共查询到20条相似文献,搜索用时 31 毫秒
1.
A. C. Yanes J. J. Velázquez J. del-Castillo J. Méndez-Ramos V. D. Rodríguez 《Journal of Sol-Gel Science and Technology》2009,51(1):4-9
Nanostructured transparent glass-ceramics with composition of 95SiO2–5LaF3 co-doped with 0.3Yb3+, 0.1Ho3+ and 0.1Tm3+ (mol%) were synthesized by thermal treatment of precursor sol–gel derived glasses. X-ray diffraction and transmission electron
microscopy analysis point out the precipitation of hexagonal LaF3 nanocrystals with diameter ranging from 11 to 20 nm in these nano-glass-ceramics. White light generation by means of efficient
blue, green and red up-conversion luminescence under infrared excitation at 980 nm was observed and involved mechanisms were
analyzed. Colour tuneability is achieved by varying the up-conversion emission ratios as a function of pump power. 相似文献
2.
A. I. Gubanov A. M. Danilenko A. I. Smolentsev N. V. Kuratieva A. B. Venediktov S. V. Korenev 《Journal of Structural Chemistry》2016,57(8):1606-1612
Double complex salts (DCS) α-[Pd(NH3)4][IrF6]·H2O (P21/m, a = 6.3181(3) Å, b = 10.8718(5) Å, с = 7.4526(4) Å, β = 103.568(2)°), β-[Pd(NH3)4][IrF6]·H2O (P21/с, a = 8.5773(3) Å, b = 10.8791(4) Å, с = = 12.6741(3) Å, β = 122.497(2)°), [Pd(NH3)4]3[IrF6]2Cl2·H2O (P-1, a = 7.6080(2) Å, b = 7.6274(2) Å, с = 11.8070(3) Å, β = 122.497(2)°), and [Pd(NH3)4]2[IrF6]NO3 (Fm-3m, a = 11.21210(10) Å) have been synthesized and structurally characterized for the first time. The existence of polymorphs for the DCS has been revealed. The influence of the chemical composition of the initial reagents on the reaction course and, respectively, the products, has been demonstrated. A hypothesis on the influence of the second coordination sphere on the formation of one or the other polymorph of the DCS has been suggested. It has been shown that the series α-[Pd(NH3)4][МF6]·H2O (M = Pt, Pd) exhibits isostructurality. 相似文献
3.
Baoling Wang Liuzheng Sun Haidong Ju Shilong Zhao Degang Deng Huanping Wang Shiqing Xu 《Journal of Sol-Gel Science and Technology》2009,50(3):368-371
CaAl2Si2O8: Eu2+, Mn2+ phosphors have been prepared by a sol–gel method. X-ray diffractometer, spectrofluorometer and UV–Vis spectrometer were used
to characterize structural and optical properties of the samples. The results indicate that anorthite (CaAl2Si2O8) directly crystallizes at 1000 °C in the sol–gel process. CaAl2Si2O8: Eu2+, Mn2+ phosphors show two emission bands excited by ultraviolet light. Blue (around 415 nm) and yellow (around 575 nm) emissions
originate from Eu2+ and Mn2+, respectively. With appropriate tuning of Mn2+ content, CaAl2Si2O8: Eu2+, Mn2+ phosphors exhibit different hues and relative color temperatures. 相似文献
4.
A. S. Kubasov E. Yu. Matveev E. S. Turyshev I. N. Polyakova K. Yu. Zhizhin N. T. Kuznetsov 《Doklady Chemistry》2017,477(1):257-260
The interaction of the [B10H10]2– and [B12H12]2– anions with aliphatic and aromatic nitro compounds (RNO2, where R = Et, n-Pr, i-Pr, tert-Bu, Ph) has been studied under irradiation with visible and UV light. It has been shown that, depending on the reaction conditions, both mono- and disubstituted nitro-closo-decaborates can be selectively obtained in yields up to 50%. 相似文献
5.
I. P. Pozdnyakov E. M. Glebov S. G. Matveeva V. F. Plyusnin A. A. Mel´nikov S. V. Chekalin 《Russian Chemical Bulletin》2015,64(8):1784-1795
Primary photophysical and photochemical processes were studied for PtIVBr6 2– and PtIVCl6 2– complexes in water and methanol by ultrafast kinetic spectroscopy upon excitation in the band region of charge transfer from the ligand-centered group π-orbitals to the eg*-orbital of PtIV complex anion (LMCT bands). The data obtained earlier upon excitation in the region of d—d bands were compared. Irrespective of the excitation wavelength, the photochemical properties of complexes are caused by the reactions of intermediates proceeding in the picosecond time range. These intermediates were identified as PtIVBr5 – upon photolysis of PtIVBr6 2– and, presumably, the Adamson radical pair [PtIIICl5 2–(C 4v )...Cl?] upon photolysis of PtIVCl6 2–. The difference in the exciting light wavelengths has an impact only on the first step of these processes, i.e., transition from the Franck—Condon excited state to intermediates. 相似文献
6.
F. Bousmina L. Zayani D. Ben Hassen-Chehimi N. Kbir-Ariguib M. Trabelsi-Ayedi 《Monatshefte für Chemie / Chemical Monthly》2003,134(5):763-768
Summary. The diagram of the ternary system Mg2+/Cl−, SO4
2−–H2O was established at 15°C by means of analytical and conductimetric measurements. Three compounds were found in this diagram,
which are MgSO4·6H2O, MgSO4·7H2O, and MgCl2·6H2O. The solubility field of MgSO4·7H2O is important whereas those of MgSO4·6H2O and MgCl2·6H2O are small. The compositions (mass-%) of the two invariant points determined by the two methods are: MgSO4:MgCl2=2.73:33.80 and MgSO4: MgCl2=3.38:28.91. Both the measured and the calculated isotherm at 15°C have been used for modelling of the diagram Mg2+/Cl−, SO4
2−–H2O between 0 and 35°C. The polythermal invariant point was approximately located between 15 and 10°C.
Corresponding author. E-mail: ariguib@planet.tn
Received October 16, 2002; accepted (revised) December 3, 2002
Published online April 24, 2003
RID="a"
ID="a" Dedicated to Prof. Dr. Heinz Gamsj?ger on the occasion of his 70th birthday 相似文献
7.
Yanluo Lu Lan Yang Min Wei Yaning Xie Tao Liu 《Journal of Solid State Electrochemistry》2007,11(9):1157-1162
Supramolecular pillared oxides were prepared through the intercalation of M2+ cations into a MnO2 host matrix by the method of ion exchange between the precursor δ-K
x
MnO2 and the corresponding guest. The materials M-MnO2 crystallize in the hexagonal system, the same structure as the precursor, with a larger interlamellar spacing. In the case
of ZrO-MnO2, extended X-ray absorption fine structure (EXAFS) determination indicates that the Zr atom locates between the MnO2 layers forming a stable structure. Compared with the precursor, the cycling property of M-MnO2 was improved distinctly, while the capacity decreased to some degree due to the strong interaction between pillars and the
host matrix. Among these pillared materials, ZrO-MnO2 has an advanced reversible capacity of 161.5 mAh·g−1 and improved cycling behavior compared with the precursor. 相似文献
8.
Nanoscale TiO2 powders doping with niobium and tantalum were prepared using TiCl3 as a source matter. Characterization of the materials was performed by Thermoanalys, particle size, XRD, BET, FTIR, Magnetic Susceptibility. The influence of niobium and tantalum ions on the phase transition was studied, the changes in the crystal size and microstain distributions obtained at 400C were analyzed. The results show that the substitutes of Nb5 +, Ta5 + for Ti4+ in the anatase structure cause distortions and improve to form rutile. When the dopant content is over certain molar percent, biphase reappears. The IR spectra and magnetic susceptibility indicate the Nb–Nb (or Ta–Ta) bonds along c-axis in rutile by two Nb5 + (Ta5 +) ions located in sites adjacent along the c-axis appear with the dopant content. The magnetic characteristics at rutile showed a weak paramagnetism. 相似文献
9.
10.
Evidence for the existence of primitive life forms such as lichens and fungi can be based upon the formation of oxalates.
These oxalates form as a film like deposit on rocks and other host matrices. The anhydrous oxalate mineral moolooite CuC2O4 as the natural copper(II) oxalate mineral is a classic example. Another example of a natural oxalate is the mineral wheatleyite
Na2Cu2+(C2O4)2·2H2O.
High resolution thermogravimetry coupled to evolved gas mass spectrometry shows decomposition of wheatleyite at 255°C. Two
higher temperature mass losses are observed at 324 and 349°C. Higher temperature mass losses are observed at 819, 833 and
857°C. These mass losses as confirmed by mass spectrometry are attributed to the decomposition of tennerite CuO. In comparison
the thermal decomposition of moolooite takes place at 260°C. Evolved gas mass spectrometry for moolooite shows the gas lost
at this temperature is carbon dioxide. No water evolution was observed, thus indicating the moolooite is the anhydrous copper(II)
oxalate as compared to the synthetic compound which is the dihydrate. 相似文献
11.
Kan Zhu Zhengwen Yang Dong Yan Zhiguo Song Dacheng Zhou Rongfei Wang Jianbei Qiu 《Journal of Sol-Gel Science and Technology》2012,62(2):149-152
Tb3+–Yb3+ co-doped Ca5(PO4)3F inverse opal photonic crystals were prepared by a self-assembly technique in combination with a sol–gel method. Upconversion
luminescence characteristics of the inverse opals were investigated. The results indicate that photonic band gap has a significant
effect on upconversion luminescence of Tb3+–Yb3+ co-doped Ca5(PO4)3F inverse opal. Significant inhibition of the green or blue upconversion luminescence was inspected if the photonic band gap
overlapped with the emission band of Tb3+ ions. 相似文献
12.
Ca3Al6Si2O16: Ce3+, Tb3+ phosphors have been prepared by sol–gel method. The structure and photoluminescence properties were studied with careful.
The results indicated that the single-phased Ca3Al6Si2O16 phosphors crystallize at 1,000 °C for 2 h in conventional furnace. With appropriate concentrations of Ce3+ and Tb3+ ions into Ca3Al6Si2O16 matrix, these materials exhibit blue phosphors and white light under ultraviolet radiation. White-light emission can be achieved
because of a 400 nm emission ascribed to transitions of Ce3+ ions and three sharp peaks at 487, 543, 585 nm, respectively, resulting from transitions of Tb3+ ions. 相似文献
13.
Interfacial electron transfer induced by 254 nm light at nanomaterial (nm) titanium dioxide/CoIII(N–N)3
3+ interface in binary mixed solvent media such as water/methanol (or 1,4-dioxane) has been probed. The distinct photo reduction
of cobalt(III) complexes, CoIII(N–N)3
3+; (N–N)=(NH3)2, en (1,2-diamino ethane), pn (1,2-diamino propane), tn (1,3-diamino propane), and bn (1,4-diamino butane), by excited nm-TiO2 particles: CoIII + nm-TiO2 + hν → TiO2 (h+;e−) + CoIII → nm-TiO2 (h) + CoII is solvent controlled. The electron transfer from the conduction band of TiO2 (e−, CB) onto the metal centre of the complex consists of (i) electron transport from CB into surface-adsorbed species A: CoIII(N–N)3
3+ (ii) solution phase species B: CoIII(N–N)3
3+
(sol.), accumulated at the surface of the nanoparticle. In addition, UV irradiation of CoIII(N–N)3
3+ stimulates generation of
\textCo\textaq\textII {\text{Co}}_{\text{aq}}^{\text{II}} ion, due to charge transfer transition, in solution phase. After UV irradiation, cobalt-implanted nm-TiO2 separated as gray ultrafine particles, which were isolated. Photo efficiency of the formation of CoII ion was estimated and the cobalt implanted nanomaterial crystals isolated from the photolyte solutions were subjected to
SEM-EDX, X-ray mapping, and HRTEM-SAED analyses. Solvent medium was found to contribute in both the formation of CoII ion and interstitial insertion of cobalt into the lattice of nm-TiO2. 相似文献
14.
V. V. Sharutin V. S. Senchurin O. K. Sharutina 《Russian Journal of Inorganic Chemistry》2012,57(3):398-401
The complex [(HOCH2)3CNH3] 2 + [HgI4]2? (I) was synthesized by reacting (trioxymethyl)methylammonium iodide with mercury dioide (2: 1 mol/mol) in acetone. X-ray crystallography shows that the complex consists of two types of crystallographically independent [(HOCH2)3CNH3]+ cations and tetrahedral anions [HgI4]2? (IHgI, 106.49(2)°–113.99(4)°; Hg-I, 2.7849(8)-2.8105(8) Å. [(HOCH2)3CNH3]+ cations are linked via hydrogen bonds O…H-N and O-H…N (O…N, 2.84–2.92 Å) to form polymer chains, which are cross-linked with one another via anions (I…H, 2.81, 2.82 Å). 相似文献
15.
B. Dong Z. Q. Feng B. S. Cao J. Z. Zheng 《Journal of Sol-Gel Science and Technology》2009,50(3):383-386
For the Er3+–Yb3+ codoped Al2O3 powders, the strong near-infrared photoluminescence (PL) centered at 1.535 μm derived from the energy transfer (ET) from
Yb3+ to Er3+ was detected by a 978 nm laser diode excitation. Compared with that of Er3+ doped Al2O3 powders, the PL intensity enhanced about 9 times, the full width at half maximum (FWHM) extended from 82 to 90 nm, and the
lifetime increased from 3.22 to 4.17 ms for Er3+–Yb3+ codoped Al2O3 powders at room temperature. The ET coefficient of 2.18 × 10−18 cm3 s−1 from Yb3+ to Er3+ was obtained based on the rate equations. The decrease of PL intensity with increasing temperature in the range of 298–733 K
was observed, due to thermally enhanced nonradiative relaxation 4I13/2 → 4I15/2 dominated over thermally enhanced phonon-assisted ET in the Er3+–Yb3+ codoped Al2O3. 相似文献
16.
A new coordination polymer, [Cd(NH3)4]2{Cd[Re3Mo3S8(CN)6]}·1.5H2O (I), was prepared by the reaction between solutions of Cd(CH3COO)2 · 2H2O in aqueous ammonia and CaK4[Re3Mo3S8(CN)6] · 8H2O in water. The crystals are cubic, space group Fm3m (Prussian blue structural type); a = 15.0268(4) Å (CIF file CSD no. 431555). According to ESR data, compound I is paramagnetic, g-factor is 2.298. Thermal stability investigation by TGA and powder X-ray diffraction showed that elimination of coordinated NH3 molecules is accompanied by sample amorphization. 相似文献
17.
Anjing Wang Junmei He Lingna Kong Naidong Zhang Tong Zheng 《Research on Chemical Intermediates》2017,43(4):2175-2186
This paper investigated the photodegradation characteristics of benzoquinones and benzoquinoneimines. The photosensitivity of benzoquinones and benzoquinoneimines were analyzed by measuring the yield of SO 4 ?· in a light/Fe2+/S2O8 2? system and the degradation mechanism of benzoquinones, then discussed benzoquinoneimines in light/Fe2+/S2O8 2? and light/S2O8 2? system. The results revealed that a more aggressive oxidation of benzoquinones and benzoquinoneimines by the sunlight/Fe2+/S2O8 2? method showed a more rapid and more complete removal of chromaticity than that of the UV/Fe2+/S2O8 2? method. It was showed that they were photosensitizers, and they could generate 1O2 and O 2 ?· which could promote the formation of SO 4 ?· and ·OH in the sunlight system. Nevertheless, for benzoquinones, the sunlight/S2O8 2? method was superior to the UV/S2O8 2? method. For benzoquinoneimines, the sunlight/S2O8 2? method was inferior to the UV/S2O8 2? method. In addition, the yield of SO 4 ?· in the sunlight/Fe2+/S2O8 2? system was more than that of the UV/Fe2+/S2O8 2? system. Therefore, the photosensitivity of benzoquinones is superior to benzoquinoneimines in water treatment. 相似文献
18.
The Er3+–Yb3+ codoped Al2O3 has been prepared by the sol–gel method using the aluminium isopropoxide [Al(OC3H7)3]-derived Al2O3 sols with addition of the erbium nitrate [Er(NO3)3 · 5H2O] and ytterbium nitrate [Yb(NO3)3 · 5H2O]. The phase structure, including only two crystalline types of doped Al2O3 phases, θ and γ, was obtained for the 1 mol% Er3+ and 5 mol% Yb3+ codoped Al2O3 at the sintering temperature of 1,273 K. By a 978 nm semiconductor laser diodes excitation, the visible up-conversion emissions
centered at about 523, 545, and 660 nm were obtained. The temperature dependence of the green up-conversion emissions was
studied over a wide temperature range of 300–825 K, and the reasonable agreement between the calculated temperature by the
fluorescence intensity ratio (FIR) theory and the measured temperature proved that Er3+–Yb3+ codoped Al2O3 plays an important role in the application of high temperature sensor. 相似文献
19.
Sovann Khan Bo-In Park Joon Soo Han Seung Yong Lee So-Hye Cho 《Research on Chemical Intermediates》2018,44(8):4619-4632
Near-infrared (NIR) quantum cutting phosphors serve as a potential material for fabricating photovoltaic spectral convertors. In many cases, quantum cutting phosphors are obtained via a wet chemical method coupled with a post-annealing treatment—a very costly process. In this report, we used continuous flame spray pyrolysis (FSP) for fabricating Y2O3:Tb3+–Yb3+ quantum-cutting phosphors without any post-treatment. Based on characterizations by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction, we found that as-synthesized Y2O3:Tb3+–Yb3+ phosphors exhibit hollow and shell-like micro-structures composed of highly crystalline and pure cubic-phase nanoparticles (< 50 nm). Photoluminescence studies of the phosphors revealed that NIR emissions appeared with the introduction of Yb to Y2O3:Tb3+. Phosphor size was successfully controlled by managing the concentration of the metal precursor solution for FSP. The Y2O3:Tb3+–Yb3+ phosphors were then embedded into transparent poly-ethylene-co-vinyl acetate (EVA) film to form a spectral convertor. The composite films of Y2O3:Tb3+–Yb3+ phosphors and poly-EVA were found to be highly transparent in the visible range (> 500 nm), making them suitable as spectral photovoltaic convertors. 相似文献
20.
Boukraa Yamina 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2016,90(13):2642-2645
A study on the extraction of copper(II), cobalt(II), and nickel(II) from solutions containing ions of both metals with N-salicylideneaniline(SAN) in chloroform has been realized. Distribution of the metal ions in wide range of pH has been studied. Extraction of copper(II) was always favored over that of cobalt(II). Extraction of copper(II) from binary metal solution is selective and it can be quantitatively separated from cobalt(II). The equilibrium constant of the extraction of cobalt and nickel from an aqueous solution containing both metals using SAN were evaluated. The separation factors for cobalt and nickel were expressed as a function of the distribution of nickel and cobalt. From these results, salicylideneaniline is an adequate extractant for extractive separation of such mixtures. 相似文献