Technical ceramics from samarium monosulfide for the thermal explosion and magnetron methods of production of SmS films

Physicotechnical foundations of producing technical ceramics from samarium monosulfide were developed. The stable daltonide-type compound SmS forms a solid solution primarily within the range of anion structural vacancies Sm_{1 + x} S_1–x [ ]_2x (x = 0–0.035) (1500°С). In the Sm–S–O system, the compound SmS is in equilibrium with the Sm3S4 and Sm2O2S phases. The surface layer of bulk samples and films of SmS contains the phases Sm3S, Sm2O2S, and xSm₂SO₄ · (1–x)Sm₂O₃. Samarium sulfide is thermally hydrolyzed (>300°C) and oxidized (>220°C) to form the Sm₃S₄ and Sm₂O₂S phases. In synthesizing samarium monosulfide from elements by an ampule method, addition of a 15–20% excess of metallic samarium to the initial mixture affords SmS in more than 95 mol % yield. The contents of the equilibrium impurities Sm₃S₄ and Sm₂O₂S are minimized. Technical ceramics based on SmS was obtained as sintered pellets 50 and 75 mm in diameter with a compressive strength of 45 MPa, a flexural strength of 1.6 MPa, and a density of 4.89 g/cm³. The rate of SmS film sputtering from a ceramic target on a NanoFab-100 platform under the optimal sputtering conditions (390 V, 150 W) was 1 Å/s. A SmS powder containing particles of 90–120 μm in size was used for thermal explosion spraying of semiconductor thermal sensors shaped as cubes with a side length of 5 and 10 mm.     

Über die Anwendung eines neuartigen Reduktionsverfahrens zur Reindarstellung von SmF2, EuF2, YbF2, SmS,YbS und EuO

On a Novel Reduction Procedure for the Preparation of Pure SmF₂, JCuF₂, YbF₂, SmS, YbS, and EuO A technique is described, by which the compounds SmF₂, EuF₂, YbF₂, SmS, YbS and EuO can be prepared by reduction of the trifluorides, sesquisulfides, and of europium sesquioxide, respectively, with the gaseous rare earth metals. By this technique the contamination of the reaction products with several specific impurities, usually contain-ed in the condensed rare earth metals; can be avoided. Analytical data and lattice para-meters of the compounds prepared by this method are communicated.     

Photophysics of Pt(II) 4,6-diphenyl-2,2′-bipyridyl complexes in solution and in LB film

Two amphiphilic platinum(II) 4,6-diphenyl-2,2′-bipyridyl complexes (1 and 2) were synthesized and characterized. LB films of these two complexes were prepared and characterized by AFM technique. Electronic absorption and emission characteristics of these complexes in solutions at room temperature, in glassy solutions at 77 K, and in LB films were studied. The emission energies of the complexes in LB films are similar to those in acetonitrile solutions at room temperature. However, the lifetimes of 1 and 2 in LB films are 4-7 times as long as those in CH₃CN solutions. The triplet transient difference absorption spectra of these complexes exhibit broad absorption in the visible region to the near-IR region. Introducing a hydroxyl substituent on the 4,6-diphenyl-2,2′-bipyridyl ligand favors the formation of intermolecular hydrogen bonding and thus helps the deposition of uniform and stable LB films and increases the self-quenching rate constant for emission of 2 in CH₃CN solution.     

Vinyltitanium as an initiator for the polymerization of acetylene

The preparation of lustrous conducting polyacetylene films by the polymerization of acetylene with vinyltitanium species as initiators was studied. Organotitanium species were generated by the alkylation of titanium vinylcarbene complexes with tert‐butyl chloride. Solid‐state ¹³C NMR and IR analyses of the obtained polyacetylene indicated that polyacetylene with a trans configuration was produced. The use of titanocene(II) species Cp₂Ti[P(OEt)₃]₂ and titanium vinylcarbene complexes for the preparation of polyacetylene films was also studied. The morphology of the films and the mechanisms of polymerization are discussed. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2663–2669, 2002     

Oxygen permeability of surfactant/polymer composite films with multibilayer and inverted hexagonal structure

The permeability of oxygen through horizontally oriented multibilayer films of polyion complexes prepared from quaternary ammonium-type surfactants [CH₃(CH₂)_n-1]₂N⁺(CH₃)₂Br^?(n = 14, 16, 18), and poly(p-styrenesulfonate) or poly[2-(acrylamido)-2-methyl-1-propanesulfonate], was measured in water using an oxygen electrode. The permeability depended mainly on the phase of the multibilayers. Thus, it increased abruptly (about 10-fold) near each phase transition temperature because of the fluidity enhancement of the multibilayer. Inverted hexagonal type nonbilayer films prepared from the polyion complexes and cholesterol had greater permeability (2–20-fold) than the multibilayer films in both phases. The large permeability of the nonbilayer films was attributed to the lack of a barrier such as the bilayer and lower crystallinity of the films. It was associated neither with an increase in thermal movement of the lipid surfactant molecules nor with an increase in the water content of the films by the addition of cholesterol. © 1993 John Wiley & Sons, Inc.     

Synthesis and evaluation of bis-β-diketonate dioxotungsten(VI) complexes as precursors for the photodeposition of WO3 films

In this paper non-stoichiometric tungsten oxide thin films have been successfully prepared by direct UV irradiation of bis-β-diketonate dioxotungsten(VI) precursor complexes spin-coated Si(1 0 0) substrates. Photodeposited films were characterized by Fourier transform-infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) and the surface morphology examined by Atomic Force Microscopy (AFM). The results of XRD analysis showed that the as-photodeposited WO_3−x films are amorphous and have a rougher surface than thermally treated films. Post-annealing of the films in air at 500 °C transforms the sub-oxides to a monoclinic WO₃ phase.     

Reactivities of d<Superscript>0</Superscript> transition metal complexes toward oxygen: Synthetic and mechanistic studies

Transition metals such as Fe in porphyrin complexes are known to bind or react with O₂, and such reactions are critical to many biological functions and catalytic oxidation using O₂. The transition metals in these reactions often contain valence d electrons, and oxidation of metals is an important step. In recent years, reactions of O₂ with d⁰ transition metal complexes such as Hf(NR₂)₄ (R = alkyl) have been used to make metal oxide thin films as insulating gate materials in new microelectronic devices. This feature article discusses our recent studies of such reactions and the formation of TiO₂ thin films. In contrast to the reactions of many d ⁿ complexes where metals are often oxidized, reactions of d⁰ complexes such as Hf(NMe₂)₄ and Ta(NMe₂)₄(SiR₃) with O₂ usually lead to the oxidation of ligands, forming, e.g., -ONMe₂ and -OSiR₃ from -NMe₂ and -SiR₃ ligands, respectively. Mechanistic and theoretical studies of these reactions have revealed pathways in the formation of the metal oxide thin films as microelectronic materials.     

Rational Development of Guanidinate and Amidinate Based Cerium and Ytterbium Complexes as Atomic Layer Deposition Precursors: Synthesis,Modeling, and Application

Owing to the limited availability of suitable precursors for vapor phase deposition of rare-earth containing thin-film materials, new or improved precursors are sought after. In this study, we explored new precursors for atomic layer deposition (ALD) of cerium (Ce) and ytterbium (Yb) containing thin films. A series of homoleptic tris-guanidinate and tris-amidinate complexes of cerium (Ce) and ytterbium (Yb) were synthesized and thoroughly characterized. The C-substituents on the N-C-N backbone (Me, NMe₂, NEt₂, where Me=methyl, Et=ethyl) and the N-substituents from symmetrical iso-propyl (iPr) to asymmetrical tertiary-butyl (tBu) and Et were systematically varied to study the influence of the substituents on the physicochemical properties of the resulting compounds. Single crystal structures of [Ce(dpdmg)₃] 1 and [Yb(dpdmg)₃] 6 (dpdmg=N,N'-diisopropyl-2-dimethylamido-guanidinate) highlight a monomeric nature in the solid-state with a distorted trigonal prismatic geometry. The thermogravimetric analysis shows that the complexes are volatile and emphasize that increasing asymmetry in the complexes lowers their melting points while reducing their thermal stability. Density functional theory (DFT) was used to study the reactivity of amidinates and guanidinates of Ce and Yb complexes towards oxygen (O₂) and water (H₂O). Signified by the DFT calculations, the guanidinates show an increased reactivity toward water compared to the amidinate complexes. Furthermore, the Ce complexes are more reactive compared to the Yb complexes, indicating even a reactivity towards oxygen potentially exploitable for ALD purposes. As a representative precursor, the highly reactive [Ce(dpdmg)₃] 1 was used for proof-of-principle ALD depositions of CeO₂ thin films using water as co-reactant. The self-limited ALD growth process could be confirmed at 160 °C with polycrystalline cubic CeO₂ films formed on Si(100) substrates. This study confirms that moving towards nitrogen-coordinated rare-earth complexes bearing the guanidinate and amidinate ligands can indeed be very appealing in terms of new precursors for ALD of rare earth based materials.     

Mo<Subscript>6</Subscript>Cl<Subscript>12</Subscript>-Incorporated Sol-Gel for Oxygen Sensing Applications

Excitation of hexanuclear molybdenum complexes such as Mo₆Cl₁₂ and its derivatives in the ultraviolet results in a strongly red-shifted luminescence centered at 750nm. Since oxygen efficiently quenches the luminescence, these thermally stable inorganic complexes are candidate lumophores for real-time, high temperature optical fiber based sensing of oxygen. Sol-gel films containing the acetonitrile complex of Mo₆Cl₁₂ were deposited on quartz substrates by dip coating. After drying, the films were heated at 200^∘C for 1 h. The luminescence lineshapes of films before and after heating were unchanged, indicating that heating did not adversely affect the cluster photophysics. Compared to solutions of the acetonitrile complex, quenching by oxygen was smaller in the as-prepared films, but heating at 200^∘C for 1 h increased the quenching, apparently due to increased oxygen permeability resulting from the loss of water or other small molecules from the matrix. These results confirm the potential of hexanuclear molybdenum complexes such as Mo₆Cl₁₂⋅2CH₃CN as the lumophores in fiber optic oxygen sensors that can operate up to 200^∘C.     

Weak Coordinating Character of Organosulfonates in Oriented Silica Films: An Efficient Approach for Immobilizing Cationic Metal-Transition Complexes

Iron (II) tris(2,2′-bipyridine) complexes, [Fe(bpy)₃]²⁺, have been synthesized and immobilized in organosulfonate-functionalized nanostructured silica thin films taking advantage of the stabilization of [Fe(H₂O)₆]²⁺ species by hydrogen bonds to the anionic sulfonate moieties grafted to the silica nanopores. In a first step, thiol-based silica films have been electrochemically generated on indium tin oxide (ITO) substrates by co-condensation of 3-mercaptopropyltrimethoxysilane (MPTMS) and tetraethoxysilane (TEOS). Secondly, the thiol function has been modified to sulfonate by chemical oxidation using hydrogen peroxide in acidic medium as an oxidizing agent. The immobilization of [Fe(bpy)₃]²⁺ complexes has been performed in situ in two consecutive steps: (i) impregnation of the sulfonate functionalized silica films in an aqueous solution of iron (II) sulfate heptahydrate; (ii) dipping of the iron-containing mesostructures in a solution of bipyridine ligands in acetonitrile. The in situ formation of the [Fe(bpy)₃]²⁺ complex is evidenced by its characteristic optical absorption spectrum, and elemental composition analysis using X-ray photoelectron spectroscopy. The measured optical and electrochemical properties of immobilized [Fe(bpy)₃]²⁺ complexes are not altered by confinement in the nanostructured silica thin film.     

Electrochemical deposition of electrochromic niobium oxide films from an acidic solution of niobium peroxo complexes

Deposition of electrochromic niobium(V) oxide films from an acidic solution of niobium peroxo complexes on a transparent conducting cathode in the form of an SnO₂ film on glass was studied. With an increase in the negative potential of the deposition of niobium(V) oxide films from a solution of niobium peroxo complexes at pH 2.5, the structure and composition of the films changed. A study of the electrochromic properties of Nb₂O₅ films revealed broadening of the bands in the electrochromic coloration spectrum with an increase in the negative potential of the deposition.     

Tb(III) complexes with 1-phenyl-3-methyl-4-stearoyl-pyrazol-5-one as a material for luminescence Langmuir–Blodgett films

Abstract

Synthesis and properties of new luminescent amphiphilic Tb(III) complexes [TbL₃·2H₂O]·3H₂O, TbL₃·bipy, [H₃O][TbL₄]·6H₂O and [H₃O][TbL′₃L]·H₂O, where HL is 1-phenyl-3-methyl-4-stearoylpyrazolone-5 and HL′ is 1-phenyl-3-methyl-4-formylpyrazolone-5, are reported. The complexes have been characterized by elemental and thermal analysis, FTIR and luminescence spectroscopy methods. Formation and properties of Langmuir–Blodgett films of the complexes are described.     

Luminescent PMMA Films and PMMA@SiO2 Nanoparticles with Embedded Ln3+ Complexes for Highly Sensitive Optical Thermometers in the Physiological Temperature Range**

In recent years, luminescent materials doped with Ln³⁺ ions have attracted much attention for their application as optical thermometers based on both downshifting and upconversion processes. This study presents research done on the development of highly sensitive optical thermometers in the physiological temperature range based on poly(methyl methacrylate) (PMMA) films doped with two series of visible Ln³⁺ complexes (Ln³⁺=Tb³⁺, Eu³⁺, and Sm³⁺) and SiO₂ nanoparticles (NPs) coated with these PMMA films. The best performing PMMA film doped with Tb³⁺ and Eu³⁺ complexes was the PMMA[TbEuL₁tppo]1 film (L₁=4,4,4-trifluoro-1-phenyl-1,3-butadionate; tppo=triphenylphosphine oxide), which showed good temperature sensing of S_r=4.21 % K⁻¹ at 313 K, whereas for the PMMA films doped with Tb³⁺ and Sm³⁺ complexes the best performing was the PMMA[TbSmL₂tppo]3 film (L₂=4,4,4-trifluoro-1-(4-chlorophenyl)-1,3-butadionate), with S_r=3.64 % K⁻¹ at 313 K. Additionally, SiO₂ NPs coated with the best performing films from each of the series of PMMA films (Tb–Eu and Tb–Sm) and their temperature-sensing properties were studied in water, showing excellent performance in the physiological temperature range (PMMA[TbEuL₁tppo]1@SiO₂: S_r=3.84 % °C at 20 °C; PMMA[TbSmL₂tppo]3@SiO₂: S_r=3.27 % °C at 20 °C) and the toxicity of these nanoparticles on human cells was studied, showing that they were nontoxic.     

Carbofunctional fluorine-containing triethoxysilanes: synthesis,film forming and properties

Novel fluorine-containing carbofunctional organosilicon monomers were synthesized: 3-pentafluorobenzylideneaminopropylethoxysilane (EtO)₃Si(CH₂)₃N=CH-C₆F₅, N-3-methoxydiethoxysilylpropyltrifluoroacetamide (EtO)₂(MeO)Si(CH₂)₃NHC(O)CF₃, and 1,1,5-trihydrooctafluoroamyl N-3-triethoxysilylpropylaminopropanoate (EtO)₃Si(CH₂)₃NH(CH₂)₂C(O)OCH₂(CF₂)₃CHF₂. Compositions for the formation of transparent thermally stable films were prepared from these monomers. The films have low absorbance intensity near 1550 nm, i.e., in the region of photosignal transmission of modern optical communication systems. The compositions can dissolve complexes with organofluorine ligands and produce transparent homogeneous films doped with rare-earth metals. The concentrations of the complexes in the matrices are 3.7–21.4 wt.% (metal concentrations are 0.6–3.7%). Fluorescence and fluorescence excitation spectra of the matrices and electronic absorption spectra of the doped films were studied. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1131–1138, May, 2005.     

Organometallic Langmuir-Blodgett films for electronics and photonics

This review provides a brief introduction to the Langmuir-Blodgett (LB) technique and to the utilization of ultrathin films in the fields of electronics and optics. The electrical and nonlinear optical properties of the Langmuir-Blodgett monolayer and multilayers of organoruthenium complexes, ferrocene derivatives, metal(4,5-dimercapto-1, 3-dithiol-2-dithiolene)₂ complexes, metallophthalocyanines, metalloporphyrins, metal(dibenzotetra-aza[14]annulene)s and siloxane polymers are presented. Possible applications of organometallic LB films in sensors, electroluminescence and electrochromic devices, optical switches, solar cells, infrared detectors and harmonic generators are discussed.     

Rhodium‐catalyzed transfer hydrogenation with aminophosphines and analysis of electrical characteristics of rhodium(I) complex/n‐Si heterojunctions

A series of novel neutral mononuclear rhodium(I) complexes of the P―NH ligands have been prepared starting from [Rh(cod)Cl]₂ complex. Structural elucidation of the complexes was carried out by elemental analysis, IR and multinuclear NMR spectroscopic data. The complexes were applied to the transfer hydrogenation of acetophenone derivatives to 1‐phenylethanol derivatives in the presence of 2‐propanol as the hydrogen source. Catalytic studies showed that all complexes are also excellent catalyst precursors for transfer hydrogenation of aryl alkyl ketones in 0.1 m iso‐PrOH solution. In particular, [Rh(cod)(PPh₂NH―C₆H₄―4‐CH(CH₃)₂)Cl] acts as an excellent catalyst, giving the corresponding alcohols in excellent conversion up to 99% (turnover frequency ≤ 588 h^?1). Furthermore, rhodium(I) complexes have been used in the formation of organic–inorganic heterojunction by forming their thin films on n‐Si and evaporating Au on the films. It has been seen that the structures have rectifying properties. Their electrical properties have been analyzed with the help of current–voltage measurements. Finally, it has been shown that the complexes can be used in the fabrication of temperature and light sensors. Copyright © 2014 John Wiley & Sons, Ltd.     

The plasma-electrolytic formation of cerium-containing surface structures on titanium and aluminum

The possibility of obtaining cerium-containing structures on aluminum and titanium by the plasma-electrolytic method with the use of aqueous solutions of electrolytes containing Ce³⁺ polyphosphate complexes was demonstrated. The amount of cerium in the films obtained depended on the molar ratio n = [polyphosphate]/[Ce³⁺] in the electrolyte. The films contained crystalline CePO₄. The growth of films on titanium was characterized by the formation of secondary layers by the mechanism involving the appearance of new phase nuclei followed by their expansion.     

双亲性希土-邻苯二甲酸正十四醇单酯-邻菲咯啉三元配合物的合成、表征、荧光特性及成膜性能

合成了双亲性的铕、铽-邻苯二甲酸正十四醇单酯-邻菲咯啉三元混配配合物，用红外光谱及差热-热重谱进行了表征。考察了发光性能。研究了它们在空气-水界面上的单分子膜行为，结果表明均具有良好的成膜行为。     

金属氧化物与现代微电子学——过渡金属前体化合物及转化为材料的化学过程

金属氧化物薄膜如HfO₂（被称为高k电介质）是现代微电子器件的关键组件,广泛用于计算机（平板电脑,笔记本电脑和台式机）、智能电话、智能电视、汽车和医疗设备中。具有大介电常数（k）的金属氧化物已经取代了介电常数小的SiO₂（k=3.9）,从而使得微电子元件进一步小型化。过渡金属化合物在化学气相沉积（CVD）和原子层沉积（ALD）中被广泛用作前体,通过与O₂、H₂O或O₃的反应生成金属氧化物薄膜。微电子金属氧化物膜是纳米材料最广泛应用的一个领域。本文概观该领域的最新进展,包括我们对d⁰过渡金属配合物与O₂反应的研究。     

Volatile Heteroligand Complexes of Copper(II): New Precursors for Chemical Vapor Deposition of Copper Films

Two heteroligand ketoiminate–diketonate complexes of copper(II), CuL(hfa) (1), L = pentane-2-imino-4-onato, CH₃COCHCNHCH ₃ ^– , and CuL′(hfa) (2), L′ = 2,2,6,6-tetramethyl-3-iminoheptane-5-onato, C(CH₃)₃COCHCNHC(CH)^–, were studied as precursors for chemical vapor deposition of copper films. The flow method was employed to measure the temperature dependences of a saturated vapor pressure of these compounds, the thermodynamic parameters of evaporation–sublimation were calculated, and the volatilities of these compounds and thermal behaviors in the condensed and gaseous phases were compared. The copper films were compared, and it was shown that comparatively high growth rates are reached when (2) is used to obtain copper films in hydrogen.