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A novel, highly efficient, reusable heterostructured nanocomposite photocatalyst and antibacterial agent was prepared successfully by combustion method. The structural and crystallinity of synthesized nanocomposites were well characterized by Powder X-ray diffraction (P-XRD) which confirms the purity and phase formation by diffraction peaks related to CuO, Cu 2 O, metallic Cu of nanocomposites. The proximity of Fe directly affects the crystallinity of Cu 2 O/CuO/Cu (CCC) and changes the morphology with observable voids and pores in Scanning Electron Microscopy (SEM). In addition, X-Ray Photoelectron Spectroscopy (XPS) results indicated the existence of doped Fe as Fe3+ and Fe2+ ions within the CCC nanocomposite lattice. The UV–Visible absorption spectroscopy illustrates a decrease in the band gap energy for the nanocomposites CCC (1.9 eV) and CCC-Fe (1.7 eV) which proves the dopant Fe hinders the recombination of e-–h+ pairs by trapping electrons and holes, causing an enhancement in this degradation process. This depicts the ability of Fe-doped CCC as a better photocatalyst under Sunlight irradiation than CCC. This was confirmed by the obtained results of photocatalytic performance of Fe doped CCC (5 mol%) on Methylene Blue (MB) and Rhodamine B (RhB) dyes. The degradation was found to be 93% and 81% respectively under irradiation of Sunlight for 60 min, whereas for CCC, the obtained result was 65% (MB) and 60% (RhB) under same condition. The CCC-Fe nanocomposite also shows considerable specific capacitance with 84.55 F/g from cyclic voltamogram and 83 F/g from charge discharge studies with durability of 2000 cycles ascertains the supercapacitor nature. Further, the remarkable antibacterial activities of Fe-doped CCC nanocomposites against E. coli and S. Aureus (100 μg/mL) were discussed. The excellent results of Fe-doped CCC nanocomposite showed a prominent multifunctionality in suppressing organic pollutants and bacteria in the environment. [ABSTRACT FROM AUTHOR]

This research deals with the facile combustion synthesis of manganese ferrite (MFO) nanoparticle with different cerium concentration and their potential application as an efficient photocatalyst and chemical sensor. The concentration of introduced cerium affects the size, structure, compositional, morphological, optical, photoluminescence and magnetic properties of the ferrite nanoparticle. The X-ray diffraction pattern affirmed the arrangement of cubic spinel structure with the formation of secondary phase CeO 2 as the cerium concentration exceed 3 mol%. SEM micrographs revealed irregular morphology with more number of pores and voids. HRTEM along with SAED pattern revealed the crystalline cubic nature. The optical band gap deduced from UV–Vis-DRS spectra was observed to be in the range 2.3–2.8 eV. PL studies indicated a significant minimization in combination of electrons & holes in MnFe 2 O 4 on addition of Ce dopant. VSM investigation demonstrated the soft magnetic nature of the prepared sample with moderate magnetization value. An excellent photocatalytic performance of Cerium doped MFO (3 mol%) towards MB and AR dye degradation was found to be 1.5 and 1.67 times more compared to host matrix under Sunlight irradiation that correlated to reduced band gap, Ce dopant and efficient separation of charge carriers. Cerium doped MFO (3 mol%) have high specific capacitance value of 471.7 and 1546.8 Fg-1 for NaNO 3 and HCl electrolytes respectively, indicating the pseudo capacitance nature due to which it can be used as a supercapacitor. The synthesized nanoparticles can sense d -Glucose and Paracetamol even at a lower concentration varying from 1 to 10 mM. The synthesized Ce-doped MnFe 2 O 4 nanomaterials have great potential to be used in the future production of promising active photocatalysts and sensitive chemical sensors for the identification and degradation of toxic industrial dyes for improved safety in the fields of environment and health care. [ABSTRACT FROM AUTHOR]

Here, we investigate the effect of temperature on solution combustion synthesized MnFe 2 O 4 nanoparticles (NPs) as supercapacitor electrode material that would affect the structural, optical, electrochemical, magnetic and sensing properties. The variation in temperature influences the structure and morphology of synthesized NPs which in turn produces defect states in NPs. Powder X-ray diffraction studies confirms the presence of cubic spinel structure with increase in crystallinity and crystallite size with increase in temperature. Scanning electron microscopy analysis indicates the morphology change in NPs from spherical to network like interlinking to the formation of polyhedron structure at higher temperature. Photoluminescence, energy dispersive X-ray analysis, X-ray photoelectron scpectroscopy and UV-visible diffused reflectance spectroscopy studies emphasize the increase in surface oxygen vacancies concentration with narrowing of band gap from 2.9 to 2.5 eV. Electrochemical studies designate the excellent performance and desirable cyclic stability of synthesized NPs. In particular, the specific capacitance of synthesized NP increases with increase in temperature, reaching highest specific capacitance from CV was 297.7 F/g for 0.1 M HCl and 158.85 F/g for 0.1 M NaNO 3 electrolytes for NP synthesized at 500 °C. The synthesized NPs show excellent stability with high capacity retention in both the electrolytes. The graphite modified electrode can also sense Paracetamol and d -Glucose at a very low concentration of 1–5 mM. Meanwhile, it acts as a very good photocatalyst to decolourize Methylene Blue and Alizarin Red S dye under Sunlight illumination due to the increase in concentration of surface oxygen vacancies with narrow band gap. Finally, the synthesized MnFe 2 O 4 NP can be used as a potential supercapacitor electrode with excellent stability and recyclability, to sense the analyte even at very low concentration and also act as a photocatalyst with high recyclability with the help of magnetic nature towards environmental cleaning. [ABSTRACT FROM AUTHOR]

Photocatalytic activity of (CuO-Cu 2 O)Cu/ZnO hetero-junction nanocomposites along with their luminescent, biological applications in the progress of anticancer and antibacterial agents is investigated. The Cu and Zn bi-components modified (CuO-Cu 2 O)Cu/ZnO nanocomposites were synthesized via facile combustion route in the presence of controlled fuel to oxidizer ratio and were characterized by X-Ray Diffraction (XRD) patterns, Transmission electron microscopy (TEM), High resolution Transmission electron microscopy (HRTEM), Scanning Electron Microscopy (SEM), X-ray photoelectron Spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), photoluminescence (PL) and energy dispersive X-ray (EDX) analysis. The PL and UV–Visible diffused reflectance spectral (UV–Vis-DRS) techniques were used to measure the optical sensitivity and tuning of band gap in the samples. The excellent photocatalytic degradation of Methylene Blue and industrial waste water under Sunlight irradiation depends on the mass ratios of Cu/Zn. The findings show that the addition of a certain proportion of CuO, Cu 2 O, ZnO, and Cu can promote efficiency in Sunlight harvesting and separation of charge carriers. Process parameters namely catalyst quantity, dye concentration and a proposal for the mechanism of degradation pathway, experiments for trapping and enhancer are investigated. The study of photoluminescence, CIE and CCT calculations suggests that the present nanocomposite may find applications as phosphor material in warm white LEDs. The second segment of this study deals with the investigation of antibacterial performance of composites upon Gram-negative and Gram-positive bacteria. The results indicate that nanocomposites can be used in antibacterial control systems and as an important growth inhibitor in various microorganisms. The cytotoxic effect of the (CuO-Cu 2 O)Cu/ZnO (CCCZ11) nanocomposite was determined by colorimetric and flow cytometric cell cycle analysis. Our experimental results show that the nanocomposite can induce apoptosis and suppress the proliferation of HeLa cells. The applications of nanocomposites based on Cu, an abundant and inexpensive metal has created much interest in various multifunctional applications. [ABSTRACT FROM AUTHOR]

This work majorly aims to synthesize and also investigate the structural, optical, magnetic and optical features of ZrO 2 /ZnFe 2 O 4 nanocomposite. Here, different ratios of novel hetero-junction ZrO 2 /ZnFe 2 O 4 were synthesized by simple and fast solution combustion route. The X-ray diffraction results showed the formation of ZrO 2 and ZnFe 2 O 4 nanoparticles and ZrO 2 /ZnFe 2 O 4 nanocomposites without any impurity. The formation of hetero-junction effectively inhibits the photo-generated charge carrier recombination. The degradation of Indigo Carmine dye by ZrO 2 /ZnFe 2 O 4 photocatalyst was achieved through synergistic effects with 98% degradation and removal of 77% COD from the industrial dye waste water under Sunlight irradiation. Mixing of ferrites with zirconia greatly improves the photocatalytic activity that has been clearly proposed with the help of mechanism. ZZFO 12 NC exhibits better photocatalytic activity due to the combined facets of photo and Fenton activity. The exposure and enhancement of fingerprints in various surfaces are achieved by a modest, extremely sensitive and eco-friendly method. ZZFO12 NC offer great potential as an active photocatalyst for degradation of 54% of organic pollutant present in industrial waste water under natural Sunlight. [ABSTRACT FROM AUTHOR]

In recent years, key study was designing nanomaterials (NMs) with tunable properties in order to obtain high functional materials. For this purpose, an attempt with great effort has been put forward to synthesize ZrO 2 :Eu:Li (1–11 mol%) NM with varying concentration of Li+ ion that can have a control over phase, size, morphology, crystallinity, band gap and surface chemistry. More importantly, addition of Li as codopant influences the phase and crystallinity change with the change in concentration. However important challenges faced by this work was to understand the phase change, crystallinity, structural change and photocatalytic activity which has to be still explored. The synthesized NMs possess mixed phase and cubic phase with change in concentration of codopant which may be attributed to presence of defect states, micro strain, distortion of lattice. The energy band gap was found to decrease for 7 mol% NM attributed to the change in the phase. Porous morphology with variation in pore length was observed. Enhanced luminescence intensity with intense orange red emissions consistent to 5D 0 →7F j (j = 0 to 4) intra configurational f-f transitions was observed for ZrO 2 :Eu:Li+(1–11 mol%) nanophosphor excited at 394 nm. The visualization of latent fingerprints using ZrO 2 : Eu: Li+ 7mol% nanophosphor on several surfaces, the powder dusting technique was adopted. The enhanced fingerprint under UV light provides well resolved ridge patterns for the identification of individual latent finger prints using ZrO 2 :Eu:Li (7 mol%) with clear resolution. Lower charge transfer resistance with enhanced photocatalytic activity for decolourization of Rhodamine B with high pore length to allow multiple reflections under UV light irradiation for 7 mol% NM with reduced band gap and optimum luminescence intensity was observed. Hence, the synthesized ZrO 2 :Eu:Li (7 mol%) can be employed in forensic science towards latent fingerprint development, as a photocatalyst for environmental remediation and as luminescent material in display applications. [ABSTRACT FROM AUTHOR]

The goal of this research is to prepare novel, inexpensive, environment friendly and efficient crystalline CuO samples by green mediated combustion and co-precipitation routes towards environmental remediation and biomedical applications. The influence of preparation routes and Aloe barbadensis miller (Aloe vera) gel on the morphology, size, crystallinity, band gap, defects, photocatalytic, antibacterial, haemolytic and anticancer behaviour of CuO samples were explored. The PXRD, XPS, SEM, TEM, HRTEM and FT-IR were performed to confirm the formation of CuO samples. FTIR studies showed all possible bands of Aloe barbadensis miller gel. FTIR displaying the occurrence of new peaks and peak shifts in the CuO synthesized by green mediated combustion route compared to co-precipitation route is an evidence of the effective interactions between CuO and Aloe vera gel. The PL and UV–Vis-DRS techniques measured the optical sensitivity and tuning of band gap of the CuO samples. The crystallinity and surface properties dependent photocatalytic activities for decolourization of MB and RhB under both UV and Sunlight irradiation were investigated. The results indicated that green mediated synthesized CuO sample displayed high photocatalytic activity compared with co-precipitation route synthesized CuO sample, which mainly resulted from the low crystallinity and crystallite size (6 nm), narrow band gap (1.73 eV) and lower recombination of charge carriers. These synthesized CuO samples also demonstrate excellent antibacterial activity against the bacteria Gram-positive (S. aureus) and Gram-negative (E. coli). The present study probes into the cytotoxicity of CuO samples employing root cells of Allium cepa. In addition, we report the haemolytic activity on goat and human blood along with the implementation of green synthesized CuO sample using an Aloe barbadensis miller extract for the evaluation of anticancer activity in human cervical cancer (HeLa) cells with IC50 value of 310.1 μg/ml. Our studies focus on developing biosynthesized nanomaterials for environmental remediation and biomedical applications. [ABSTRACT FROM AUTHOR]

Novel crystalline tetragonal ZrO 2 : Eu 3+ phosphors were prepared by a facile and efficient low temperature solution combustion method at 400 ± 10 °C using oxalyl dihydrazide (ODH) as fuel. The powder X-ray diffraction patterns and Rietveld confinement of as formed ZrO 2 : Eu 3+ (1–11 mol%) confirmed the presence of body centered tetragonal phase. The crystallite size estimated from Scherrer’s and W–H plots was found to be in the range of 7–17 nm. These results were in good agreement with transmission electron microscopy studies. The calculated microstrain in most of the planes indicated the presence of tensile stress along various planes of the particles. The observed space group ( P4 2 /nmc ) revealed the presence of cations in the 2b positions (0.75, 0.25, 0.25) and the anions in the 4d positions (0.25, 0.25, 0.45). The optical band gap energies estimated from Wood and Tauc’s relation was found to be in the range 4.3–4.7 eV. Photoluminescence (PL) emission was recorded under 394 and 464 nm excitation shows an intense emission peak at 605 nm along with other emission peaks at 537, 592, 605 and 713 nm. These emission peaks were attributed to the transition of 5 D 0 → 7 F J ( J = 0, 1, 2, 3) of Eu 3+ ions. The high ratio of Intensity of ( 5 D 0 → 7 F 2 ) and ( 5 D 0 → 7 F 1 ) infers that Eu 3+ occupies sites with a low symmetry and without an inversion center. CIE color coordinates indicated the red regions which could meet the needs of illumination devices. [ABSTRACT FROM AUTHOR]

Eco-friendly, cost effective and bio template route was used for the preparation of cubic Gd 2 O 3 :Eu 3+ nanophosphors using Euphorbia tirucalli ( E. tirucalli ) plant latex as fuel. As – formed Gd 2 O 3 :Eu 3+ (7 mol%, 1–7 ml), calcined Gd 2 O 3 :Eu 3+ (7 mol%, 1–7 ml) and Gd 2 O 3 :Eu 3+ (1–11 mol%, 7 ml) samples were characterized using XRD, SEM and UV–Vis absorption spectrophotometer. With increase in latex concentration, the nanophosphor gets transformed from nano plates to rose – like nanoflowers with size varying from 20 to 30 nm. X-ray diffraction pattern of as – formed product shows hexagonal Gd (OH) 3 : Eu 3+ phase and it converts to pure cubic phase of Gd 2 O 3 :Eu 3+ on calcination at 600 °C for 3 h. Rietveld refinement of Gd 2 O 3 :Eu 3+ (7 mol%, 7 ml) revealed the presence of cations in the 8 b (0.25, 0.25, 0. 25) and 24 d positions (−0.0287, 0.00, 0. 25) and the anions in the 48 e positions (0.39, 0.15, 0. 37) with space group Ia -3(206). The photoluminescence intensities of transitions between different J levels depend on the symmetry of the local environment of Eu 3+ ion activators and the high ratio of intensity of ( 5 D 0 → 7 F 2 ) and ( 5 D 0 → 7 F 1 ) provides the conclusion that Eu 3+ ion occupies sites with a low symmetry and without an inversion centre. The chromaticity and the CIE coordinates were very close to the standard red color region. The absorption observed in the excitation spectra shows the suitability of the nanophosphor obtained in this study for getting excited in UV, NUV and visible regions for variety of display applications. Further, the Gd 2 O 3 :Eu 3+ (7 mol%, 1–7 ml) samples were experimented towards the photocatalytic behavior on Congo red (CR) and correlated with emission of PL intensity. The decolorization of dye was found to decreased from 83 to 54% with increase in the plant latex concentration. [ABSTRACT FROM AUTHOR]

ZrTiO 4 (ZTO) nanoparticles (NPs) are synthesized by solution combustion method using chemical fuel (Glycine) (ZTOG) and green (Aloevera) extract (ZTOA) as a reducing agent (15–25 ml) and calcined at 700 °C. The synthesized samples are characterized and its multi-functional properties such as Photoluminescence, Sensor and Supercapacitor properties were discussed in detail. Powder X-ray diffraction pattern of ZTOG and ZTOA shows the Bragg's reflection corresponding to ZrTiO 4. The pure orthorhombic phase is retained in ZTOA whereas in ZTOG, monoclinic and cubic phases are observed. The crystallite size estimated by PXRD matches well with TEM analysis. From the Wood and Tauc's relation, the energy band gap was found to be 2.8 and 3.2 eV which was further confirmed by band structure using density of states. The photoluminescence emission peaks (λ = 350 nm), CIE and CCT of ZTOA and ZTOG clearly confirms that the present nanophosphor might be a good nanophosphor material for blue light emitting diodes. X-ray/Gamma ray absorption properties are also studied which clearly shows the ZrTiO 4 might be a good absorbing material. Furthermore, Cyclic voltammetry (CV) analysis of ZTOA nanorods shows very good redox peaks as compared to ZTOG. From the Electrochemical Impedance Spectroscopy (EIS) measurements, the charge-transfer resistance for prepared nanorods ZTOA and ZTOG was found to be 180 and 261 Ω respectively. The modified graphite electrode with ZTOA shows good sensing activity for both paracetamol and ascorbic acid rather than ZTOG. [ABSTRACT FROM AUTHOR]

Black appearance and flat absorber, i.e., high solar absorptance (α s) and high IR emittance (ε ir) surfaces, are essential for optical benches and optical mounts in astronomical and scientific payloads/spacecraft. Generally, these optical benches and optical mounts are fabricated by Ti6Al4V alloy due to its superior mechanical and thermal properties. However, bare Ti6Al4V is restricted for spacecraft thermal control applications due to its low emittance, intermediate absorptance, and moderate corrosion resistance behaviors. Hence, plasma electrolytic oxidation (PEO) technique was utilized to develop black and flat absorber coatings on bare Ti6Al4V alloy. Sodium silicate (SS), sodium hypophosphate (SHP), and potassium fluoride (KF) were used for the preparation of the electrolytic bath. Process parameters such as current density, duty cycle, frequency, the concentration of electrolytes, and duration were judiciously altered to get uniform PEO coatings with the flat absorbing property. Six numbers of PEO coatings were finally chosen for further in-depth characterizations as they showed adequate flat absorbing property. The phase composition, microstructure, roughness, and wettability of those PEO coatings were thoroughly studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), profilometry, and water contact angle measuring techniques, respectively. Thermo-optical properties viz., ε ir and α s of the coatings were recorded by portable IR emissometer and solar reflectometer, respectively, and electrical sheet resistance was measured by two probe method. The Nanomechanical properties of the coatings, such as modulus (E) and nanohardness (H), were evaluated by the nanoindentation technique. The PEO coatings were also investigated with respect to potentiodynamic polarization to investigate corrosion resistance of the PEO coatings. The highest ε ir value of PEO coating was achieved as 0.87 for a 20% duty cycle with a combination of SS + SHP electrolytes, while the maximum α s value was achieved as 0.83 for the same 20% duty cycle with a combination of SS + SHP + KF electrolytes. [ABSTRACT FROM AUTHOR]

The study reports green mediated combustion route for the synthesis of Tb 3+ ion activated Y 2 O 3 nanophosphors using Aloe Vera gel as fuel. The concentration of Tb 3+ plays a key role in controlling the morphology of Y 2 O 3 nanostructures. The formation of different morphologies of Y 2 O 3 : Tb 3+ nanophosphors were characterized by PXRD, SEM, TEM and HRTEM. PXRD data and Rietveld analysis evident the formation of single phase Y 2 O 3 with cubic crystal structure. The influence of Tb 3+ ion concentration on structural morphology, UV–visible absorption and PL emission were investigated systematically. The PL emission of Y 2 O 3 : Tb 3+ (1–11 mol%) nanophosphors were studied in detail under 271 and 304 nm excitation wavelengths. The CIE coordinates lies well within green region and correlated color temperature values were found to be 6221 and 5562 K under different excitations. Thus, the present phosphor can serve as an excellent candidate for LEDs. Further, prismatic Y 2 O 3 : Tb 3+ (3 mol%) nanophosphor showed significant antibacterial activity against Pseudomonas desmolyticum and Staphylococcus aureus . The present study successfully demonstrates Y 2 O 3 : Tb 3+ nanophosphors can be used for display applications as well as in medical applications for controlling pathogenic bacteria. [ABSTRACT FROM AUTHOR]

The Present work involves the production of Eu3+ (1–11 mol %) doped MgNb 2 O 6 nanophosphors (NPs) by combustion technique using ODH as a fuel for the first time and well characterized. The average crystallite and the energy gap of the samples were found to be in the range of 20–45 nm and 4.65–5.66 eV respectively, TEM results reflects the same crystallite size values. The effect of doping was confirmed by the characteristic emission peaks recorded at ~535, 590, 614, 642 and 698 nm may be attributed to the 4f–4f intra shell transitions (5D 0 →7F j=0,1,2,3,4) of Eu3+ cations when bombarded at 395 nm energy. Judd–Ofelt parameters (Ω 2 , Ω 4), transition probabilities (A T), quantum efficiency (η), luminescence lifetime (τ rad) are discussed in detail. From the emission spectra, CIE (Commission International de I' Eclairage) chromaticity co-ordinates and Correlated color temperature (CCT) were estimated. Langmuir-Hinshelwood model was used to study the photocatalytic degradation of AR-88 dye. The above results confirmed that the present phosphor can be potentially used for display and photocatalytic applications. [ABSTRACT FROM AUTHOR]

Two dimensional (2D) materials stacked with Van der waals bonding to obtain a heterostructure have always generated tailored physical and chemical properties. In this paper, the development and application of single-phase 2D Bi 2 MoO 6 -reduced graphene oxide (BMO-RGO) heterostructure by one-pot supercritical water (SCW) method is reported for the first time. The as-synthesized nanocomposite of BMO-RGO with single-phase orthorhombic crystal structure is confirmed by XRD. The 2D nanoflake morphology was observed under transmission electron microscopy (TEM). X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and Fourier transform infrared spectroscopy is performed to confirm the presence of BMO-RGO, RGO, and other functional groups, respectively. The specific capacities obtained through charge-discharge measurements from BMO and BMO-RGO heterostructure nanocomposites are compared and the optimization of RGO wt% is established. After 50 cycles, the capacity retention is around 202 mA h g−1 for BMO with 24 wt% RGO (BMO-24RGO) nanocomposite. This value is higher in comparison to pure BMO nanoflakes which have a capacity retention of 25 mA h g−1. These results show the influence of RGO content on the performance of electrochemical measurements when compared to pure BMO and BMO-24RGO electrodes. One-pot SCW synthesis is found to be a reliable method for the synthesis of BMO-RGO nanocomposite. [ABSTRACT FROM AUTHOR]

Green combustion synthesis using Calotropis gigantea latex as fuel, NaCl as flux were employed for the synthesis of Y 2 SiO 5 :Ce 3+ (1 mol%):Sm 3+ (0.2–1 mol%) nanoparticles. The 1000 °C calcined phosphors were characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The powder X-ray diffraction (PXRD) patterns of the sample revealed a monoclinic phase with space group P 21/ C (n.14). The crystallite size using Scherer's formula and W–H plot was found to be in the range 34–39 nm and the same was confirmed by transmission electron microscopy (TEM) studies. Scanning electron microscopy (SEM) pictures show porous with agglomerated crystallites. The effect of Sm 3+ ions on the luminescence characteristics of Y 2 SiO 5 :Ce 3+ nanoparticles was studied and the results were discussed in detail. The phosphors exhibit bright orange red emission upon 404 nm excitation. The emission spectra consists of sharp emission peaks at 566, 601 and 654 nm which were attributed to typical 4 G 5/2 → 6 H 5/2 , 4 G 5/2 → 6 H 7/2 and 4 G 5/2 → 6 H 9/2 transitions of Sm 3+ ions, respectively. The Commission International de I’Eclairage (CIE) chromaticity co-ordinates were estimated from emission spectra which falls in white region of the CIE spectra. Further, color correlated temperature (CCT) was found to be 5011 K. Hence, the present phosphor was highly useful for mercury free solid state lighting (SSL) and also for white display applications. [ABSTRACT FROM AUTHOR]

Dy 3+ doped Mg 2 SiO 4 nanoparticles have been synthesized by the solution combustion method at 350 °C temperature. The crystallinity and changes of lattice parameters with the incorporation of the Dy 3+ ions are studied by means of Powder X-Ray Diffraction studies. Fourier transform infrared data indicate the formation of bonds and capping of the nanoparticles. Scanning electron microscopy pictures evident for the product is porous and agglomerated. The nano size of the product is confirmed by means of transmission electron microscopy. The characteristic emission peaks and the Judd–Ofelt intensity parameters of Mg 2 SiO 4 :Dy 3+ nanoparticles are studied. The emission can be tuned from green (0.238, 0.348) to white (0.276, 0.347) which indicates, the prepared phosphors can be effectively used for white light emitting diodes and biosensors. Further, the degradation of dyes is found to be enhancing in the presence of Dy 3+ ions due to suppress of the e − CB and h + VB recombination. [ABSTRACT FROM AUTHOR]

Tunable white light emissive (YSO) Y 2 SiO 5 : 5Dy 3+ , x Eu 3+ ( x = 0.5 – 4.5 mol%) phosphors were synthesized by the solution combustion method. The 1000 °C phosphors were characterized by powder X-ray diffraction (PXRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The average crystallite size estimated by Debye – Scherer's and Williamson – Hall plots were found to be in the range of 10 – 50 nm. Samples calcined at 1000 °C, show pure monoclinic X1 phase. Co-doping with Eu 3+ compensated the red emission component of the YSO:Dy 3+ phosphor. Furthermore, the energy transfer from Dy 3+ to Eu 3+ was confirmed based on the luminescence spectra. The intense white light emissions are suggestive exploration for the potential phosphor for optical materials applications used in the ultraviolet excited white light emitting diodes. [ABSTRACT FROM AUTHOR]

CeO 2 nanoparticles (NPs) were synthesized by a facile low temperature solution combustion method using citric acid as fuel. The structural and morphological properties of as-formed and calcined products were characterized by PXRD, SEM, TEM, Raman, UV–visible absorption spectroscopy techniques. Further, the NPs were subjected to photoluminescence (PL) and thermoluminescence (TL) studies. PXRD results and Rietveld refinement analysis confirms the formation of single and pure cubic phase in both as-formed and calcined CeO 2 NPs. In both the NPs, Raman spectra exhibit the symmetrical stretching mode of Ce-O vibrational unit at 465 cm −1 . The PL emission peak appeared with CeO 2 upon 237 nm excitation can be assigned to the oxygen related defects. The CIE and CCT coordinates clearly indicates the possible potential application of CeO 2 nanophosphor in display devices. TL studies revealed well resolved glow peak at 224 °C along with a small shouldered peak at 131 °C. The glow peak intensity increases linearly with γ-dose which suggest CeO 2 sample is suitable candidate for radiation dosimetric applications. The activation energy, order of kinetics and frequency factor was estimated using glow peak shape method. The study successfully demonstrates a facile simple route for the synthesis of multifunctional CeO 2 NPs. [ABSTRACT FROM AUTHOR]

Green synthesis of multifunctional Zinc oxide nanoparticles (NPs) with a variety of morphologies were achieved by low temperature solution combustion route employing neem ( Azadirachta indica ) extract as fuel . The nanoparticles were characterized by PXRD, FTIR, XPS, Raman and UV–Visible spectroscopic studies. The Morphologies were studied by SEM and TEM analysis. The NPs were subjected for photoluminescence, photocatalytic, antibacterial and antioxidant activity studies. PXRD pattern confirmed the hexagonal wurtzite structure of the product. SEM images indicated the transformation of mushroom like hexagonal disks to bullets, buds, cones, bundles and closed pine cone structured NPs with increase in the concentration of neem extract in reaction mixture. The NPs exhibited prominent green emission due to the presence of intrinsic defect centers. The as-formed bullet shaped ZnO with 4 ml of neem extract was found to decolorize Methylene blue (MB) under Sunlight and UV light irradiation. The antibacterial studies indicated that ZnO NPs of concentration 500, 750 and 1000 μg resulted in significant antibacterial activity on Klebsiella aerogenes and Staphylococcus aureus but not against Escherichia coli and Pseudomonas aeruginosa in agar well diffusion method. Further, ZnO NPs exhibited significant antioxidant activity against scavenging DPPH free radicals. The current investigation demonstrated green engineering method for the synthesis of multifunctional ZnO NPs with interesting morphologies using neem extract. [ABSTRACT FROM AUTHOR]

Europium doped lanthanum aluminate nanophosphors were synthesized by a combustion process using Oxalyl di-hydrazide as fuel. The nanophosphors calcined at 900 °C for 3 h were characterized by PXRD, FTIR spectroscopy, SEM and TEM. The average crystallite size determined by TEM and Scherrer's method was found to be in the range 20–50 nm. The characteristic emission peaks (λ exi - 395 nm) recorded at ∼ 591, 616, 646 and 696 nm ( 5 D 0 → 7 F j=0,1,2,3 ) may be attributed to the 4f–4f intra shell transitions of Eu 3+ ions. The estimated CIE chromaticity co-ordinates were calculated from emission spectra, were close to the national television standard committee value of red emission. Correlated color temperature was found to be 1929 K. [ABSTRACT FROM AUTHOR]

MgO:Fe 3+ (0.1–5 mol%) nanoparticles (NPs) were synthesized via eco-friendly, inexpensive and simple low temperature solution combustion route using Aloe vera gel as fuel. The final products were characterized by SEM, TEM and HRTEM. PXRD data and Rietveld analysis revealed the formation of cubic system. The influence of Fe 3+ ion concentration on the structure morphology, UV absorption, PL emission and photocatalytic activity of MgO:Fe 3+ NPs were investigated. The yellow emission with CIE chromaticity coordinates (0.44, 0.52) and average correlated color temperature value was found to be 3540 K which corresponds to warm light of NPs. The control of Fe 3+ on MgO matrix influences the photocatalytic decolorization of methylene blue (MB) under UV light. The enhanced photocatalytic activity of MgO:Fe 3+ (4 mol%) was attributed to dopant concentration, effective crystallite size, textural properties, decreased band gap and capability for reducing the electron–hole pair recombination. Further, the trends of inhibitory effect in the presence of different radical scavengers were explored. These findings open up new avenues for the exploration of Fe-doped MgO in eco-friendly water applications and in the process of display devices. [ABSTRACT FROM AUTHOR]

Facile and green route was employed for the synthesis of Y 2 O 3 :Dy 3+ (1–11 mol%) nanostructures (NSs) using Aloe vera gel as fuel. The formation of different morphologies of Y 2 O 3 :Dy 3+ NSs were characterized by SEM, TEM and HRTEM. PXRD data and Rietveld analysis evident the formation of single phase Y 2 O 3 with cubic crystal structure. The influence of Dy 3+ ion concentration on the structure morphology, UV absorption, PL emission and photocatalytic activity of NSs were investigated. NSs exhibited an intense warm white emission with CIE chromaticity coordinates (0.32, 0.33) and average CCT value ∼5525 K which corresponds to vertical day light. The control of Dy 3+ ion on Y 2 O 3 matrix influences the photocatalytic decolorization of Metanil Yellow as a model compound was evaluated. The enhanced photocatalytic activities of core shell structured Y 2 O 3 :Dy 3+ (1 mol%) was attributed to co-operation effect of dopant concentration, crystallite size, textural properties and capability for reducing electron–hole pair recombination. Further, the recycling catalytic ability of Y 2 O 3 :Dy 3+ (1 mol%) nanostructure was also evaluated and found promising photocatalytic performance with negligible decrease in decolorization efficiency even after sixth successive cyclic runs. Considering its green, facile synthesis and recyclable feature from an aqueous solution, the present Y 2 O 3 :Dy 3+ (1 mol%) nanophosphor can be considered as one of the ideal photocatalyst for various potential applications. [ABSTRACT FROM AUTHOR]

Spherical shaped cerium dioxide (CeO 2 ) nanoparticles (NPs) were synthesized via bio mediated route using Leucas aspera (LA) leaf extract. The NPs were characterized by PXRD, SEM, UV–Visible techniques. Photoluminescence (PL), photocatalysis and antibacterial properties of NPs were studied. PXRD patterns and Rietveld analysis confirm cubic fluorite structure with space group Fm-3m . SEM results evident that morphology of the NPs was greatly influenced by the concentration of LA leaf extract in the reaction mixture. The band gap energy of the NPs was found to be in the range of 2.98–3.4 eV. The photocatalytic activity of NPs was evaluated by decolorization of Rhodamine-B (RhB) under UVA and Sun light irradiation. CeO 2 NPs show intense blue emission with CIE coordinates (0.14, 0.22) and average color coordinated temperature value ∼148,953 K. Therefore the present NPs quite useful for cool LEDs. The superior photocatalytic activity was observed for CeO 2 NPs with 20 ml LA under both UVA and Sunlight irradiation. The enhanced photocatalytic activity and photoluminescent properties were attributed to defect induced band gap engineered CeO 2 NPs. Further, CeO 2 with 20 ml LA exhibit significant antibacterial activity against Escherichia coli (EC) and Staphylococcus aureus (SA). These findings show great promise of CeO 2 NPs as multifunctional material for various applications. [ABSTRACT FROM AUTHOR]

We report the synthesis of Y 2 O 3 : Eu 3+ (1–11 mol%) nanoparticles (NPs) with different morphologies via eco-friendly, inexpensive and simple low temperature solution combustion method using Aloe Vera gel as fuel. The formation of different morphologies of Y 2 O 3 : Eu 3+ NPs were characterized by PXRD, SEM, TEM, HRTEM, UV–Visible and PL techniques. The PXRD data and Rietveld analysis confirms the formation of single phase Y 2 O 3 with cubic crystal structure. The influence of Eu 3+ ion concentration on the morphology, UV–Visible absorption, PL emission and photocatalytic activity of Y 2 O 3 : Eu 3+ nanostructures were investigated. Y 2 O 3 : Eu 3+ NPs exhibit intense red emission with CIE chromaticity coordinates (0.50, 0.47) and correlated color temperature values at different excitation ranges from 1868 to 2600 K. The control of Eu 3+ ion on Y 2 O 3 matrix influences the photocatalytic decolorization of methylene blue (MB) as a model compound was evaluated under UVA light. Enhanced photocatalytic activity of conical shaped Y 2 O 3 : Eu 3+ (1 mol%) was attributed to dopant concentration, crystallite size, textural properties and capability of reducing the electron–hole pair recombination. The trend of inhibitory effect in the presence of different radical scavengers followed the order SO 4 2− > Cl − > C 2 H 5 OH > HCO 3 − > CO 3 2− . These findings show great promise of Y 2 O 3 : Eu 3+ NPs as a red phosphor in warm white LEDs as well as eco-friendly heterogeneous photocatalysis. [ABSTRACT FROM AUTHOR]

Mg 2 SiO 4 :Sm 3+ (1–11 mol%) nanoparticles were prepared by a rapid low temperature solution combustion route. The powder X-ray diffraction (PXRD) patterns exhibit orthorhombic structure with α-phase. The average crystallite size estimated using Scherer’s method, W–H plot and strain–size plots were found to be in the range 25–50 nm and the same was confirmed by Transmission Electron Microscopy (TEM). Scanning electron microscopy (SEM) pictures show porous structure and crystallites were agglomerated. The effect of Sm 3+ cations on luminescence of Mg 2 SiO 4 was well studied. Interestingly the samples could be effectively excited with 315 nm and emitted light in the red region, which was suitable for the demands of high efficiency WLEDs. The emission spectra consists of four main peaks which can be assigned to the intra 4-f orbital transitions of Sm 3+ ions 4 G 5/2 → 6 H 5/2 (576 nm), 4 G 5/2 → 6 H 7/2 (611 nm), 4 G 5/2 → 6 H 9/2 (656 nm) and 4 G 5/2 → 6 H 11/2 (713 nm). The optimal luminescence intensity was obtained for 5 mol% Sm 3+ ions. The CIE (Commission International de I’Eclairage) chromaticity co-ordinates were calculated from emission spectra, the values (0.588, 0.386) were close to the NTSC (National Television Standard Committee) standard value of red emission. Coordinated color temperature (CCT) was found to be 1756 K. Therefore optimized Mg 2 SiO 4 :Sm 3+ (5 mol%) phosphor was quite useful for solid state lighting. [ABSTRACT FROM AUTHOR]

The current study involves synthesis of a series of Tb 3+ doped ZrO 2 nanophosphors by solution combustion method using oxalyl dihydrazide as fuel. The as-formed ZrO 2 :Tb 3+ nanophosphors having different concentrations of Tb 3+ (1–11 mol%) were characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–Visible spectroscopic techniques and the materials were subjected to photoluminescence and photocatalytic dye decolorization studies. The PXRD analysis indicates the formation of tetragonal symmetry up to 5 mol% concentration of Tb 3+ . Further increase in Tb 3+ concentration has lead to cubic phase formation and the same was confirmed by Rietveld refinement analysis. SEM images revealed that material was highly porous in nature comprising of large voids and cracks with irregular morphology. TEM and SAED images clearly confirm the formation of high quality tetragonal nanocrystals. The emissive properties of nanophosphors were found to be dependent on Tb 3+ dopant concentration. The green emission of the material was turned to white emission with the increase of Tb 3+ ion concentration. The photocatalytic activities of these nanophosphors were probed for the decolorization of Congo red under UV and Sunlight irradiation. All the photocatalysts showed enhanced activity under UV light compared to Sunlight. The photocatalyst with 7 mol% Tb 3+ showed enhanced activity attributed to effective separation of charge carriers due to phase transformation from tetragonal to cubic. The influence of crystallite size and PL on charge carrier trapping–recombination dynamics was investigated. The study successfully demonstrates synthesis of tetragonal and cubic ZrO 2 :Tb 3+ green nanophosphors with superior photoluminescence and photocatalytic activities. [ABSTRACT FROM AUTHOR]

ZnAl 2 O 4 :Cr 3+ nanophosphors were synthesized for the first time by a simple and environment friendly route using Calotropis procera milk latex as fuel. The structural and surface morphological studies were carried out using powder X-ray diffraction (PXRD), scanning electron microscopy and transmission electron microscopy techniques. The photoluminescence (PL) properties of ZnAl 2 O 4 :Cr 3+ as a function of dopant concentration and calcination temperature was studied in detail. The PXRD patterns and Rietveld confinement confirmed the cubic crystal system with space group Fd - 3m . The crystallite size estimated from Scherrer’s and W–H plots was found to be in the range of 16–26 nm. The PL spectrum shows an intense peak at ∼688 and ∼699 nm assigned to spin – forbidden 2 E g → 4 A 2g transition of Cr 3+ ions. The PL measurements for two excitations (∼410 and 527 nm) and with respect to calcination temperature indicated no significant change in the shape and position of emission peak except PL intensity. The CIE chromaticity coordinates lies well within the white region. Thermoluminescence (TL) studies revealed well resolved glow peak at ∼212 °C with a small shoulder at 188 and 233 °C. The glow peak intensity at ∼212 °C increases linearly with γ-dose which suggest ZnAl 2 O 4 :Cr 3+ is suitable candidate for radiation dosimetric applications. The activation energy ( E in eV), order of kinetics ( b ) and Frequency factor ( s ) were estimated using glow peak shape method. [ABSTRACT FROM AUTHOR]

For the first time nanoparticles of Tb 3+ doped (1–11 mol%) Mg 2 SiO 4 have been prepared using low temperature (350 °C) solution combustion technique with magnesium nitrate as precursor and oxalyl di-hydrazide (ODH) as fuel. The Powder X-ray diffraction (PXRD) patterns of the sample revealed orthorhombic structure with α-phase. The average crystallite size using Scherer’s formula, W – H plot and Size–strain plot is found to be 28 nm and the same is confirmed by Transmission electron microscopy (TEM) studies. Scanning electron microscopy (SEM) pictures show a porous structure and the crystallites were agglomerated. The effect of Tb 3+ cations on luminescence characteristics of Mg 2 SiO 4 is studied and the results are discussed in detail. The phosphors exhibit bright green emission upon near ultra violet (NUV) 377 nm excitation. The characteristic photoluminescence emission peaks at 417, 436, 458 nm in blue region due to 5 D 3 → 7 F J ( J = 5, 4, 3) of Tb 3+ ions and the emission peaks at 486, 541, 584 and 621 nm in green region corresponds to 5 D 4 → 7 F J ( J = 6, 5, 4, 3) transitions of Tb 3+ ions owing to f–f transitions of Tb 3+ cations in the given host lattice and are due to dipole–quadropole interactions. The CIE chromaticity co-ordinates are calculated from emission spectra and falls in green region. Therefore the present phosphor is highly useful for mercury free solid state lighting (SSL) and also for display applications. [ABSTRACT FROM AUTHOR]