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.     

Conductivite ionique du lithium dans les verres du systeme B2O3  Li2O  LiCl

New vitreous electrolytes with lithium ion carriers have been obtained in the B₂O₃  Li₂O  LiCl system. They are ionic conductors with high performances. Evolution of their electrical properties as a function of the composition in Li₂O and LiCl is specified and discussed.     

Etude comparative des verres AgPS3  AgX ET AgPO3  AgX avec X = I,Br

The glass-forming regions in the systems AgPS₃  AgX with X = I, Br were determined and the study of the electrical conductivity of these glasses was carried out. As observed in the AgPO₃  AgX glasses the ionic conductivity increase both with the amount of AgX and with the size of the halogen for a given concentration of AgX. The maximum value of the conductivity i.e, 10^?2 and 10^?3 (ohm cm)^?1 at 25° C for AgI and AgBr respectively, is obtained at the limit of the glass-forming region. The structural model previously described for AgPO₃  AgI systems is extended to AgPS₃  AgX glasses.     

Conductivite ionique dans les systems Na1+xZr2−xLx(PO4)3 (L = Cr,Yb)

Ionic conductivity measurements in the solid solution Na_1+xZr_2?xL_x(PO₄)₃ (L = Cr, Yb) have been carried out. The materials have a Nasicon-type structure in a 0 ? x ? x^max._L range (x^max._Cr = 2.0 and x^max._Yb = 1.9). A small monoclinic distortion appears at low temperature for Na₃Cr₂(PO₄)₃. As in the Na_1+xZr₂P_3?xSi_xO₁₂ system a strong increase of the conductivity with rising x has been observed. The results are discussed in connection with temperature and structural parameters.     

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.     

Conductivite ionique des oxydes Li8MO6 (M = Ce,Hf)

The electrical conductivity of the oxides Li₈CeO₆ and Li₈HfO₆, which are thermodynamically stable against Li (1), has been studied under oxygen atmosphere in the temperature range between room temperature and 200°C. As for Li₈ZrO₆ and Li₈SnO₆ (2), the materials can be considered as solid electrolytes with medium conductivity. The interpretation of the results, considering the Ca²⁺ ions as impurities, are in agreement with those based on the diffusion mechanisms of the Li⁺ ions recently established by ⁷Li NMR in isostructural oxides by Simpson et al. (3).     

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.     

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.     

Conductivite electrique et spectres de diffusion raman des verres mixtes AgPO3 − MI2 AVEC M = Cd,Hg, Pb. Correlation entre conductivite et structure

The glass-forming regions in the AgPO₃ ? MI₂ systems with M = Cd,Pb,Hg were determined. Electrical conductivity measurements and Raman spectra were carried out. A maximum conductivity value of $\text{10}{}^{\mathrm{?2}}\text{(Ω}\text{cm}\text{)}{}^{\mathrm{?1}}$ at 25°C is obtained for a mole fraction of 0,19 in PbI₂ or in CdI₂, whereas a value of $\text{3×10}{}^{\mathrm{?5}}\text{(Ω}\text{cm}\text{)}{}^{\mathrm{?1}}$ at 25°C is found for a mole fraction of 0,5 in HgI₂. The conductivity results and Raman spectra are examined and compared with those of AgPO₃ ? AgI. An exchange between Ag⁺ and M²⁺ ions is proposed leading to AgI species in AgPO₃ ? CdI₂ and AgPO₃ ? PbI₂ glasses. It could explain the high conductivity values obtained and the similarities observed in Raman spectra.     

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.     

Remarkable Piezophoto Coupling Catalysis Behavior of BiOX/BaTiO3 (X = Cl,Br, Cl0.166Br0.834) Piezoelectric Composites

Polarization field engineering of piezoelectric materials is considered as an advisable strategy in fine‐tuning photocatalytic performance which has drawn much attention recently. However, the efficient charge separation that determines the photocatalytic reactivities of these materials is quite restricted. Herein, a judicious combination of piezoelectric and photocatalytic performances of BiOX/BaTiO₃ (X = Cl, Br, Cl_0.166Br_0.834) to enable a high piezophotocatalytic activity is demonstrated. Under the synergic advantages of chemical potential difference and piezoelectric potential difference in BiOX/BaTiO₃ composites, the photoinduced carriers recombination is largely halted, which directly contributes to the significantly promoted piezophotocatalytic activity of piezoelectric composites. Inspiringly, the BiOBr/BaTiO₃ composites under light irradiation with auxiliary ultrasonic activation result in an ultrahigh and stable photocatalytic performance, which is much higher than the total of those by isolated photocatalysis and piezocatalysis, and can rival current excellent photocatalytic system. In fact, the theoretical piezoelectric potential difference of BiOBr/BaTiO₃ composites reaches 100 mV, which far exceeds the pure BaTiO₃ of 31.21 mV and BiOBr of 30 mV, respectively. First, fabrication of BiOX/BaTiO₃ piezoelectric composites and its remarkable piezophoto coupling catalysis behavior lays new ground for developing high‐efficiency piezoelectric photocatalysts in purifying wastewater, killing bacteria, and other piezophototronic processes.     

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).     

Verres formes dans les systemes Ga2S3La2X3MnS (X = S,O)

Preparation of glasses. Glass forming domains in the ternary systems [Ga₂S₃, (La₂S₃, La₂O₂S or La₂O₃), MnS]. Thermal behaviour. U.V. and visible spectroscopy. E.P.R. spectra. Manganese has an octahedral environment of sulfur.     

Nouveaux verres fluores transmetteurs dans l'infrarouge dans les systemes LnF3BaF2ZnF2

A new family of fluoride glasses have been isolated in the ternary systems LnF₃BaF₂ZnF₂ with Ln = rare earth and yttrium. The melt must be quenched to reduce the crystallization. These glasses have a good I.R. transmission: the absorption edge is in the 9 μ region.     

基于BiOX(X=Cl、Br、I)新型高性能光催化材料的最新研究进展

铋系半导体BiOX(X=Cl、Br、I)因其独特的层状结构和合适的禁带宽度而表现出优异的光催化活性与稳定性, 已成为光催化材料领域极具应用前景的材料体系。本文首先针对BiOX(X=Cl、Br、I)光催化材料研究中的关键科学问题进行了深入分析, 进一步综述了国内外解决上述关键问题所采取的有效措施, 包括: 微结构调控、半导体复合、贵金属沉积、离子掺杂和表面敏化等, 并针对纳米结构BiOX(X=Cl、Br、I)负载于合适载体上实现固载的研究进展进行了概述, 从而对基于BiOX(X=Cl、Br、I)新型高性能光催化材料的最新研究进展进行了全面深入的综述, 最后展望了BiOX光催化材料的研究方向与趋势。     

Etudes structurales et optiques des phases du type Cd2A3X (A = As,P; X = Cl,Br, I) et de leur solution solide

The structure of the compounds with general formula Cd₂A₃X (A = As, P; X = Cl, Br, I) was found from X-ray powder diffractograms. The variation of the cell parameter in Cd₂As_3?xP_xI solid solution was studied. The basic transition energy as well as its variation with temperature was obtained from transmission spectra on monocristals. Both results are discussed.     

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.     

Etude des verres fluores dans les quaternaires ZnF2ThF4AlF3MF2 (M = Mg,Ca, Sr,Ba)

Fluoride glasses have been investigated in the ZnF₂AlF₃ThF₄MF₂ (M = Ba, Sr, Ca, Mg) systems. The vitreous areas are given for the basic ternary diagrams and at a constant 40 % ZnF₂ content. Small samples may be prepared for the compositions: 40 % ZnF₂, 20 % AlF₃, 20 % ThF₄, 20 % MF₂ (M = Ba, Sr, Ca). The glassy transition occurs between 310° C and 350° C and the fusion between 650° C and 750° C. The optical transmission range lies from 240 nm to 7500 nm. The average values of refractive index, thermal expansion coefficient and density are: n_D ～ 1.48, α ～ 15.10^?6° K^?1d ～ 5. The high compactness of the anion array is compared to that of close-packed crystalline fluorides.     

A neutron, X-ray and electron diffraction study of the structures of Pb3O2X2 (X = Cl, Br)

The crystal structures of the compounds Pb₃O₂Br₂ and Pb₃O₂Cl₂ have been re-refined from neutron powder diffraction data. They are found to be more closely isostructural than previous reports suggested. The major difference between the present refinements and previous refinements is in the oxygen position of the bromide compound which has moved significantly along b from y=0.024(5) to 0.9933(4), rather more in keeping with the previously reported structure of the chloride compound. Electron diffraction was used, prior to refinement, to determine the appropriate space group symmetry, given some previous ambiguity in the literature. The space group symmetry was thereby shown to be at least Pn2₁a, but most probably Pnma. Evidence for some displacive disorder along b was also found in the form of weak diffuse streaking perpendicular to b^∗.