Crystallite Particle Size Research Articles

A straightforward approach for the synthesis of nanostructured Y2O3 particles: Synthesis, morphology, microstructure and crystal imperfection

Abstract A facile and straightforward approach has been implemented for the synthesis of nanostructured Y2O3 particles via sol-gel method from yttrium nitrate solution. The individual effects of calcination temperature, precipitation-chelating agent and precursor concentration on microstructural parameters, crystal defects and morphology of Y 2O3 were investigated in detail. The morphology of synthesized nanostructured Y2O3 particles was revealed by scanning electron microscopy (SEM). X-ray diffraction (XRD) and Williamson Hall analysis were used to find out how Y2O3 crystallite size , lattice strain-stress, dislocation density and morphology affect the sol-gel process parameters. Comparative studies for determining crystallite size of particles were carried out by Modified Debye-Scherer and Williamson Hall analysis. A more detailed microstructural analysis and investigation of crystallographic imperfections were conducted by Williamson- Hall (W-H) method. W-H analysis was carried out on Y 2O3 particles with spherical shape and sponge morphology for the first time. Results reveal that as calcination temperature is increased from 700 °C to 900 °C, the crystallite size increases from 37.15 nm to 49.49 nm while lattice strain increases from 8.154 × 10−4 to 8.696 × 10−4. It is also found that, an increment in solution concentration from 0.1 mol/L to 0.2 mol/L results in crystallite size decrement from 47.27 nm to 44.37 nm. A further increment from 0.2 mol to 0.4 mol/L leads to crystallize size increase from 44.37 nm to 49.67 nm.

Preparation and Characterisation of Cellulose Nanocrystal from Sugarcane Peels by XRD, SEM and CP/MAS 13C NMR

Sugarcane peels are agro-waste resources discarded before taking the sugarcane juice. In the present study, cellulose nanocrystal was isolated from sugarcane peel by sulphuric acid hydrolysis. Two pretreatments, alkaline treatment and bleaching with acidified sodium chlorite, were applied. Sulphuric acid hydrolysis was performed at 450C for 45 min using 64% concentrated sulphuric acid. The resulting cellulose nanocrystal (CNC) of the sugarcane peel was characterised by studying the surface morphology using scanning electron microscope (SEM). X-ray diffraction (XRD) was studied to identify the crystalline nature of the CNC. CP/MAS 13C solid-state NMR was used to evaluate the purity and molecular structure of the CNC. The SEM image of the nanocrystal showed that the bundles of fibre were separated into individual CNC, with the size decreasing to a nanosize indicating an effective removal of the amorphous region. XRD diffraction pattern showed that the CNC possessed the cellulose crystalline configuration with crystallinity index of 99.2% and crystallite particle size dimension of 5.56 nm. The NMR spectra of the CNC revealed that all the signals have six carbon atoms of cellulose and the disappearance of several signals also indicated the disruption of the amorphous region. The results revealed effective synthesis of CNC from sugarcane peel, suggesting the leaching of the amorphous domain, apparent crystallinity and purity of the CNC. The cellulose nanocrystal prepared is considered to be a potent material for various industrial applications.

Methane Production from the Pyrolysis–Catalytic Hydrogenation of Waste Biomass: Influence of Process Conditions and Catalyst Type

The production of methane through the optimization of various operating parameters and the use of different catalysts has been investigated using a two-stage, pyrolysis–catalytic hydrogenation reactor. Pyrolysis of the biomass in the first stage produces a suite of gases, including CO2 and CO, which undergo catalytic hydrogenation in the presence of added H2 in the second stage. The influence of the biomass pyrolysis temperature, catalyst temperature, and H2 gas space velocity has been investigated for the optimization and enhancement of the methane yield. In addition, different metal catalysts (Co/Al2O3, Mo/Al2O3, Ni/Al2O3, Fe/Al2O3), the influence of different metal loadings, catalyst calcination temperature, and different support materials (Al2O3, SiO2, and MCM-41) were investigated. The yield of methane was linked to the properties of the catalysts including the preparation calcination temperature and support material which influenced the catalyst surface area and metal crystallite particle size by sintering. The highest methane yield of 7.4 mmol g–1biomass was obtained at a final pyrolysis temperature of 800 °C, catalyst temperature of 500 °C, and H2 gas hourly space velocity of 3600 mL h–1 g–1catayst. This optimization process resulted in 75.5 vol % of methane in the output gaseous mixture.

Effect of cerium content on textural and hydrodesulfurization performance for dibenzothiophene over a bulk Ni2P catalyst

A series of ceria promoted Ni2P catalysts were prepared and evaluated in dibenzothiophene hydrodesulfurization steam. These catalysts were characterized by X-ray diffraction, N2 adsorption–desorption, CO chemisorptions, and X-ray photoelectron spectroscopy. The results showed that the addition of ceria into the bulk Ni2P catalyst was conducive to the formation of the Ni2P phase and contributed to a higher surface area, leading to a better dispersion and smaller crystallite size of Ni2P particles. The CexNi2P catalysts showed higher dibenzothiophene hydrodesulfurization activity than Ni2P catalyst and the Ce0.09Ni2P catalyst showed the highest dibenzothiophene hydrodesulfurization activity. The Ce0.09Ni2P catalyst showed a dibenzothiophene hydrodesulfurization conversion of 94.5% at the reaction conditions of 320°C, 4.0 MPa, a H2/oil ratio of 500 (V/V), and a weight hourly space velocity of 8.0 h−1. The dibenzothiophene was mainly transformed through desulfurization pathway.

Design and Development of Bismuth Ferrite Based Environmental Friendly Multiferroic for Devices

Abstract Recently, researches are mainly focussed on the development of eco-friendly materials for multifunctional devices. In the present communication, synthesis and detailed characterization of Bi(Ni0.30Ti0.30Fe0.40)O3 multiferroic material has been reported. This compound has been synthesized via a cost-effective (solid-state reaction or mixed oxide) technique in air atmosphere. Based on the analysis of X-ray diffraction data (collected on powder sample) crystal system, unit cell dimension and crystallite (particle) size of material were determined. The calculated particle size of the material is in the range of 28 to 52 nm. Analysis of the field emission scanning electron micrograph (FE-SEM) depicts uniform distribution of grains of varying dimension. Furthermore, the correlation between dielectric and impedance parameters is established using experimental data collected by a phase sensitive multimeter at various temperature and frequency. The impedance spectroscopic studies are performed in a broad range of temperature (300–780 K) and ac field frequencies (103 –106 Hz). As a result, the addition of Ni (nickel) and Ti (titanium) at the Fe (iron) site of BiFeO3 enhances electrical as well as multiferroic properties of the material.

Collagen functionalized graphene sheets decorated with in situ synthesized nano hydroxyapatite electrospun into fibers

We report the in situ synthesis of hydroxyapatite nanoparticles on 1–3 layers of colloidal collagen-graphene composites. Varying calcium and phosphate: graphene ratio two different composites were synthesized. Crystallite size, particle size and degree of crystallinity of hydroxyapatite nanoparticles changes with a change in graphene concentration. Transmission electron microscopy shows that these graphene composites change shape from spherical to elongated needle-like structures because of the varying nitrogen content in collagen-graphene. Fourier-transform Infrared Spectroscopy peaks suggests an interaction between calcium and the colloidal composites. X-ray Photo Electron spectroscopy data shows the interaction between graphene, collagen and hydroxyapatite through pyridinic N-oxide moiety. High-resolution lattice images confirm the co-existence of both graphene and hydroxyapatite. Anti-bacterial tests of the colloidal composites with two different bacteria S. Marcences and E. Coli show improved anti- bacterial property with increased graphene concentration. The colloidal composites were further electrospun into fibers, and their electrochemical stability in simulated body fluids estimated. The electrochemical test data show that the fiber made of composites would be extremely useful for biomedical applications such as internal bandages and burns.

Effect of Sm3+ substitution on the structural and magnetic properties of Ni-Co nanoferrites

Samarium doped nanoferrites Ni0.5Co0.5SmxFe2−xO4 with (x = 0.00, 0.025, 0.05, 0.075, 0.10, 0.125) samples were prepared by using auto-combustion route. XRD pattern analysis confirmed the single-phase cubic spinel structure with no evidence of secondary phase. It is observed that, the lattice constant decreased from 8.342 Å (x = 0) to 8.321 Å (0.100) and again increased to 8.370 for x = 0.125. The crystallite size and particle size indicate the nano sized nature of the prepared ferrites. Crystalite size varies nonlinearly between 33 nm and 25 nm with addition of Sm3+ content in Ni-Co nanoferrites. The agglomerated grain structure revealed the high surface interaction among magnetic nanoparticles. FTIR spectra revealed the characteristics features of ferrite skeleton formation. The saturation magnetization, coercivity and remanence magnetization are found to decreases with the substitution of Sm3+ ions.

Effect of MgO Addition on the Monoclinic to Tetragonal Transition of ZrO2 Fabricated by High Energy Ball Milling

In this work, we studied the formation of partially stabilized zirconia by a high energy ball milling (HEBM) approach. Zirconia powder was mixed with 8 mol% MgO and the powder mixture was milled for 10 hours. The structural and morphological evolutions of the powder particles were studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The Williamson-Hall method was used to calculate the crystallite size of the zirconia powder particles. The results show that the tetragonal zirconia phase (t-ZrO2) can be very well stabilized after the addition of 8 mol% MgO. The formation of t-ZrO2 was identified by XRD analysis after 3 hours of ball milling. In addition, SEM results demonstrated a great refinement in the size of the ZrO2 particles whose distribution was in the sub-μm to nm range indicating better microstructural characteristics. (Received July 18, 2018; Accepted August 16, 2018)

Hyperthermia System Based on Extrinsically Magnetic Poly (Butylene Succinate)

In this work, an extrinsically magnetic composite based on modified magnetite and poly (butylene succinate) (PBS) is prepared. The magnetic composite is obtained by the emulsion–solvent evaporation method. Several analytical tests confirm the synthesis of the composites. Among them, Nuclear magnetic resonance (NMR) results in comparison with literature confirms the synthesis of PBS. X‐Ray Diffraction (XRD) shows the characteristic peaks of PBS, in its monoclinic structure. The crystallite size (Lc) of magnetic particles inside the composite, is equal to 13 nm. Thermogravimetric analysis (TGA) reveals the presence of 5.3 wt% magnetite in the composite and demonstrates that the inclusion of magnetite does not affect the thermal stability of the polymer. The analysis of Fourier transform infrared attenuated total reflection spectra (FTIR‐ATR) indicates the synthesis of desired products as well as the encapsulation of magnetite in PBS polymer matrix. The composite presents magnetic force, which allows its magnetic guidance to a target area. Besides, the magnetic induction heating test promotes heating within the therapeutic range from 40 to 45 °C, being able, according to literature, to promote the death of several types of cancer's cells. Therefore, the material here presented possesses potential to be deeply researched as a future cancer treatment tool.

Efficacy of newly developed nano-crystalline calcium oxide catalyst for biodiesel production

The present work proposes the synthesis of nanocrystalline calcium oxide by sonication assisted reverse emulsion technique. The synthesized and the commercially available calcium oxide were characterized by various techniques. The prepared material possesses 1.53 times higher specific surface area as compared to commercial calcium oxide due its smaller crystallite size and particle size. The performance of both the calcium oxide as a catalyst were investigated for the transesterification reaction of soybean oil under ultrasound irradiation with identical reaction conditions of power and frequency. The influence of different operating parameters on the conversion of soybean oil were studied for the synthesized catalyst. Under the optimal operating conditions viz. nanocrystalline catalyst loading of 4 wt% of oil, methanol to oil molar ratio of 6:1, temperature of 60 °C and ultrasonic power of 212.89 kW/m2, the conversion of oil was 89.89% in 80 min of reaction time. The synthesized catalyst shows 18.81% enhanced conversion of oil as compared to commercial catalyst at the same operating conditions. Finally, the activation energy of reaction was also determined at the optimized operating conditions for the synthesized catalyst and was found to be 54.26 kJ/mol.

Hydroconversion of methyl laurate over silica-supported Ni–Mo catalysts with different Ni sizes

In this study, silica-supported Ni–Mo catalysts were prepared by co-loading Ni and Mo species on silica materials with different specific surface areas to investigate the effects of the supporting material's surface area on the physicochemical properties of the loaded metal species and the catalytic performance in the hydroconversion of methyl laurate. Notably, supporting materials with higher specific surface areas enabled the metal species to be highly dispersed to produce smaller metallic Ni crystallites, resulting in the formation of smaller metal particles consisting of Ni and Mo species. Moreover, in the hydroconversion of methyl laurate, all silica-supported Ni–Mo catalysts predominantly produced n-undecane followed by n-dodecane. In addition, the decrease in Ni crystallite size increased the number of active sites, thereby improving the catalytic activity in the hydroconversion of methyl laurate to hydrocarbons. In contrast, the product distribution was less sensitive to the Ni crystallite and metal particle sizes, suggesting that the reaction paths over the silica-supported Ni–Mo catalysts were only slightly sensitive to the morphology of the metal particles that served as active sites.

Effect of pH value on structural and magnetic properties of CuFe2O4 nanoparticles synthesized by low temperature hydrothermal technique

The present study deals with the effect of pH value on structural and magnetic properties of copper ferrite (CF) nanoparticles synthesized via low temperature hydrothermal approach. In particular, the pH is varied from 9 to 12, in order to elucidate the behavior of structural, morphological, magnetic and optical properties of CF nanoparticles. The diffraction pattern revealed the formation of mixed (cubic & tetragonal) phase and cubic single phase structure. Later on, the structure, average crystallite size (D), grain size (G), particle size, saturation magnetization (Ms), anisotropy constant (K1), magnetic moment (miB), octahedral (ν1) & tetrahedral (ν2) locations are also evaluated. Moreover, the cation distribution was performed for all the samples. The superparamagnetic nature of CF nanoparticles is confirmed by M-H curves.

Role of pH on the photocatalytic activity of TiO2 tailored by W/T mole ratio

Tailoring of TiO2 properties by controlling W/T mole ratio (70, 140, 210 and 280) was carried out by sol–gel method using TTIP as Ti precursor and H2O as O2 precursor. The anatase phase evolution with Ti and O2 composition variations was verified, respectively, through X-ray diffraction and EDX analysis. The spherical topography of TiO2 particles was elucidated by FESEM, which was noticeably affected with W/T mole ratio. The quantitative measurement of particles’ size, shape and their distribution were directly observed at a scale approaching a bunch of atoms by HRTEM. The numerical values of crystallite size and particle size, as measured by the XRD peak broadening and TEM techniques, differ slightly. The optical study, by UV–Visible spectroscopy, registered blue shift in the absorption edge wavelength of TiO2 as well as increase in the band gap energy, with increase in W/T mole ratio. The presence of functional groups at the interface of TiO2 nanoparticles was confirmed by FTIR. Considering MB dye as a model pollutant, the characterization of photo-oxidation kinetics was also performed to assess the effect of pH and W/T mole ratio on removal efficiency of TiO2. Excellent photocatalytic performance of TiO2-70 R under UV light irradiation for 180 min was observed at a pH of 11; the corresponding photocatalytic kinetics, denoted by first order degradation rate constant (Kappa) was found to be approximately 0.00404 min−1.

Role of oxygen vacancies and interstitials on structural phase transition, grain growth, and optical properties of Ga doped TiO2

A systematic study on the effect of gallium (Ga) doping (0 ≤ x ≤ 0.10) on the structural phase transition and grain growth of TiO2 is reported here. X-ray diffraction spectroscopy and Raman spectroscopy confirm that Ga doping inhibits the phase transition. Activation energy increases from 125 kJ/mol (x = 0.00) to 300 kJ/mol (x = 0.10) upon Ga incorporation. X-ray photoelectron spectroscopy shows the presence of Ti3+/Ga3+ interstitials, substitution (Ti4+ by Ga3+), and oxygen vacancies in the samples. At lower doping (x ≤ 0.05), interstitials play a more significant role over substitution and oxygen vacancies, thereby resulting in a considerable lattice expansion. At higher doping (x ≥ 0.05), the effect of interstitials is compensated by both the effect of substitution and oxygen vacancies, thereby resulting in relatively lesser lattice expansion. Inhibition of the phase transition is the result of this lattice expansion. The crystallite size (anatase) and particle size (rutile) both are reduced due to Ga incorporation. It also modifies optical properties of pure TiO2 by increasing the bandgap (from 3.06 to 3.09 eV) and decreasing the Urbach energy (from 58.59 to 47.25 meV). This happens due to regularization of the lattice by the combined effect of substitution/interstitials and oxygen vacancies.

Microstructural evolution of aluminum hydroxide gel during the hydration of calcium sulfoaluminate under different alkali concentrations

The present paper discusses the microstructural evolution of aluminum hydroxide (AH3) formed during the hydration of calcium sulfoaluminate in neutral and alkaline solutions (0-M NaOH, 0.01-M NaOH, 0.1-M NaOH, 1-M NaOH, 5-M NaOH and 8-M NaOH). Rietveld method and field emission scanning electron microscopy measurements were used to observe the evolution of crystallite size and particle size distribution, respectively. Furthermore, various characterization methods were used to complement the microstructure of AH3 phase. The result of 27Al MAS-NMR spectroscopy indicated the absence of the amorphous AH3 phase in all hydrated pastes. The degree of crystallinity, with respect to the AH3 phase, improved with increasing alkali concentration. However, AH3 phase can also react with OH− ion and even disappear in high alkaline conditions. In low alkaline conditions (i.e., 0-M NaOH, 0.01-M NaOH, 0.1-M NaOH), the AH3 phase had a nanocrystalline structure with an average crystallite size of about 8–9 nm and particle size distribution ranging from 110 nm to 210 nm. In high alkaline conditions (i.e., 5-M NaOH and 8-M NaOH), the AH3 phase presented a well-crystalline nature. The average crystallite size increased up to about 30–40 nm and the particle size distribution was mostly 800–1400 nm (5-M NaOH) or 1000–1500 nm (8-M NaOH).

A Facile Method Using a Flux to Improve Quantum Efficiency of Submicron Particle Sized Phosphors for Solid-State Lighting Applications

This work successfully verified that the addition of a flux (NH4F, NH4Cl, and H3BO3) during synthesis has an impact on the crystallite size and quantum efficiency of submicron-sized particles of CaMgSi2O6:Eu2+ phosphors. The addition of NH4F or NH4Cl increased the crystallite size in the submicron-sized particles, yielding an increase in emission intensity and quantum efficiency. On the other hand, the use of the H3BO3 flux crystallized a secondary phase, SiO2, and changed the lattice parameters, which degraded the luminescent properties. In addition, an excessive amount of NH4Cl was examined, resulting in nucleation of a secondary phase, CaSiO3, which changed the lattice parameters with no improvement in luminescent properties. These results demonstrate that the addition of a flux could be a method to improve the quantum efficiency of submicron-sized particles composed of nanocrystallites; however, a judicious choice of the flux composition and amount has to be carefully considered.

Phosphorous-doped TiO2 nanoparticles: synthesis, characterization, and visible photocatalytic evaluation on sulfamethazine degradation.

Mesoporous phosphorous-doped TiO2 (TP) with different wt% of P (0.5, 1.0, and 1.5) was synthetized by microwave-assisted sol-gel method. The obtained materials were characterized by XRD with cell parameters refinement approach, Raman, BET-specific surface area analysis, SEM, ICP-OES, UV-Vis with diffuse reflectance, photoluminescence, FTIR, and XPS. The photocatalytic activity under visible light was evaluated on the degradation of sulfamethazine (SMTZ) at pH8. The characterization of the phosphorous materials (TP) showed that incorporation of P in the lattice of TiO2 stabilizes the anatase crystalline phase, even increasing the annealing temperature. The mesoporous P-doped materials showed higher surface area and lower average crystallite size, band gap, and particle size; besides, more intense bands attributed to O-H bond were observed by FTIR analysis compared with bare TiO2. The P was substitutionally incorporated in the TiO2 lattice network as P5+ replacing Ti4+ to form Ti-O-P bonds and additionally present as PO43-on the TiO2 surface. All these characteristics explain the observed superior photocatalytic activity on degradation (100%) and mineralization (32%) of SMTZ under visible radiation by TP catalysts, especially for P-doped TiO2 1.0wt% calcined at 450°C (TP1.0-450). Ammonium, nitrate, and sulfate ions released during the photocatalytic degradation were quantified by ion chromatography; the nitrogen and sulfur mass balance evidenced the partial mineralization of this recalcitrant molecule.

Quasi Crystal Al (1xxx)/Carbonised Coconut Shell Nanoparticles: Synthesis and Characterisation

AbstractA novel synthesis of Al (1xxx)/carbonised coconut shell (CCS) nanoparticles using a ball milling technique was investigated. Initial Al/0.1%CCS powders of an average size of 51.06μm was milled for a period of 70 h. The milled particles at 16, 46 and 70 h were characterized using X-ray diffractomer (XRD), scanning electron microscope (SEM), transmission electron microscope and UV-Vis spectrophotometer. Result revealed that the calculated particle crystallite size from XRD aided with Scherrer’s equation is consistent with particle image sizes obtained from SEM aided with software. TEM image depicted variation in orientation and appearance of the Al 1xxx/0.1% CCS nanoparticles at different milling time. The wide variation in the particle size is attributable to different ball impacts on the individual powders during the ball milling process. Increased maximum absorbance observed with the milled particles when compared with the initial powders is an indication of quantum/nanosizing effect due to ball milling.

A Method to Improve Quantum Efficiency of Phosphors in the Submicron Size Regime Using a Flux for Solid State Lighting Applications

Micron sized phosphors have been widely studied by using a solid-state reaction method for application in near UV-emitting LEDs. This method produces large crystallite size powders, but have higher quantum efficiencies than smaller crystallite size powders. For the phosphor configuration, the packing density of these large particles on the device is thus low and generates substantial light-scattering. To overcome this issue, phosphors with a small, narrow size distribution are required. If the particle radii are < ~400 nm, scattering from these particles will be negligible on visible and UV radiation. However, submicron-sized phosphors with nano-sized crystallites have poor quantum efficiency compared to micron-sized phosphors with micron-sized crystallites. An addition of flux (NH4F, NH4Cl, or H3BO3) to the CaMgSi2O6:Eu2+ phosphors during synthesis was performed and the effect of the flux on the crystallite size and quantum efficiency of nanocrystalline and submicron phosphors particles was examined. The use of NH4F or NH4Cl increased the crystallite size in the submicron sized particles, which yielded an increase in emission intensity and quantum efficiency. Adding the H3BO3 flux crystallized SiO2 and changed lattice parameters, degrading the luminescent properties. Excessive NH4Cl was also examined and it resulted in nucleation of a second phase and changed lattice parameters with no improvement in luminescent properties. These results demonstrate that a careful selection and use of a flux is a method to improve the quantum efficiency of submicron particles sized phosphors. This work is supported by the National Science Foundation, Ceramics Program Grant (DMR-1411192).

Investigasi Struktur dan Energi Band Gap Partikel Nano Tio2 Hasil Sintesis Menggunakan Metode Sol-Gel

TiO 2 is a semiconductor material that widely applied in various fields due to its superiority both in terms of physical and chemical properties. In this study, the TiO 2 nanoparticles was synthesized using sol-gel method. The synthesis of TiO 2 nanoparticles was started by reacted TiCl 3 with aquades and titrated with ammonium hydroxide and then followed by calcination process at 600 0 C for 1.5 hours. The structural characteristics were investigated using XRD. The fungsional groups of the TiO 2 nanoparticles were characterized by FTIR. The optical properties of the TiO 2 nanoparticles were determined using UV-Vis spectrometer. The morphology of the sample was characterized using SEM. The results show that the TiO 2 has structure as anatase phase. The data analysis using the Scherrer’s equation show that the particle crystallite size of is about of 9.77 nm. The energy band gap value of the TiO 2 is 3.28 eV. Based on the SEM image, the agglomeration of the sample was formed with the average diameter of particle size of TiO 2 is about 92 nm. DOI: http://dx.doi.org/10.17977/um024v3i12018p008