离子型晶体的点电荷电量的确定和晶体的化学键性质MX(M=Mg,Ca,Sr,Ba,X=O,S,Se,Te;不含MgTe)

离子型晶体的点电荷电量的确定和晶体的化学键性质ＭＸ（Ｍ＝Ｍｇ，Ｃａ，Ｓｒ，Ｂａ，Ｘ＝Ｏ，Ｓ，Ｓｅ，Ｔｅ；不含ＭｇＴｅ）孟庆波武志坚张思远（中国科学院长春应用化学研究所稀土无机材料实验室，长春１３００２２）ＮｅｔＣｈａｒｇｅａｎｄＣｈｅｍｉｃａｌＢｏｎ...

稀土对Al-Mg-Si建筑铝型材性能的影响

研究了稀土对Ａｌ－Ｍｇ－Ｓｉ建筑铝型材性能的影响。其微观结构及组成采用金相显微镜、扫描电子显微镜及光电子能谱分析，同时测量了样品的机械强度和耐蚀性能。结果表明其挤压预热温度降至４３０℃，速度达到６．２８～７．３６ｍｍ／ｓ，在Ａｌ－Ｍｇ－Ｓｉ材料中加入适量的稀土可以细化晶粒并且增加了材料的机械强度和耐蚀性能。

稀土对高强Al-Zn-Mg-Cu合金耐蚀性能的影响

采用化学失重法，考察了稀土对Al－Zn－Mg－Cu高强铝合金耐腐蚀性能的影响。研究结果表明，在不同介质中，加稀土的Al-Zn-Mg-Cu比Al-Zn-Mg-Cu高强铝合金有较高的耐腐蚀性能，在还原性介质中的耐腐蚀性更好。稀土含量控制在0．05％为宜。

Luminescence of Pb2+ and energy transfer from Pb2+ to rare earth ions in silicate oxyapatites

The Pb2+ luminescence in a series of silicate oxyapatites Me(2)(Y, Gd)(8)(SiO4)(6)O-2, Me(4)Y(6)(SiO4)(6)O (Me = Mg: Ca, Sr) is reported and discussed in relation to the crystal structure. The maximum wavelengths of the excitation (S-1(0)-P-3(1)) and emission (P-3(1)-S-1(0)) bands of Pb2+ are independent of the Mc:Y ratio (2:8 or 4:6) but they have lower energies in MgY-oxyapatites than in CaY- and SrY-oxyapatites. The Stokes shift of Pb2+ luminescence amounts to 11 100 to 11 400 cm(-1): which does not depend strongly on the host composition. There exists a mutual energy transfer between Pb2+ and Gd3+ in Sr2Gd8(SiO4)(6)O-2. At last, the dependence of the energy transfer efficiency of Pb2+-Sm3+, Tb3+: Dy3+ in Sr-2(La: Gd)(8)(SiO4)(6)O-2 and Ca-2(Y, Gd)(8)(SiO4)(6)O-2 on their doping concentrations was studied in more detail.

The reactivity of lanthanide alkyl compounds with phenylacetylene: Synthesis and structure of [(Bu(t)Cp)(2)LnC CPh](2) (Ln=Nd, Gd)

[(Bu(t)Cp)(2)LnCH(3)](2) (Ln = Nd, Gd) react with PhC=CH to form the dimeric alkynide-bridged complexes [(Bu(t)Cp)(2)LnC=CPh](2) [Ln = Nd (I), Gd (II)]. Both compounds crystallized from toluene in the monoclinic space group C2/c. The two complexes are homologous, composed of asymmetric metal-alkynide bridges with Nd-C, Gd-C (alkynide) bond lengths of 2.602(4), 2.641(5) (I) and 2.532(6), 2.601(7) Angstrom (II), respectively. The average Nd-C (ring) and Gd-C (ring) distances are 2.746(13) and 2.703(19)Angstrom.

High-yield Synthesis and Extraction of Gd@C-2n

Endohedral metallofullerene Gd@C-2n were synthesized with high-yield using the carbon-arc discharge method of activating the Gd2O3-containing graphite anode in situ and back-burning technique. A series of Gd@C-2n for 2n from 70 to 96 were effectively extracted by toluene at high-temperature and under high-pressure condition. Gd@C-82, Gd@C-74 were considered to be fairly stable and soluble metallofullerene species.

The phase transitions of hetero atoms substituted molecular sieves Me-VPI-5(Me=Mg, Ti, Sn, Si) and their influence on spectra structures of Eu(III) ion

The hetero atom substituted aluminophosphate molecular sieves Me-VPI-5(Me = Mgt Ti, Sn, Si) were synthesized hydrothermally. Rare earth ions are originally doped into these microporous materials by aqueous solution ion exchange procedures. The phase transitions of the microporous materials are investigated by high-temperature and high-pressure experimental techniques. The influence of the phase transitions on the rare earth ions' spectral structures is discussed, With the increase of temperature, Eu(II)Mg-VPI-5 is converted into Eu(II)Mg-AIPO(4)-8, then into tridymite phase. The pressure has a notable influence on Eu(II) ion's spectral structures. The spectral structures have changed regularly with the increase of pressure.

Preparation, structure and some physical properties of scheelite-related AgLnMo(2)O(8) compounds

We present the synthesis of the AgLnMo(2)O(8) oxides with Ln = La-Nd, Sm, Gd, Tb and Y. These compounds represent a scheelite-related structure type characterized by MoO42- tetrahedrons. The IR spectra show three transmittance bands in the region of 1000-400 cm(-1), which correspond respectively to the nu(1), nu(2), and nu(3) modes of the tetrahedral MoO42- groups. All of AgLnMo(2)O(8) are insulator materials at room temperature. The temperature dependence of the magnetic susceptibilities of AgLnMo(2)O(8) (Ln = Ce-Nd, Sm, Gd, Tb) show Curie-Weiss Law behaviors with two anomalies occurring at low temperature, whereas AgLaMo2O8 and AgYMo2O8 both exhibit diamagnetic properties as expected. The magnetic moments at room temperature fit very well with those corresponding to rare earth sesquioxides. This suggests that rare earth ions exist in +3 oxidation state in all AgLnMo(2)O(8) compounds.

Synthesis and crystal structure of (eta(8)-C8H8)Gd(eta(5)-C6H5CH2C5H4)center dot DME

LnCl(3) reacted with C6H5CH2C5H4Na in THF (tetrahydrofuran) in the ratio 1.1 at room temperature for 1 h giving C(6)H(5)CH(2)C(6)H(4)LnCl(2) . nTHF, which reacted with C8H8K2/THF and the crystals obtained were recrystallized in DME to yield the title complex. The crystal structure of (C8H8) Ln (C6H5CH2C5H4). DME was determined revealing that the Gd complex has one conformation. One benzylcyclopentadienyl (eta(5)), one cyclooctatetraenyl (eta(8)) and the two oxygen atoms of DME (dimethoxyethane) are coordinated to Gd with the effective coordination number of 10.

杂原子Me－VPI－5（Me＝Mg，Ti，Sn，Si）相转变及其对Eu（Ⅲ）光谱结构的研究

用水热同晶置换法合成了杂原子磷酸铝分子筛Ｍｅ－ＶＰＩ－５（Ｍｅ＝Ｍｇ，Ｔｉ，Ｓｎ，Ｓｉ）．通过水相离子交换法掺杂稀土离子，考察了高温和高压下的相变行为．讨论了相变过程对稀土离子光谱的影响．随着温度升高，Ｅｕ（Ⅲ）Ｍｇ－ＶＰＩ－５先转变为Ｅｕ（Ⅲ）－ＡｌＰＯ４－８，然后又转变成致密的磷石英相．压力对Ｅｕ（Ⅲ）光谱结构具有显著影响．随着压力增加，Ｅｕ（Ⅲ）光谱结构发生规律性变化．

Ce~（3＋）在钙钛矿型KMF_3（M＝Mg、Ca、Sr、Ba）基质中的发光特性

采用高温固相反应法，在Ａｒ气氛中合成了ＫＭＦ３（Ｍ＝Ｍｇ、Ｃａ、Ｓｒ、Ｂａ）基质化合物和掺杂Ｃｅ３＋的磷光体。经Ｘ射线衍射分析确定，ＫＭｇＦ３和ＫＣａＦ３属于立方晶系、钙钛矿型结构，ＫＳｒＦ３和ＫＢａＦ３具有类似的结构。测定了ＫＭＦ３∶Ｃｅ３＋的发光光谱，观察到与其结构对应的分为二种不同的光谱结构，讨论了Ｃｅ３＋的取代格位

Studies on the synthetic, structural, electrical and magnetic properties of Ln(n)MCo(n)O(3n+1) (Ln=Sm, Gd; M=Sr, Ba; n=1,2)

Three new oxides Sm2SrCo2O7, Sm2BaCo2O7 and Gd2SrCo2O7 have been synthesized successfully by solid state reaction mathod. The X-Ray diffraction spectra show that they are all isostructural with Sr3Ti2O7, and Ln(2)SrCo(2)O(7)(Ln=Sm,Gd) crystallized in tetragonal system, Sm2BaCo2O7 in orthrhombic system. The Co-O bonds in CoO2 planes of Ln(2)SrCo(2)O(7) are shorter than those of LnSrCoO(4)(Ln=Sm, Gd), and so their delectrons are more delocalized and their electrical resistivities are smaller. The electrical resistivities versus temperature in the range 300 similar to 1100K showed that the five brides show the characters of weakly localized systems. In the lower temperature range, the magnetic behaviors of Gd2SrCo2O7 and GdSrCoO4 fit Curie-Weiss law well, and the magnetic exchange reaction in CoO2 sublattices of Gd2SrCo2O7 is ferromagnetic, but that of GdSrCoO4 is antiferromagnetic. The other three oxides with Sm3+ showed complex magnetic behaviors which is perhaps related with the complexity of Sm3+.

EXTENDED SOLUBILITY AND SPIN-GLASS BEHAVIOR IN A AG-GD SOLID-SOLUTION PREPARED BY MECHANICAL ALLOYING

The effects of mechanical alloying on the solubility in a Ag-Gd solid solution have been investigated. The study shows that the solubility of Gd in Ag can be extended to about 5 at. % Gd by mechanical alloying from the equilibrium solubility of less than 0.95 at. % Gd. Ag85Gd15 prepared by mechanical alloying exhibits a spin-glass-type transition at similar to 5 K. A Curie-Weiss behavior at higher temperatures and x-ray patterns of the material indicate that Gd atoms are either dissolved in the Ag matrix or in the form of small clusters of diameters of a few nanometers;

LUMINESCENCE OF DY3+ ENHANCED BY SENSITIZATION

Four types of sensitized luminescence of Dy3+ are reported: (1) by a host having a broad-band spectrum as in Na3Y0.99Dy0.01(VO4)(2); (2) by a sensitizer having a broad-band spectrum as in Ca2B2O5:Dy3+, Bi3+; (3) by a sensitizer having a narrow-band spectrum as in Mg2Gd7.9Dy0.1(SiO4)(6)O-2; (4) by a sensitizer having a broad-band spectrum and energy migration as in Gd compounds such as Ca1.96Pb0.04Gd7.9Dy0.1(SiO4)(6)O-2. The luminescent intensity of Dy3+ can be enhanced in these ways.