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Although serogroup W ST-11 complex (cc11) (W:cc11) Neisseria meningitidis has been widespread in China over the past ten years, its origin and genetic relatedness has not yet been described. In this study, we described the genetic relatedness and discuss the possible origin of Chinese W:cc11 isolates by comparing their genome sequences with those of other cc11 strains globally. Comparative genomic analysis with geo-temporally diverse cc11 isolates showed that the Chinese W:cc11 isolates exclusively formed two closely related subclusters within a distinct sublineage (proposed as the Chinese-strain sublineage) of lineage 11.1 close to the interface between the Hajj-strain sublineage and the South American-strain sublineage. Several isolates from Africa and Europe were closely related to the Chinese subclusters which were largely segregated from one another among distinct provinces of China. No alleles were identified that were unique to the Chinese isolates as a whole, though each subcluster possessed unique alleles differentiating itself from the other subcluster as well as closely related isolates within the extended sublineage. Three genes differentiated the two subclusters with allele combinations that were each present among the non-Chinese isolates within the wider sublineage. These results indicate that the Chinese W:cc11 isolates formed part of a previously undescribed W:cc11 sublineage that is closely related to, but distinct from, the Hajj-strain sublineage and South American-strain sublineage. The geographical source of the Chinese subclusters was indeterminate based on available data. [ABSTRACT FROM AUTHOR]

Objective To study the prevalence of the fHbp genes in Neisseria meningitidis ( N. meningitidis ) isolates for further evaluation and development of serogroup B meningococcal vaccines in China. Methods A panel of 1012 N. meningitidis strains was selected from the national culture collection from 1956 to 2016, according to the years of isolation, locations, and strain sources. These were tested by FHbp variant typing. Multi-locus sequence typing (MLST) was performed on 822 of these samples, including 242 strains from clinical strains and 580 carrier-derived strains. Analysis based on sequence types, serogroups, and FHbp variations were used to summarize the prevalence and characteristics of N. meningitidis. Results There were 8 serogroups of N. meningitidis as well as a collection of nongroupable strains in this study. 1008 of 1012 N. meningitidis strains tested were positive for the fHbp gene. Serogroup A N. meningitidis (MenA) strains belonging to ST-1 and ST-5 clonal complexes harbored genes only encoding variant 1 (v1) FHbp. All MenW strains encoded v2 FHbp. 61.9% of clinical MenB strains were positive for v2 FHbp vs. 32.1% that were positive for v1. Among fHbp -positive carrier-derived MenB strains, v2 FHbp accounted for 90.8%. 79.7% of clinical MenC strains were positive for v1 FHbp and 20.3% were positive for v2 FHbp. Among carrier-derived MenC strains, v2 FHbp predominated. The number of major serogroups of N. meningitidis analyzed by MLST was 822, and the encoded FHbp showed CC- or ST-specific characteristics. Conclusion fHbp genes were detected in almost all N. meningitidis strains in this study. Therefore, it is possible that a vaccine against MenB or meningococci irrespective of serogroups, which includes FHbp, could be developed. Meningococcal vaccine development for China is a complex issue and these findings warrant further attention with respect to vaccine development. [ABSTRACT FROM AUTHOR]

Zinc oxide (ZnO) microrods with high aspect ratio and microstructures with flowerlike morphologies have been synthesized successfully in a glycerol/water reaction system by a simple solvothermal method without adding any surfactants or templates at 180°C. Experimental results indicated that the flowerlike ZnO microstructures were transformed into rodlike ones with increasing amounts of zinc acetate dihydrate (Zn(Ac)2·2H2O) and sodium hydroxide (NaOH) because of the rapid nucleation and growth, indicating that the concentration of reactants is the key to control the morphologies of ZnO samples. In contrast, double-columned and double-hemisphered ZnO microstructures were fabricated using similar solvothermal conditions without adding NaOH by adjusting the proportion of glycerol and water, for these crystallites were generated mainly by esterification between Zn(Ac)2·2H2O and glycerol. Time-dependent experiments have also been conducted to explore the evolution of ZnO morphologies. The growth mechanism of as-prepared ZnO structures synthesized in different conditions was discussed. [ABSTRACT FROM AUTHOR]

CdTe0.5Se0.5/Cd0.5Zn0.5S core/shell quantum dots (QDs) with a tunable photoluminescence (PL) range from yellow to dark red (up to a PL peak wavelength of 683 nm) were fabricated using various reaction systems. The core/shell QDs created in the reaction solution of trioctylamine (TOA) and oleic acid (OA) at 300 °C exhibited narrow PL spectra and a related low PL efficiency (38%). In contrast, the core/shell QDs prepared in the solution of 1-octadecene (ODE) and hexadecylamine (HDA) at 200 °C revealed a high PL efficiency (70%) and broad PL spectra. This phenomenon is ascribed that the precursor of Cd, reaction temperature, solvents, and ligands affected the formation process of the shell. The slow growth rate of the shell in the solution of ODE and HDA made QDs with a high PL efficiency. Metal acetate salts without reaction with HDA led to the core/shell QDs with a broad size distribution. [ABSTRACT FROM AUTHOR]

Abstract: Hydrophobic oleic acid-capped CdSe/Cd x Zn1−x S core/shell quantum dots (QDs) with high photoluminescence (PL) efficiency of 62% and a PL peak wavelength of 602nm were assembled in SiO2 particles through a novel silanization technique. Ligand exchange (3-mercaptopropyltrimethoxysilane (MPS) instead of oleic acid) occurred via the connection of mercapto groups and QDs when MPS was added in the toluene solution of the QDs. After being silanized using MPS, partially hydrolyzed tetraethyl orthosilicate (TEOS) was attached to the surface of the silanized QDs. The hydrophobic CdSe/Cd x Zn1−x S QDs were then transferred from toluene phase to water phase by the hydrolysis of TEOS through the addition of ethanol, ammonia, and water. Further hydrolysis and condensation of the TEOS and MPS causes them to form assemblies in the water phase. MPS is crucial for proper assembly of the QDs in SiO2 particles and for controlling the size of resulting SiO2 particles. The resulting SiO2 particles exhibited tunable diameters from several tens to 100nm. After being encapsulated in SiO2 particles, the QDs revealed a PL efficiency of 25%. Because of the resulting SiO2 particles encapsulating multiple hydrophobic CdSe/Cd x Zn1−x S QDs and having a functional surface (mercapto group), they are applicable to bio-probes. [Copyright &y& Elsevier]

Abstract: Eu3+ doped yttrium zirconate ((Y1−x Eu x )2Zr2O7) nanocrystals were synthesized by a simple sol–gel combustion method, and characterized by X-ray diffractometry (XRD), transmission electron microscopy (TEM), UV–vis absorption and photoluminescence (PL) spectroscopy. Photoluminescence spectra of (Y1−x Eu x )2Zr2O7 (x =0.005–0.15) show multi-peaks corresponding to the f–f transitions 5 D 0–7 F J (J =1, 2, 3, 4 and 5) of Eu3+. Both the 5 D 0–7 F 1 magnetic dipole transition and the 5 D 0–7 F 2 electric dipole transition are intense and the 5 D 0–7 F 2 emissions split into several peaks depending on the doping concentration. The fine structure of the PL spectra is related to host lattice and the local situation around Eu3+. [Copyright &y& Elsevier]

Abstract: A series of rare-earth zirconate RE2Zr2O7 nanocrystals (RE=La, Nd, Eu and Y) were prepared by a simple combustion method. These compounds possess either a pyrochlore structure (P-RE2Zr2O7) or a defect fluorite structure (F-RE2Zr2O7), which depends on the ionic radius of RE3+. The photoluminescence (PL) property of the as-prepared RE2Zr2O7 nanocrystals was studied, and the observed emissions in the UV and visible range were attributed to different transition mechanisms for RE2Zr2O7 with different RE ion. A PL mechanism has been proposed, associated with the transition between the valence band and a mid-gap state related to oxygen vacancies. Divalent Pb ions were introduced into RE2Zr2O7 nanocrystals and the luminescence of the Pb2+-doped samples was also recorded for comparison. The PL property of RE2Zr2O7 was found to be intimately related to their intrinsic defect structure, and PL was thought as a new method to estimate the degree of disorder in the A2B2O7 structure (from pyrochlore structure to defect fluorite structure). [Copyright &y& Elsevier]

Abstract: A facile and energy saving sol–gel combustion method has been used to prepare La2Zr2O7 nanocrystallines. The pyrochlore La2Zr2O7 nanocrystals have been obtained at a relatively low temperature with the grain size ranging from 45 to 70nm. Eu3+ and Dy3+ have been introduced into the La2Zr2O7 crystal structure, respectively, and the intense photoluminescence was observed. The relative intensity of electric dipole transition and magnetic dipole transition is considered for luminescence emission both of Eu3+ and Dy3+. The dependence of luminescence intensity on dopant concentration and the effect of Dy3+ co-doping on Eu3+ luminescence are also discussed. [Copyright &y& Elsevier]

Objective To systematically investigate the prevalence and genetic characteristics of 4CMenB and rLP2086 vaccine candidates among Neisseria meningitidis serogroup B (NmB) in China. Methods A total of 485 NmB strains isolated in 29 provinces of China between 1968 and 2016 were selected from the culture collection of the national reference laboratory according to the isolation year, location, and source. Multi-locus sequence typing (MLST) and porA gene sequencing were performed on all 485 study strains; PCR was used to detect the fHbp , nadA, and nhba gene of 432 strains; positive amplification products from the fHbp and nadA genes from all strains, as well as those of the nhba gene from 172 representative strains, were sequenced. Results MLST results showed that the predominant (putative) clonal complexes (CCs) of NmB isolates have changed over time in China. While strains that could not be assigned to existing (p)CCs were the biggest proportion, CC4821 was the most prevalent lineage (36.0%) since 2005. PCR and sequence analysis revealed that the 4CMenB and rLP2086 vaccine candidates were highly diverse. Respectively, 152 PorA genotypes and 83 VR2 sequences were identified with significant diversity within a single CC; the complete nadA gene was found in ten of 432 study strains; fHbp was present in most strains (422/432) with variant 2 predominating (82.9%) in both patient- and carrier- derived isolates; almost all strains harbored the nhba gene while sequences were diverse. Conclusions With regards to clonal lineages and vaccine candidate proteins, NmB isolates from China were generally diverse. Further studies should be performed to evaluate the cross-protection of present vaccines against Chinese NmB strains. [ABSTRACT FROM AUTHOR]

Abstract: Eu3+-doped SrZrO3 nanocrystals with a size of about 10nm were synthesized by a simple sol–gel combustion method, and characterized by X-ray diffraction, transmission electron microscopy and photoluminescence spectroscopy. The nanocrystalline intend to assemble to a porous morphology. Both intrinsic defects related and activator luminescence were observed. The red emission of Eu3+ is intense and the spectra show a minor difference with different excitation wavelengths. [Copyright &y& Elsevier]

Heavy metal waste poses an environmental and health hazard. Zinc-containing sludge is a particular problem. However, the conversion of this sludge into a spinel-based ceramic material is an environmentally friendly, space-saving, and cost-effective method for preventing heavy-metal pollution. However, silicates are frequently present in such sludge, and can reduce the porosity of the produce ceramic material, which limits their potential applications in membrane-separation technology. To ensure the conversion of the zinc component into a highly porous spinel-based ceramic, in this study, additives were used to convert the silica component to whisker-form mullite. Thus, a primary pore structure was formed between spinel particles, and secondary pore channels were formed by the mullite whiskers in the primary pores. Crucially, the oriented growth of a ceramic containing 15% ZnO at 1150 °C resulted in a porosity of 40.5%. In contrast, the unmodified ceramic had a porosity of 6.3%. The unique structure also reduced the tortuosity of the ceramic to less than unity, which improved the permeation flux for membrane applications. The optimal ceramic was tested for the separation of oil-in-water emulsions, yielding a promising oil-rejection rate of 96%. [ABSTRACT FROM AUTHOR]

Abstract: The oxidation behaviour of nanometre and micrometre sized Al2O3–TiC–Co composites is investigated at 800–1000°C in air for 25h. The oxidation resistance of nanometre sized samples is better than of micrometre sized. Phase compositions and microstructures were studied by XRD and SEM. The values of general rate constant k and oxidation exponent n are dependent on oxidation temperature and composites. The oxidation kinetics followed a rate that is slightly faster than the parabolic-rate law at 800–1000°C. The activation energy of the nanometre sized is higher than of micrometre sized in the range of 800–1000°C. [Copyright &y& Elsevier]

Abstract: CdTe nanocrystals (NCs) were coated with a hybrid SiO2 shell containing CdS-like clusters by a facile reflux. These hybrid SiO2-coated CdTe NCs exhibited tunable photoluminescence (PL) and high fluorescence quantum yields (QYs) up to 70% (the QY of initial CdTe NCs is 24%) due to the CdS-like cluster in the SiO2 shell nearby the CdTe core. The average fluorescence lifetime of the hybrid SiO2-coated NCs and the CdTe NCs are 36 and 25ns, respectively. Because increased fluorescence QYs and slightly blue-shifted PL peak wavelength for these hybrid NCs were observed after the removing of TGA and Cd2+, the hybrid SiO2 shell can sufficiently passivate PL, improve chemical stability, and prevent the surface deterioration of the CdTe NCs. This is crucial for applications in biolabeling and optoelectronic devices. [Copyright &y& Elsevier]

Abstract: Highly luminescent euxenite phased YNbTiO6:Eu3+ and Li+-doped YNbTiO6:Eu3+ red phosphors have been prepared through a facile sol–gel combustion process and investigated for the first time. The introduction of Li+ ions into YNbTiO6:Eu3+ is able to result in significant changes of the crystallinity and particle size, and bring a clear red-shift of absorption edge. A dominant red emission peak at 611nm due to the 5D0 → 7F2 transition of Eu3+ was observed from photoluminescence spectra of the YNbTiO6:Eu3+ and Li+-doped YNbTiO6:Eu3+ phosphors. In particular, the emission intensity of the optimal Li+-doped YNbTiO6:Eu3+ was examined to be close to 400% of commercial Y2O3:Eu3+ phosphor. The mechanism of the enhanced emission by Li+ doping was discussed. [Copyright &y& Elsevier]

The high aggregation ability of anammox granular sludge is an issue of wide concern; however, the mechanism needs to be further clarified. In this study, selective hydrolysis experiments were performed to determine the role of exopolysaccharide (PS) branched chains and proteins for the aggregation mechanism of anammox granular sludge. The results revealed that selective hydrolysis of proteins hardly affected the granular aggregation while the hydrolysis of PS branched chains led to a decrease in the sludge zeta potential by 17.3% (β-amylase group) and 24.1% (isoamylase group), a decrease of hydrophobicity by 11.6% (β-amylase group) and 17.7% (isoamylase group), an increase of surface free energy by 36.8% (β-amylase group) and 55.1% (isoamylase group) and the deterioration of the PS self-assembly ability. In addition, FTIR and XPS spectra analysis showed that the disruption of PS branched chains resulted in a higher proportion of hydrophilic and electronegative groups, which hindered bacterial aggregation, which was further confirmed by XDLVO theory. The key role of the PS chain structure in sludge aggregation is a critical finding of this work that provides helpful insights for the application of anammox process. Unlabelled Image • Role of polysaccharide branched chains in granular aggregation was first proven. • Polysaccharide branched chains favour aggregation of granules via self-assembly. • Destruction of PS branches reduces the zeta potential and hydrophobicity of sludge. • Hydrolysis of PS branches leads to a higher repulsive barrier for sludge aggregation. [ABSTRACT FROM AUTHOR]

Hierarchical urchin-like WO 2.72 microspheres decorated by uniform Au nanoparticles were synthesized via a two-step deposition process. The two-step deposition process, including weak reduction deposition and photo-deposition, ensures uniform size and well-dispersed Au nanoparticles. The gas-sensing properties of WO 2.72 and Au/WO 2.72 for trimethylamine (TMA) were investigated. The results show that Au/WO 2.72 has more outstanding gas-sensing performances, especially 3 wt% Au-loaded WO 2.72 (A3/WO 2.72). A3/WO 2.72 not only has superior selectivity and response for TMA gas but also exhibits fast response and recovery time. The response of A3/WO 2.72 –100 ppm of TMA at 260 °C can attain 87.3, which is approximately 6.1 times of pure WO 2.72. Besides, the good long-term effectiveness of A3/WO 2.72 -based sensor also can be observed. The mechanism of enhanced gas-sensing performances derived from the synergy of morphology, composition, and the sensitization effect of Au nanoparticles is proposed, which will facilitate the design and development of sensors decorated by noble metal. [ABSTRACT FROM AUTHOR]

The ultrafine α-Al 2 O 3 powder has been successfully synthesized via two-step hydrolysis of aluminum isopropoxide. The effects of synthesis parameters on the α-Al 2 O 3 were investigated. The experimental results indicated that the concentration of aluminum isopropoxide, water bath temperature, the molar ratio of aluminum isopropoxide to isopropanol and aluminum isopropoxide to deionized water greatly affect the amount of nuclei and the microstructure of α-Al 2 O 3 . Additionally, the water bath temperature affects the rate of nucleation and growth of crystals. Transmission electron microscopy (TEM) images display that the well-dispersed α-Al 2 O 3 powder with particle size about 100 nm was obtained via the method after calcination at 1200 °C for 1 h. The coalescence of crystal particles led to the formation of vermicular α-Al 2 O 3 particles. The X-ray diffraction (XRD) and Fourier transform infrared spectra (FTIR) analysis demonstrated the possible phase transition process of α-Al 2 O 3 . The scanning electron microscopy (SEM) images of samples calcined at various temperatures showed the microstructure transformation. Brunauer-Emmett-Teller (BET) surface area and mean pore size of the samples varied with the calcination temperature. The addition of cetylrimethylammonium bromide (CTAB) has impacts on the phase transformation of α-Al 2 O 3 . [ABSTRACT FROM AUTHOR]

CeO 2 nanostructures with various morphologies were prepared through controlling preparation conditions via a hydrothermal method without any surfactants and templates. Cerium acetate, cerium chloride and cerium nitrate were used as cerium precursors to investigate the influence of anions on the growth process of CeO 2 nanostructures. The morphology evolution of CeO 2 and Ce(OH) 3 nanostructures indicates that the anions play an important role for the growth kinetics of resulting samples. Cl − and Ac − ions promoted the formation of one dementional (1D) CeO 2 nanostructures such as nanowires, nanorods and nano hexagonal prisms, while the oxidizing anion NO 3 - facilitated the synthesis of CeO 2 nanocubes. The hydrothermal reaction temperature is another key to govern the morphologies of CeO 2 nanostructures. The formation process of the nanostructures was explored and the possible growth mechanism was discussed. The variety of CeO 2 nanostructures represented inequable catalytic performance for CO oxidation. Because of different surface areas and structures, CeO 2 nanowires revealed the best catalysis performance while that of the nanocubes is the worst. [ABSTRACT FROM AUTHOR]

ZnO flowers consisting of single crystal nanosheets with exposed { 1   1 ¯   0   0 } facets were fabricated from trisodium citrate via hydrothermal at 180 °C. The single crystal nanosheet has the thickness of about 70 nm and a well-crystalline structure with dominant surfaces as { 1   1 ¯   0   0 } planes. The site-specific nucleation-growth process contributes to the formation of hierarchical flower-like ZnO structures. The ZnO flowers exhibited white emission. The visible emission gradually decreased with time and the UV emission suggests that the recombined rate of photogenerated electrons and holes of samples varied with the synthesis parameters. The ZnO flowers displayed an enhanced photocatalytic performance compared with ZnO microspheres. The maximized exposure of the reactive { 1   1 ¯   0   0 } facets also favors the enhanced photocatalytic performance. Additionally, the special loose structural feature with an open microstructure has more important influences on the photocatalytic activity than specific surface area. [ABSTRACT FROM AUTHOR]

Highlights: [•] YNbTiO6-based phosphors were synthesized by a sol–gel combustion method. [•] The annealing temperature plays the key role of PL properties and particle size. [•] Luminescence of Mn2+, Er3+, and Dy3+-doped YNbTiO6 host was achieved. [•] Luminescent mechanism of Er3+ or Dy3+-doped samples is dipole–dipole interaction. [•] Mn2+ →Er3+ (Dy3+) energy transfers were observed for co-doped phosphors. [Copyright &y& Elsevier]

Abstract: The oxidation behavior of nano-sized Al2O3–TiC–Co composite sintered at different temperature was investigated at 200–1000°C in air for 25h. Microstructures and phase compositions of oxidation surfaces were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results indicated that the oxidation reaction would take place when oxidation temperatures are 800°C and 1000°C. The oxidation resistance of Al2O3–TiC–Co composite increased with the sintering temperature rising when the sample was oxidized at 800°C and 1000°C. The mechanism of oxidation has been analyzed using thermodynamic and kinetics considerations. The oxidation kinetics follows a rate that is faster than the parabolic rate law at 800°C and 1000°C. The activation energy of the composite for oxidation in the range of 800°C to 1000°C was found to be 142.21kJ/mol. [Copyright &y& Elsevier]

Abstract: Undoped and Eu3+-activated Bi3TiNbO9 (BTNO) nanophosphors have been successfully synthesized by sol–gel combustion method. The effects of thermal annealing on the phase structure and crystallinity, morphology and UV–vis absorption of BTNO particles were investigated. Photoluminescence (PL) properties show that a broad blue emission was detected for BTNO nanoparticles, and the characteristic Eu3+ ion 5D0 → 7F J (J =1, 2, 3, 4) transitions were observed for the doped samples. Further investigation illuminates that the Eu3+ ions substituted for Bi3+ ions at A site in the pseudo-perovskite layers. It can be confirmed from high bright fluorescence image and short decay time that the novel orange-red phosphor has the potential applications in luminescence devices. [Copyright &y& Elsevier]

Abstract: Bi4Ti3O12 thin films with bismuth-layered perovskite structure have been successfully fabricated by means of chemical solution decomposition (CSD) and characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and UV–vis spectrophotometry in this study. The photocatalytic activity of Bi4Ti3O12 thin films has been evaluated by photodegrading methyl orange solution, and the optimum processing parameters for the photocatalytic activity have been found. Moreover, it has been found that La-doping can improve the photocatalytic activity of Bi4Ti3O12 thin films and hinder the increase of crystallite sizes during calcination. [Copyright &y& Elsevier]

Abstract: Dopant-free Bi2Ti2O7 thin films with pyrochlore structure and La-doped bismuth titanate thin films have been fabricated by means of chemical solution decomposition, and characterized by X-ray diffraction, atomic force microscopy, scanning electron microscopy and UV–Vis spectrophotometry in this study. Their photocatalytic activities have been evaluated by photodegrading methyl orange solution, and the optimum processing parameters for the highest photocatalytic activity have been found. Moreover, the effects of La-doping on the phase transformation and the photocalalytic activity have been studied. It has been deduced from the experiment result that substituted La3+ ions can act as a stabilizer of Aurivillus phase BLT and a grain–growth inhibitor in BLT thin films. [Copyright &y& Elsevier]

Abstract: Nb2O5 nanorods have been prepared using water/ethanol media. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV–visible absorption and photoluminescence spectroscopy. The as-prepared Nb2O5 nanorods appeared to be single pseudohexagonal (TT-Nb2O5) phase. From the photoluminescence spectrum, two emission bands at 407 and 496nm, respectively, were observed. The origin of the luminescence was discussed in detail. [Copyright &y& Elsevier]

Abstract: A novel red luminescent material Li0.9Y0.9Zr0.1O2 doped with trivalent europium ions and dysprosium ions was synthesized by solution–combustion method. X-ray diffractometry, transmission electron microscopy and optical spectroscopy were used to valuate the crystallinity, the morphological characterization and the optical properties of the products. The results showed that combustion at 800°C was enough to obtain highly crystalline and phase-pure samples. Photoluminescence spectra of Li0.9Y(0.9−x−y)Zr0.1O2:Eu x 3+,Dy y 3+ samples indicated the dominant red emissions (613nm) at a single-wavelength ultraviolet excitation (395nm) due to 5D0 → 7F2 transition. The relation between the luminescence intensity and dopant concentration was also discussed. [Copyright &y& Elsevier]

Abstract: Three-dimensional reticular-structured luminescence SrAl2O4:Eu,Dy powders were prepared by refluxing- and sonication-combustion synthesis without using any surfactant for the first time and were characterized using X-ray diffraction, transmission electron microscopy, scanning electron microscopy. All the samples have a very porous, open and spongelike morphology with fractal properties. The excitation and emission spectra of the products have been measured by Edinburgh FLS920 at room temperature. The new formation-mechanism of the three-dimensional reticular-structure was proposed in this article. [Copyright &y& Elsevier]

Abstract: Pure and Mn-doped SrNb2O6 nanoparticles have been prepared by sol–gel combustion method using citric acid as fuel and complexing agent and nitrates as oxidants at a relatively low temperature compared to solid-state reaction method. X-ray diffraction (XRD) patterns of the pure SrNb2O6 samples show that the SrNb2O6 nanoparticles exhibited orthorhombic phase. Photoluminescence (PL) properties of all the undoped and Mn-doped samples were studied in detail. For the pure SrNb2O6 samples, a strong blue emission band centered at 442nm and two weak emission bands centered at 524nm and 626nm, respectively, can be observed. For the Mn-doped SrNb2O6 samples, no emission from Mn2+ was observed while the blue emission intensity of SrNb2O6 varied with the Mn-doping concentration. This novel PL characteristic of the doped samples was explained. [Copyright &y& Elsevier]