Search

Design and development of novel highly efficient diluted magnetic semiconductors for spintronic devices and photocatalytic application is of great importance. In this regard, we report on the synthesis and analysis of new class of highly efficient pure CeO2, Ce0.42Fe0.04Co0.04O50, Ce0.42Co0.04Ni0.04O50 and Ce0.38Fe0.04Co0.04Ni0.04O50 nanoparticles. The crystal structure, phase, optical characteristics, magnetic properties and photocatalytic characteristics of synthesized nanoparticles were measured using various analytical techniques. The comprehensive structural analyses revealed that incorporation of Fe, Co and Ni ions in host lattice without change their original structure. Presence of defect sites in synthesized nanoparticles was confirmed through photoluminescence studies. Room temperature magnetic measurements revealed that pure CeO2 and Ce0.42Fe0.04Co0.04O50 nanoparticles showed paramagnetic nature as well as Ce0.42Co0.04Ni0.04O50 and Ce0.38Fe0.04Co0.04Ni0.04O50 nanoparticles exhibited mixed behavior of paramagnetic and ferromagnetic characteristics. Further, Ce0.38Fe0.04Co0.04Ni0.04O50 nanoparticles showed better photocatalytic activity with pseudo first order rate constant 0.0157 (min−1) and it is 1.7 times larger than that of pristine CeO2 nanoparticles.

Nano-ZnO and ZnO doped with Cu: Mn samples (Mn = 2% and Cu = 2% and 4%) have been synthesized by combustion synthesis. The effect of Cu content (Cu/Mn co-dopant) on the structural, optical, and magnetic properties has been studied. X-ray diffraction studies revealed hexagonal Wurtzite structure, and the particle size is around 36–18 nm. From scanning electron microscopy (SEM) analysis, morphology of all the samples was spherical in shape with high porous structure. The elemental composition of the synthesized samples was investigated using energy dispersive X-ray analysis (EDAX), which confirmed the presence of selective elements in the samples near stoichiometric ratio. FTIR spectra confirmed the presence of functional groups in synthesized samples. From UV–Vis absorbance spectra, blue shift is observed with increasing dopant concentration. From VSM studies, the enhanced magnetization properties were observed in doped samples. From photoluminescence (PL) studies, decrease in rate of recombination of electron–hole pairs is observed. The simultaneous enrichment of magnetic and optical properties of Cu doped ZnO: Mn nanoparticles can be used in future spintronic and optoelectronic devices.

ZnO nanoparticles at different temperatures were synthesized by using the combustion method. The effect of synthesis temperature on the properties of the nanoparticles was studied by using XRD, FESEM, EDS, TEM, photoluminescence (PL), Raman, diffuse reflectance spectra (DRS), and VSM characterization techniques. The XRD results reveal that the grown nanoparticles have a hexagonal wurtzite structure without any impurities and agreed with EDS results. FESEM and TEM micrographs show that the ZnO nanoparticles possess a spherical shape with agglomeration free, and the size increases with increase of synthesis temperature. From DRS studies, it was noticed that the band gap decreases with increase of synthesis temperature. In PL studies, blue peak at 465 nm may be due to defect-related transitions. A sharp intense peak in Raman spectra at 485 cm−1 represents E2H mode is a characteristic of a hexagonal wurtzite structure. The magnetic studies show that the magnetization decreases from 0.0172 to 0.0042 emu/g as the synthesis temperature increases from 400 to 550 °C. ZnO synthesized at 500 °C has a large squareness ratio. These materials are potential candidates for memory devices.

EDTA surfactant assisted bare and Cu doped CdS nanoparticles were prepared by simple chemical coprecipitation method. As the prepared samples were characterized by energy dispersive analysis of X-rays (EDAX), X-ray diffraction patterns (XRD), transmission electron microscopy (TEM), Raman spectroscopy and photoluminescence spectroscopy (PL). Existence of Cu in host lattice with near stoichiometric ratio was corroborated by EDAX spectra. X-ray diffraction patterns revealed that cubic structure as that of CdS host lattice. TEM images suggested that spherical nature of nanoparticles with a size ranging from 4–6 nm. Room temperature photoluminescence (PL) spectra revealed that pristine host lattice nanoparticles demonstrate a strong green emission peak located at 525 nm as well as weak red emission shoulder situated at 598 nm. Auxiliary in Cu doped CdS samples, the luminescence intensity was gradually reduced as well as the green emission peak was shifted to red region (660 nm). With increase of Cu content in host matrix a red shift is found in the PL emission peak.

A simple sol-gel technique is used to synthesize zero-dimensional pure and Er-doped BiFeO3 (BFO) nanoparticles. The effect of Er dopant on morphology, structure, optical, magnetic, and photoluminescence properties of single-phase BFO was studied. X-ray diffraction (XRD) studies reveal that the structural phase transformation is noticed from rhombohedral to orthorhombic with substitution of Er to pure BFO. From scanning electron microscopy (SEM) and transmission electron microscopy (TEM), morphology of the synthesized samples were spherical in shape. Agglomeration and particle size reduced with substitution of Er, particle size is around ∼ 30 nm. Energy-dispersive analysis of X-ray (EDAX) spectra confirms the presence of selective elements in synthesized samples. Fourier transform infrared spectra (FTIR) confirms that all the bonds strongly correspond to BFO. The substitution of Er in BFO nanoparticles also demonstrates a strong reduction in optical band-gap energy compared with pure BFO. Magnetization studies were carried out by using vibrating sample magnetometer (VSM), and the saturation magnetization increases with increasing substitution of Er. A photoluminescence (PL) spectrum reveals that the substitution of Er suppressed the recombination of electron-hole pairs.

Nanoparticles (Nps) of Ba (0, 1 to 5 at.%)-doped BiFeO3 were synthesized by a sol-gel route at 100 °C using tartaric acid as a chelating agent. The obtained results were studied by using XRD, SEM with EDAX, TEM, UV-vis diffusion reflectance spectra, VSM, and impedance analyzer. EDAX spectra confirmed the presence of Bi, Ba, and Fe in the samples. X-ray diffraction studies showed that BiFeO3 and Bi1−xBaxFeO3 samples exhibited the expected rhombohedral perovskite structure up to a Ba concentration of 3%, whereas 4 and 5% of Ba concentration exhibited the tetragonal phase. TEM studies indicate the particle sizes in the range of 08–28 nm. Reflectance spectra measurements showed a decrease in band gap with increasing Ba concentration. Magnetic properties indicated that the undoped BiFeO3 and Ba-doped BiFeO3 samples were ferromagnetic at room temperature. The dielectric constant (e′) and loss (e″) show large dispersion behavior. The dielectric constant increases with an increase of dopant concentration, but a very high value of the dielectric constant was noticed for x = 0.05.

Here in, we synthesized pure BiFeO3 (BFO) and Bi0.8-XCaXEr0.2FeO3 (x = 0.0, 0.05, 0.1, and 0.15 at.%) nanoparticles using sol–gel technique and investigated their optical, magnetic, and electrical properties. X-ray diffraction studies reveals structural transformation in BFO from the rhombohedral structure to orthorhombic, without forming any defect phases, with the doping of Er or Ca/Er into BFO. EDX analysis confirms the presence of doped elements (Er and Ca) along with the Bi, Fe and O elements corresponding to BFO host material. TEM images indicate the significant reduction in particle size with increasing the Ca dopant concentration. Further, the band gap of pure BFO nanoparticles (2.30 eV) decreases notably to a minimum of 1.81 eV for Ca and Er co-doped BFO nanoparticles. All samples exhibited the ferromagnetic behavior, Bi0.8-XCaXEr0.2FeO3 (x = 0.05 at.%) nanoparticles yielded 2.9 times higher saturation magnetization compared to BFO nanoparticles. In addition, the conductivity increases by 11.8 times for Bi0.8-XCaXEr0.2FeO3 (x = 0.05 at.%) nanoparticles compared to BFO nanoparticles.

Hierarchical 1-D CdS nanorods adorned with MoS2-SnS2 nanocomposites were developed by a simple solvothermal method at nano-regime. In the present work, we noticed a tremendous enhancement in H2 evolution by loading MoS2-SnS2 nanostructures on 1D-CdS nanorods under the solar light irradiation. Notably, for the CdS/MoS2-SnS2 (6 wt%) nanocomposites, the hydrogen production rate reached to 185.36 mmol. h−1. g−1., this is much higher than that of pristine CdS (2.5 mmol. h−1. g−1) and 6 wt% of MoS2 loaded CdS nanorods (123 mmol. h−1. g−1). The efficient photocatalytic performance in MoS2-SnS2 loaded CdS nanorods could be due to high light harvesting capability, bifurcation of electron-hole pairs, trapping sites, active catalytic zones, migration of charge carriers towards the surface of a semiconductor, and suitable energy levels. We strongly believe that the current design plan on the synthesis of MoS2-SnS2 loaded CdS nanorods and its efficiency for catalytic performance towards hydrogen evolution is an inherent alternative route for sustainable energy production.

In the era of modern technology, the development of spintronic devices using diluted magnetic semiconductor nanoparticles has drawn significant attention from the world researchers. In this work, we report on novel Cu1−x Mn x S (x = 0.00, 0.01, 0.03 and 0.05) compounds synthesized at room temperature through a simple precipitation method via EDTA as a capping agent. XRD patterns suggested that the entire synthesized nanoparticles exhibit covellite-phase hexagonal configuration like CuS. Reflectance measurements indicated energy band gap reduction by augmentation of Mn content. Photoluminescence spectra of prepared nanoparticles showed strong blue, green and weak yellow emissions at 471, 533 and 583 nm, respectively. The room-temperature VSM measurements suggested that bare CuS showed a diamagnetic nature, while Mn-doped CuS nanoparticles exhibited paramagnetism, which is enhanced with increasing Mn dopant concentration.

In this paper, we report systematic investigations on the effects of Ni doping on the structural, optical, magnetic and photocatalytic characteristics of CuS nanoparticles synthesized by simplistic wet chemical co-precipitation route via EDTA molecules as templates. XRD studies confirmed that accurate phase formation of synthesized nanoparticles and chemical composition were obtained by EDX. Magnetic measurements revealed that 3% Ni doped CuS nanoparticles show signs of good ferromagnetism at room temperature and transition of magnetic signs from ferromagnetic to paramagnetic nature by increasing the Ni dopant concentration in CuS host matrix. The photocatalytic degradation efficiency of the prepared pure and Ni doped CuS nanoparticles were evaluated as a function of simulated sunlight irradiation via RhB organic dye pollutant as a test molecule. Particularly, in the presence of 3% Ni doped CuS nanoparticles in pollutant solution 98.46% degradation efficiency was achieved within 60 min of sunlight irradiation; meanwhile bare CuS attained only 83.22%. Further, after five cycles 3% Ni doping CuS nanoparticles exhibit good photocatalytic stability with very negligible catalyst loss. We believe that the investigations in this study provides adaptable pathway for the synthesizing of various diluted magnetic semiconductor nanoparticles and their applications in spintronic devices as well as sunlight-driven photocatalysts intended for wastewater purification.

The authors have presented synthesis and structural and magnetic properties of Tb (0, 2, 4, and 6 at.%)doped ZnS semiconducting nanoparticles and employed via chemical co-precipitation process using polyethylene glycol (PEG) as capping agent. X-ray diffraction (XRD) and selected area electron diffraction (SAED) studies confirm the formation of singlephase, cubic structure, nanometric samples (˜10 nm). Highresolution transmission electron microscopy (HRTEM) analyses of the suspensions revealed the size of the particles in the range 5–8 nm. The undoped ZnS sample displayed the expected diamagnetic behavior and the terbiumdoped ZnS samples exhibited room temperature paramagnetic character as a function of Tbdoping concentration.The observed paramagnetism may be due to the random distribution of the terbium ions into the ZnS crystal lattice giving rise to the formation of feeble interaction.

The development of novel highly efficient semiconductor metal oxide catalysts for enhanced photocatalytic dye degradation had of great significance. Herein, we report the synthesis of novel and highly efficient CuO/BiOI nanocomposite (0, 10, 20, 30, 40 wt % of CuO) semiconductor photocatalysts by a facile hydrothermal method. High crystallinity of tetragonal structure had observed from XRD studies. From SEM and TEM studies flower like morphology had observed up to 30% of CuO in CuO/BiOI nanocomposite and for 40% of CuO nanoflower like morphology slightly diminishes. EDAX and XPS spectra depict the presence of Bi, O, I, Cu only no other impurities had observed. Stretching and bending vibrational modes had observed from FTIR analysis. Bandgap decreases gradually upto 30% of CuO in CuO/BiOI nanocomposite and slightly increases for 40% of CuO in CuO/BiOI nanocomposite. Decrease in peak intensity due to charge carriers were observed from Photoluminescence studies Photocatalytic activity had estimated by the degradation of methyl orange (MO) solution under visible light irradiation. The flower-like morphology of 30% CuO in CuO/BiOI nanocomposite showed the high absorption ability to facilitate the generation of charge carriers as well as active oxygen species.

The present work is planned for a simple, inexpensive and efficient approach for the synthesis of Cu1-xFexS (x = 0.00, 0.01, 0.03, 0.05 and 0.07) nanoparticles via simplistic chemical co-precipitation route by using ethylene diamine tetra acetic acid (EDTA) as a capping molecules. As synthesized nanoparticles were used as competent catalysts for degradation of rhodamine-B organic dye pollutant. The properties of prepared samples were analyzed with energy dispersive analysis of X-rays (EDAX), X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-visible optical absorption spectroscopy, Fourier transform infrared (FTIR) spectra, Raman spectra and vibrating sample magnetometer (VSM). EDAX spectra corroborated the existence of Fe in prepared nanoparticles within close proximity to stoichiometric ratio. XRD, FTIR and Raman patterns affirmed that configuration of single phase hexagonal crystal structure as that of (P63/mmc) CuS, without impurity crystals. The average particle size estimated by TEM scrutiny is in the assortment of 5–10 nm. UV-visible optical absorption measurements showed that band gap narrowing with increasing the Fe doping concentration. VSM measurements revealed that 3% Fe doped CuS nanoparticles exhibited strong ferromagnetism at room temperature and changeover of magnetic signs from ferromagnetic to the paramagnetic nature with increasing the Fe doping concentration in CuS host lattice. Among all Fe doped CuS nanoparticles, 3% Fe inclusion CuS sample shows better photocatalytic performance in decomposition of RhB compared with the pristine CuS. Thus as synthesized Cu0·97Fe0·03S nanocatalysts are tremendously realistic compounds for photocatalytic fictionalization in the direction of organic dye degradation under visible light.

Pristine and Co doped covellite CuS nanoparticles were synthesized in aqueous solution by facile chemical co-precipitation method with Ethylene Diamine Tetra Acetic Acid (EDTA) as a stabilizing agent. EDAX measurements confirmed the presence of Co in the CuS host lattice. Hexagonal crystal structure of pure and Co doped CuS nanoparticles were authenticated by XRD patterns. TEM images indicated that sphere-shape of nanoparticles through a size ranging from 5 to 8 nm. The optical absorption edge moved to higher energies with increase in Co concentration as indicated by UV–vis spectroscopy. Magnetic measurements revealed that bare CuS sample show sign of diamagnetic character where as in Co doped nanoparticles augmentation of room temperature ferromagnetism was observed with increasing doping precursor concentrations. Photocatalytic performance of the pure and Co doped CuS nanoparticles were assessed by evaluating the degradation rate of rhodamine B solution under sun light irradiation. The 5% Co doped CuS nanoparticles provide evidence for high-quality photocatalytic activity.

The present paper brings out the results concerning the preparation and optical properties of Sm 3+ and Dy 3+ each ion separately in different concentrations (0.3, 0.5, 1.0 and 1.5 mol.%) and also together doped (x mol.% Dy 3+ + 1.5 mol.% Sm 3+ ): Li 2 O-LiF-B 2 O 3 -ZnO (where x = 0.5, 1.0 and 1.5 mol.%) glasses by a melt quenching method. Structural and thermal properties have been extensively studied for those glasses by XRD and TG/DTA. The compositional analysis has been carried out from FTIR spectral profile. Optical absorption spectral studies were also carried out. Sm 3+ : LBZ glasses have displayed an intense orange emission at 603 nm ( 4 G 5/2 → 6 H 7/2 ) with an excitation wavelength at 403 nm and Dy 3+ : LBZ glasses have shown two emissions located at 485 nm ( 4 F 9/2 → 6 H 15/2 ; blue ) and 574 nm ( 4 F 9/2 → 6 H 13/2 ; yellow ) with an excitation wavelength at 385 nm. Remarkably, it has been identified that the significant increase in the reddish orange emission of Sm 3+ ions and diminished yellow emission pertaining to Dy 3+ ions in the co-doped LBZ glass system under the excitation of 385 nm which relates to Dy 3+ ions. This could be due energy transfer from Dy 3+ to Sm 3+ . The non-radiative energy transfer from Dy 3+ to Sm 3+ is explained in terms of their emission spectra, donor lifetime, energy level diagram and energy transfer characteristic factors. These significantly enhanced orange emission exhibited glasses could be suggested as potential optical glasses for orange luminescence photonic devices.

Zn1−xDyxS (x=0, 0.02 and 0.04) nanoparticles (NPs) were synthesized by chemical refluxing technique at 100 °C. The prepared samples were analyzed by studying their compositional, morphological, structural, optical and magnetic properties. EDS analysis confirmed the presence of zinc, dysprosium and sulfur in the samples in near stoichiometric ratio. The X-ray diffraction patterns do not show any Dy related peaks for the as-synthesized ZnS nanoparticles. The average diameter of the particles confirmed by TEM studies, was in the range 2–4 nm. Raman studies revealed that all the samples are single phase and exhibit cubic structure. From DRS studies, the band-gap was found to be in the range of 3.85–3.70 eV. All the doped ZnS nanoparticles exhibit ferromagnetic behavior with the Curie temperature higher than room temperature and the magnetic properties of doped ZnS nanoparticles depend on the concentration of Dy ions.

Nanoparticles of ZnS:Nd (0, 2 and 4 at%) were synthesized by a chemical co-precipitation method at 300 K using PEG as capping agent. The effect of Nd doping on the structural, optical and magnetic properties of ZnS nanoparticles was investigated. EDAX spectra confirmed the presence of Zn, Nd and S in the samples. X-ray diffraction studies showed that all the samples exhibited the expected zinc blende structure. Raman studies revealed the cubic structure and absence of impurities in the undoped and Nd doped ZnS nanoparticles. TEM studies indicated that the particles were a few nm (

Multiferroic BiFeO3 and Bi0.8-XGdXEr0.2FeO3 (X = 0.0, 0.05, 0.1 & 0.15) nanoparticles have been prepared by sol-gel technique. The effect of Gd content (in Gd/Er co-dopant) on the structural, magnetic, dielectric, and optical properties of the BiFeO3 materials has been studied. X-ray diffraction analysis revealed rhombohedral to orthorhombic phase transition of BiFeO3 when doped with Er or Er/Gd. All samples composed of aggregated spherical nanoparticles and the size of the particles is decreased with increasing the Gd content in Gd/Er co-doped BiFeO3 nanoparticles. Energy dispersive spectra confirm the presence of all the selective elements in synthesized samples and are in near stoichiometric ratio. The Fourier transform Infrared spectra confirmed the presence of functional groups of elements of synthesized nanoparticles only. Optical properties of the samples, as studied by UV–visible spectroscopy, showed the decreased optical band gap with increasing the Gd content in Bi0.8-XGdXEr0.2FeO3 nanoparticles. The Er/Gd co-doping in BiFeO3 had a significant effect on the magnetic properties and effectively reduced the leakage current. The simultaneous enrichment of magnetic and electric properties indicates the potential application of Bi0.8-XGdXEr0.2FeO3 (X = 0.0, 0.05, 0.1 & 0.15) nanoparticles in future multifunctional devices.

Nanoparticles of ZnS:Fe (0, 1, 3, and 5 at%) were synthesized by a refluxing route at 80 °C. All the samples exhibited cubic structure as revealed by X-ray powder diffraction studies. Blue emission of undoped samples was totally quenched by Fe doping. Magnetic measurements showed that the undoped ZnS was diamagnetic whereas all the doped samples were paramagnetic at room temperature. EPR signal characteristic of Fe3+ was observed in all the doped samples at room temperature. The paramagnetism of the present samples is attributed to the presence of uncoupled Fe3+ ions mediated by cation vacancies.

We are the first to report a systematic study on the structural, optical and magnetic properties of chromium and cobalt co-doped SnO 2 nanoparticles synthesized by the simple co-precipitation method using polyethylene glycol (PEG) as capping agent. EDAX spectra confirmed the presence of Sn, O, Cr and Co elements in the samples with near stoichiometry. X-ray diffraction studies revealed that all the samples were in single phase rutile type tetragonal crystalline structure. Peak broadening analysis was used to evaluate the average crystallite size and lattice strain using Scherer’s equation and Williamson–Hall (W–H) method. From TEM images particle size was found be around 9–12 nm. Redshift of absorption edge and related bandgap narrowing was observed from the optical absorption spectra. FTIR studies indicated that PEG simply co-exists on the surface of the nanoparticles and acts as the capping agent preventing agglomeration of the nanoparticles. Discrepancy in saturation of magnetization with inclusion of Co content in host matrix can be attributed to antiferromagnetic interactions as anticipated by the BMP model.

Single crystalline nano-sized multiferroic BiFeO3 (BFO) powders were synthesized through simple chemical co-precipitation method using polyethylene glycol (PEG) as capping agent. We obtained pure phase BiFeO3 powder by controlling pHand calcination temperature. From X-ray diffraction studies the nanoparticles were unambiguously identified to have a rhombohedrally distorted perovskite structure belonging to the space group of R3c. No secondary phases were detected. It indicates single phase structure. EDX spectra indicated the appearance of three elements Bi, Fe, O in 1:1:3. From the UV-Vis diffuse reflectance spectrum, the absorption cut-off wavelength of the BFO sample is around 558nm corresponding to the energy band gap of 2.2 eV. The size (60-70 nm) and morphology of the nanoparticles have been analyzed using transmission electron microscopy (TEM).   Linear M−H behaviour and slight hysteresis at lower magnetic field is observed for BiFeO3 nanoparticles from Vibrating sample magnetometer studies. It indicates weak ferromagnetic behaviour at room temperature. From dielectric studies, the conductivity value is calculated from the relation s = L/RbA Sm-1 and it is around 7.2 x 10-9 S/m.

The rutile phase Sn0.99-xMnxCr0.01O2 (x = 0.00, 0.01, 0.03, 0.05 and 0.07) nanoparticles were synthesized by facile chemical co-precipitation method using poly ethylene glycol (PEG) as a capping agent. The samples were characterized by EDAX to confirm the expected stoichiometry. The X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy analyses of these samples showed the formation of impurity free crystals with a single phase rutile type tetragonal crystal structure as that of (P42/mnm) of SnO2. Optical absorption spectra and corresponding Tauc's plots showed a redshift of the absorption edge in SnO2 after being co-doped with Cr and Mn. The samples were examined for its magnetic property using vibrating sample magnetometer which indicated that transition of magnetic signals from ferromagnetic to the paramagnetic nature with inclusion of Mn content in SnO2: Cr host matrix. The observed magnetic behavior is well supported with the bound magnetic polarons (BMPs) model.

Pure and Cr (1, 3, 5 and 7 at%) doped SnO 2 nanoparticles were synthesized in aqueous solution by a simple chemical co-precipitation method using polyethylene glycol (PEG) as a stabilizing agent. The effect of Cr doping on the structural, optical and magnetic properties of SnO 2 nanoparticles was investigated. EDAX spectra confirmed the presence of Sn, O and Cr in near stoichiometry. XRD patterns revealed that particles of all samples were crystallized in single phase rutile type tetragonal crystal structure (P4 2 /mnm) of SnO 2 . The peak positions with Cr concentration shifted to higher 2 θ values. Lattice parameters were also decreased with increasing Cr concentration. TEM studies indicated that the particle size is in the range of 8–10 nm. The optical absorption studies indicated that the absorption edge shifted towards lower wavelengths with inclusion of Cr content. FTIR spectrum displays various bands that are due to fundamental overtones of PEG and O–Sn–O entities. Further it revealed that the undoped and as well as Cr doped SnO 2 nanoparticles were capped by PEG. Magnetization measurements at room temperature revealed that all the doped samples were ferromagnetic in nature. Well defined strong room temperature ferromagnetic hysteresis loop was observed for 1% Cr doped SnO 2 nanoparticles.

CdS microstructures with uniform rose-flower-like morphology were successfully synthesized on a large scale through the physical vapor deposition method. The morphology, crystal structure and optical properties of the final product were characterized using SEM, XRD, TEM, SAED, Raman spectroscopy and photoluminescence spectroscopy. The flower-like CdS microstructures are assembled by many interleaving nanosheets which have a uniform thickness of about 40 nm and a high-crystalline structure with dominant surfaces as {2 1 ¯ 1 ¯ 0} planes. The room temperature photoluminescence spectrum of the rose-like microflowers reveals a strong green emission at 513 nm corresponding to band edge emission. On the basis of SEM and TEM observations, a comprehensive mechanism for the formation and growth of CdS microflowers is proposed.

We are the first to report a systematic study on the structural, optical and magnetic properties of cobalt and aluminum codoped CdS nanoparticles synthesized by simple co precipitation method. XRD patterns confirm the formation of single phase cubic structure for all the compositions. From diffuse reflectance spectra (DRS), three characteristic reflectance minima peaks present for all samples at 686, 729 and 750 nm associated with d–d transitions 4 A 2 (F)→3/2U 1 , 4 A 2 (F)→E 11 and 4 A 2 (F)→5/2U 1 confirm the substitution of Cd 2+ ion by Co 2+ ion in CdS. Blueshift of absorption edge with the incorporation of Al into CdS:Co nanoparticles is the evidence for the substitution of Cd 2+ ion by Al 3+ ion. Bandgap widening observed with increasing Al content can be explained by Burstein–Moss effect. Photoluminescence spectra revealed the transition of defect related green emission into near band edge blue emission by aluminium codoping, which can be attributed to the reduction of defect levels. In the present study, Cd 0.96− x Co 0.04 Al x S nanoparticles system is found to be capable of retaining a part of room temperature ferromagnetic (RTFM) portion even at x =0.07.

Diluted magnetic semiconducting (DMS) ZnS:Ni (Ni=0, 1, 3 and 5 at%) nanoparticles were synthesized by the refluxing technique at 80 °C. X-ray diffraction studies showed that undoped ZnS and Ni doped ZnS nanoparticles exhibited the expected zinc blende structure. X-ray photoelectron spectroscopy results revealed that the Ni ions existed in a +2 state in these nanoparticles. Reflectance measurements showed a decrease in band gap with increasing Ni concentration. Room temperature photoluminescence (PL) studies indicated that all the samples exhibited broad and asymmetric PL peaks covering a wide visible range. Gaussian fitting of PL data resulted in three deconvoluted peaks corresponding to blue and green emissions. Dramatic enhancement in fluorescence efficiency was observed in the doped ZnS nanoparticles indicating their possible applications in photoluminescent devices. Magnetic studies revealed that all the doped samples exhibited carrier mediated ferromagnetism at room temperature. Saturation magnetization ( M s ) increased with increasing Ni content reaching a maximum for 3 at% Ni and decreased for samples of 5 at% Ni.

CdS nanoparticles codoped with cobalt and manganese are synthesized by the surfactant assisted simple chemical coprecipitation method. Single cubic structure without any secondary phase formation is revealed by the XRD data. Small particle size around 4–5 nm is estimated from the TEM images. EPR hyperfine splitting constant A around 95 G associated with the presence of Mn ions on the surface of the nanocrystals is observed for all the samples. Variation of ferromagnetic order with Mn content studied by a vibration sample magnetometer is ascribed to the antiferromagnetic (AFM) interactions between the magnetic ions as explained by the bound magnetic polaron (BMP) theory. Surface defect related green emission is observed through photoluminescence (PL) studies. Absence of Mn characteristic emission further confirms the local structure of Mn ions evidenced by EPR results.

Un-doped and Al doped ZnS nanoparticles were prepared via an efficient and low cost chemical co-precipitation method using Poly Ethylene Glycol (PEG) as stabilizer. In the present study effect of Al concentration on the morphological, structural, and optical properties is studied using X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Raman analysis, Fourier transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) studies. XRD, TEM, FTIR and Raman analysis indicated the formation of impurity-free nanocrystals with cubic structure. DRS studies revealed that as the Al dopant concentration increases the band gap increases in the range of 3.73–4.01 eV. The PL spectra of all samples exhibit a broad emission band in the range of 350–650 nm. The Gaussian fitting emission bands for ZnS are located at 382, 398, 417 and 445 nm. For Al doped ZnS nanoparticles in addition to the pure ZnS peaks two extra peaks are observed at 472 and 493 nm. Further, enhanced photoluminescence was observed with increasing Al content up to 8 at.% and beyond this photoluminescence quenching was noticed.

Zn0.97−xAlxCr0.03S (x=0.00, 0.02, 0.04, 0.06, 0.08, 0.10 and 0.12) nanoparticles were synthesized by the chemical co-precipitation method using Ethylene Di-amine Tetra Acetic acid (EDTA) as capping agent. The effect of Al co-dopant on the structural, optical and magnetic properties is discussed on the basis of EDS, SEM, XRD, TEM, SAED, DRS, FTIR, PL, EPR and VSM results. EDS studies indicated the presence of Zn, S, Cr and Al elements in the samples with near stoichiometry. XRD, TEM and SAED studies revealed that samples of all concentrations exhibited cubic structure. The absorption edge in DRS spectra shifted towards higher wavelength with increasing Al concentration indicating a decrease of band gap from 4.05 to 3.85 eV. Enhanced photoluminescence was observed with increasing Al concentration up to 4 at% and beyond this photoluminescence quenching was observed. FTIR spectral studies indicated that EDTA simply co-exists on the surface of the nanoparticles and acts as the capping agent preventing agglomeration of the nanoparticles. EPR spectral studies indicated that the EPR signal intensity, linewidth and number of spins increased with Al concentration. VSM studies revealed that Al co-doping suppressed the room temperature ferromagnetism in ZnS:Cr nanoparticles.

Photocatalytic H2 generation through water splitting using heterogeneous semiconductor nanostructures under the beneath of sunlight is a significant route for alternation of renewable energy. In this perception we fabricated novel hierarchical CdS/MoS2-CoSe2 nanostructures via facile solvothermal route combined with ultra-sonication technique. Optical studies explored that synthesized nanostructures are most reliable host lattices for harvesting of visible light owing to their optimum energy band gap. The MoS2-CoSe2 encumbered on CdS nanorods component provided immense of hydrogen evolution (191.5 mmolg−1 h−1) with outstanding stability. It is noteworthy that the observed H2 evolution rate is much higher in synthesized structures as compared to numerous reported CdS based nanohybrids. The robust H2 evolution rate and outstanding stability may be owing to fast charge carriers separation and migration between CdS and MoS2-CoSe2, creation of huge surface area and broad light harvesting nature. It is evident from PL, optical, photocurrent and impedance results. From the obtained results we believe that the proposed design strategy is preferable path way to develop new type of photocatalysts with robust H2 evolution rate.

In recent days, 2-dimensional materials (2D) have become auspicious for gas sensor applications. Usually, the gas kinetics is poor at room temperature (RT). Considering the power consumption, photon excitation is an alternative way to enhance the gas kinetics at RT. In this work, we demonstrated the gas sensing properties of molybdenum disulfide (MoS2) monolayer at low temperature (RT ~ 27 °C to 100 °C). The monolayer MoS2 gas sensor has been developed using atomic-layered MoS2 synthesized by facile chemical vapor deposition (CVD), and structural properties were carried out by Raman spectroscopy. The NO gas was tested at three different operating temperatures (27 °C, 50 °C and 100 °C) and the effect of photonic energy on gas sensing performance at RT also manifested. The experimental results revealed that atomic MoS2 sensor exhibited a response of about 25% at RT, and improved response (70%) was observed to NO gas under UV light (λ = 254 nm). A large number of charge carriers perturbed on the surface of MoS2 under UV illumination, which could be contributed to enhance the response of the MoS2 sensor at RT.

Pure and cobalt doped CdS nanoparticles were successfully synthesized by surfactant assisted simple chemical co-precipitation method. Size of the particles around 3 nm and cubic zincblende structure were revealed by the X-ray diffraction pattern. From TEM images particle size was found be around 4–5 nm. Redshift of absorption edge and bandgap narrowing (from DRS spectra) can be attributed to increase in the carrier concentration by the inclusion of cobalt ions and creation of defect levels in the bandgap. Three characteristic reflectance minima only in cobalt doped samples can be related to d–d transitions 4 A 2 (F) → 3/2U 1 , 4 A 2 (F) → E 11 and 4 A 2 (F) → 5/2U 1 . Strong green emission was exhibited by all the samples through photoluminescence studies can be attributed to the transitions of trapped electrons from donor levels to the valance band or mid gap surface states. Intensity of the luminescence peak was found to be maximum for 2% and quenching was observed beyond 2%. Well defined room temperature ferromagnetic hysteresis loop was observed for 4% Co doped CdS nanoparticles. Saturation of magnetization M S and retentivity M R mounts up with cobalt content up to 4% and then decreases.

CdS:Mn (0%, 1.9% and 3%) nanowires with significant room-temperature ferromagnetism have been synthesized by chemical vapor deposition method using Au as catalyst. The X-ray diffraction, Raman spectroscopy and transmission electron microscopy analyses of these samples showed the formation of impurity free crystals with wurtzite CdS structure. SEM results reveal a uniform size distribution of the nanowires throughout the substrate. Photoluminescence spectra of undoped CdS reveals a weak band edge emission and a strong red emission related to surface defects. The luminescence is found to be decreased with Mn doping. Quenching of red emission intensity observed with the doping of Mn ions into CdS confirmed the changed defect structure in Mn doped CdS lattice. The enhancement of room temperature ferromagnetism was observed with increasing Mn doping concentration.

ZnS:Co (0, 1, 2, 3 and 5 at.%) nanoparticles were synthesized by refluxing technique at 80°C, with PVP as stabilizer. The effect of cobalt doping on the structural, optical and magnetic properties is investigated. EDAX spectra confirmed the presence of Zn, Co and S in the samples. X-ray diffraction patterns showed a single phase that of zincblende and Transmission Electron Microscopy (TEM) indicated that the particles were a few nm (

Undoped and Cr doped ZnS nanoparticles with Cr concentrations of 3.0 at.% were prepared by a chemical co-precipitation method for the fist time, using 2-Mercaptoethanol as the capping agent and annealed the synthesized particles at 600°C for 3h in air. The effect of annealing on morphological, structural and optical properties of ZnS and ZnS:Cr have been studied and compared with as prepared samples. EDAX measurements confirmed the presence of Cr in the ZnS lattice and it also confirms the conversion of ZnS into ZnO after annealed at 600 0C/3h. Surface morphologies of all samples were characterized using scanning electron microscopy (SEM). XRD spectra of as synthesized nanoparticles of ZnS and ZnS:Cr exhibited cubic phase. After annealing, the cubic phase is transformed into hexagonal phase. The particle sizes of the ZnS:Cr powders were increased from 5 to 30 nm when the powders were annealed at 600°C. A stable blue emission peak at 445 nm is observed from the as prepared samples (pure ZnS and Cr doped ZnS) but annealed at 600 0C the PL peaked at 500 nm for pure ZnS and Cr doped ZnS nanoparticles exhibited PL peak at 500 nm as well as 654 nm. The emission intensity decreased in annealed particles compared to as synthesized samples.

Nanocrystalline ZnS and Ni doped ZnS powders were synthesized by a simple chemical co-precipitation method at room temperature using sodium sulfide and acetates of Zinc and Nickel. 2-Mercapto ethanol is used as a capping agent. Structural and optical properties of as prepared samples were characterized using X-Ray diffraction (XRD), Scanning electron microscopy (SEM), Energy Dispersive Analysis using X-rays (EDAX) and Photoluminescence studies (PL). EDAX measurements confirmed the presence of Zn, Ni and S in the prepared samples. XRD analysis reveals that the Zn1-xNixS (x= 0.00 and 0.01) nanoparticles crystallized in zincblende structure. The average particle sizes of the nanoparticles are in the range of 2-3 nm. Shifting of photo luminescence peak to higher wavelength along with intensity quenching is observed for doped ZnS nanocrystals (NCs).

One dimensional CdS nanostructures of different morphologies (nanowires, nanorods and nanobelts) and sizes were synthesized by a simple one step thermal evaporation of CdS powder using Au as catalyst. By controlling various experimental parameters such as temperature and position of the substrates in the furnace, different shapes of CdS nanostructures were fabricated. Morphology, size and structure were determined by scanning electron microscopy, X-ray powder diffraction and transmission electron microscopy. Room temperature photoluminescence spectra of all samples reveal a weak green emission corresponding to band edge emission and strong red emission corresponding to surface defects. Morphology dependent variations in intensities of band edge and defect related emissions were observed.

Room temperature ferro-magnetism in Fe-doped CdS nanoparticles (NPs) synthesized by a wet chemical precipitation method is reported. Magnetic studies revealed that pure CdS NPs exhibit diamagnetic behavior as like bulk material, where as 3% Fe doped CdS NPs shows the ferromagnetic behavior. At room temperature, ESR signal characteristic of Fe3+ was observed in doped NPs.

ZnS and Zn 0.97 Mn 0.03 S, Zn 0.97 Cr 0.03 S and Zn 0.94 Mn 0.03 Cr 0.03 S nanoparticles were synthesized by chemical co-precipitation method using ethylene diamine tetra acetic acid (EDTA) as stabilizer. energy-dispersive spectroscopy (EDS) confirmed the presence of Mn and Cr in the samples in near stoichiometric ratio. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) studies showed that Mn and Cr dopants entered the ZnS cubic lattice as substituents. The band-gap was found to be in the range of 3.81–4.09 eV from diffusion reflectance spectral (DRS) studies. In PhotoLuminescence (PL) spectra a sulfur–vacancy related PL band around 430 nm, a PL band associated with the 4 T 1 → 6 A 1 transition of Mn 2+ and PL peaks associated with Cr were observed. Electron paramagnetic resonance (EPR) spectra exhibited resonance signals characteristic of Mn 2+ and Cr 3+ . Vibrating sample magnetometer (VSM) studies revealed that ZnS:Cr nanoparticles exhibited room temperature ferromagnetism and in ZnS:Cr nanoparticles co-doped with Mn a suppression of room temperature ferromagnetism was noticed.

Undoped and Fe doped CdS nanocrystals with Fe content of 2–5 at% of average crystallite size 1.2–2 nm have been obtained using chemical co-precipitation method with 2-mercaptoethonal as capping agent at 80 °C. X-ray diffraction (XRD) results showed that the undoped CdS nanocrystals were in mixed phase of cubic and hexagonal, where as the doped CdS nanocrystals were in hexagonal phase. Room-temperature ferromagnetism has been observed in Fe-doped CdS nanocrystals. Magnetic studies indicated diamagnetism in undoped, ferromagnetism in lightly doped (2 and 3 at%) and paramagnetism in samples of higher Fe content (4 and 5 at%). The substitutional incorporation of Fe 3+ ion in Cd 2+ sites was reflected in structural and electron paramagnetic resonance (EPR) measurements. Isolated as well as interacting Fe 3+ ions are observed in EPR.

Zn0.97−xCuxCr0.03S (x = 0.00, 0.01, 0.02, 0.03, 0.04 and 0.05) nanoparticles were synthesized by chemical co-precipitation method for the first time. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive analysis of X-rays (EDAX). Diffuse reflectance spectra (DRS) and photoluminescence spectra (PL). EDAX spectra confirmed the presence of Cr and Cu in the samples with expected stoichiometry. XRD patterns showed that dopant atoms of Cr and Cu were incorporated at the Zn sites in the cubic structure without disturbing the original ZnS cubic structure. However, at a concentration of 5 at.% the planes corresponding to Cu were observed. This shows the immiscibility of Cu in ZnS for a concentration of 5 at.%. Reflectance of Cu co-doped samples decreased with increase in Cu concentration. Photoluminescence for pure ZnS was observed in the blue region. 1 at.% Cu doping in ZnS:Cr resulted in a significant enhancement of PL intensity. Higher dopant concentrations resulted in a strong quenching of PL intensity. PL emission peak showed a red shift with increase in Cu content. FTIR studies revealed that the nanoparticles were sterically stabilized by EDTA. Magnetization studies indicated that Cu co-doping enhanced significantly the room temperature ferromagnetism of the samples.

Cadmium sulfide (CdS) semiconductor nanocrystals (NCs) doped with Fe3+ have been synthesized via a solution-based method utilizing dopant concentrations of (0–5%) and employing 2-mercaptoehonal as a capping agent. X-ray diffraction (XRD) results showed that the undoped CdS NCs are in mixed phase of cubic and hexagonal, where as the doped CdS NCs are in hexagonal phase. The crystallite size was increased from ∼1.2 nm to ∼2 nm. Diffuse reflectance spectroscopy studies (DRS) reveals that the band gap energy was decreased with Fe doping and it lies in the range of 2.58 - 2.88 eV. Photoluminescence (PL) spectra of undoped CdS NCs show a strong green emission peak centered at 530 nm and a weak red emission shoulder positioned at 580 nm. After doping all the luminescence intensity was highly quenched and the green emission peak was shifted to orange region (580 nm), but the position of weak red emission shoulder was unaltered with doping. FTIR studies revealed that the NCs were sterically stabilized by 2-mercaptoethanol. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

ZnSe nanowires have been successfully synthesized through chemical vapor deposition assisted by laser ablation in a tube furnace on a silicon substrate coated with a gold film of 2 nm thickness. X-ray powder diffraction measurements reveal that the synthesized products had pure hexagonal wurtzite structure. The microstructures and chemical composition of the as-grown nanowires have been investigated by means of electron microscopy, energy dispersive spectroscopy, photoluminescence and Raman spectroscopy. The results reveal that the as-grown material consists of ZnSe nanowires with diameters ranging from 60 – 100 nm and with lengths up to several tens of micrometers. High resolution transmission electron microscopy and selected area electron diffraction indicated that as-synthesized nanowires were single crystalline in nature. Micro-photoluminescence studies on ZnSe nanowire reveal strong emission at 460 nm. The Raman peak at 251 cm−1 is attributed to the longitudinal optic phonon mode of ZnSe.

Cr-doped ZnS nanoparticles with Cr concentrations of 0.5, 1, 2 and 3 atm.% were successfully synthesized by the chemical co-precipitation method using ethylenediaminetetraacetic acid (EDTA) as the capping agent. The structural, optical and magnetic properties of the prepared samples were studied. Energy dispersive spectroscopy (EDS) measurements showed the presence of Cr in the Cr-doped ZnS. No mixed phase was observed from X-ray diffraction (XRD) studies and all the peaks were indexed to the cubic phase of ZnS. The average diameter of the particles was in the range of 6–10 nm, and it was confirmed by TEM studies. The magnetic behavior of the nanoparticles for different chromium concentrations was investigated by magnetism measurements using a vibrating sample magnetometer (VSM). The nanoparticles with lower Cr concentration exhibited strong ferromagnetism, where as in samples of higher Cr concentrations the ferromagnetism suppressed. The electron paramagnetic resonance (EPR) spectra of the nanocrystals showed the resonance of electron centers with a g-value of 1.989. The signal intensity and linewidth of the EPR signal increased with increasing Cr content. FTIR studies indicated that the nanoparticles were sterically stabilized by EDTA.