Search

The various gas sensors were designed for detection of different gases in the air using different oxides and impurities [13]. For example the manufacturing of ammonia sensors on the basis of CuxS-micro-porous-Si structure includes manufacture of micro-porous silicon, drawing on it of SiO2 isolating layer, and then the CuxS layer [4, 5]. The special equipment for all these processes is needed. More usable method for sensor production is so-called soft chemistry or sol– gel synthesis [6, 7]. Sol–gel process can be used to produce a wide range of various compounds (usually oxides) including their thin films, nanopowders, fibers, glasses, ceramics, organic-inorganic hybrids, and so on. The sol–gel process can be characterized by a series of discrete steps. Step 1: formation of the “sol” i.e. colloidal suspension of solid particles (usually salts of necessary materials) in a liquid (solvent for necessary materials). Step 2: gelation resulting from the formation of an oxide network (the gel) by a polycondensation that results in a dramatic increase in the viscosity of the solution. This network structure may result from physical or chemical bonds, as well as crystallites or other junctions that remain intact within the extending fluid. Step 3: formation of a xerogel a solid formed from a gel by drying usually in air atmosphere. As a result all solvent components that are not bonded with oxide network abandon the gel. A lot of various vanadium hydrated compounds were synthesized by using this simple method [8]. The sol–gel technology is also widely used for the production of the humidity sensors based on the vanadium hydrated compounds [9, 10]. The chemical composition of produced materials was investigated using the X-ray photoelectron spectroscopy (XPS) method. XPS is known as the surface analysis method which provides the direct information on the species concentration and their valence states. So we use these features of the method for studies of the surface composition of investigated xerogels. In the present paper, we introduce the ammonia gas sensor based on the vanadiummolybdenum-ammonium oxide hydrate that could operate at the room temperature area.

Previously we reported the synthesis of novel organic-inorganic composite indium tin oxide (ITO) foam precursor leading to the formation of “sponge-like” ITO by burning away the organics. This newly made sponge-like ITO possesses relatively high electrical conductivity due to phonon confinement with reasonable pore structure and may have potential application as functional materials in semiconducting dye absorbing layer in dye-sensitized solar cell (DSSC) and also as the receptor of electrons injected from the quantum dots (QDs) of organic-inorganic hybrid QD based solar cell. This report is a short review of “sponge-like” ITO described as a lecture note on its future use as an alternative new prospective material for photoanode of solar cell in the domain of sustainable energy.

PbZr0:5Ti0:5O3 nanopowders (~27 nm) have been prepared by a controlled reconstructive thermal decomposition and crystallization from an amorphous polymeric precursor with polyvinyl alcohol (PVA) and sucrose at 400 to 700 °C in air. The Rietveld refinement of the XRD profiles which were recorded at room temperature for the PbZr0:5Ti0:5O3 powder prepared by a thermal treatment at 700 °C for 2 h, confirmed the P4mm tetragonal crystal structure of the as prepared PbZr0:5Ti0:5O3 nanopowders, with a = 0.4036 nm and c = 0.4147 nm. A hexagonal symmetry (R3c), with a = 0.5774 nm and c = 1.4212 nm, was also detected from Rietveld refinement analysis. Thus, tetragonal and hexagonal phases were found to coexist with the as prepared PbZr0:5Ti0:5O3 nanopowders. The average particle size (D) of the PbZr0:5Ti0:5O3 powders, estimated with the help of the specific surface area, measured by BET method, was 26.1 nm. Average D value, calculated by D2θ1/2 in the XRD peaks with the Debye-Scherrer relation was ~24 nm. TEM study made it possible to measure the particle size of PbZr0:5Ti0:5O3 powders with an average diameter of 27 nm.

In this work, a series of mesoporous alumina materials exhibiting high surface areas have been synthesized, characterized and used in the preparation of CO 2 sorbents. The mesostructured powders were prepared through a soft chemistry route, employing aluminum tri-sec-butoxide-derived sol precursors in the presence of different surfactants. Structural and microstructural characterization techniques showed that γ-Al 2 O 3 powders were composed of nanocrystals, and the samples presented high surface area values (238.6–496.7 m 2 g −1 ) produced by a high mesostructured order, depending on the surfactant used as structure-directing agent. Based on the textural features, selected γ-Al 2 O 3 materials were employed as supports for the preparation of potassium-based sorbents for CO 2 capture at low temperatures (30–80 °C). Potassium-loaded alumina supports were synthesized by a wet impregnation method, and the CO 2 sorption tests were conducted via thermogravimetric analysis. The surface area and pore volume of the potassium-impregnated supports experienced a noticeable reduction, in comparison with the original values, suggesting the inclusion of potassium inside the support porosity. Nevertheless, the sorbents showed excellent reactivity; in fact, the potassium/γ-Al 2 O 3 sorbent prepared with 40 wt% potassium content had a maximum CO 2 capture capacity of 4.03 mmol CO 2 /g sorbent at the relatively low temperature of 80 °C in the presence of water vapor. These results suggest that both the potassium content and textural properties of mesostructured γ-Al 2 O 3 supports could provide an enhancement of the CO 2 absorption properties.

Soft chemical reactions such as ion-exchange and acid–base reactions have been extensively investigated to synthesize novel metastable layered inorganic solids, to exfoliate them into individual nanosheets, and to re-assemble them as thin films and nanocomposite materials. These reactions proceed at relatively low temperature and enable the synthesis of a rich variety of structures by stepwise reactions. In recent years, the toolbox of soft chemical reactions has been utilized to rationally design and tailor the properties of functional layered transition metal oxides. Layer-by-layer assembly and intercalation chemistry have provided insight into covalent interactions that stabilize oxide-supported nanoparticle catalysts. In addition, topochemical reactions have been utilized to tune the compositions of layered perovskite oxides in order to break inversion symmetry, resulting in piezoelectric and ferroelectric properties. This review focuses on the use of soft chemical approaches to design functional layered transition metal oxides with tunable properties. Soft chemical reactions enable the design of functional materials for diverse applications that include artificial photosynthesis, catalysis, energy storage, fuel cells, optical sensors, ferroics, and high-k dielectrics.

International audience; This work reports a proof of concept to obtain a shaped porous metallic alloy by the reduction at low temperature of an oxide precursor shaped at high temperature. A mixed cations oxide selected for potential applications in solid oxide fuel cells (SOFCs), is prepared using Pechini's polymer route and consolidated using the spark plasma sintering (SPS) technique at temperature in the 900 °C – 1,100 °C range. A pellet of pure AB2O4 spinel‐like structure with 10% of open porosity is obtained. The reduction of this pellet under H2 flow at low temperature (800 °C) allows obtaining a highly porous (48%) metallic pellet which meets all necessary characteristics to be used as mechanical support for the third generation of SOFC (3G‐SOFC). The use of oxide precursors widen the accessible temperature range allowing the possibility to stack in one step an oxide precursor of the 3G‐SOFC with full densification of the electrolyte. This proof of concept opens the way to the easy and cheap “one step” building of an oxide precursor of 3G‐SOFC which will be in situ activated during the warming up of the cell.

A soft chemistry synthetic strategy based on a Friedel-Crafts alkylation reaction is developed for the textural engineering of phenolic resin (PR) with a robust mesoporous framework to avoid serious framework shrinkage and maximize retention of organic functional moieties. By taking advantage of the structural benefits of molecular bridges, the resultant sample maintains a bimodal micro-mesoporous architecture with well-preserved organic functional groups, which is effective for carbon capture. Moreover, this soft chemistry synthetic protocol can be further extended to nanotexture other arene-based polymers with robust frameworks.

Iron oxide nanoparticles (γ-Fe2O3) have been synthesized using soft chemistry in aqueous media. The particles were then stabilized on a surface using bifunctional coating agents bearing terminal functional groups which enable post functionalization with the desired catalyst (proline derivatives, peptides). The hybrid nanomaterials were characterized with various techniques in order to determine their properties. The catalysts’ activities were evaluated using aldolization and 1,4-Michael addition as model reactions. For both reactions the crucial impact of the nanocatalyst surface functionalisation on the catalytic properties is demonstrated. For the Michael addition, good selectivity was achieved using a small amount of nano-catalyst.

The main goal of this thesis is to obtain multiferroic materials via the intercalation of organic molecules in a magnetic inorganic matrix made of layered simple hydroxide. The possibility to use phosphonic acid as grafting moiety for the functionalization of layered simple hydroxides has been demonstrated during this thesis. Pre-functionalization techniques has allowed the functionalization of layered simple hydroxides of copper and cobalt with a wide variety of molecules (fluorenes, benzenes, thiophenes or transition- metal complexes) to bring an additional property to the magnetic properties of the layered hydroxide. The first measurements revealed a coupling between magnetic ordering temperature and dielectric anomaly. The dielectric properties measurements proved to be difficult with the samples (on cold-pressed pellets) and shown the usefulness of developing new methods to improve the cristallite size. To that end, new syntheses procedures led to the obtention of mono crystals of copper-hydroxidodecylsulfonate allowing to get additional structural informations.; Le but de cette thèse est l’obtention de matériaux multiferroïques par l’insertion de molécules organiques dans une matrice magnétique d’hydroxide simple lamellaire. Durant cette thèse a été démontré la faisabilité de la fonctionnalisation d’hydroxides simples lamellaires de cuivre et de cobalt par des molécules possédant des fonctions d’accroche acide phosphonique. Le développement des techniques de pré-fonctionnalisation a permis de fonctionnaliser ces hydroxides simple lamellaire par une variété importantes de molécules (fluorènes, benzènes, thiophènes et complexes de métaux de transition) afin d’apporter une propriété additionnelle au magnétisme de l’hydroxyde. Les premières mesures ont permis de mettre en évidence un couplage entre temperature d’ordre magnétique et anomalie diélectrique. La complexité de la mesure des propriétés diélectriques avec ces échantillons (sur poudre pastillées à froid) ont mis en lumière la nécessité d’obtenir des tailles de cristallites plus importantes. Des efforts sur la taille des cristallites ont donc été effectués et ont permis d’obtenir des monocristaux d’hydroxy- dodecylsulfate de cuivre.

International audience; Elaborating advanced nanomaterials based on the assembly of nanoparticles (NPs) is a versatile route for targeting and tuning a wide variety of properties like optical, magnetic, and electrical properties or sensing. This route usually employs a so-called soft chemistry which has the advantage of being quite cheap and transferable to an industrial level. However, getting quantitative information on the quality of the mechanical consolidation of the nanoparticle assembly (ordered or disordered) in a nondestructive manner is not often achieved, although it is crucial for applications and integration of materials in devices. Therefore, we present in this Article a complete method where we evaluate the elasticity of weakly (van der Waals nanocontacts) to strongly (covalent-hydrogen nanocontacts) interacting nanoparticle assemblies. This complete work is realized on a disordered silica nanoparticle network obtained by the sol–gel method. A precise control of the chemical and physical properties of the nanoparticle surface molecular landscape is achieved thanks to infrared, visible, and ultraviolet spectroscopies as well as surface tension measurements and atomic force microscopy, while the nanoparticle assembly elastic stiffness is evaluated by ultrafast nanoacoustics based on an optical pump–probe method.

While the soft chemistry of layered alkali metal oxides is adequately understood, the effect of the post-synthesis thermal treatment on their structure, composition, and properties has been underexplored. In this article, we thoroughly investigated the bulk and surface modifications of K0.8M0.4Ti1.6O4 (M = Ni, Cu, Zn) lepidocrocite titanate thermally treated within 200 °C above its synthetic temperature under air. This practice was typically employed in e.g., specimen fabrication for physical property measurements. We observed the expansion of the interlayer distance (b/2) accompanied by a reduction in layer charge density. These findings can be explained by the deintercalation of interlayer K+ ions and the loss of intralayer Ti, M, and O species. Meanwhile, the enrichment of potassium and carbonate on the surfaces was evident. The slight differences in dielectric properties of the pellets thermally treated at different temperatures were attributed to the combination of bulk and surface modifications. At 103 Hz and RT-250 °C, the maximum dielectric constants e'max of ∼104 with the dielectric loss (tan δ) ∼0.9-1.5 were obtained for K0.8Zn0.4Ti1.6O4.

Filled tetrahedral semiconductors are a rich family of compounds with tunable electronic structure, making them ideal for applications in thermoelectrics, photovoltaics, and battery anodes. Furthermore, these materials crystallize in a plethora of related structures that are very close in energy, giving rise to polytypism through the manipulation of synthetic parameters. This Minireview highlights recent advances in the solution-phase synthesis and nanostructuring of these materials. These methods enable the synthesis of metastable phases and polytypes that were previously unobtainable. Additionally, samples synthesized in solution phase have enhanced thermoelectric performance due to their decreased grain size.

Polycrystalline randomly oriented CaMnO3 films were successfully deposited on sapphire substrates by soft chemistry methods. The precursor solutions were obtained from a mixture of metal acetates dissolved in acids. The Seebeck coefficient and the electrical resistivity were measured in the temperature range of 300 K < T < 1000 K. Modifications of thermal annealing procedures during the deposition of precursor layers resulted in different power factor values. Thermal annealing of CaMnO3 films at 900 °C for 48 h after four-layer depositions (route A) resulted in a pure perovskite phase with higher power factor and electrical resistivity than four-layer depositions of films annealed layer by layer at 900 °C for 48 h (route B). The studied films have negative Seebeck coefficients indicative of n-type conduction and electrical resistivities showing semiconducting behavior.

Vertical graphene nanosheets (VGNs) are the material of choice for next-generation electronic device applications. The growing demand for flexible devices in electronic industry brings in restriction on growth temperature of the material of interest. However, VGNs with better structural quality is usually achieved at high growth temperatures. The difficulty associated with the direct growth on flexible substrates can overcome by adopting an effective strategy of transferring the well grown VGNs onto arbitrary flexible substrates through soft chemistry route. Hence, we demonstrated a simple, inexpensive and scalable technique for the transfer of VGNs onto arbitrary substrates without disrupting its morphology and structural properties. After transfer, the morphology, chemical structure and electronic properties are analyzed by scanning electron microscopy, Raman spectroscopy and four probe resistive methods, respectively. Associated characterization investigation indicates the retention of morphological, structural and electrical properties of transferred VGNs compared to as-grown one. Furthermore the storage capacity of the VGNs transferred onto flexible substrates is also examined. A very lower sheet resistance of 0.67 kOhm/sq. and excellent supercapacitance of 158 micro-Farrad/cm2 with 91.4% retention after 2000 cycles confirms the great prospective of this damage-free transfer approach of VGNs for flexible nanoelectronic device applications

This manuscript proposes a soft-chemistry method to develop superhydrophobic and highly IR-reflective hollow glass microspheres (HGM). The anatase TiO2 and a superhydrophobic agent were coated on the HGM surface in one step. TBT and PFOTES were selected as the Ti source and the superhydrophobic agent, respectively. They were both coated on the HGM, and after the hydrothermal process, the TBT turned to anatase TiO2. In this way, a PFOTES/TiO2-coated HGM (MCHGM) was prepared. For comparison, PFOTES single-coated HGM (F-SCHGM) and TiO2 single-coated HGM (Ti-SCHGM) were synthesized as well. The PFOTES and TiO2 coatings on the HGM surface were demonstrated through X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive detector (EDS) characterizations. The MCHGM showed a higher contact angle (153°) but a lower sliding angle (16°) than F-SCHGM, with a contact angle of 141.2° and a sliding angle of 67°. In addition, both Ti-SCHGM and MCHGM displayed similar IR reflectivity values, which were about 5.8% higher than the original HGM and F-SCHGM. Also, the PFOTES coating barely changed the thermal conductivity. Therefore, F-SCHGM, with a thermal conductivity of 0.0479 W/(m·K), was quite like the original HGM, which was 0.0475 W/(m·K). MCHGM and Ti-SCHGM were also similar. Their thermal conductivity values were 0.0543 W/(m·K) and 0.0543 W/(m·K), respectively. The TiO2 coating slightly increased the thermal conductivity, but with the increase in reflectivity, the overall heat-insulation property was enhanced. Finally, since the IR-reflecting property is provided by the HGM coating, if the coating is fouled, the reflectivity decreases. Therefore, with the superhydrophobic coating, the surface is protected from fouling, and its lifetime is also prolonged.

The Squarate complex of Ni(II) with 4, 4-bipyridine compound and [Ni(C4H2O4)2(C10H8N2)2]+2.2Cl-formula was synthesized by soft chemistry, using co-precipitation method. The structure was characterized using infrared spectroscopy for main functional groups confirmation and powder XRD witch show that it crystallize in the monoclinic system, with cell lattice parameters a=9.9674 A, b=10.538, c=18.7066 A, V=1940.83 A3. The structure is based on SBU of NiO2N2 lied to organic entities. The nickel (II) is tetracoordinated with the two donor atoms of 4, 4 bipyridine and two oxygen atoms of the squarate, building a distorted tetraedral around the metal ion.

Calcium manganate Ruddlesden–Popper phases Ca2MnO4–δ were prepared by soft chemistry and treated with acid to extract a part of the calcium ions. Combined structural, morphological and spectroscopic analyses by XRD, SEM/EDX, TEM and Raman revealed an amorphization of the treated surface with a preserved inner crystalline phase in the core of the particles. The inner part of the particles consists of Ca2MnO4–δ and the outer part of hydrated amorphous manganese oxide MnO2·xH2O. Although pristine Ca2MnO4–δ is not electrochemically active, electrochemical characterization of the acid-treated powders shows a significant change in capacity that correlates to the amount of extracted calcium. The cycling stability of the Ca2 + extracted compounds was improved by more than a factor of 10 in comparison to pure MnO2·xH2O. The acid-treated Ca2MnO4–δ showed enhanced capacity retention of up to 50% after 70 cycles compared to 4% for bare MnO2·xH2O due to its crystalline core.

Lanthanum zirconate with a pyrochlore structure exhibits interesting thermal and structural properties for thermal barrier coating applications operating at high temperature. This study focused on the synthesis of La2Zr2O7 powders by soft chemistry (citrate, coprecipitation, and sol–gel methods), and the effects of the solvent and the nature of the precursors used on the powder properties were investigated. The nature of the counter-cation influenced the structural phase of the compound. A low polarizable counter-cation (chloride) permitted the elaboration of a pyrochlore structure within a larger range of parameters compared with highly polarizable counter-cations (nitrate and acetate). Moreover, the nature of the solvent, and specifically the strength of the interactions within it, had an impact on the particle size. Specifically, the use of water, which is a solvent with strong interactions, led to a smaller particle size than the use of ethanol, which has weaker interactions. Based on these results, the crystalline phase of the powders can be predicted as a function of the precursor and the solvent used for the different synthesis routes, and the particle size can be used to evaluate the reactivity of the powders.

A facile soft chemistry route was described to prepare a composite material of Nb2O5 nanowires modified with Pd nanoparticles having an average diameter of 7.9 nm. The Pd/w-Nb2O5 catalyst was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), Brunauer–Emmett–Teller (BET) and X-ray photoelectron spectroscopy (XPS) techniques. In comparison with Pd/s-Nb2O5 and Pd/Al2O3, the Pd/w-Nb2O5 had a more substantial catalysis effect on the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) under ambient conditions. The results showed that the conversion rate of 4-NP (20 mg L−1, 100 mL) was about 98.3% after 4 min using 10 mg of the catalyst, Moreover, after the catalyst had been reused 10 times, the conversion rate still remained 85.3%. The significant enhancement in the catalysis activity can be ascribed to acidity and morphology of the catalyst support Nb2O5.

The BaF2-ScF3 system is studied using coprecipitation from aqueous solutions. Compound Ba3Sc2F12 is found to form over a wide range (10–60 mol %) of scandium concentrations in the initial solution. At higher scandium concentrations in solution, a new phase of provisional composition BaSc2F8 · 2H2O (hexagonal system, a = 9.6346 A, c = 4.0483 A) was obtained. Scandium fluoride hydrolysis is not observed by energy-dispersive X-ray analysis.

The perovskite CaCu3Ti4O12, with giant electric permittivity, was prepared by a soft chemistry route and by the solid state synthesis technique. The main purpose of this work is to verify the effects of the synthesis techniques on the powder characteristics, and the microstructure and dielectric properties of the sintered materials. The synthesized nanopowders were calcined, pressed into pellets and sintered using the same procedures as for the materials prepared by the conventional method. Phase analysis was performed by X-ray diffraction, microstructure observations were carried out by scanning electron microscopy, and the dielectric properties were studied by impedance spectroscopy. The electric permittivity ranged from 11,600 to 27,000 and from 5,000 to 9,000 for specimens prepared by the conventional and the soft chemistry techniques, respectively, and the dielectric losses varied between 0.1 and 1.3 (conventional) and 0.095 and 0.3 (soft chemistry) depending on the sintering temperature.

Zinc oxide nanostructures have been done by many scientists but amongst the soft chemistry methods, chelating agents are normally used. In this work zinc oxide nanostructures have been synthesized using a soft chemistry method without using a chelating agent. The precursor were annealed at various temperatures of 400 °C, 500 °C, 600 °C, 700 °C, 800 °C and 1200 °C for 24 h. Nanostructures are found with rod-like shapes and they are compared with larger oval morphology. X-Ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), and UV-Vis spectroscopy were used for characterization. XRD results confirm that all peaks were pure and single phase without the presence of any impurities. It was found from electron microscopy results that the morphology of the materials annealed at 400 °C possesses nanorod shape and as the calcination temperature increases, the material consists of mixed rod, spherical and oval shapes. The aspect ratio of the materials decreases when the annealing temperature increases. The absorption edges of the materials annealed at higher temperatures show a red-shift implying that narrowing of the band gaps occur in the materials. Band gap were evaluated and found to be between 3.32 to 3.19 eV.

Spinel Li4Ti5O12 nanorods coated with poly (3,4-ethylenedioxythiophene) (PEDOT) layer as an anode material for lithium ions battery were synthesized by a facile soft chemistry approach. The highly conductive and uniform PEDOT layer coated on the surface of Li4Ti5O12 nanorods significantly improves the electrochemical performance of the composite, which exhibits higher reversible capacity and better rate capability compared with the pure Li4Ti5O12 and Li4Ti5O12/C composite. The reversible capacity of Li4Ti5O12/PEDOT nanorods can be up to 171.5 mA h g−1 at the rate of 0.2 C. And a capacity of 168.7 mA h g−1 was retained with only 0.5% capacity loss after 100 charge-discharge cycles at the rate of 1 C, which confirms the good cycling behavior of Li4Ti5O12/PEDOT nanorods. The superior electrochemical performance of the Li4Ti5O12/PEDOT nanorods could be attributed to the one-dimensional (1D) morphology and uniform conducting polymer layer, which shortens the lithium-ion diffusion path and improves the electrical conductivity of Li4Ti5O12.

Lithium vanadate, LiVO3, has been successfully synthesized by a soft chemistry route with subsequent calcinations. The influence of synthesis temperature on the structure properties including lattice parameters and crystallite size were investigated by X-ray powder diffraction. The LiVO3 compound fabricated at 350 °C has the smallest particles with diameters ranging from 500 nm to 1 μm, and possesses the best performance including high discharge capacity, good rate capability and cyclic stability as cathode materials for lithium batteries. Highly stable specific capacities of 257, 233, 203.8, 173.7 and 141.9 mA h g−1 can be achieved at current densities of 100, 200, 400, 800 and 1500 mA g−1, respectively. The phase transition of the discharged electrode has been evaluated by the ex-situ XRD techniques. Electrochemical impedance spectra (EIS) measurements were carried out to determine the influence of phase transition on the lithium diffusion coefficients.

Nanoparticles (NPs) of the Sn1−xCdxO2 (0.0 ≤ x ≤ 0.04) were synthesized through soft chemistry method. These NPs were characterized for structural, morphological and electrical properties by X-ray diffraction, High resolution transmission electron microscopy and dielectric spectroscopy techniques respectively. Structural analysis confirms that all the NPs are having single phase rutile tetragonal structure. The NPs are of spherical shape and average size of these is found to decrease with Cd doping. Dielectric permittivity and AC conductivity of all the NPs were evaluated as a function of frequency and composition at room temperature. The frequency response of er, ei, tan δ and σ ac show that the dispersion is due to the interfacial polarization and these parameters decrease with doping of Cd in the SnO2 matrix. The possible correlation between observed dielectric properties and size of NPs, and hence disorder in the system are explored.

Substitution of cations in metal oxides result in differences of materials characteristics. Substitution resulting in isostructural materials is not easy. In this work, Cu has been used as the substitution element for Zn in Zinc oxide. The Zn(1-x)CuxO (x=0.01, 0.02, 0.03, 0.04, 0.05) materials were prepared via a simple soft chemistry method without using any chelating agents. Results showed that some of the samples are pure but the heavily doped samples contain a very small amount of CuO as an impurity. XRD and microscopy results agree with each other.

Nanodimensional Fe(III)-TiO2 crystalline particles have been obtained by the soft chemistry technique in an aqueous solution without calcination. The crystallization of the products of hydrolysis of titanium dioxide used as a precursor was carried out by boiling in the presence of acidic peptizing agents, which facilitated the temperature dehydration of hydroxo and oxo compounds. A phase of nanodimensional magnetite was used as a center of crystallization, which resulted in the doping of the crystalline lattice of TiO2 of an anatase modification. The powders and films that formed from solutions showed high photocatalytic activity under the action of visible light. According to morphological analysis, nanodimensional Fe(III)-TiO2 crystalline particles possess a narrow size distribution of pores and a high specific surface area.

Alumina and scandia doped zirconia was prepared through a soft chemistry synthesis route and sintered at 1873 K. X-ray diffraction patterns indicate a pure cubic phase for the composition of 0.88ZrO2-0.112Sc2O3-0.008Al2O3. Thin films were fabricated on Al2O3 〈0001〉 substrates using pulsed laser deposition technique. Dense films of 0.941 μm thickness were obtained at 873 and 1023 K substrate temperatures at an oxygen partial pressure of 15 Pa. The ionic conductivity of both thin film and sintered pellet was measured using ac impedance spectroscopy in air. The conductivity values are higher for thin films compared to that of sintered pellets.

Lu2O3:Yb3+/Er3+ nanocrystals with various sizes and shapes (nano-aggregates, sub-micrometer wires, and nanospheres) have been synthesized by the soft chemistry coprecipitation route. By regulating the reactant ratio of rare earth to urea precipitant ([RE3+]/(NH2)2CO), uniform spherical Lu2O3:Yb3+/Er3+ nanoparticles with the sizes of 45, 100, 165, 200, and 250 nm were obtained in the experiments. The phases, morphologies, as well as the luminescence properties of as-prepared samples were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and upconversion luminescence (UCL) spectra, respectively. Under the excitation of a 980 nm diode laser, the Lu2O3:Yb3+/Er3+ samples showed size-dependent upconversion luminescence property. From the results of Fourier transform infrared (FTIR) spectra and dynamical analysis, it was confirmed that the surface effect is dominant in influencing the UCL of Er3+ in the spherical Lu2O3:Yb3+/Er3+ samples. By coating Lu2O3:Yb3+/Er3+ nanospheres with different shell layers, UCLs of Er3+ were changed greatly in these core–shell samples. The possible physical mechanism involved in size/surface-dependent upconversion processes was discussed in detail.

Structural and thermoelectric transport properties of Ba2+ containing lanthanum cobaltate (La1 xBaxCoO3; x = 0.01 0.03 0.05) prepared by soft chemistry method were investigated and discussed. The influence of the fuel to oxidizer ratio (U) of the redox mixture on the powder microstructure was studied. The agglomeration grade of the nanocrystalline perovskite phases can be influenced due to initial composition of the redox mixture. Since the different burning characteristic of the polymerized gels results in different xerogel structures the as calcined single phase perovskite samples show different compacting and sintering behavior. The thermoelectric transport properties were measured in the 300–1300 K temperature range. It was found that the electrical and thermal conductivity of the sintered pellets show strong dependence on microstructure. In addition increasing Ba2+ content in the samples results in lower thermal conductivity values (j < 1.5 W/K m). The calculated dimensionless figure of merit (ZT) showed maximum value in the 400–500 K range.

Silver orthophosphate powders with superior quality used in phosphorus-doped conductive pastes for solar cell metallization were obtained by precipitation from phosphate precursors. The powders were investigated by X-ray diffraction, scanning electron microscopy coupled with energy dispersive spectrometry, Fourier-transform infrared spectroscopy, thermal analysis, and diffuse reflectance spectroscopy. Spherical silver orthophosphate particles with a size of 0.8 to 10 μm were obtained by chemical precipitation, and the compound crystallized in a cubic symmetry. Relatively smaller crystallites were obtained from disodium hydrogen phosphate. The optical gap determined from the diffuse reflectance spectra using the Kubelka-Munk function varied between 2.05 and 2.30 eV. The electrical conductivity is characteristic of a semiconducting behaviour with activation energy of 0.20 eV. To improve the metal-semiconductor interface, the uniformity of powders of the deposited paste must be enhanced.

This review presents thoughts on some of the fundamental features of conceptual models applied in the design of fine particles in the frames of colloid and soft chemistry. A special emphasis is placed on the limitations of these models, an acknowledgment of which is vital in improving their intricacy and effectiveness in predicting the outcomes of the corresponding experimental settings. Thermodynamics of self-assembly phenomena illustrated on the examples of protein assembly and micellization is analyzed in relation to the previously elaborated thesis that each self-assembly in reality presents a co-assembly, since it implies a mutual reorganization of the assembling system and its immediate environment. Parameters used in the design of fine particles by precipitation are discussed while referring to solubility product, various measures of supersaturation levels, induction time, nucleation and crystal growth rates, interfacial energies, and the Ostwald-Lussac law of phases. Again, the main drawbacks and inadequacies of using the aforementioned parameters in tailoring the materials properties in a soft and colloidal chemical setting were particularly emphasized. The basic and practical limitations of zeta-potential analyses, routinely used to stabilize colloidal dispersions and initiate specific interactions between soft chemical entities, were also outlined. The final section of the paper reiterates the unavoidable presence of practical qualitative models in the design and control of nanoparticulate colloids, which is supported by the overwhelming complexity of quantitative relationships that govern the processes of their formation and assembly.

Li-stabilized Na-β″/β-Al2O3(Na1.61Li0.29Al10.70O17) nanorods were prepared by a soft chemistry process using a 1-alkyl-3-methylimidazolium bromide ([CXmim]Br, X = 4, 12, 16) ionic liquid as a template. Pure Na-β″/β-Al2O3 rods were obtained by heating at 1100 °C with [C16mim]Br as the template, resulting in nanorods of approximately 50 nm in diameter and 200–300 nm in length. It is demonstrated that alkyl chain length is the main factor determining the aspect ratio of the nanorods. The specific surface area of the powder is 81.3 m2/g, which is more than one order of magnitude higher than that of the powder prepared by a conventional solid state reaction process. The formation mechanism of the nanorods is proposed.

Ultrathin Ag2Mo3O10·2H2O nanowires (NWs) were synthesized by soft chemistry under atmospheric pressure from a hybrid organic-inorganic polyoxometalate (CH3NH3)2[Mo7O22] and characterized by powder X-ray diffraction, DSC/TGA analyses, FT-IR and FT-Raman spectroscopies, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Their diameters are a few tens of nanometers and hence much thinner than that found for silver molybdates commonly obtained under hydrothermal conditions. The optical properties of Ag2Mo3O10·2H2O NWs before and after UV irradiation were investigated by UV-vis-NIR diffuse reflectance spectroscopy revealing, in addition to photoreduction of Mo(6+) to Mo(5+) cations, in situ photogeneration of well-dispersed silver Ag(0) nanoparticles on the surface of the NWs. The resulting Ag@Ag2Mo3O10·2H2O heterostructure was confirmed by electron energy-loss spectroscopy (EELS), X-ray photoelectron spectroscopy (XPS), and Auger spectroscopy. Concomitant reduction of Mo(6+) and Ag(+) cations under UV excitation was discussed on the basis of electronic band structure calculations. The Ag@Ag2Mo3O10·2H2O nanocomposite is an efficient visible-light-driven plasmonic photocatalyst for degradation of Rhodamine B dye in aqueous solution.

The objective of this study is to develop a cost-effective and environmentally friendly synthesis using soft chemistry based on Chemical Solution Deposition (CSD) using ink-jet printing for the deposition of ceramic thin films. The main advantages are the lower investment, the faster deposition with higher yield and the processing under ambient pressure enabling a complete continuous processing. The materials chosen for this study are TiO2 for development of photocatalytic layers; Yttria-stabilized zirconia (YSZ) is chosen as electrolyte material for Solid Oxide Fuel Cells (SOFC's) and for production of Thermal Barrier Coatings (TBC's); Lanthanum-Strontium-Manganese-Oxides (LSMO) magneto-resistive systems have been developed for obtaining functional magneto-resistive patterns.

In the present work, nanoporous alumina microspheres have been synthesized by sol–gel technique. Acid deficient aluminum nitrate and a mixture of equimolar HMTA-Urea were used as starting materials. The prepared sol then injected as droplets into hot oil column to give spherical shape. After calcinations the samples were characterized by scanning electron microscope, fourier transform infra-red spectroscopy, thermogravimetry–differential thermal analysis, X-ray diffraction and N2 adsorption–desorption isotherms. With respect to the results achieved from the above analyses, it was found that nanoporous alumina microspheres with controllable size and morphology can successfully be produced through sol–gel method.

LaNiO perovskite is a promising electrocatalyst for the oxygen reduction reaction (ORR). In this work we study the effects of several key structural and morphological features on the performance of LaNiO perovskites for the ORR. We have prepared a series of LaNiO oxides via soft chemistry and calcined the final materials at different temperatures from 500 to 1000 °C. With the aim of obtaining morphological and structural information relevant to their performance the prepared oxides have been thoroughly characterized by BET, Power Neutron Diffraction (PND), XRD, HRTEM, STEM-HAADF and XPS. We have analysed the effect of extrinsic (surface area and particle size) and intrinsic factors (formation of oxygen vacancies, Ni oxidation states and occupancy of the e levels) on the current densities and specific activity, respectively, of several samples of LaNiO. The catalysts with higher catalytic activity are those in which the perovskite structure is properly formed, but display high surface areas., María Retuerto acknowledges the Juan de la Cierva program of the Spanish Ministry of Economy and Competitiveness for a grant (FPDI-2013-17582). Economic support from projects ENE2013-42322-R from the Spanish Ministry of Economy and Competitiveness, and project 201480E122 from the CSIC are also acknowledged. Project S2013/MAE-2882 is also acknowledged. J. A. Alonso and M. Teresa Fernández-Diaz thank the financial support of the Spanish Ministry of Science and Innovation to the project MAT2013-41099-R. Amaru González acknowledges the SECAT for a grant.

International audience; A barium boron aluminosilicate sealing glass for IT-SOFC or SOFC applications was synthesized using different routes. Notably, sol-gel and solid state processes were used in order to obtain homogeneous glasses at 1100–1300 °C. Sol-gel processes consist in a soft chemistry route allowing a better homogeneity between cationic precursors in the mixture and a better reactivity of the material. The influence of the process and of the glass processing temperature on the thermo-mechanical properties of the glasses were investigated after different heat treatments in air atmosphere, i.e. glass processing, sealing (850 °C-2 h) and ageing (800 °C-100 h) procedures. It had been observed that the grain size of the glass powder (obtained after the glass processing and used for the sealing operation) is determining in order to manage the sealing procedure. Some large pores were formed during the devitrification step of the glass made by solid state route while glass sealants synthesized by the sol-gel route even at 1100 °C remained suitable for SOFC applications after thermal treatments, which proved that the sol-gel process is useful to decrease the glass processing temperature.

We have developed a vanadyl phosphate/tetraethylorthosilicate (VPO/TEOS) nanocomposite comprised of silicate chains interleaved with VPO layers, prepared by using an n -alkylamines such as octylamine as the structure directing agent. The nanocomposites were synthesized by reacting amine-intercalated vanadyl phosphate with tetraethylorthosilicate via the soft chemistry approach. The synthetic procedure encompassed the exfoliation of the layered vanadyl phosphate as well as the reorganization of this exfoliated solid into a mesostructured lamellar phase with the same V–P–O connectivity as in the original matrix. TEOS incorporation into the vanadyl phosphate was achieved by expanding the lamellar structure with n -alkylamine (Δ d = 13 A with n -octylamine). The specific surface area increased from 15 m 2 g −1 in the vanadyl phosphate matrix to 237 m 2 g −1 in VPOcT, and the isotherm curves revealed the characteristic hysteresis of mesoporous materials. Upon thermal treatment up to 500 °C, the surface area increased to 837 m 2 g −1 , which is suitable for catalytic purposes.

The preparation of a nano-sized LaFeO 3 powder by a soft-chemistry method using starch as complexing agent is described herein. Phase evolution and development of the specific surface area during the decomposition process of (LaFe)-gels were monitored up to 1000 °C. A phase-pure nano-sized LaFeO 3 powder with high specific surface area of 25.7 m 2 /g and a crystallite size of 37 nm was obtained after calcining at 570 °C. TEM investigations reveal a porous powder with particles in the range of 20 to 60 nm. Calcinations to 1000 °C result in crystallite sizes up to 166 nm. The dilatometric measurements of the sintering behaviour show that the beginning of shrinkage of pellets from the nano-sized powder is downshifted by more than 300 °C compared to the coarse-grained mixed-oxide powder. The orthorhombic ⇆ rhombohedral phase transition was observed at 980 °C in DTA measurements for the coarse-grained ceramic bodies. The enthalpy change ( ΔH ) during the phase transition and the thermal expansion coefficient ( α dil ) for the ceramics were determined as 410 J/mol and 11.8·10 − 6 K − 1 , respectively. Whereas the enthalpy changes during the phase transition of the nano-sized LaFeO 3 powders are ≤ 200 J/mol.

The thermoelectric properties of W-substituted CaMn1-xWxO3-δ (x = 0.01, 0.03; 0.05) samples, prepared by soft chemistry, were investigated from 300 K to 1000 K and compared to Nb-substituted CaMn0.98Nb0.02O3-δ. All compositions exhibit both an increase in absolute Seebeck coefficient and electrical resistivity with temperature. Moreover, compared to the Nb-substituted sample, the thermal conductivity of the W-substituted samples was strongly reduced. This reduction is attributed to the nearly two times greater mass of tungsten. Consequently, a ZT of 0.19 was found in CaMn0.97W0.03O3-δ at 1000 K, which was larger than ZT exhibited by the 2% Nb-doped sample. Fil: Alfaruq, Dimas S.. EMPA. Solid State Chemistry and Catalysis; Suiza; Fil: Eilertsen, James. EMPA. Solid State Chemistry and Catalysis; Suiza; Fil: Thiel, Philipp. EMPA. Solid State Chemistry and Catalysis; Suiza; Fil: Aguirre, Myriam H.. EMPA. Solid State Chemistry and Catalysis; Suiza; Fil: Otal, Eugenio Hernan. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Subsede Instituto Universitario Aeronáutico; Argentina; EMPA. Solid State Chemistry and Catalysis; Suiza; Fil: Populoh, Sascha. EMPA. Solid State Chemistry and Catalysis; Suiza; Fil: Yoon, Songhak. EMPA. Solid State Chemistry and Catalysis; Suiza; Fil: Weidenkaff, Anke. EMPA. Solid State Chemistry and Catalysis; Suiza

Here we report the synthesis and some physical properties of superoxides CuYO2.51 and CuYO2.25 prepared from the delafossite CuYO2 respectively by thermal oxidation at 380 °C under O2-flow and soft chemistry in NaBrO (5N) solution and their applications as catalysts for solar energy conversion in a chemical H2 evolution, upon visible light. The oxygen insertion was accompanied by partial oxidation of Cu+ lattice. For CuYO2.25 , the chemical analyses as well as magnetic data reveal the presence of mixed valent states containing at least formally an equal number of Cu+ and Cu2+. In air, CuYO are thermally stable up to 500 °Cabove wich they undergo . an irreversible 2+X conversion into CuY2O5. The oxides are chemically stable in basic media and under illumination, they are stabilizsd by hole consumption reactions involving SO32- and S2- as holes scavengers. The flat band potentials lying between 0,17 and 0,17 eV, are located above the H2O/H2 level, leading to a spontaneous H2- evolution. The rate of H2-formation is altered by the oxygen insertion and the best photoactivity is obtained over CuYO2.25 immersed at 0.025 M sulfide S2- solution. A photoelectrochemical study is reported for comparison with photoactivity results.

Molecules 21(10), 1399(2016). doi:10.3390/molecules21101399, The aim of the present review is to highlight the state of the art in high-pressure design of new advanced materials based on boron nitride. Recent experimental achievements on the governing phase transformation, nanostructuring and chemical synthesis in the systems containing boron nitride at high pressures and high temperatures are presented. All these developments allowed discovering new materials, e.g., ultrahard nanocrystalline cubic boron nitride (nano-cBN) with hardness comparable to diamond, and superhard boron subnitride B$_{13}$N$_2$. Thermodynamic and kinetic aspects of high-pressure synthesis are described based on the data obtained by in situ and ex situ methods. Mechanical and thermal properties (hardness, thermoelastic equations of state, etc.) are discussed. New synthetic perspectives, combining both soft chemistry and extreme pressure–temperature conditions are considered. View Full-Text, Published by MDPI, Basel

Sr1−xCaxCrO3−δ (x = 0.25, 0.50, 0.75) solid solutions have been synthesised using the ‘hard–soft’ technique and structurally characterised. Sr1−xCaxCrO3 phases were prepared under ‘hard’ high pressure and high temperature synthesis and then reduced at ‘soft’ low temperature conditions. Analysis by powder X-ray diffraction and Rietveld refinements reveals that the reduction of each composition gives two crystalline products, with 6H and 15R structure types previously reported in SrCrO3−δ. analogues. These results demonstrate that the 6H and 15R structures are stable for very high calcium contents up to x = 0.75 in Sr1−xCaxCrO3−δ, although different structural motifs are observed for CaCrO3−δ. The Sr1−xCaxCrO3−δ phase diagram shows that the lower temperature for superstructure formation has a maximum near x = 0.5, evidencing an influence of Ca/Sr cation disorder on oxygen vacancy order.