成,并随着烧结温度的升高而增多,柱状晶体的存在可能促使Q×f值较大的提高,当烧结温度过高时(1350℃),由于柱状晶体过多使得烧结体不均匀导致Q×f值下降。Bi2O3、CuO、B2O3的加入没有改变烧结体的晶相组成,因此所有烧结体均有近零的温度系数。结果表明,加入0.2wt%B2O3的5Ca0.6La0.267TiO3-5Ca(Mg1/3Nb2/3)O3在1325℃烧结温度具有最佳的介电性能:εr=54.87,Q×f=55 726 GHz,τf=-0.6 ppm/℃。     

Synthesis and structure of {NH2(C2H5)2}2[(UO2)2(C2O4)(CH3COO)4] · 2H2O

Single crystals of the compound {NH₂(C₂H₅)₂}₂[(UO₂)₂C₂O₄(CH₃COO)₄] · 2H₂O (I) are synthesized, and their structure is investigated using X-ray diffraction. Compound I crystallizes in the monoclinic system with the unit cell parameters a = 9.210(2) ?, b = 14.321(3) ?, c = 12.659(3) ?, β = 105.465(13)°, V = 1609.2(6) ?³, space group P2₁/c, Z = 2, and R = 0.0198. The structural units of crystals I are binuclear groups of the composition [(UO₂)₂C₂O₄(CH₃COO)₄]²⁻ with an island structure, which belong to the crystal-chemical group A ₂ K ⁰² B ₄⁰¹ (A = UO₂²⁺, K ⁰² = C₂O₄²⁻, B ⁰¹ = CH₃COO⁻) of the uranyl complexes, diethylammonium cations, and water molecules. The uranium-containing groups are joined into a three-dimensional framework through electrostatic interactions with diethylammonium cations and a system of hydrogen bonds, which are formed with the participation of the atoms involved in the composition of the water molecules, oxalate ions, acetate ions, and diethylammonium cations. Original Russian Text ? L.B. Serezhkina, A.V. Vologzhanina, N.A. Neklyudova, V.N. Serezhkin, 2009, published in Kristallografiya, 2009, Vol. 54, No. 1, pp. 65–67.     

Fe2O3掺杂(Ba0.7Ca0.3)TiO3-Ba(Zr0.2Ti0.8)O3无铅压电陶瓷的制备与性能

采用固相合成法制备了Fe2O3掺杂(Ba0.7Ca0.3)TiO3-Ba(Zr0.2Ti0.8)O3(简称BCZT)无铅压电陶瓷。借助XRD、SEM、阻抗分析仪等对该陶瓷的相组成、显微结构以及压电和介电性能进行了研究。结果表明,Fe2O3掺杂降低了BCZT无铅压电陶瓷的烧结温度并使居里温度Tc从85℃提高到95℃;当Fe2O3掺杂为0.02wt%～0.1wt%时,陶瓷样品均为ABO3型钙钛矿结构;少量Fe2O3掺杂促进了陶瓷晶粒的生长,但随着Fe2O3掺杂量进一步增加,陶瓷晶粒随之细化;当Fe2O3掺杂量为0.04wt%时,陶瓷样品具有最优综合电性能,其压电常数d33、机电耦合系数kp、机械品质因数Qm、介电损耗tanδ和介电常数εr分别为400 pC/N,0.40,51,0.023和3482。     

Sandwich-Type Manganese-Substituted Polyoxometalate, [(α-B-ZnW9O34)2W2Mn2(H2O)2]8?

Abstract  

The novel dimeric manganese-substituted polyoxotungstate Na₁₀[(α-B-ZnW₉O₃₄)₂W₂Mn₂(H₂O)₂](OH)₂·34H₂O (1) has been designed and synthesized from the hydrothermal reaction of Na₂WO₄·2H₂O, MnCl₂·4H₂O, and ZnCl₂ in a Teflon-lined stainless steel autoclave at 140°. X-ray diffraction analysis results reveal that compound (1) crystallizes in the monoclinic system, space group P2(1)/n, with a = 13.0901(3) ?, b = 17.8242(4) ?, c = 21.2401(5) ?, β = 93.6380(10)°, Z = 1, V = 4945.8(2) ?³, F(000) = 5244, Dc = 3.974 g/cm⁻³, μ(Mo-Kα) = 2.4037 cm⁻¹, λ(Mo-Kα) = 0.71073 ?. The structure was refined to R = 0.0631 and wR = 0.1532. The polyoxoanion of [(α-B-ZnW₉O₃₄)₂W₂Mn₂(H₂O)₂]⁸⁻ consist of two Keggin lacunary α-B-ZnW₉O₃₄ ¹²⁻ moieties linked via a rhomblike W₂Mn₂O₁₆ group leading to a sandwich-type structure.     

Investigations of 2-Thiazoline-2-thiol as a Ligand: Synthesis and X-ray Structures of [Mn2(CO)7(μ-NS2C3H4)2] and [Mn(CO)3(PPh3)(κ2-NS2C3H4)]

Abstract  Treatment of Mn₂(CO)₁₀ with 2-thiazoline-2-thiol in the presence of Me₃NO at room temperature afforded the dimanganese complexes [Mn₂(CO)₇(μ-NS₂C₃H₄)₂] (1) and [Mn₂(CO)₆(μ-NS₂C₃H₄)₂] (2) in 51 and 34% yields, respectively. Compound 1 was quantitatively converted into 2 when reacted with one equiv of Me₃NO. Reaction of 1 with triphenylphosphine at room temperature furnished the mononuclear complex [Mn(CO)₃(PPh₃)(κ ²-NS₂C₃H₄)] (3) in 66% yield. All three new complexes have been characterized by elemental analyzes and spectroscopic data together with single crystal X-ray diffraction studies for 1 and 3. Compound 1 crystallizes in the orthorhombic space group Pbca with a = 12.4147(2), b = 16.2416(3), c = 19.0841(4) ?, β = 90°, Z = 8 and V = 3848.01(12) ?³ and 3 crystallizes in the monoclinic space group P 2₁/n with a = 10.41730(10), b = 14.7710(2), c = 14.9209(2) ?, β = 91.1760(10)°, Z = 4 and V = 2295.45(5) ?³. Graphical Abstract  Two new dimanganese complexes [Mn₂(CO)₇(μ-NS₂C₃H₄)₂] (1) and [Mn₂(CO)₆(μ-NS₂C₃H₄)₂] (2) were formed when [Mn₂(CO)₁₀] was treated with 2-thiazoline-2-thiol in the presence of Me₃NO. Compound 2 reacts with PPh₃ to give the monomeric complex [Mn(CO)₃(PPh₃ )(κ ²-NS₂C₃H₄)]. The structures of 1 and 3 were established by crystallography. Shishir Ghosh, Faruque Ahmed, Rafique Al-Mamun, Daniel T. Haworth, Sergey V. Lindeman, Tasneem A. Siddiquee, Dennis W. Bennett, Shariff E. Kabir Investigations of 2-thiazoline-2-thiol as a ligand: Synthesis and X-ray structures of [Mn₂(CO)₇(μ-NS₂C₃H₄)₂] and [Mn(CO)₃ (PPh3)(κ ²-NS₂C₃H₄)].      

Reactivity of [Re2(CO)8(MeCN)2] With 1-vinylimidazole: X-ray Structures of [Re2(CO)8{η1-NC3H3N(CH=CH2)}2] and [ReCl2(CO)2{η1-NC3H3N(CH=CH2)}2]

Abstract  Treatment of [Re₂(CO)₈(MeCN)₂] with excess 1-vinylimidazole in refluxing benzene gives three new compounds [Re₂(CO)₉{η ¹-NC₃H₃N(CH=CH₂)}] (1), [Re₂(CO)₈{η ¹-NC₃H₃N(CH=CH₂)}₂] (2) and [ReCl₂(CO)₂{η ¹-NC₃H₃N(CH=CH₂)}₂] (3) in 11, 32 and 2% yields, respectively. The solid-state structures of complexes 2 and 3 have been determined by single crystal X-ray diffraction studies. Compound 2 crystallizes in the monoclinic space group C2/c, with lattice parameters a = 13.8378(5) ?, b = 11.8909(5) ?, c = 14.4591(6) ?, β = 116.6470(10)°, Z = 4 and V = 2131.99(15) ?³. Compound 3 crystallizes in the monoclinic space group C2/c, with lattice parameters a = 10.1028(3) ?, b = 13.5640(5) ?, c = 12.5398(4) ?, β = 109.637(2)°, Z = 4 and V = 1618.4(9) ?³. The disubstituted dinuclear compound 2 contains two 1-vinylimidazole ligands coordinated through the imino nitrogen atoms at the equatorial sites, whereas the mononuclear compound 3 contains two carbonyl ligands, two N coordinated η ¹-1-vinylimidazole ligands and two terminal Cl ligands. Graphical Abstract  Two dinuclear complesxes [Re₂(CO)₉{η ¹-NC₃H₃N(CH=CH₂)}] (1) and [Re₂(CO)₈{η ¹-NC₃H₃N(CH=CH₂)}₂] (2) and the mononuclear [ReCl₂(CO)₂{η ¹-NC₃H₃N(CH=CH₂)}₂] (3) were obtained from the reaction of [Re₂(CO)₈(MeCN)₂] with excess 1-vinylimidazole at 80 °C. The X-ray structrures of 2 and 3 are described.      

Synthesis and Structural Studies of [Na(C7H6O4)(H2O)3](C7H5O4)?·?2H2O

Abstract  The mononuclear complex [Na(C₇H₆O₄)(H₂O)₃](C₇H₅O₄) · 2H₂O has been synthesized and characterized by IR, single crystal X-ray and thermal analysis. The compound crystallizes in the monoclinic space group P2₁ with a = 3.623(2) ?, b = 15.872(6) ?, c = 15.650(5) ?, β = 93.13(4)°, V = 896.6(7) ?³ and Z = 2. The central sodium ion is six coordinated with distorted octahedral geometry by two oxygen atoms from two bridging 3,5-dihydroxybenzoate ligands and four ones from different water molecules. The notable feature of the title complex is the formation of a three-dimensional network, through the combination of coordination bonds, hydrogen bonds and π···π interactions. There are one-dimensional channels in the structure, filled in by water molecules. The compound dehydrates in the temperature range of 70–125 °C and then is stable up to 230 °C. Index Abstract  The mononuclear complex [Na(C₇H₆O₄)(H₂O)₃](C₇H₅O₄) · 2H₂O has been synthesized and characterized by IR, single crystal X-ray and thermal analysis.      

Synthesis and X-ray structural investigation of K8[(UO2)2(C2O4)2(SeO4)4] · 2H2O

Single crystals of the compound K₈[(UO₂)₂(C₂O₄)₂(SeO₄)4] · 2H₂O (I) are synthesized, and their structure is investigated using X-ray diffraction. Compound I crystallizes in the monoclinic system with the unit cell parameters a = 14.9290(4) ?, b = 7.2800(2) ?, c = 15.3165(4) ?, β = 109.188(1)°, V = 1572.17(7) ?³, space group P2₁/n, Z = 2, and R = 0.0297. The uranium-containing structural units of crystals I are dimers of the composition [(UO ₂)₂(C₂O₄)₂(SeO₄)₄]⁸⁻, which belong to the crystal-chemical group AB ⁰¹ B ² M ¹ (A = UO₂²⁺, B ⁰¹ = C₂O₄²⁻, B ² = SeO₄²⁻, M ¹ = SeO₄²⁻) of the uranyl complexes. The [(UO₂)₂(C₂O₄)₂(SeO₄)₄]⁸⁻ dimers are joined into a three-dimensional framework through electrostatic interactions with the outer-sphere potassium cations. Original Russian Text ? L.B. Serezhkina, E.V. Peresypkina, A.V. Virovets, A.G. Verevkin, D.V. Pushkin, 2009, published in Kristallografiya, 2009, Vol. 54, No. 1, pp. 68–71.     

Synthesis and structure of K2[(UO2)4(O)2(OH)2(C2O4)(CH3COO)2(H2O)2]·2H2O

Single crystals of the compound K₂[(UO₂)₄(O)₂(OH)₂(C₂O₄)(CH₃COO)₂(H₂O)₂]·2H₂O (I) are synthesized, and their structure is investigated using X-ray diffraction. Crystals of compound I belong to the triclinic system with the unit cell parameters a = 7.6777(6) ?, b = 7.9149(7) ?, c = 10.8729(9) ?, α = 72.379(2)°, β = 86.430(3)°, γ = 87.635(2)°, V = 628.33(9) ?³, space group P , Z = 1, and R ₁ = 0.0323. The main structural units of the crystals are [(UO₂)₄(O)₂(OH)₂(C₂O₄)(CH₃COO)₂(H₂O)₂]²⁻ chains, which belong to the crystal-chemical group A ₄ M ₂³ M ₂² K ⁰² B ₂⁰¹ M ₂¹ (A = UO₂²⁺, M ³ = O²⁻, M ² = OH⁻, K ⁰² = C₂O₄²⁻, B ⁰¹ = CH₃COO⁻, M ¹ = H₂O) of the uranyl complexes. The chains are formed by linking the centrosymmetric tetramers of the composition (UO₂)₄(O)₂(OH)₂(CH₃COO)₂(H₂O)₂ via tetradentate bridging oxalate ions. The uranium-containing groups are joined into a three-dimensional framework through the electrostatic interaction with potassium cations and a system of hydrogen bonds, which are formed with the participation of atoms involved in the composition of the water molecules, hydroxide ions, and uranyl ions. Original Russian Text ? L.B. Serezhkina, A.V. Vologzhanina, N.A. Neklyudova, V.N. Serezhkin, 2009, published in Kristallografiya, 2009, Vol. 54, No. 3, pp. 483–487.     

Sr2+和F-对Ca7Si2O8Cl6:Eu2+荧光粉发光性能的影响

采用高温固相法制备了系列蓝绿色Ca7Si2O8Cl6∶Eu2+荧光粉,并对样品进行了XRD分析、发光性能和色参数的测试。结果表明,合成的样品为单相Ca7Si2O8Cl6;在紫外光激发下,样品呈现一个不对称宽峰结构;分别监测这个发射峰,得到一个较宽的激发谱。同时研究了在样品中分别加入Sr2+和F-后荧光粉的激发和发射光谱,得到了这些离子的加入量与样品发光性能的关系,并探究了发生该现象的原因。结果表明,加入Sr2+或F-后可以得到较好的蓝绿色发光材料。