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Metal chalcogenide copper sulfide nanoparticles exhibit a broad spectrum of applications, encompassing solar cells, photovoltaics, optical devices, ionic materials and more. In this investigation, CuS nanoparticles were synthesized through a facile co-precipitation method. The synthesis involved employing copper sulfate and thiourea as precursors for Cu and S, respectively. Quantitative analysis, confirming the presence of Cu–S and S–S bonds, was conducted through Raman spectroscopy. X-ray diffraction (XRD) was employed to ascertain the structural phases. The semiconducting behavior of the synthesized CuS nanoparticles was studied through UV–Vis spectroscopy, correlating optical absorption and energy bandgap. The comprehensive findings suggest that the prepared CuS nanoparticles hold promise for advancements in photovoltaic technology and optical devices.

A series of composite ferrites with chemical formula (1–x)[Mn_0.5Zn_0.5Fe₂O₄]·x[SiO₂](x = 0.0, 0.20, 0.30, 0.40, 0.50) were prepared by the co-precipitation technique. The samples were finally sintered at 1150°C followed by air quenching. The x-ray diffraction analysis confirms the phases precipitated out in the samples. AC magnetic susceptibility of these samples has been measured using the low field mutual inductance technique over the temperature range 298 K to 550 K at a frequency of 250 Hz. The magnetic parameters like Curie constant, C, Curie temperature, T_c, Lande splitting factor, g, effective magnetic moment, P_eff, exchange integral, J/kB, and characteristic temperature, θ(K) were calculated. The reciprocal of susceptibility versus temperature curves of each sample follows the Curie Weiss behaviour above the Curie temperature. Below the Curie temperature, all the samples show the ferrimagnetic behaviour. It was concluded that the magnetic properties were enhanced by the addition of silicon as is evident by the variation of magnetic interactions J, with Si-concentration and followed subsequently by the P_eff, θ(K) and T_c etc.

Nano-crystalline particles of barium ferrite have been prepared by co-precipitation route using aqueous and non-aqueous solutions of iron and barium chlorides with a Fe/Ba molar ratio of 11. Water and a mixture of diethylene glycol and water with volume ratio of 3:2 were used as solvents in the process. Co-precipitated powders were annealed at various temperatures for 1 h. Phase composition of the samples was evaluated by XRD while their morphology was studied by TEM and SEM techniques. The XRD results showed that the single phase barium ferrite obtained at 750°C when diethylene glycol/water mixture was used as a solvent. This temperature increased to 900°C when the starting materials dissolved in water. Nano-size particles of barium ferrite with mean particle size of almost 50 and 80 nm were observed in the SEM micrographs of the samples synthesized in diethylene glycol/water solution after annealing at 750°C and 800°C for 1 h, respectively. The corresponding mean crystallite size measured by TEM for sample annealed at 800°C was 40 nm.

In the present study, samarium doped ceria (SDC) and SDC-based composite with the addition of K₂CO₃ were prepared by co-precipitation route and effects of pH of the solution and calcination temperature on microstructure of SDC and SDC-K₂CO₃, respectively, were investigated. Furthermore, experimentation was performed to investigate into the ionic conductivity of pure SDC by co-doping with yttrium i.e., YSDC, XRD and SEM studies show that the crystallite size and particle size of SDC increases with the increase in pH. The SEM images of all the samples of SDC synthesized at different pH values showed the irregular shaped and dispersed particles. SDC-K₂CO₃ was calcined at 600${}^{\circ }$C, 700${}^{\circ }$C and 800${}^{\circ }$C for 4 h and XRD results showed that crystallite size increases while lattice strain, decreases with the increase in calcination temperature and no peaks were detected for K₂CO₃ as it is present in an amorphous form. The ionic conductivity of the electrolytes increases with the increase in temperature and SDC-K₂CO₃ shows the highest value of ionic conductivity as compared to SDC and YSDC. Chemical compatibility tests were performed between the co-doped electrolyte and lithiated NiO cathode at high temperature. It revealed that the couple could be used up to the temperature of 700${}^{\circ }$C.

In this paper, pure NiO and Cu-doped NiO nanoparticles are prepared by co-precipitation method. The electrical resistivity measurements by applying high pressure on pure NiO and Cu-doped NiO nanoparticles were reported. The Bridgman anvil set up is used to measure high pressures up to 8 GPa. These measurements show that there is no phase transformation in the samples till the high pressure is reached. The samples show a rapid decrease in electrical resistivity up to 5 GPa and it remains constant beyond 5 GPa. The electrical resistivity and the transport activation energy of the samples under high pressure up to 8 GPa have been studied in the temperature range of 273–433 K using diamond anvil cell. The temperature versus electrical resistivity studies reveal that the samples behave like a semiconductor. The activation energies of the charge carriers depend on the size of the samples.

Rare-earth (RE) activated (Dy${}^{3+}$/Sm${}^{3+}$ and Ce${}^{3+}$/Tb${}^{3+}$) polycrystalline CaSO₄ phosphors were prepared by co-precipitation method. Powder XRD pattern confirmed their structure and phase, while FE-SEM investigation reflected the particle morphology. The optical absorption and emission analysis were carried out to find efficient energy transfer within codoped phosphors, a possible energy transfer mechanism was discussed and energy transfer efficiencies were calculated. The multicolor emission from these materials suggests sustainable and well-defined approach towards possibility of obtaining tunable emission for producing while light emission, which finds potential applications in field emission display (FED) and white light-emitting diodes (W-LEDs).

Zinc oxide (ZnO) nanopowder samples were prepared by using co-precipitation method, with varying parametric conditions. Rietveld refinement technique is used to study the structural properties of synthesized samples. XRD and UV spectroscopy techniques have been used to characterize the samples which resemble ZnO nanostructures. Observed lattice parameters are $a=b=3.2482$ Å and $c=5.2011$ Å for sample A, $a=b=3.2500$ Å and $c=5.2062$ Å for sample B, $a=b=3.2497$ Å and $c=5.2017$ Å for sample C, $a=b=3.2550$ Å and $c=5.2122$ Å for sample D. The varying unit cell volume and axial ratio for all samples are calculated as 47.52–47.82 Å and 1.6006–1.6019. VESTA software is used to calculate the bond angles and lengths of Rietveld refinement data. UV-Vis spectroscopy analyzed the absorption, transmission, refractive index and band gap of samples for their possible use in different industrial applications.

Active powder of Cu-substituted Mn-Zn ferrite was synthesized by soft chemical approach called co-precipitation method. The initial permeability, density, grain size, Curie temperature and dc resistivity were studied. X-ray diffraction (XRD) method confirmed the sample to be a single-phase spinel and of nano-structure (~ 65 nm). Further, scanning electron micrograph (SEM) also confirmed nano-phase and the uniformity of the particles. The initial permeability values did not exhibit much variation with temperature, except near Curie temperature where it falls sharply. The initial permeability was found to increase with the increase in sintering temperature. This is attributed to the increase in the grain size.

In this study, the co-precipitation approach was used to make nanostructured nickel oxide (NiO) commencing with sodium hydroxide (NaOH) and nickel (II) chloride hexahydrate (NiCl2$\cdot$6H2O). Through the use of X-ray diffraction (XRD), scanning electron microscopes (SEM), UV-visible (UV–Vis) absorption, and Fourier transform infrared (FTIR) imaging, structural and optical studies were investigated. FTIR, photoluminescence (PL), cyclic voltammetry (CV) studies are taken. The synthesized nanoparticles were annealed at ${300}^{\circ }$C and ${400}^{\circ }$C. The face-centered cubic (FCC) structure of the NiO and highly crystallized nanoparticles were revealed by XRD investigations. Observation of FTIR spectra validated the composition of functional groups. Scanning electron microscopy image shows the average size is 24 nm. NiO optical band gap at ${300}^{\circ }$C (3.37 eV) and ${400}^{\circ }$C (2.7 eV) is revealed from UV studies. From CV graph, the sample annealing at ${300}^{\circ }$C and ${400}^{\circ }$C the specific capacitance was 543.6 and 519.8 F/g, respectively. This study signifies the supercapacitor application of nanosized metal oxide.

Indium tin oxide (ITO) nanoparticles were synthesized by co-precipitation method using ammonia as a precipitator in absence/presence of various surfactants (LABS and Triton X-100). The synthesized nanoparticles were investigated by scanning electron microscopy, resistance measurement, photoluminescence (PL) spectroscopy and X-ray diffractometry (XRD) techniques. The XRD patterns of nanoparticles were also studied by Rietveld refinement method for calculation of crystallite size, micro-strain and lattice parameter. The results indicate that by application of LABS and Triton X-100 as surfactant the particle size was increased. Two luminescence bands were observed in PL spectra of ITO nanoparticles with the excitation energy lower than their band gaps. It was found that the ratios of luminescence bands have relation with resistances and colors of ITO nanoparticles. In addition, the band structure of ITO nanoparticles was described considering the obtained results.

Nanosize particles of barium hexaferrite were prepared by co-precipitation route using solution of iron and barium chlorides with a Fe⁺³/Ba⁺² molar ratio of 11. Water and a mixture of water/ethanol with volume ratio of 1:3 were used as solvents. Co-precipitated powders were calcined at various temperatures. XRD results showed that single phase barium hexaferrite forms at 900°C for sample synthesized in aqueous solution and its formation is resulted from the reaction between mainly crystalline phases, while this temperature decreased to 700°C for sample synthesized in water/ethanol solution and the formation of barium hexaferrite consists of reactions between amorphous phases with crystalline phases. SEM micrographs of the calcined samples at 800°C indicated that the morphology of particles was affected by the type of solvent. Nano size particles of barium hexaferrite with mean particle size of almost 80 nm were observed in the SEM micrograph of sample synthesized in water/ethanol solution after calcination at 800°C. Barium hexaferrite crystallites with mean size of 35 nm, which was approximately consistent with size obtained from XRD line broadening technique, could be seen in TEM image of this sample after calcination at 700°C.

Nanocrystalline cobalt–ferrite particles of size 20–30 nm have been prepared by a reverse coprecipitation technique under the assistance of ultrasonic irradiation and heat-treatment at different temperatures (from 473 K to 1073 K). Both X-ray diffraction and transmission electron microscope analysis confirms the reduction of strain present in the material with annealing temperature. Enhancement of coercivity and magnetization value has been observed without increase in the particle size for whole range of annealing temperature. Temperature dependent magnetization loop shows considerable magnetic hardening at low temperature. The observed enhancement of the coercivity value has been attributed to the increase in magneto-crystalline anisotropy, surface effects and exchange anisotropy. The mechanical properties of the pure cobalt–ferrite samples and cobalt–ferrite reinforced alumina samples were also examined. The Vickers microhardness and the compressive properties obtained from the stress–strain relation showed higher value with annealing temperatures and higher nanoparticle content.

The aim of the work is to synthesize Mn substituted ZnO nanoparticles by co-precipitation method with chemical formula Zn_1-xMn_xO, where x = 0.00, 0.05, 0.10 and 0.15 and to characterize its structural, morphological and magnetic properties. X-ray diffraction studies confirm the presence of wurtzite (hexagonal) crystal structure for doped samples similar to un doped ZnO, indicating that doped Mn replacing Zn. Lattice parameters and unit cell volume were found to increase with increasing Mn concentration, indicating the homogeneous substitution of Mn²⁺ for Zn²⁺. TEM analysis shows the average diameter of the nanoparticles in the range of 20–50 nm. Room temperature magnetic measurements indicate the existence of ferromagnetism in x = 0.00 and 0.05 nanoparticles and co-existence of ferro, para magnetism in x = 0.10 and 0.15 nanoparticles.

The Williamson–Hall (W–H) analysis and size-strain plot method (SSP) were used to study the lattice stress, strain and crystalline size of zinc (ZnFe₂O₄) and manganese (MnFe₂O₄) ferrite nanoparticles. These nanoparticles were synthesized by chemical co-precipitation method and characterized by powder X-ray diffraction analysis (PXRD). The PXRD results revealed that the sample product was crystalline with mixed type spinel with cubic structure. The crystalline development in the ZnFe₂O₄ and MnFe₂O₄ was investigated by X-ray peak broadening. The physical parameters such as strain, stress and energy density values were calculated more precisely for all the reflection peaks of PXRD using the W–H plots and SSP method. The variation in particle size, lattice strain, stress and energy density calculated from W–H analysis and SSP method reveals a nonuniform strain in the particles. This nonuniform strain was increased when the particle sizes were increased.

Zinc oxide (ZnO) is a wide bandgap semiconductor with excellent photoresponse in ultra-violet (UV) regime. Tuning the bandgap of ZnO by alloying with cadmium can shift its absorption cutoff wavelength from UV to visible (Vis) region. Our work aims at synthesis of Zn${}_{1-x}$Cd_xO nanoparticles by co-precipitation method for the fabrication of photodetector. The properties of nanoparticles were analyzed using X-ray diffractometer, UV–Vis spectrometer, scanning electron microscope and energy dispersive spectrometer. The incorporation of cadmium without altering the wurtzite structure resulted in the red shift in the absorption edge of ZnO. Further, the photoresponse characteristics of Zn${}_{1-x}$Cd_xO nanopowders were investigated by fabricating photodetectors. It has been found that with Cd alloying the photosensitivity was increased in the UVA-violet as well in the blue region.

Pure nano-Fe₃O₄ and cobalt-doped nano-Fe₃O₄ particles are successfully synthesized by co-precipitation method using tetramethylammonium hydroxide (TMAOH) as alkali. Several key factors that may affect preparation are carefully discussed such as alkali concentration, alkali dosage, reaction temperature, iron salt solution concentration and dispersant agents. Such nano-Fe₃O₄ particles prepared have good dispersibility and a very narrow size distribution with the average diameter about 38 nm, which are proved to be cubic spinel Fe₃O₄ crystal by XRD pattern. It is also found that the addition of PEG-4000 surfactant can improve the dispersibility of nanoparticles. In our work, effects of cobalt dopant concentration on magnetic properties of cobalt-doped nano-Fe₃O₄ are also discussed. The result shows that the coercivity of cobalt-doped nanoparticles changes greatly with the variation of cobalt dopant concentration. The maximum coercivity reaches as high as 1628 Oe, which is very meaningful for preparation of materials with high coercivity.

Undoped and Mn-doped ZnO nanoparticles (Zn${}_{1-x}$Mn_xO), with nominal weight percentages $(0.00\le x\le 0.10)$, have been synthesized by co-precipitation technique. The synthesized nanoparticles are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV) and Fourier transform infrared spectroscopy (FTIR). From XRD analysis, the compound ZnMnO₃ is formed for $x\ge 0.05$ with cubic structure ($a=8.3694$Å) and its concentration increases with x. Moreover, XRD analysis reveals the wurtzite hexagonal crystal structure for ZnO. The lattice parameters (a and c) of Zn${}_{1-x}$Mn_xO are calculated and they increase with the doping concentration of Mn as a consequence of the larger ionic size of Mn${}^{2+}$ ions compared to Zn${}^{2+}$ ions. The crystallite size is calculated for all the samples using Debye–Scherrer’s method (SSM), Williamson–Hall methods (UDM, USDM and UDEDM) and Size-Strain Plot method (SSP), and the results are in good agreement with TEM. The presence of functional groups and the chemical bonding is confirmed by FTIR spectra that shows a peak shift between undoped and doped ZnO. The energy bandgap $(E_g)$ is calculated for different concentrations of Mn $(0.00\le x\le 0.10)$ by using the UV-visible optical spectroscopy, between 300nm and 800nm, showing a noticeable drop in $E_g$ with x. At room temperature, the magnetization of the samples reveals the intrinsic ferromagnetic (FM) behavior of undoped ZnO, ferromagnetic behavior of Zn_xMn${}_{1-x}$O $(0.01\le x\le 0.03)$ and the co-existence of ferromagnetic and paramagnetic behavior for Zn_xMn${}_{1-x}$O $(0.05\le x\le 0.10)$. This ferromagnetism is decreased for the doped samples as a consequence of antiferromagnetic coupling between Mn ions. The two samples correspond to $x=0.01$ and $x=0.10$, tend to be superparamagnetic because of the formation of single domain particles as a consequence of small particle size. $x=0.03$ shows an optimum value of Mn concentration for maximum saturation magnetization and the best ferromagnetic nature.

Mn co-precipitation method combined with Raman spectroscopy were used to determine trace heavy metals (copper, zinc, cadmium and lead) in water sample. Different concentrations of heavy metals including copper, zinc, cadmium and lead in water samples were separated and enriched by Mn²⁺-phen-SCN- ternary complex co-precipitation procedure. The Raman spectra of co-precipitation sediments were collected using confocal micro-Raman spectrometry. Different preprocessing treatments and regression calibration methods were compared. The best models using partial least squares regression (PLS) of copper, zinc, cadmium and lead were built with a correlation coefficient of prediction (R_p) of 0.979, 0.964, 0.956 and 0.972, respectively, and the root mean square error of prediction (RMSEP) of 6.587, 9.046, 9.998 and 7.751 μg/kg, respectively. The co-precipitation procedure combined with Raman spectroscopy method are feasible to detect the amount of heavy metals in water.

Zirconium dioxide (ZrO₂) nanoparticles were synthesized using co-precipitation technique and their structural, particle size, UV-Visible (UV–vis), and gas sensing properties were studied. In this paper, the particle size-dependent properties of ZrO₂ have been investigated. XRD analysis indicated that the crystal structure of ZrO₂ nanoparticles varies with sintering temperature, while crystallite size decreases with an increase in sintering temperature. A small variation in the optical energy band gap is observed in UV–vis spectroscopy. Resistance versus time data was carried out for the gas sensing application, and it was observed that the particle size and nature of the gas play a key role in the sensing of the gases. In the present case, ZrO₂ nanoparticles possess more sensitivity to acetone than methanol.

Yttrium oxide–magnesium oxide (Y₂O₃–MgO) composite nanopowders were synthesized via three distinct methods: sol–gel, co-precipitation and glycine–nitrate process. The synthesized powders were calcined at various temperatures, and their microstructure, specific surface area and particle size were characterized. A comparative study was conducted to assess the impact of the synthesis method on the microstructure and transparency of the resulting ceramic sintering. Notably, the powder synthesized by the sol–gel technique exhibited the highest specific surface area and superior light transmittance, reaching a maximum of 85.33% at a wavelength of 5.31$\mu$m.