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The phosphor-converted warm W-LED have being rapidly developed due to the stringent requirements of general illumination. Here, we utilized a strategy to synergistically enhance the red region and emission intensity of novel Eu-activated yellow-emitting LaSiO2N phosphors. This was realized by predicting optimum crystal structure and governing the concentration of doping ions as well as preparation temperature. By using these straight-forward methods, we were able to vary the valence to enhance the red region and improve the quantum efficiency of LaSiO2N phosphor. The warm W-LED lamp fabricated with this red region enhanced LaSiO2N:Eu phosphor exhibited high CRI (Ra = 86), suitable CCT (5783 K) and CIE chromaticity (0.33, 0.36), indicating this synergistically enhanced strategy could be used for design of yellow-emitting phosphor materials to obtain warm W-LEDs.

Uniform silica nanoparticles and jellyfish-like nanowires were synthesized by a chemical vapour deposition method on Si substrates treated without and with Ni(NO3)2, using silicon powder as the source material. Composition and structural characterization using field emission scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and fourier-transform infrared spectroscopy showed that the as-prepared products were silica nanoparticles and nanowires which have amorphous structures. The form of nanoparticles should be related to gas-phase nucleation procedure. The growth of the nanowires was in accordance with vapour-liquid-solid mechanism, followed by Ostwald ripening to form the jellyfish-like morphology. Photoluminescence and cathodoluminescence measurements showed that the silica products excited by different light sources show different luminescence properties. The emission spectra of both silica nanoparticles and nanowires are due to the neutral oxygen vacancies (≡Si-Si≡). The as-synthesized silica with controlled morphology can find potential applications in future nanodevices with tailorable photoelectric properties.

Highlights: ► ZrN–sialon composites were directly synthesized from zircon and γ-Al{sub 2}O{sub 3}. ► The morphologies and phase compositions of products changed with the temperature. ► The comprehensive and systematic thermodynamic relation of the reaction process was analyzed comprehensively. ► This new technique for synthesizing ZrN–sialon composites can reduce the cost and energy consumption. -- Abstract: ZrN–sialon composites were synthesized from zircon and γ-Al{sub 2}O{sub 3} via carbothermal reduction–nitridation. The effects of reaction temperature on the phase compositions and product morphologies were studied. The equilibrium relationship curves of the condensed phases were drawn and the temperature dependence of the phase stability was investigated. The results show that products with different phase compositions and morphologies can be obtained at different temperatures. The optimum temperature for acquiring ZrN–sialon composites was 1550 °C. Granular ZrN and short prismatic β-sialon (Si{sub 3}Al{sub 3}O{sub 3}N{sub 5}) were formed at 1500 °C, accompanied by surplus Al{sub 2}O{sub 3} and ZrO{sub 2}. The dominant products at 1550 °C were ZrN and Si{sub 3}Al{sub 3}O{sub 3}N{sub 5}, whereas they were ZrN and 15R-SiAl{sub 4}O{sub 2}N{sub 4} at 1600 °C. β-sialon had perfect crystals with a long-column morphology, whereas 15R-SiAl{sub 4}O{sub 2}N was plate-like.

The mechanical properties of the 8 mol% yttria stabilized zirconia (8YSZ), as a promising anodic material for solid oxide fuel cell, should be improved to increase its reliability and service life. NiCr–Al2O3–ZrO2(8Y) ceramic composites were successfully fabricated by pressureless sintering in the carbothermal protecting atmosphere, and the mechanical properties and microstructure were investigated as well. The results showed that 8YSZ matrix composites had good mechanical properties due to the NiCr alloy and α-Al2O3 secondary phases. The bending strength and fracture toughness could reach at a range of 224–300 MPa, 3.8–4.6 MPa m1/2, respectively, when 0–12 vol.% of NiCr alloy and 10 vol.% alumina particles were added into 8YSZ ceramic. 10 vol.% α-Al2O3 obviously enhanced the densification of the 8YSZ ceramic.

Aluminium boron carbide (Al 8 B 4 C 7 ) ceramic powder was synthesized via a solid state reaction method using Al, B 4 C and graphite powders as raw materials. The effects of synthesis temperature, carbon source (graphite and coke powder) and raw materials ratio on the phase transformation and micro-morphology of Al 8 B 4 C 7 were investigated by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicated that the optimized process for preparing the Al 8 B 4 C 7 was 3 h sintering at 1600 °C in flowing argon atmosphere. Graphite was more appropriate than coke powder and carbon black as carbon source for synthesizing pure Al 8 B 4 C 7 , and 10 mol% excess of graphite resulted in higher purity of Al 8 B 4 C 7 . The stoichiometric amount of aluminium was essential for obtaining pure Al 8 B 4 C 7 , because second phase-Al 4 C 3 would occur if excessive aluminium was used.

Single-phase (Ca,Dy)-α-Sialon with elongated crystals and high aspect ratios was prepared at 1700°C by carbothermal reduction and nitridation (CRN) with Y-α-Sialon seed crystals. Effects of Y-α-Sialon seeding and holding time on the phase assemblage and crystal morphology of CRN products were discussed. The results showed that adding seed crystals and prolonging holding time could facilitate not only phase transformation, but also crystal refinement. Moreover, they resulted in the increase of the aspect ratios of α-Sialon crystals, due to the decreasing range in the crystal width exceeding that in the length. In addition, a highly unusual phenomenon of crystal size reduction during reaction was observed in the seeded samples with the holding time extending from 2 to 4 h. Crystallization from liquid phase and growth followed by nucleation based on the surface of existing large crystals were the growth modes of elongated α-Sialon crystals.

This paper mainly discusses the influences of heating temperatures and CeO2 additive contents on the phase transformations of zirconia from zircon ore by carbothermal reduction. The phase transformations of zirconia from zircon ore by carbothermal reduction were monitored by X-ray diffraction. The microstructure of the product was characterized by scanning electron microscopy. The results show that without adding CeO2, the optimized heating temperature of zircon carbothermal reduction was 1600 °C and the main phases of the product were m-ZrO2, ZrC and β-SiC, t-ZrO2; After adding CeO2, the main phase of the products consists of t-ZrO2, m-ZrO2, ZrC and β-SiC when the heating temperature is 1600 °C. CeO2 additive can be introduced into zirconia lattice and can cause it to form cerium stabilized zirconia. Zirconia in the product would be turned into partially stabilized zirconia with cerium addition from 5 wt% to 20 wt%. However, the form of zirconia in the product is not changed greatly with the amount of CeO2 additive increase.

Single-crystallize phase Li-α-Sialon with equiaxial morphology has been successfully synthesized by solid state reaction at 1700 °C for 1 h under a N 2 atmosphere. The effects of additions SiO 2 and Al 2 O 3 , holding time at 1050 °C and packing powders, on the phase compositions and Li contents of products have been investigated by XRD, SEM, EDS and ICP-OES. The results showed that additions SiO 2 and Al 2 O 3 , holding time at 1050 °C and packing powders played an important role in retarding the vaporization of lithium and forming Li-α-Sialon, where the former two ways were by formation of more Li-containing liquid while the latter was by providing a source of Li-containing vapor and increasing partial pressure of Li in the surrounding gaseous environment resulting in preventing volatilization of Li from the sample. However, there were more or less AlN, AlSi 0.5 O 2.5 , β-Sialon present in the products when these factors were ignored.

AlN-polytypoid materials are hard to be sintered and usually need a hot-pressing (HP) technique and very high sintering temperatures ( � 1750°C). In this study, densified AlN-polytypoid based composites were successfully fabricated in situ via a pressureless sintering method at a relatively lower temperature of 1650°C by compositional design. Moreover, the room temperature mechanical properties of the composites were comparable with those sintered by HP method. The results showed that 15R-based composite was sintered via a transient liquid-phase sintering mechanism with the aid of U-phase Sialon. The pressureless-sintered composites were mainly composed of platelet 15R, hexagonal b-Sialon, and intergranular U-phase Sialon grains, which exhibited both intercrystalline and transcrystalline fracture behaviors. Partial 15R grains were of twin structure, which was found to be positive for toughening of the composites.

(Ca,Dy) co-stabilized α-Sialon with elongated grains was prepared from SiO2–AlN–CaF2–Dy2O3 powders by carbothermal reduction-nitridation (CRN) at 1700°C. Detailed investigations on the formation process of (Ca,Dy)-α-Sialon elongated grains performed under various firing conditions revealed that the big quartz particles were initially reduced and decomposed gradually by carbon, and a large number of ball-shaped particles consisting of amorphous (Si,Al,Ca,Dy)x(O,N)y were formed. With increasing temperature, nitrogen continuously diffused into the liquid to form nitrogen-rich solid balls. Further increasing the temperature to 1700°C and held for 2 h, hollow α-Sialon spheres with nanometric particles were obtained from nitrogen-rich solid balls. Subsequently, the framework structure of hollow spheres was destroyed at 1700°C for 3 h, and (Ca,Dy)-α-Sialon grains grew up continuously by consuming nanometric particles in the rough interface via Ostwald ripening and growth stages moving on the smooth interface. Finally, (Ca,Dy)-α-Sialon developed well-defined crystalline elongated grains because the growth rate of rough surfaces is more rapid than that of smooth surfaces.

In this paper, the effects of reductant addition and reaction temperature on phase behavior of serpentine by in situ carbothermal reduction nitridation (CRN) treatment were studied. A brief discussion on the synthesis mechanism of CRN process was also included. The results show that temperature and carbon content were two essential factors that determined the nitridation of serpentine and the formation of β-Si 3 N 4 grains. Serpentine could be transformed into high-temperature composites containing Mg 2 SiO 4 , β-Si 3 N 4 , Si 2 N 2 O and β-SiC at temperatures higher than 1400 °C. At 1550 °C, more Si 2 N 2 O was nitrided to β-Si 3 N 4 as the increase of carbon content, in the final products of samples with carbon addition excess 100 wt.% of theoretical quantity, Mg 2 SiO 4 coexisted with β-Si 3 N 4 as the main crystal phases. This transformation provided a feasible way of dealing with serpentine waste for high-temperature utilization.

The effects of SiCp addition on the z-value, microstructure and mechanical properties of ¢-Si6¹zAlzOzN8¹z­SiCp were investigated. The results showed that z-value of ¢-Sialon decreased from 2.66 to 1.20 with the increase of SiCp addition, while the apparent porosity of ¢-Sialon­SiCp composites increased. The bending strength and compressive strength decreased due to the increase of the apparent porosity and the weak cohesion resulted from the thermal expansion coefficient mismatch between SiCp and ¢-Sialon matrix. Moreover, a linear regression model used to identify the relationship between the content of SiC and z value of ¢-Sialon is fitted.

TiN-Si3N4 composite powders were prepared by carbothermal reduction nitridation using rutile and quartz as raw materials. The influence of temperature and carbon addition on the phase evolution and microstructure of the products were investigated. The equilibrium phase diagram of Si-C-N-O and Ti-C-N-O system at different temperatures under 0.2 MPa nitrogen pressure was drew. The results show that the optimum parameters for synthesizing TiN-Si3N4 by carbothermal reduction nitridation process are carbon addition of stoichiometric content, temperature of 1873 K for 4 h and nitrogen pressure of 0.2 MPa. The produced TiN-Si3N4 in this experiment exist in granular and hexagonal columnar shape, and the average particle size of the synthesized powders is 2 ~ 10 ?m.

Rare-earth aluminate ceramics for thermal-barrier coatings (TBCs) are synthesized. The Young's modulus and thermal properties decrease with erbium additive increasing. The Y3−xErxAl5O12 ceramics (x = 1, 3) possess a much-lower thermal conductivity compared with 8YSZ. The lower Young's modulus and thermal-expansion coefficient are due to the larger atomic weight of the Er substitutional atom. Additional phonon-scattering effects also contribute to the lower thermal conductivity. The results indicate that Y3−xErxAl5O12 can be explored as a candidate material for TBC systems. A theoretical model that describes the influence of point defects on the thermal conductivity is discussed.

Aluminosilicate-reinforced carbon foams have been prepared by chemical foaming with phenolic resin as matrix precursor and aluminosilicate as the additive. The effects of the amount of aluminosilicate used on the microstructure, mechanical properties and oxidation resistance of the carbon foams have been investigated by scanning electronic microscopy, mechanical testing, and oxidation weight loss, respectively. The results show that the amount of aluminosilicate added has a significant influence on the surface roughness and the structure uniformity of carbon foams. The compressive strengths are usually higher than that of the pure carbon foam sample by as much as 60%. The percentage of weight loss of the carbon foams drops with increasing aluminosilicate content up to 11 wt%, but then increases.

Single crystals of JEM-phase NdSi(6-z)Al(1+z)O(z)N(10-z) were successfully prepared from starting powders of Si₃N₄, AlN and Nd₂O₃ at 1700 °C for 3 h under nitrogen atmosphere. The z value of Nd-doped JEM-phase was determined to be 0.4 via determination of oxygen and nitrogen by elemental analysis. This result may be beneficial for overcoming the difficulty on preparation of single-phase JEM-phase Sialon materials and further characterization on their properties. The detailed crystal structure of Nd-Sialon was solved on the basis of single-crystal X-ray diffraction data for the first time. The space group is Pbcn (no. 60); a = 9.3060(6) Å, b = 9.7224(6) Å, c = 8.8777(5) Å; Z = 4; V = 803.22(8) ų; D(c) = 3.971 g cm⁻³; R₁ = 0.0297 and wR₂ = 0.0739 for all reflections refined against F², with GooF value of 1.031.

In this research, light-weight magnesium stabilized zirconia (MgSZ) refractories were prepared by a casting process using polystyrene spheres (PS) and sawdust as pore former materials and polyvinyl alcohol solution as binder. The effects of the addition and size of the polystyrene spheres on the properties of light-weight refractories were studied. With the total addition of 12 mass-% content of PS, with a size ratio of (1–1.5 mm):(0.2–0.5 mm) = 3:7, the bulk density and compressive strength of the light-weight porous MgSZ refractory samples were 0.79 g/cm3 and 2.6 MPa, which are suitable for the requirements of industrial applications.

Porous calcium hexa-aluminate (CA6) ceramics were in-situ synthesized by heated CaCO3 and α-Al2O3 in a NaCl-based salt at 1400°C for 3 h, and then characterized by X-ray diffraction (XRD), scanning electron microscopy, (SEM) and mercury porosimetry. The size and morphology of the CA6 crystals and pores were gradually changed with the increase of NaCl addition in the raw material, indicating that the molten salt not only provided a liquid environment for synthesis of CA6, but also generated considerable pores.

The LaMgAl11O19:Dy3+ phosphors were prepared by the high-temperature solid-state reaction method. The phase structure, luminescence properties, and the thermal stability of the phosphors were investigated. Under the excitation of 349 nm, the LaMgAl11O19:Dy3+ phosphors exhibited three emission peaks at 475 nm, 570 nm, and 664 nm, which respectively corresponded to the 4F9/2→6H15/2, 4F9/2→6H15/2, and 4F9/2→6H11/2 transitions. It was proved that dipole–dipole interaction resulted in the concentration quenching with a quenching concentration of 0.1 mol. The emission intensity at 150 °C was stronger than that at 25 °C, indicating the good thermal stability of LaMgAl11O19:Dy3+ phosphors. The CIE coordinates of LaMgAl11O19:Dy3+ phosphors are very close to the white light coordinates (x=0.3333 and y=0.3333). Therefore, LaMgAl11O19:Dy3+ phosphor is a promising single-phase phosphor for white light emitting diodes.

Ba2FeMoO6 has been reported to exhibit a ferromagnetic to a paramagnetic transition with a Curie temperature above room temperature, and thus it is a potential material for spintronics. These exciting properties are related, at least in part, to combined structural and magnetic instabilities. A conventional analysis of lattice parameter data from the present study and literature in terms of spontaneous strain shows that the magnetic ordering is accompanied by a significant volume strain, which implies a strong coupling behavior of magneto-elastic properties in Ba2FeMoO6. In addition, to address the correlation between anti-site defects (ASD) and magnetic properties, we have carried out a comparative study of six cubic Ba2FeMoO6 polycrystals with different degrees of ASD. The correlations among the Curie temperature, low-temperature saturation magnetism, and ASD are discussed in detail using a combination of diffraction and magnetic measurements. This systematic study, especially the strain analysis, of Ba2FeMoO6 will facilitate its potential applications in the field of spin electronics and thin film engineering.

Phase change materials (PCMs) have been widely investigated for thermal energy storage due to their excellent heat storage densities and narrow operating temperature. However, their poor thermal conductivity and shape stability during utilization always restrict their further application. In this paper, polyethylene glycol/expanded perlite phase change materials with Cu powder phase-change materials (PEG-Cu/EP PCMs) are prepared by vacuum impregnation to overcome these problems. The results indicated that Cu particles are well dispersed in PEG and uniformly enwrapped inside the pores and surfaces of EP due to their excellent physical interactions by capillary force and surface tension. Thus the as-prepared composites exhibit superior shape stability around the working temperature around 253 °C. Furthermore, when 9.35% Cu powders are added into PEG, its thermal conductivity of corresponding composite is significantly enhanced by 129.9%, with a nearly invariable phase change enthalpy at the same time. Therefore, the PEG-Cu/EP PCMs are confirmed to be promising energy storage materials for applications in solar energy generation, building energy conservation, and industrial waste heat utilization.

Expanded graphite/β-SiC nanowires composites (ESNC) were prepared through chemical vapor deposition, and paraffin/expanded graphite/β-SiC nanowires composites (PESNC) were made through vacuum impregnation to overcome liquid leakage during phase transition and enhance the thermal conductivity of paraffin. Fourier transform infrared spectroscopy showed no chemical interactions between the paraffin and ESNC. Differential scanning calorimetry estimated the temperature and latent heat of PESNC during melting to 45.73 °C and 124.31 J g−1, respectively. The respective values of these quantities during freezing were recorded as 48.93 °C and 124.14 J g−1. The thermal conductivity of PESNC was estimated to 0.75 W mK−1, which was 3.26-folds that of pure paraffin (0.23 W mK−1). PESNC perfectly maintained its phase transition after 200 melting–freezing cycles. The resulting ideal thermal conductivity, good chemical stability, thermal properties and thermal reliability of PESNC are promising for use in energy efficient buildings and solar energy systems.

Highly densified Al 2 O 3 /LiTaO 3 (ALT) ceramic composites were fabricated by hot-pressing in a nitrogen atmosphere. The addition of Al 2 O 3 particles could significantly improve the densification of LiTaO 3 . Sintering mechanism of the LiTaO 3 ceramic incorporated with Al 2 O 3 particles is proposed. Dielectric constant of 5 vol.% Al 2 O 3 /LiTaO 3 (5ALT) composite ceramic was slightly increased in the range from 30 kHz to 10 6 Hz, but the dielectric loss was lowered in the whole range from 10 3 Hz to 10 6 Hz. Piezoelectric constant ( d 33 ) of the 5ALT ceramic composite is about 50% of that of LiTaO 3 single crystal.

A novel metal–ceramic matrix composite of Fe/Mo–Sialon was prepared by hot-pressed sintering. The phase composition and mechanical properties of the ceramic were studied. The results showed that main phases in Fe/Mo–Sialon contained β-Sialon, Mo, FeMo and FeSi 2 . The flexural strength initially increased, and then decreased with increasing FeMo70 alloy addition. The hardness decreased gradually with increasing FeMo70 alloy addition. With a flexural strength of 426.7 MPa and a Vickers hardness (H V0.5 ) of 19.3 GPa, Fe/Mo–Sialon ceramic with 19.3 wt.% FeMo70 added exhibited the best mechanical properties.

High density (>99.5%) Al 2 O 3 /LiTaO 3 (ALT) composite was obtained by hot pressing at 1300 °C/25 MPa in nitrogen atmosphere. The microstructure, which included a domain structure in LiTaO 3 grains, was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Most of the domains observed in LiTaO 3 grains of the Al 2 O 3 /LiTaO 3 (ALT) composites belong to a non-180° type domain, which cannot exist in LiTaO 3 single crystals. This non-symmetry domain microstructure belongs to ferroelectric twinning with { 1 ¯ 0 1 2 } twin composition plane. The non-180° domains formation mechanism was proposed.

Permeable porous nanomaterials have extensive applications in engineering fields. Here, we report a novel system of porous calcium aluminate/phosphate (CaAl-CaP) nanocomposites fabricated by pore generator free processing. The CaAl rich samples have close micropores and are not permeable. Interestingly, the CaP rich composites have a unique three-dimensional nanosieve structure with interconnected nanopores and exhibit excellent liquid permeability and adsorbability. The pore size has a narrow distribution of 200-500 nm. The CaAl nanoplatelets in the CaP rich composite have a thickness of 202 nm, a diameter of 1600 nm and an aspect ratio of 8. The porosity is from 19% to 40%. The bending strength and compressive strength are 40.3 MPa and 195 MPa, respectively. The CaP rich nanocomposite is highly permeable so that a water droplet can completely penetrate in 10 seconds (1 mm thick disk). The blue dye can be desorbed in 45 min by ultrasonic vibration. Given the nanosieve porous structure, good permeability/adsorbability and high mechanical properties, the CaP rich nanocomposite has big potential in applications for chemical engineering, biomedical engineering and energy/environmental engineering.

The ordered double-perovskite $\mathrm{S}{\mathrm{r}}_{2}\mathrm{FeMo}{\mathrm{O}}_{6}$ (SFMO) possesses remarkable room-temperature low-field colossal magnetoresistivity and transport properties which are related, at least in part, to combined structural and magnetic instabilities that are responsible for a cubic-tetragonal phase transition near 420 K. A formal strain analysis combined with measurements of elastic properties from resonant ultrasound spectroscopy reveal a system with weak biquadratic coupling between two order parameters belonging to ${\mathrm{\ensuremath{\Gamma}}}_{4}^{+}$ and $m{\mathrm{\ensuremath{\Gamma}}}_{4}^{+}$ of parent space group $Fm\overline{3}m$. The observed softening of the shear modulus by \ensuremath{\sim}50% is due to the classical effects of strain/order parameter coupling at an improper ferroelastic $({\mathrm{\ensuremath{\Gamma}}}_{4}^{+})$ transition which is second order in character, while the ferromagnetic order parameter $(m{\mathrm{\ensuremath{\Gamma}}}_{4}^{+})$ couples only with volume strain. The influence of a third order parameter, for ordering of Fe and Mo on crystallographic B sites, is to change the strength of coupling between the ${\mathrm{\ensuremath{\Gamma}}}_{4}^{+}$ order parameter and the tetragonal shear strain due to the influence of changes in local strain heterogeneity at a unit cell scale. High anelastic loss below the transition point reveals the presence of mobile ferroelastic twin walls which become pinned by oxygen vacancies in a temperature interval near 340 K. The twin walls must be both ferroelastic and ferromagnetic, but due to the weak coupling between the magnetic and structural order parameters it should be possible to pull them apart with a weak magnetic field. These insights into the role of strain coupling and relaxational effects in a system with only weak coupling between three order parameters allow rationalization and prediction of how static and dynamic properties of the material might be tuned in thin film form by choice of strain contrast with a substrate.

Ultra-long, single crystal, α-Si3N4 nanowires sheathed with amorphous silicon oxide were synthesised by an improved, simplified solid-liquid-solid (SLS) method at 1150 °C without using flowing gases (N2, CH4, Ar, NH3, etc.). Phases, chemical composition and structural characterisation using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM/HRTEM), Fourier-transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) showed that the nanowires had Si3N4@SiOx core-shell structures. The growth of the nanowires was governed by the solid-liquid-solid (SLS) mechanism. The room temperature photoluminescence (PL) and cathodoluminescence (CL) spectra showed that the optical properties of the α-Si3N4 nanowires can be changed along with the excitation wavelength or the excitation light source. This work can be useful, not only for simplifying the design and synthesis of Si-related nanostructures, but also for developing new generation nanodevices with changeable photoelectronic properties.

Radial mesoporous silica (RMS) sphere was tailor-made for further applications in producing shape-stabilized composite phase change materials (ss-CPCMs) through a facile self-assembly process using CTAB as the main template and TEOS as SiO2 precursor. Novel ss-CPCMs composed of polyethylene glycol (PEG) and RMS were prepared through vacuum impregnating method. Various techniques were employed to characterize the structural and thermal properties of the ss-CPCMs. The DSC results indicated that the PEG/RMS ss-CPCM was a promising candidate for building thermal energy storage applications due to its large latent heat, suitable phase change temperature, good thermal reliability, as well as the excellent chemical compatibility and thermal stability. Importantly, the possible formation mechanisms of both RMS sphere and PEG/RMS composite have also been proposed. The results also indicated that the properties of the PEG/RMS ss-CPCMs are influenced by the adsorption limitation of the PEG molecule from RMS sphere with mesoporous structure and the effect of RMS, as the impurities, on the perfect crystallization of PEG.

Titanium dioxide (TiO2) is one of the most common photocatalysts. In this study, TiO2-vermiculite composite nanofibers with a mesh structure and a diameter of approximately 300 nm were prepared via sol–gel approach combined with electrospinning technique. The samples were characterized by X-ray diffraction, scanning electron microscopy, ultraviolet–visible spectroscopy, etc. The photocatalytic property was also evaluated. The TiO2-vermiculite composite nanofibers annealed at 550 °C for 3 h exhibited the best absorption and photo-degradation ability for the treatment of methylene blue. The results implied that the combination of mineral vermiculite powders with TiO2 enhanced the absorption-degradation performance of the as-prepared photocatalytic materials, consequently promoting the materials’ ability to degrade methylene blue. Electronic supplementary material The online version of this article (doi:10.1186/s11671-015-0977-1) contains supplementary material, which is available to authorized users.

TiO2-based nanofibers were synthesized using a sol-gel method and electrospinning technique. The as-spun composite fibers were heat-treated at different temperatures (500°C, 550°C, 600°C, and 650°C) and atmospheres (ammonia and nitrogen) for 4 h. The fibers had diameters of 50 to 200 nm and mainly featured anatase and rutile phases. The anatase phase decreased and the rutile phase increased with increasing temperature. Different nitrogen conditions exerted minimal effects on the TiO2 crystalline phase. Different nitriding atmospheres during preservation heating yielded various effects on fibers. The effect of nitrogen in ammonia atmosphere is better than that in nitrogen atmosphere. The fibers heat-treated at 600°C and subjected to preservation heating in NH3 showed high photocatalytic activity.

The KMg4(PO4)3:Eu2+ phosphor was prepared by the conventional high temperature solid-state reaction. The crystal structure, luminescence and reflectance spectra, thermal stability, quantum efficiency and the application for N-UV LED were studied respectively. The phase formation and crystal structure of KMg4(PO4)3:Eu2+ were confirmed from the powder X-ray diffraction and the Rietveld refinement. The concentration quenching of Eu2+ in the KMg4(PO4)3 host was determined to be 1mol% and the quenching mechanism was certified to be the dipole–dipole interaction. The energy transfer critical distance of as-prepared phosphor was calculated to be about 35.84Å. Furthermore, the phosphor exhibited good thermal stability and the corresponding activation energy ΔE was reckoned to be 0.24eV. Upon excitation at 365nm, the internal quantum efficiency of the optimized KMg4(PO4)3:Eu2+ was estimated to be 50.44%. The white N-UV LEDs was fabricated via KMg4(PO4)3:Eu2+, green-emitting (Ba,Sr)2SiO4:Eu2+ and red-emitting CaAlSiN3:Eu2+ phosphors with a near-UV chip. The excellent color rendering index (Ra = 96) at a correlated color temperature (5227.08K) with CIE coordinates of x = 0.34, y = 0.35 of the WLED device indicates that KMg4(PO4)3:Eu2+ is a promising blue-emitting phosphor for white N-UV light emitting diodes (LEDs).

Metallic bonding at an interface is determined by the application of heat and/or pressure. The means by which these are applied are the most critical for joining nanoscale structures. The present study considers the feasibility of room-temperature pressureless joining of copper wires using water-based silver nanowire paste. A novel mechanism of self-generated local heating within the silver nanowire paste and copper substrate system promotes the joining of silver-to-silver and silver-to-copper without any external energy input. The localized heat energy was delivered in-situ to the interfaces to promote atomic diffusion and metallic bond formation with the bulk component temperature stays near room-temperature. This local heating effect has been detected experimentally and confirmed by calculation. The joints formed at room-temperature without pressure achieve a tensile strength of 5.7 MPa and exhibit ultra-low resistivity in the range of 101.3 nOhm·m. The good conductivity of the joint is attributed to the removal of organic compounds in the paste and metallic bonding of silver-to-copper and silver-to-silver. The water-based silver nanowire paste filler material is successfully applied to various flexible substrates for room temperature bonding. The use of chemically generated local heating may become a potential method for energy in-situ delivery at micro/nanoscale.

The large-scale synthesis of Si3N4 nanobelts from quartz and graphite on a graphite-felt substrate was successfully achieved by catalyst-assisted carbothermal reduction–nitridation. The phase composition, morphology and microstructure of Si3N4 nanobelts were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, energy-dispersive spectroscopy, transmission electron microscopy and high-resolution transmission electron microscopy. The Si3N4 nanobelts were ~4–5 mm long and ~60 nm thick and exhibited smooth surfaces and flexible shapes. The Si3N4 nanobelts were well crystallized and grow along the [101] direction. The growth is dominated by the combined mechanisms of vapor–liquid–solid base growth and vapor–solid tip growth. The Fe(NO3)3 played a crucial role in promoting the nanobelt formation in the initial stage. The room-temperature photoluminescence spectrum of Si3N4 nanobelts consists of three emission peaks centered at 413, 437 and 462 nm, indicating potential applications in optoelectronic nanodevices.

LiTaO3 (5--25vol%) dispersed Al2O3 matrix composite (LTA) with high relative density were fabricated by hot pressing at 1300°C. The microstructure and mechanical properties of the composite were studied. The main results are as follows: Al2O3 was found to be phase compatible with piezoelectric LiTaO3 during high temperature sintering process. The relative density of the LTA composites was greatly improved by the addition of LiTaO3 particles. Domains are clearly discerned in LiTaO3 grains in the LTA composite, confirming that LiTaO3 particles remain ferroelectrics. 90 degree domains were observed in LiTaO3 grains constrained strongly by Al2O3 matrix, which has never been found in LiTaO3 single crystal before. Comparing with those of pure Al2O3, sintered at same temperature (1300°C), both the flexural strength and the fracture toughness of the composites are all enhanced. Domain switching is suggested as a new toughening mechanism in the ferroelectric particles dispersed structural ceramics.

An Al2O3 ceramic coating (A), a 13 wt.% TiO2-Al2O3 (13TA) composite ceramic coating, and a Ni-Al-13wt.%TiO2-Al2O3 (NA-13TA) gradient composite ceramic coating were prepared on Q235 steel by plasma spraying. The corrosion behavior of samples sprayed with these coatings in a boiling 5% HCl solution was investigated. It was shown that an A ceramic coating and a 13TA composite ceramic coating were destroyed after immersion for 17 and 23 h, respectively. The NA-13TA gradient composite ceramic coating was still sound after 14 days of immersion. The corrosion resistance of samples with the NA-13TA gradient composite ceramic coating was sharply improved due to the decreased amount of connected pores in the coating. The corrosion of the sample sprayed with the gradient ceramic coating included the partial corrosion of the surface ceramic coating and the interlayer coatings. The corrosion weight loss depended on the degree of open porosity.

The corrosion behavior of plasma-sprayed Ni/Al–Al 2 O 3 and Ni/Al–Al 2 O 3 +13 wt.% TiO 2 graded ceramic coatings in 5%HCl solution was investigated. It was shown that the corrosion resistance of a Ni/Al–Al 2 O 3 graded coating was 130 times that of a single Al 2 O 3 coating. The corrosion resistance of Ni/Al–Al 2 O 3 +13%TiO 2 graded coatings was increased by 39.2% compared to a Ni/Al–Al 2 O 3 graded coating with the same compositional gradient. The improvement in corrosion resistance of graded ceramic coatings mainly resulted from the change of corrosion behavior due to the change in structure of the coating. The bond layer alloy particles in the transition layers were distributed isolated in the ceramic matrix. Thus, the connected pores in the working layer were actually pseudo-connected pores. As a result, the electrochemical corrosion between the bond layer and the matrix was restrained. In addition, the pseudo-connected porosity in graded coatings lay on not only the open porosity but also the structure of the graded coating.

A series of blue-to-white emitting Mg2Al4Si5O18: Eu2+, Mn2+ phosphors are prepared via high-temperature solid-state reaction of stoichiometric amounts of MgO, Al2O3, H2SiO3, MnCO3, and La2O3 (8 wt%) as a flux (alumina crucible, 1300 °C, 6 h, 10% H2/N2 reducing atmosphere).

The cation substitution-dependent phase transition was used as a strategy to discover new solid solution phosphors and to efficiently tune the luminescence property of divalent europium (Eu2+) in the M3(PO4)2:Eu2+ (M = Ca/Sr/Ba) quasi-binary sets. Several new phosphors including the greenish-white SrCa2(PO4)2:Eu2+, the yellow Sr2Ca(PO4)2:Eu2+, and the cyan Ba2Ca(PO4)2:Eu2+ were reported, and the drastic red shift of the emission toward the phase transition point was discussed. Different behavior of luminescence evolution in response to structural variation was verified among the three M3(PO4)2:Eu2+ joins. Sr3(PO4)2 and Ba3(PO4)2 form a continuous isostructural solid solution set in which Eu2+ exhibits a similar symmetric narrow-band blue emission centered at 416 nm, whereas Sr2+ substituting Ca2+ in Ca3(PO4)2 induces a composition-dependent phase transition and the peaking emission gets red shifted to 527 nm approaching the phase transition point. In the Ca3–xBax(PO4)2:Eu2+ set, the validity of crystalloc...

Transparent and flexible electrodes on cost effective plastic substrates for wearable electronics have attract great attention recently. Due to the conductivity and flexibility in network form, metal nanowire is regarded as one of the most promising candidates for flexible electrode fabrication. Prior to application, low temperature joining of nanowire processes are required to reduce the resistance of electrodes and simultaneously maintain the dimensionality and uniformity of those nanowires. In the present work, we presented an innovative, robust and cost effective method to minimize the heat effect to plastic substrate and silver nanowires which allows silver nanowire electrodes been directly written on polycarbonate substrate and sintered by different electrolyte solutions at room temperature or near. It has been rigorously demonstrated that the resistance of silver nanowire electrodes has been reduced by 90% after chemical sintering at room temperature due to the joining of silver nanowires at junction areas. After ∼1000 bending cycles, the measured resistance of silver nanowire electrode was stable during both up-bending and down-bending states. The changes of silver nanowires after sintering were characterized using x-ray photoelectron spectroscopy and transmission electron microscopy and a sintering mechanism was proposed and validated. This direct-written silver nanowire electrode with good performance has broad applications in flexible electronics fabrication and packaging.

A series of blue-to-white emitting Mg2Al4Si5O18: Eu(2+), Mn(2+) phosphors were synthesized via high-temperature solid-state method, and their luminescence properties were investigated in detail. Under near-ultraviolet (UV) light excitation of 365 nm, Eu(2+)-doped Mg2Al4Si5O18 exhibits a broad blue emission band peaked at 469 nm, and Mn(2+)-doped Mg2Al4Si5O18 shows a broad orange-red emission band near 600 nm. The energy transfer from Eu(2+) to Mn(2+) in Mg2Al4Si5O18 host matrix can be found, and the resonant type is demonstrated by a dipole-quadrupole mechanism. The emission hue can be tuned from blue (0.17, 0.17) to bluish green (0.22, 0.29) and finally to white (0.31, 0.33) by properly varying the ratio of Eu(2+)/Mn(2+). The thermal quenching property of the sample was investigated, and the activation energy ΔE was estimated to be 0.30 eV. Additionally, the energy transfer critical distance between Eu(2+) and Mn(2+) was calculated. With appropriate tuning of activator content, the Mg2Al4Si5O18: Eu(2+), Mn(2+) phosphor may have potential application for UV light-emitting diodes.

Blue emitting α-Mg2Al4Si5O18:Eu 2+ phosphor is prepared via conventional solid-state reaction of stoichiometric amounts of MgO, Al2O3, H2SiO3, and Eu2O3 using excess La2O3 as a flux (alumina crucible, air, 1300 °C, 6 h).

The red-emitting phosphor LaMgAl11O19:Sm(3+), Eu(3+) was prepared by solid-state reaction at 1600 °C for 4 h. The phase formation, luminescence properties, and energy transfer from Sm(3+) to Eu(3+) were studied. With the addition of 5 mol % Sm(3+) as the sensitizer, the excitation wavelength of LaMgAl11O19:Eu(3+) phosphor was extended from 464 to 403 nm, and the emission intensity under the excitation at 403 nm was also enhanced. The host material LaMgAl11O19 could contain the high doping content of Eu(3+) (20 mol %) without concentration quenching. This energy transfer from Sm(3+) to Eu(3+) was confirmed by the decay times of energy donor Sm(3+). The mechanism of energy transfer (Sm(3+) → Eu(3+)) was proved to be quadrupole-quadrupole interaction. Under the 403 nm excitation at 150 °C, the emission intensities of the characteristic peaks of Sm(3+) and Eu(3+) in LaMgAl11O19:0.05Sm(3+), 0.2Eu(3+) phosphor were decreased to 65% and 56% of the initial intensities at room temperature, and the relatively high activation energy proved that this phosphor had a good thermal stability. The CIE coordinate was calculated to be (x = 0.601, y = 0.390). The LaMgAl11O19:0.05Sm(3+), 0.2Eu(3+) phosphor is a candidate for copper phthalocyanine-based solar cells and white light-emitting diodes.

Calcium hexaluminate (CA6) was incorporated into the matrix of magnesio aluminate spinel-alumina (MA-A) via infiltration of a porous preform fabricated from α-Al2O3 and MgO powders with a saturated calcium acetate solution and subsequent firing, forming CA6/(MA-A) functionally composites with graded fracture toughness. Actually, the porous preform was partially and perpendicularly immersed (1/4 of its length) in the solution. Owing to the capillary action, the calcium acetate solution was absorbed into the porous preform, and the different absorption distance led to the graded solution concentration in the height direction of the porous preform. The in-situ formation of CA6 conferred graded microstructures, as well as improved mechanical properties on the resultant composites. The CA6 content decreased gradually along the solution absorption direction, i.e., from one end [CA6/(MA-A) region] immersed in solution to the other end [MA-A region], reducing evidently the formation of layered structure along the direction, while increasing gradually the formation of spherical alumina particles. The CA6/(MA-A) region had a better toughness that could prevent the crack propagation and improve the spalling resistance. Meanwhile, the MA-A region could provide structural support, because of the higher Vickers hardness and density.