Systemes CuX (X = Cl,Br)HgS. etude des composes CuHgSX (X = Cl,Br)

Powder samples of CuHgSCl and CuHgSBr have been synthesized, they crystallize in an orthorhombic structure, space group Pbam. The structure is built up of a three dimensional network of SHgS chains in z = 0 planes connected together with CuS₂X₂ (X = Cl, Br) tetrahedrons. S and X atoms build up a distorted cubic centered lattice.     

Cu magic angle spinning (MAS) nuclear magnetic resonance (NMR) study of CuX crystals (X=Cl, Br, and I) and CuX-based glasses (X=Cl, Br, and I)

⁶³Cu MAS NMR spectra of CuX crystals (X=Cl, Br, and I) and CuX-based glasses (X=Cl, Br, and I) have been measured. The CuCl and CuI crystals gave the isotropic chemical shift values around 0 ppm, and the CuBr crystal, around −55 ppm. The peak positions of the chlorocuprate(I), bromocuprate(I), and iodocuprate(I) glasses were very close to those of the CuX crystals, respectively. This result indicates that these glasses mainly consist of CuX₄ tetrahedra (X=Cl, Br, and I). The halogen coordination environments around Cu⁺ in bromochlorocuprate(I) glasses were dependent on the kind of modifying cation and the Br⁻/(Cl⁻+Br⁻) ratio. The bromochlorocuprate(I) glasses were mainly composed of CuCl_mBr_4−m or CuCl_nBr_4−n tetrahedra (m=0, 1, 2, and 4; n=0, 1, and 4).     

New halide glasses of the CdX2-PbX2-KI (X=Cl,Br) systems

The glass forming regions and some properties of the CdBr₂-PbBr₂-KI (10 to 50 mol % CdBr₂, 10 to 70 mol % PbBr₂, 20 to 40 mol % KI), CdCl₂-PbBr₂-KI (10 to 50 mol % CdCl₂, 10 to 80 mol % PbBr₂, 10 to 70 mol % KI) and CdCl₂-PbCl₂-KI (20 to 50 mol % CdCl₂, 10 to 70 mol % PbCl₂, 5 to 60 mol % KI) ternary systems were studied. Glasses exhibit remarkably high transmittance (up to 80%) in the visible and IR region (down to 250 cm^–1 for CdBr₂-PbBr₂-KI, 300 cm^–1 for CdCl₂-PbBr₂-KI and 400 cm^–1 for CdCl₂-PbCl₂-KI for 1 mm thick plates). The values of glass transition temperature lie between 343 to 353 K and crystallization temperature between 343 to 403 K.     

PbX2（X：I,Br,Cl）基非氟卤化物玻璃的形成行为

为了获得具有实用意义的非氟卤化物玻璃，有必要探索新的玻璃形成系统，本文获得了 新的Ｃ ＰｂＸ２（Ｘ：Ｉ，Ｂｒ，Ｃｌ）为基质的三元非氟卤化物玻璃形成系统，并且首次发现ＰｂＩ２可以单独形成玻璃，所得的三元玻璃形成系统均表现出了良好的玻璃形成能力，此外，还从晶体结构，化学键的特怀，离了半径应电负性等角度探讨了各卤化物在玻璃形成过程中所坊的作用，结果表明，这些因素对玻璃形成均具有重要的作用。     

Structural, Spectroscopic Studies and Magnetic Properties of Doped Sillenites-Type Oxide Bi12[M]O20 M=Fe, Co

Layered structure of sillenites-type oxides Bi₁₂MO₂₀, the M position can be occupied by tetravalent or trivalent cations. This study focuses in Bi₁₂MO₂₀, M=Co, Fe, and Co/Fe, polycrystalline samples which are prepared by the solid-state reaction method. Infrared (IR) optical absorption, Raman scattering, and Foner magnetometer (BS2) techniques were used for systematic characterization of sillenite type oxide. IR and Raman scattering results showed the appearance of a band, at 850 cm^?1 and at 680 cm^?1, attributed to the (MO₄)^?3. Magnetic susceptibility measurements of all samples were done in a temperature range 2–300 K. The interaction of the M cations with each other through M–O–M linkages of approximately 180^° is expected to be dominant, and this would be paramagnetic in nature.     

Electrical relaxation of superionic conducting glasses AgX-AgPO3 (X=I,Br, Cl)

The complex impedance of superionic conducting glasses (AgX)_0.3-(AgPO₃)_0.7 (X = I, Br, Cl) was measured in the frequency range 5 Hz–500 kHz and temperatures between 299 K and 348 K. The frequency dependence of (the real part of complex conductivity) shows two regions: low and high frequencies. The first is attributed to the electrode-electrolyte polarization, while the second is attributed to the bulk conduction. The replacement of AgCl by AgBr or Agl at the same molar fraction is found to improve the bulk conductivity of the studied glasses. The electrical conductivity spectra exhibit one relaxation peak associated with dielectric loss which arises from the thermally activated jumps of Ag⁺ ions. The dependence of the relaxation time upon the halogen type is discussed in terms of the structural aspects, where the silver halides tend to form microdomains. The special characteristic of fast ionic conduction depending upon halide type is emphasized.     

Conduction mechanism in composite solid electrolytes,PbX 2-Al2O3 (X = Cl,Br, l) systems

Composite solid electrolytes PbX ₂-Al₂O₃ (X=Cl, Br, l) have been synthesized by the powder metallurgical process, and investigated by complex impedance analysis. X-ray diffraction (XRD), differential thermal analysis (DTA) and scanning electron microscope (SEM) techniques. The phase analyses reveal that the composites are two-phase systems. No chemical reaction nor solid solution formation takes place between Al₂O₃ and the respective matrix phases. SEM photomicrographs show that Al₂O₃ particles are uniformly dispersed in the matrix phase for various systems. While PbCl₂-Al₂O₃ and PbBr₂-Al₂O₃ composites show a decrease in conductivity over their respective pure phases; Pbl₂-Al₂O₃ composites exhibit enhanced conductivity. By using the known diffusion and mobility data of the mobile species it has been shown that enhancement in conductivity is possible only in case of Pbl₂.     

Synthesis and transformation of zero-dimensional Cs3BiX6 (X = Cl,Br) perovskite-analogue nanocrystals

The unique structure of zero-dimensional (0D) perovskite-analogues has attracted a great amount of research interest in recent years. To date, the current compositional library of 0D perovskites is largely limited to the lead-based Cs₄PbX₆ (X = Cl, Br, and I) systems. In this work, we report a new synthesis of lead-free 0D Cs₃BiX₆ (X = Cl, Br) perovskite-analogue nanocrystals (NCs) with a uniform cubic shape. We observe a broad photoluminescence peak centered at 390 nm for the 0D Cs₃BiCl₆ NCs at low temperatures. This feature originates from a self-trapped exciton mechanism. In situ thermal stability studies show that Cs₃BiX₆ NCs remain stable upon heating up to 200 °C without crystal structural degradation. Moreover, we demonstrate that the Cs₃BiX₆ NCs can transform into other bismuth-based perovskite-analogues via facile anion exchange or metal ion insertion reactions. Our study presented here offers the opportunity for further understanding of the structure-property relationship of 0D perovskite-analogue materials, leading toward their future optoelectronic applications.

     

Preparation and luminescence of Pb2OFX; X=Cl,Br, I

The title compounds were prepared and crystallized with the ideal Perite structure. Low temperature luminescence spectra are presented.     

Conductivite ionique dans les verres LiPO3LiX (X = I,Br, Cl)

The glass-forming regions in the systems LiPO₃LiX with X = I, Br, Cl were determined and the study of the electrical conductivity of glasses belonging to these systems was carried out. The conductivity increases with increasing halogen ion size and reaches maxima values of the order of 10^?6, 3, 2 10^?7, 10^?7 (ohm cm)^?1 at 25° C with LiI, LiBr, LiCl respectively : they are obtained at the limit of glass forming region. The Raman spectra do not show any modifications. The study of the electrical conductivity shows that the conduction is essentially ionic in nature.     

{[Cd(Ⅱ)L(NCS)2](DMF)2}n(L=1,4-二[2-(2-吡啶基)苯并咪唑基]丁烷)的合成,晶体结构与荧光光谱研究

合成了一种新的包含咪唑基团的双端四齿鳌合配体1,4-二[2-(2-吡啶基)苯并咪唑基]丁烷,并用其作为桥联配体与金属离子共同构筑配位聚合物.用Cd2 金属离子和L在DMF/H2O混合溶液中,存在KSCN的条件下,合成一种新型的一维链状配位聚合物{[Cd(Ⅱ)L(NCS)2](DMF)2}n(L=1,4-二[2-(2-吡啶基)苯并咪唑基]丁烷).单晶X-射线分析仪分析表明,该晶体属三斜晶系,P-1空间群,晶胞参数为:a=8.869(1)A,b=11.278(2)A,c=19.328(4)A,α=89.83(3)°,β=89.52(3)°,γ=74.28(3)°,V=1860.9(7)(A)3,Z=2,7250个独立衍射点中,6039个可观测点满足F2≥2σ(F2o),R=0.0543,wR2=0.1442.它是由一维的锯齿形链[Cd(Ⅱ)L(NCS)2]n和游离的DMF分子组成.在链内金属原子与来自于2个具有不同结构的配体L中的4个N原子和2个SCN-阴离子中的2个N原子形成八面体配位.该固态配合物在室温下用389nm的紫外光激发时在453nm处发射出强的荧光.     

Crystal Structure of K[UO2(NO3)3] and Some Features of Compounds M[UO2(NO3)3] (M = K,Rb, and Cs)

Greenish-yellow transparent crystals of K[UO₂(NO₃)₃] were prepared from aqueous solutions as by-product in synthesis of potassium chromatouranylates. The crystal structure was solved by the direct methods and refined to R ₁ = 0.037 (wR ₂ = 0.070) for 1452 reflections with |F _hkl| 4|F _hkl|. Mono- clinic system, space group C2/c, a = 13.4877(10), b = 9.5843(7), c = 7.9564(6) Å, = 116.124(2)°, V = 923.45(12) ų. The structure of K[UO₂(NO₃)₃] contains isolated complex ions [UO₂(NO₃)₃]^- whose uranyl groups are aligned parallel to the [-101] plane. The K⁺ cations, coordinated by twelve oxygen atoms, are located between the complex anions. Comparison of the structure with known data on M[UO₂(NO₃)₃] compounds (M = K, Rb, Cs) suggests the possibility of phase transitions due to relatively small displacements of [UO₂(NO₃)₃]^- anions and K⁺ cations, retaining the general structural motif.     

Synthesis of CsPbX3 (X = Cl/Br,Br, and Br/I)@SiO2/PMMA composite films as color-conversion materials for achieving tunable multi-color and white light emission

All-inorganic cesium lead halide based perovskite nanocrystals(PNCs)exhibit promising optoelectronic properties,but their poor stability and anion exchange reaction limit their broad commercial applications.Herein,we demonstrated the successful synthesis of blue-green-red emitting CsPbX₃(X=Cl/Br,Br,and Br/I)PNCs via hot injection method,followed by silica-coating and embedding in poly(methylmethacrylate)(PMMA)matrix.The photoluminescence(PL)spectra of SiO₂/PMMA-coated PNCs can be tuned continuously by regulating precursor composition ratio,from blue(CsPb(Cl_0.5/Br_0.5)₃;460 nm)to red(CsPb(Br_0.4/I_0.6)₃via green(CsPbBr₃;519 nm).The PNCs composite films exhibit improved stability(thermal-,moisture-,and photo-stability)because of the barrier formed by Si0₂/PMMA coating and also displayed exceptional photoluminescent quantum yield(PLQY of blue,green,and red-emitting Si0₂/PMMA coated PNCs are 37%,86%,and 71%,respectively)with longer lifetimes inhibiting anion exchange.Eventually,the PNCs-encapsulated Si0₂/PMMA composite films were integrated into the UV LED chip as down-converting materials to construct a prototype white-peLED unit.The designed white-peLED unit demonstrated bright white light generating CIE coordinates(0.349,0.350),a luminous efficiency(LE)of 39.2%and a color rendering index(CRI)of 84.7.The wide color gamut of 121.47%of NTSC and 98.56%of Rec.2020 is also achieved with the built w-LED system.Therefore,the results demonstrated that CsPbX₃(X=Cl/Br,Br,and Br/I)PNCs@SiO₂/PMMA composite films can be employed as efficient UV to visible color conversion materials for white-LEDs and backlighting.     

Phase diagrams of the ternary liquid systems [Ce(NO3)3(TBP)3]-C10H22-[UO2(NO3)2(TBP)2] and [Ce(NO3)3(TBP)3]-C10H22-[Th(NO3)4(TBP)2] and of the quaternary liquid system [Ce(NO3)3(TBP)3]-C10H22-[UO2(NO3)2(TBP)2]-[Th(NO3)4(TBP)2]

The phase diagrams of the ternary liquid systems [Ce(NO₃)₃(TBP)₃]-C₁₀H₂₂-[UO₂(NO₃)₂(TBP)₂] and [Ce(NO₃)₃(TBP)₃]-C₁₀H₂₂-[Th(NO₃)₄(TBP)₂] and of the quaternary liquid system [Ce(NO₃)₃(TBP)₃]-C₁₀H₂₂-[UO₂(NO₃)₂(TBP)₂]-[Th(NO₃)₄(TBP)₂] at T = 298.15 K are constructed. The phase diagrams are characterized by areas of homogeneous solutions and of two-phase liquid systems (systems with phase separation), with one phase (I) enriched in [Ce(NO₃)₃(TBP)₃], [Th(NO₃)₄(TBP)₂], and [UO₂(NO₃)₂(TBP)₂], and the other phase (II), in C₁₀H₂₂. Using the data on the mutual solubility of the components in the systems under consideration and equations of the NRTL model, the parameters of intermolecular interactions and the excess Gibbs energies (G ^ex) were calculated for the binary, ternary, and quaternary systems. Passing from the ternary system [Ce(NO₃)₃(TBP)₃]-C₁₀H₂₂-[Th(NO₃)₄(TBP)₂] to the quaternary system [Ce(NO₃)₃(TBP)₃]-C₁₀H₂₂-[UO₂(NO₃)₂ (TBP)₂]-[Th(NO₃)₄(TBP)₂] does not appreciably affect the distribution of C₁₀H₂₂ between phases I and II, but leads to the redistribution of [Ce(NO₃)₃(TBP)₃] into phase II and of [Th(NO₃)₄(TBP)₂] into phase I.     

The thallous chalcogenides Tl6X4Y (X = Cl,Br, I; Y = S,Se)

Single crystals of Tl₆X₄Y(X = Cl, Br, I; Y = S, Se) were prepared by the Bridgman technique. The compounds were characterized by complete X-ray structural analyses. All are isotypic, space group $\text{P}\text{4}\text{mnc}$, with a = 843.3(2) pm, c = 917.2(2) pm for Tl₆Cl₄S, a = 872.1(2) pm, c = 932.8(1) pm for Tl₆Br₄S, a = 917.6(3) pm, c = 960.8(1) pm for Tl₆I₄S and a = 917.8(3) pm, c = 967.5(1) pm for Tl₆I₄Se. FIR spectra as well as photoacoustic spectra are given.     

Non-Redox Assisted Oxygen-Oxygen Bond Homolysis in Titanocene Alkylperoxide Complexes: [Cp(2)Ti(eta-OOBu)L], L = Cl, OTf, Br, OEt(2), Et(3)P

The titanium(IV) alkylperoxide complex Cp(2)Ti(OO(t)Bu)Cl (1) is formed on treatment of Cp(2)TiCl(2) with NaOO(t)Bu in THF at -20 degrees C. Treatment of 1 with AgOTf at -20 degrees C gives the triflate complex Cp(2)Ti(OO(t)Bu)OTf (2), which is rapidly converted to the bromide Cp(2)Ti(OO(t)Bu)Br (3) on addition of (n)Bu(4)NBr. The X-ray crystal structures of 1 and 3 both show eta(1)-OO(t)Bu ligands. Complex 2 is stable only below -20 degrees C; (1)H, (13)C, and (19)F NMR spectra suggest that it also contains an eta(1)-OO(t)Bu ligand. Removal of the chloride from 1 with [Ag(Et(2)O)(2)]BAr'(4) (Ar' = 3,5-(CF(3))(2)C(6)H(3))) yields the etherate complex [Cp(2)Ti(OO(t)Bu)(OEt(2))]BAr'(4) (4). Again, coordination of a fourth ligand to the Ti center indicates an eta(1)-OO(t)Bu ligand in 4. These peroxide complexes do not directly oxidize olefins or phosphines. For instance, the cationic etherate complex 4 reacts with excess Et(3)P simply by displacement of the ether to form [Cp(2)Ti(eta(1)-OO(t)Bu)(Et(3)P)]BAr'(4) (5). Compounds 1-5 all decompose by O-O bond homolysis, based on trapping and computational studies. The lack of direct oxygen atom transfer reactivity is likely due to the eta(1) coordination of the peroxide and the inability to adopt more reactive eta(2) geometry. DFT calculations indicate that the steric bulk of the (t)Bu group inhibits formation of the hypothetical [Cp(2)Ti(eta(2)-OO(t)Bu)](+) species.