Influence of CuO on the formation and coexistence of 3CaO·SiO2 and 3CaO·3Al2O3·CaSO4 minerals

The influence of CuO on the formation and coexistence of 3CaO·SiO₂ and 3CaO·3Al₂O₃·CaSO₄ minerals in Portland cement containing 3CaO·3Al₂O₃·CaSO₄ mineral is reported in this paper. The results show that a suitable amount of CuO can lower the clinkering temperature and improve the burn-ability of clinkers. It can also promote the formation of 3CaO·SiO₂ and 3CaO·3Al₂O₃·CaSO₄ minerals and facilitate the coexistence of the two minerals in the clinkers. But adding 1% CuO to the raw material can cause the decomposition of 3CaO·3Al₂O₃·CaSO₄.     

Structural transition of Friedel's salt 3CaO·Al2O3·CaCl2·10H2O studied by synchrotron powder diffraction

The structural phase transition occurring in Friedel's salt, the chlorinated compound 3CaO·Al₂O₃·CaCl₂·10H₂O (AFm phase), was studied by synchrotron and standard X-ray powder diffraction. The compound transforms at 35 °C from a rhombohedral (rh) high-temperature (HT) phase [R−3c; a=5.744(2) Å, c=46.890(3) Å] to a monoclinic (m) low-temperature (LT) phase [C2/c; a=9.960(4) Å, b=5.7320(2) Å, c=16.268(7) Å, β=104.471(2)°]. The LT and HT phases were refined with the Rietveld method from synchrotron data recorded at 20 and 40 °C. Variations of the lattice parameters as a function of temperature are reported between 8 and 48 °C. The rh→m transition is characterized by a unit cell volume expansion of 1% and a movement of the interlayer species: a shift of 0.45 Å of the Cl⁻ anions along [010]_h and a shift of 0.25 Å of the water molecules along [210]_h of the hexagonal cell. The m phase distortion is due to an ordering of the hydrogen bonds between chloride anions and H-atoms of the water molecules.     

Influence of MgO on the formation of Ca3SiO5 and 3CaO·3Al2O3·CaSO4 minerals in alite-sulphoaluminate cement

The influence of MgO on the formation of Ca₃SiO₅ and 3CaO·3Al₂O₃·CaSO₄ minerals in alite-sulphoaluminate cement is reported in this paper. The results show that adding a suitable amount of MgO can lower the clinkering temperature, promote the formation of Ca₃SiO₅ and 3CaO·3Al₂O₃·CaSO₄ minerals, and help in the coexistence of the two minerals in the clinker. MgO may obviously decrease the formation of Ca₃Al₂O₆, and increase the SiO₂ content incorporated into the interstitial phase.     

Crystal structure of Kuzel's salt 3CaO·Al2O3·1/2CaSO4·1/2CaCl2·11H2O determined by synchrotron powder diffraction

The crystal structure of Kuzel's salt has been successfully determined by synchrotron powder diffraction. It crystallizes in the rhombohedral R3? symmetry with a = 5.7508 (2) Å, c = 50.418 (3) Å, V = 1444.04 (11) ų. Joint Rietveld refinement was realized using three X-ray powder patterns recorded with a unique wavelength and three different sample-to-detector distances. Kuzel's salt is the chloro-sulfoaluminate AFm phase and belongs to the layered double hydroxide (LDH) large family. Its structure is composed of positively charged main layer [Ca₂Al(OH)₆]⁺ and negatively charged interlayer [Cl_0.50·(SO₄)_0.25·2.5H₂O]⁻. Chloride and sulfate anions are ordered into two independent crystallographic sites and fill successive interlayer leading to the formation of a second-stage compound. The two kinds of interlayer have the compositions [Cl·2H₂O]⁻ and [(SO₄)_0.5·3H₂O]⁻. The crystal structure explains why chloride and sulfate anions are not substituted and why the formation of extended solid solution in the chloro-sulfate AFm system does not occur.     

Catalytic steam reforming of ethane and propane over CeO2-doped Ni/Al2O3 at SOFC temperature: Improvement of resistance toward carbon formation by the redox property of doping CeO2

Ni/Al₂O₃ with the doping of CeO₂ was found to have useful activity to reform ethane and propane with steam under Solid Oxide Fuel Cells (SOFCs) conditions, 700-900 °C. CeO₂-doped Ni/Al₂O₃ with 14% ceria doping content showed the best reforming activity among those with the ceria content between 0 and 20%. The amount of carbon formation decreased with increasing Ce content. However, Ni was easily oxidized when more than 16% of ceria was doped. Compared to conventional Ni/Al₂O₃, 14%CeO₂-doped Ni/Al₂O₃ provides significantly higher reforming reactivity and resistance toward carbon deposition. These enhancements are mainly due to the influence of the redox properties of doped ceria. Regarding the temperature programmed reduction experiments (TPR-1), the redox properties and the oxygen storage capacity (OSC) for the catalysts increased with increasing Ce doping content. In addition, it was also proven in the present work that the redox of these catalysts are reversible, according to the temperature programmed oxidation (TPO) and the second time temperature programmed reduction (TPR-2) results.During the reforming process, in addition to the reactions on Ni surface, the gas-solid reactions between the gaseous components presented in the system (C₂H₆, C₃H₈, C₂H₄, CH₄, CO₂, CO, H₂O, and H₂) and the lattice oxygen (O_x) on ceria surface also take place. The reactions of adsorbed surface hydrocarbons with the lattice oxygen (O_x) on ceria surface (C_nH_m+O_x→nCO+m/2(H₂)+O_x−n) can prevent the formation of carbon species on Ni surface from hydrocarbons decomposition reaction (C_nH_m⇔nC+m/2H₂). Moreover, the formation of carbon via Boudard reaction (2CO⇔CO₂+C) is also reduced by the gas-solid reaction of carbon monoxide (produced from steam reforming) with the lattice oxygen (CO+O_x⇔CO₂+O_x−1).     

Single crystal nanobelts of V3O7·H2O: A lithium intercalation host with a large capacity

In this study, single crystal V₃O₇·H₂O nanobelts were successfully synthesized using a simple hydrothermal route, in which templates or catalysts were absent. The synthesized V₃O₇·H₂O nanobelts are highly crystalline and have lengths up to several tens of micrometers. The width and thickness of the nanobelts are found to be about 30-50 and 30 nm, respectively. A lithium battery using V₃O₇·H₂O nanobelts as the positive electrode exhibits a high initial discharge capacity of 409 mAh g⁻¹, corresponding to the formation of Li_xV₃O₇·H₂O (x = 4.32). Such a high degree of electrochemical performance is attributed to the intrinsic properties of the single-crystalline V₃O₇·H₂O nanobelts.     

Soft template synthesis of mesoporous Co3O4/RuO2·xH2O composites for electrochemical capacitors

Co₃O₄/RuO₂·xH₂O composites with various Ru content (molar content of Ru = 5%, 10%, 20%, 50%) were synthesized by one-step co-precipitation method. The precursors were prepared via adjusting pH of the mixed aqueous solutions of Co(NO₃)₂·6H₂O and RuCl₃·0.5H₂O by using Pluronic123 as a soft template. For the composite with molar ratio of Co:Ru = 1:1 annealed at 200 °C, Brunauer-Emmet-Teller (BET) results indicated that the composite showed mesoporous structure, and the specific surface area of the composite was as high as 107 m² g⁻¹. The electrochemical performances of these composites were measured in 1 M KOH electrolyte. Compared with the composite prepared without template, the composite with P123 exhibited a higher specific capacitance. When the molar content of Ru was rising, the specific capacitance of the composites increased significantly. It was also observed that the crystalline structures as well as the electrochemical activities were strongly dependent on the annealing temperature. A capacitance of 642 F/g was obtained for the composite (Co:Ru = 1:1) annealed at 150 °C. Meanwhile, the composites also exhibited good cycle stability. Besides, the morphologies and textural characteristic of the samples were also investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM).     

Hydrothermal synthesis and electrochemical capacitance of RuO2·xH2O loaded on benzenesulfonic functionalized MWCNTs

Amorphous RuO₂·xH₂O was well coated on the benzenesulfonic functionalized multi-wall carbon nanotubes (f-MWCNTs) successfully via hydrothermal method. The decorated benzenesulfonic groups served as a bifunctional role both for solubilizing and dispersing MWCNTs into aqueous solution and for tethering Ru³⁺ precursor to facilitate the following uniform chemical deposition of RuO₂·xH₂O. The electrochemical performance of RuO₂/f-MWCNTs and utilization of RuO₂·xH₂O were evidenced by cyclic voltammetry and galvanostatic charge/discharge tests. The specific capacitance of 1143 Fg⁻¹ for RuO₂·xH₂O was obtained from RuO₂/f-MWCNTs with 32 wt.% RuO₂·xH₂O, which was much higher than that of just 798 Fg⁻¹ for the RuO₂/p-MWCNTs. Even though the RuO₂·xH₂O loading increases to 45 wt.%, the utilization of RuO₂·xH₂O still possesses as high as 844.4 Fg⁻¹, indicating a good energy capacity in the case of high loading.     

Atom transfer radical polymerizations of methyl methacrylate catalyzed by EBiB/SnCl2·2H2O(FeCl2·4H2O)/FeCl3·6H2O/MA5-DETA systems

The ATRP of methyl methacrylate (MMA) with the system of FeCl₂·4H₂O, N,N,N′,N″,N″-penta(methyl acylate)diethylenetriamine (MA₅-DETA) and ethyl 2-bromoisobutyrate (EBiB) showed high activity and is not well-controlled. The addition of a certain amount of FeCl₃·6H₂O as the additive into the above system results in the decrease of the polymerization rate and the improvement of the controllability. When SnCl₂·2H₂O was added instead of FeCl₂·4H₂O, a novel catalyst system SnCl₂·2H₂O/FeCl₃·6H₂O/EBiB/MA₅-DETA formed shows better controllability, higher catalytic activity and higher initiating efficiencies (more than 90%) in comparison with the system FeCl₂·2H₂O/FeCl₃·6H₂O/EBiB/MA₅-DETA. The polydispersities of the polymers kept range from M_w/M_n=1.18-1.26. The real active species in the new system is Fe (II) formed from the reaction of FeCl₃·6H₂O with the active radical species produced from the reaction of SnCl₂·2H₂O with EBiB.     

Sol-gel derived 6CaO·6SrO·7Al2O3 thin films using metal alkoxides

The novel 6CaO·6SrO·7Al₂O₃ (C6S6A7) thin films were deposited onto soda lime glass substrate using calcium, strontium, aluminium isopropoxide and 2-methoxy ethanol as starting materials via sol-gel dip coating technique. The electrical and optical properties of C6S6A7 films were investigated for films sample annealed at 450 °C for 2 h in air and hydrogen (H₂) atmosphere, respectively. X-ray diffraction pattern and Fourier transformed infrared spectroscopy analysis confirms cubic structure to the C6S6A7 material. The optical transmission spectra of C6S6A7 films showed the high transparency in wide visible range of ∼ 88 and 80% for air and H₂ annealed samples, respectively. The C6S6A7 films sheet resistance of 528 and 0.65 k Ohm/square has been observed for films annealed in air and H₂ atmosphere at 450 °C, respectively.     

Grass blade-like microparticle MnPO4·H2O prepared by a simple precipitation at room temperature

Grass blade-like microparticle MnPO₄·H₂O was synthesized by a simple precipitation at room temperature using a mixture of manganese sulphate monohydrate, phosphoric acid and water at pH = 7. The thermogravimetric study indicates that the synthesized compound is stable below 500 °C and its final decomposed product is Mn₂P₂O₇. The pure monoclinic phases of the synthesized MnPO₄·H₂O and its final decomposed product Mn₂P₂O₇ are verified by XRD data. FTIR spectra indicate the presences of the PO₄³⁻ ion and water molecules in the MnPO₄·H₂O structure and the P₂O₇⁴⁻ ion in the Mn₂P₂O₇ structure. The thermal stability, crystallite size, and grass blade-like microparticle of MnPO₄·H₂O in this work are different from previous reports, which may be caused by the starting reagents and reaction condition for the precipitation.     

Lithium insertion property of Li2 2V2O5·nH2O

Lithium vanadium oxides have been prepared by the new solution processing in an aqueous hydrogen peroxide solution with lithium and vanadium alkoxides, LiO-n-C₃H₇ and VO(O-i-C₃H₇)₃, at low temperature, compared with conventional high temperature solid state reaction. Oxides having a layered structure isomorphic to that of γ-phase Li_xV₂O₅ were obtained. This “γ-like phase” oxide can be obtained at the nominal Li/V ratio of 1.5 almost as a single phase. However, formation of ω phase cannot be confirmed. The γ-like phase oxide contained water and organic compounds, and the water content n in Li_xV₂O₅·nH₂O was found to be about 2.4 for the γ-like phase oxide. Further as the result of the atomic absorption spectrometric method, the lithium content x in Li_xV₂O₅·nH₂O was estimated to be 2.2, and water molecules presumably exist in the interlayer space.Water content of the γ-like phase oxides, affects charge and discharge behaviours markedly. The lithium extraction-insertion capacity of the γ-like phase oxides were smaller, but the oxides had higher average potential compared with those of γ-phase oxide. As water content of γ-like phase oxides decreased, the lithium extraction-insertion capacity increased. Moreover, it should be noted that the average potential of γ-like phase oxides is at least 1 V higher than that of γ-LiV₂O₅.     

Anion water in gypsum (CaSO4·2H2O) and hemihydrate (CaSO4·1/2H2O)

The bonding nature of water in gypsum, CaSO₄·2H₂O, and hemihydrate, CaSO₄·1/2H₂O, was suggested by characteristic absorption bands of water and sulphate ions. The infrared spectral data indicate the presence of anion water in gypsum and hemihydrate through hydrogen bonding. Negative shifting of bending vibration of SO₄ ion and lowering and broadening of the O-H stretching vibration at around 3600 cm⁻¹ indicate the presence of both anion water and hydrogen bonding in gypsum and hemihydrate     

Controllable synthesis and flame retardant properties of bunch-, chrysanthemum-, and plumy-like 4ZnO·B2O3·H2O nanostructures

Three kinds of new 4ZnO·B₂O₃·H₂O nanostructures of bunch-, chrysanthemum-, and plumy-like morphologies have been synthesized under hydrothermal conditions at 140 °C in the presence of ethanol. The as-synthesized products were characterized by the chemical analysis, TG, XRD, FT-IR, SEM and TEM. All the synthesized 4ZnO·B₂O₃·H₂O nanostructures consist of nanoribbons. A series of control experiments confirmed that the morphologies of the products were influenced by the reaction time, temperature, and the presence of the surfactant of PEG-300. Furthermore, the flame retardant properties of the synthesized 4ZnO·B₂O₃·H₂O nanostructures were investigated by the thermal analysis method, demonstrating that they had the better behaviors than the non-nanostructure sample.     

Synthesis and characterization of ZnxMg1 − xGa2O4:Co fabricated by low-temperature burning method

A series of Zn_xMg_1 − xGa₂O₄:Co²⁺ spinels (x = 0, 0.25, 0.5, 0.75, and 1.0) was successfully produced through low-temperature burning method by using Mg(NO₃)₂·4H₂O, Zn(NO₃)₂·6H₂O, Ga(NO₃)₃·6H₂O, CO(NH₂)₂, NH₄NO₃, and Co(NO₃)₂·6H₂O as raw materials. The product was characterized by X-ray diffraction, transmission electron microscopy, and photoluminescence spectroscopy. The product was not merely a simple mixture of MgGa₂O₄ and ZnGa₂O₄; rather, it formed a solid solution. The lattice constant of Zn_xMg_1 − xGa₂O₄:Co²⁺ (0 ≤ x ≤ 1.0) crystals has a good linear relationship with the doping density, x. The synthesized products have high crystallinities with neat arrays. Based on an analysis of the form and position of the emission spectrum, the strong emission peak around the visible region (670 nm) can be attributed to the energy level transition [⁴T₁(⁴P) → ⁴A₂(⁴F)] of Co²⁺ in the tetrahedron. The weak emission peak in the near-infrared region can be attributed to the energy level transition [⁴T₁(⁴P) → ⁴T₂(⁴F)] of Co²⁺ in the tetrahedron.     

Solid solution between Al-ettringite and Fe-ettringite (Ca6[Al1 − xFex(OH)6]2(SO4)3·26H2O)

The solid solution between Al- and Fe-ettringite Ca₆[Al_1 − xFe_x(OH)₆]₂(SO₄)₃·26H₂O was investigated. Ettringite phases were synthesized at different Al/(Al + Fe)-ratios (= X_Al,total), so that X_Al increased from 0.0 to 1.0 in 0.1 unit steps. After 8 months of equilibration, the solid phases were analyzed by X-ray diffraction (XRD) and thermogravimetric analysis (TGA), while the aqueous solutions were analyzed by inductively coupled plasma optical emission spectroscopy (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). XRD analyses of the solid phases indicated the existence of a miscibility gap between X_Al,total = 0.3-0.6. Some of the XRD reflections showed two overlapping peaks at these molar ratios. The composition of the aqueous solutions, however, would have been in agreement with both, the existence of a miscibility gap or a continuous solid solution between Al- and Fe-ettringite, based on thermodynamic modeling, simulating the experimental conditions.     

Ethanol steam reforming reactions over Al2O3 · SiO2-supported Ni-La catalysts

Nickel-based catalysts supported on Al₂O₃ · SiO₂ were prepared with modification of the second metal involving La, Co, Cu, Zr or Y, of which the catalytic behaviors were assessed in the ethanol steam reforming reaction. Activity test indicated that addition of La resulted in higher selectivity of hydrogen and lower selectivity of carbon monoxide, compared with Co-doped nickel catalyst. Influences of lanthanum amounts on catalytic performance were studied over 30NixLa/Al₂O₃ · SiO₂ (x = 5, 10, 15), and characterizations by XRD, TPR and XPS indicated that low amount of lanthanum additives (5%) was superior to inhibit the crystal growth of nickel as well as beneficial to the reduction of nickel oxide. Finally 100 h test for the optimal catalyst 30Ni5La/Al₂O₃ · SiO₂ indicated its good long-term stability to provide high hydrogen selectivity and low carbon monoxide formation, as well as good resistance to coke deposition at low temperature.     

Preparation and ladle slag resistance mechanism of MgAlON bonded Al2O3 -MgAlON-Zr2Al3C4-(Al2CO)1-x(AlN)x refractories

MgAlON bonded Al₂O₃-MgAlON-Zr₂Al₃C₄-(Al₂CO)_1-x(AlN)_x refractories were prepared at high temperatures from 1300?℃ to 1600?℃ in N₂-flowing based on the design of Al-AlN core-shell. The refractory prepared at 1500?℃ was chosen to conduct the ladle slag resistance test at 1600?℃ in air. All the refractories are composed of MgAlON, Zr₂Al₃C₄, (Al₂CO)_1-x(AlN)_x and Al₂O₃. The ladle slag resistance test for the chosen refractory presents a good result and there exist two different reaction layers —— the reacted slag layer and the spinel solid solution layer. The reacted slag layer consists of spinel solid solution, Ca-ZrO₂ and gehlenite/gehlenite solution, where the formation of those phases has changed the chemical composition and phase composition of the original ladle slag. The compact spinel solid solution layer forms by the decomposition of MgAlON into rich-Al₂O₃ spinel and the incorporation of Mn²⁺ and Fe^2+/3+ into rich-Al₂O₃ spinel, which plays an important role in slag penetration resistance.     

Simple fabrication of polyhedral grain-like microparticle Cu0.5Zn0.5HPO4·H2O and porous structure CuZnP2O7

Polyhedral grain-like microparticle Cu_0.5Zn_0.5(HPO₄)·H₂O was simply synthesized by heterogeneous reaction using a mixture of CuCO₃, ZnO, phosphoric acid and water at room temperature for 30 min. The thermogravimetric study indicates that the synthesized compound is stable below 250 °C and its final decomposed product is CuZnP₂O₇. The pure monoclinic phases of the synthesized Cu_0.5Zn_0.5(HPO₄)·H₂O and its final decomposed product CuZnP₂O₇ are verified by XRD data. The presences of the HPO₄²⁻ ion and H₂O molecule in the Cu_0.5Zn_0.5(HPO₄)·H₂O structure and the P₂O₇⁴⁻ ion in the CuZnP₂O₇ structure are confirmed by FTIR data. The thermal stability, the morphology based on polyhedral grain-like microparticles and porous structure of the studied compounds are different from previously reported phosphates, and may affect their activities for potential applications (catalysis, electronics, etc.).     

Hydrothermal synthesis and characterizations of 2D and 3D 4ZnO·B2O3·H2O nano/microstructures with different morphologies

2D and 3D nano/microstructures of 4ZnO·B₂O₃·H₂O with different morphologies have been successfully synthesized by a hydrothermal route in the presence of surfactant polyethylene glycol-300 (PEG-300). Lamellar-like nanoparticles and microsphere organizations of nano and microrods are fabricated by varying the reaction conditions. The products have been characterized by XRD, FT-IR, TG-DTA and SEM. The XRD data indicate the as-prepared samples present at pure phase 4ZnO·B₂O₃·H₂O with monoclinic symmetry. The SEM results reveal that the lamellar-like particles are about 30 nm in thickness and around several hundred nanometers in diameter. The microsphere organizations have different diameters, and the secondary structures are made from rod-like particles with different size and mode, respectively. The morphologies of products strongly depend on surfactant, hydrothermal temperature and time.