X-ray Diffraction Spectrometer Research Articles

Study on the preparation and optoelectronic properties of nano-ZnO arrays

ABSTRACTNano-ZnO arrays with high degree of orientation and good dispersion were prepared by sol-gel method and hydrothermal method. The morphology, structure and photoluminescence properties of samples were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) and fluorescence spectrometer. The results showed that the prepared samples are hexagonal wurtzite structure and the growth of the (002) crystal surface is preferred. The samples have a strong characteristic absorption and UV absorption capacity at 371.5 nm, and there is a high UV emission peak at 387 nm, besides, there is a relatively weak blue emission peak at 468 nm. Moreover, The field emission characteristics tests of samples were conducted and revealed the low turn-on field is 1 V/μm, in addition,the field emission current density is 210 μA/cm2 under the condition of electric field of 7.5 V/μm. Finally, field emission mechanism of nano-ZnO array is discussed.

Electrochemical removal of thiamethoxam using three-dimensional porous PbO2-CeO2 composite electrode: Electrode characterization, operational parameters optimization and degradation pathways

Highly performed electrode is one of the key factors affecting the efficiency of electrochemical oxidation toward organic pollutants. In the present work, three-dimensional porous PbO2-CeO2 composite electrodes (3D/PbO2-CeO2) were fabricated by composite electrodeposition method using oxygen bubbles as template, to eliminate neonicotinoid thiamethoxam in aqueous solution. The surface morphology, structure, and composition of the 3D/PbO2-CeO2 electrodes were well characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). Then the influence of the applied current density, the initial concentration of thiamethoxam, the concentration of supporting electrolyte, and initial pH value on the thiamethoxam removal ratio were also optimized. Amount to twenty deductive intermediates of thiamethoxam degradation were identified by HPLC-MS analysis, and dechlorination, hydrogen abstraction, denitration, and hydroxylation were observed in electrochemical oxidation process of thiamethoxam. Based on these identified byproducts, a hypothetical degradation mechanism has been proposed, which was divided into two parallel pathways according to the different initial oxidation position on thiamethoxam, such as chlorine atom on thiazole ring and nitro group on 1,3,5-oxadiazinane ring. All the intermediates were ultimately mineralized into H2O and CO2. The electrochemical oxidation based on 3D/PbO2-CeO2 electrodes in this work is a promising approach to effective removal of thiamethoxam.

Ultra-fast, highly efficient and green synthesis of bioactive forsterite nanopowder via microwave irradiation

Forsterite (Mg2SiO4) has recently attracted considerable attention in different fields because of its wide range of applications. In this paper, pure forsterite nanopowders were synthesized by an ultra-fast, highly efficient and green method for the first time. Microwave irradiation was used to synthesize forsterite nanopowder. The formation of highly crystalline forsterite nanopowder was confirmed by X-ray diffraction (XRD) and energy dispersive X-ray spectrometer (EDS) analyses. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses showed that the agglomerated powder composed of nanocrystalline particles with the mean particle size of ~100 nm. Microwave irradiation significantly accelerated the rate of the reactions and dramatically decreased reaction times from hours to minutes and seconds. In vitro bioactivity evaluation was performed by soaking the forsterite samples in simulated body fluid (SBF). Results indicated that synthesized forsterite nanopowder via microwave irradiation method possessed excellent apatite-forming ability in SBF. Cell viability results showed that synthesized forsterite nanopowder not only showed no cytotoxicity but also improved cell proliferation. Alkaline phosphatase (ALP) activity assay indicated that the fabricated forsterite nanopowder could facilitate the MG63 osteoblast-like cells to proliferate and differentiate. Therefore, microwave-assisted synthesis technique could be considered as a novel, safe and high efficient method in saving time and energy for bioactive forsterite nanopowder production.

Study of bio-synthesised transition nano metal oxides dispersed polyester composites as enhanced protectors for mild steel in 0.5 M H2SO4 medium-a green approach

A facile, efficient and eco-friendly synthesis of transition nano metal oxides like zinc oxide (ZnO), copper oxide (CuO), tin oxide (SnO) from Persea americana. Mill was executed followed by ex-situ polymerization favoring poly (glycerol succinate) (PGS)/nano metal oxide composite for the first time. The incorporation of nanofillers was confirmed by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction spectrometer (XRD), Scanning electron microscopy (SEM) and Energy dispersive spectroscopy (EDS). As a comparative approach, the extent of metal dissolution was evaluated in presence of precursor as well as nano dispersed forms for various concentrations (10, 50, 100, 500, 1000 ppm) under the cluster of electrochemical and non-electrochemical techniques. Enhanced inhibition efficiency of 97% was observed in the case of CuO dispersion which was additionally supported by XRD particle size determination. The increase in charge transfer resistance (Rct) and a decrease in corrosion current (Icorr) elicited from electrochemical measurements strictly proved the role of metal – oxide nanoparticles. Further, the mode of inhibitor was found to be predominantly cathodic.

Formation of black patina on an ancient Chinese bronze sword of the Warring States Period

In general, black patina is formed upon the surface of the ancient bronze mirrors. Recently, a kind of black patina is found on an ancient bronze sword, which was made 2500 years ago during the Warring States Period of China. In this paper, chemical compositions and microstructures of the black patina were characterized by using instruments including optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and Raman spectrometer (Raman). The results revealed that the formation of the black patina on the bronze sword is due to two reasons: (1) high tin (Sn) content reaches to 22.92 wt%; (2) damp, wet and acid burial environment. Therefore, it conforms to the natural corrosion formation mechanism, i.e., after selective dissolution of elements Cu and Pb from the matrix, element Sn was oxidized and then, the gel-like SnO2·xH2O filled the vacancies left by the selective corrosion of Cu and Pb. This work will be helpful for better restoration and preservation of the bronze cultural relics.

Influence of Si3N4 on Ti-6Al-4V via spark plasma sintering: Microstructure, corrosion and thermal stability

The objective of this research was to study the influence Si3N4 on Ti-6Al-4V via spark plasma sintering process. The experiments were performed at a temperature of 1000 °C with a holding time of 6 min under a pressure of 50Mpa.Ti-6Al-4V powder was admixed with different weight proportions of Si3N4 powder. Sintered composite samples were produced from the mixture and the influence of Si3N4 on the microstructure; mechanical and thermal properties of the composites were investigated. Scanning electron microscope (SEM-EDS) was used to study the bulk morphology of the sintered composites. The phases present in the fabricated sintered composites were observed by energy dispersive X-ray diffraction spectrometer (XRD). Microhardness was investigated by the means of high impact diamond Durascan micros hardness tester. Electrochemical behavior of the sintered samples was measured by potentiodynamic polarization method. The thermal performances of the sintered composites were explored by a Thermal gravimetric analyser (TGA). The experimental results revealed that the microstructure, corrosion resistance and thermal stability properties of the material were improved by the addition of Si3N4. The effect of Si3N4 on the performance characteristics of Ti6AI4V alloy was seen to be compactable and useful in aerospace application.

Intrinsic defects in ZnO films deposited by RF sputtering

ABSTRACTZinc oxide thin films were deposited on Si (100) substrates using RF magnetron sputtering by adjusting sputtering power. The film properties were characterized by scanning electron microscopy with energy dispersive X-Ray spectroscopy, X-ray diffraction spectrometer and photoluminescence spectroscopy. Intrinsic defects could be adjusted just by modifying the sputtering power. Variation of Zn to O ratio, defects and their relative concentration of the films with the sputtering power were investigated in details.

The Suspension of Platinum Nanoparticles Prepared by Electric Discharge Method in Ethanol

Platinum nanoparticles were prepared in ethanol by electric discharge method. The absorption of platinum nano-colloid was measured by UV–Visible Spectrophotometer (UV–Vis). Measurement of Zetasizer showed that the zeta potential is − 40.8 mV, representing the good suspension of platinum nano-colloid with a size of nanoscale. Platinum nano-colloid was identified by X-ray diffraction and Raman spectrometer. Transmission electron microscope (TEM) was used to observe the actual distribution of platinum nanoparticles. The results show that size of platinum nanoparticles are divided into three groups. Size distribution of 3 nm accounts for the majority, which is similar to the results of chemical preparations. The well distribution of platinum nanoparticles was observed clearly without precipitation by TEM.

Competitive adsorption of Cd2+, Pb2+ and Ni2+ onto Fe3+-modified argillaceous limestone: Influence of pH, ionic strength and natural organic matters

In present study, the feasibility of applying a natural adsorbent with Fe3+ modification (Fe3+-modified argillaceous limestone, FAL) on the competitive adsorption of heavy metals (i.e., Cd2+, Pb2+ and Ni2+) was evaluated. The current results revealed an efficient adsorption on Cd2+, Pb2+ and Ni2+ in mono-metal system. Further experiments demonstrated a high selectivity of Pb2+ during the competitive adsorption of Cd2+, Pb2+ and Ni2+. The adsorption selectivity of the metal ions followed the order of Pb ≫ Cd > Ni. In addition, both pH and ionic strength are important factors affecting the metal adsorptions. It is interestingly that various NOMs (i.e., humic acid (HA) and glycine (Gly)) exerted different effects on the adsorption behaviors, probably due to the different affinities for Pb2+, Cd2+ and Ni2+ and the redistribution of newly-formed metal-DOM complexes. X-ray photoelectron spectroscopy (XPS) analysis together with X-ray diffraction (XRD) and energy dispersive spectrometer (EDS) analysis revealed that the metal adsorptions were mainly regulated via the synergistic mechanisms of ion exchange by Na+, Ca2+, and Al3+, precipitation to form CdCO3 and Pb2(OH)2(CO3)2, as well as complexes of FAL-OPb and FAL-ONi by hydroxyl groups on the surface of FAL. The application of FAL would be a promising option in leading to an efficient heavy metal removal.

Metallic 1T Phase MoS2 Nanosheets for Supercapacitor Application

In the present study, a molybdenum disulfide MoS2 nanosheets (MoS2 NSs) were synthesized via a lithium intercalation and exfoliation method. The morphology and structure of the as-prepared MoS2 was characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Raman spectrometer. The MoS2 NSs electrode exhibited higher specific capacitance (148 Fg-1 at 1 mVs-1 or 142 Fg-1 at 1 Ag-1) with excellent cycling stability, compared with bulk MoS2. The result shows that MoS2 is a promising electrode material for electrochemical supercapacitor.

Effect of Temperature and Duration of Sintering on Perovskite Material (La1-xAgx)0.8Ca0.2MnO3

Lanthanum compounds of (La1-xAgx)0.8Ca0.2MnO3 have been prepared for x = 0 and x = 0.5 by using sol-gel method. Bulk samples were sintered by varying temperature and duration of sintering processes. The sintering temperature was varied at two conditions, 600 °C for 5 h and 900 °C for 24 h. Crystal structure of the samples was observed by X-Ray diffraction spectrometer. Rietveld refinement of X-Ray diffraction results showed that the sample with x = 0, both sintered at 600 °C for 5 h and at 900 °C for 24 h are single phase and they have an orthorhombic structure with Pnma space group. The sample with x = 0.5 sintered at 900 °C for 24 h did not show a single phase due to the appearance of Ag peaks, and they have a perovskite structure. Meanwhile, the sample with x = 0.5 sintered at 600 °C for 5 h, also did not show a single phase due to the appearance of Ag and LaO peaks. This results showed that for x = 0.5, temperature and duration of sintering are influenced by nucleation processes in the samples. The higher temperature and more longer duration of sintering will make the nucleation processes in the sample better.

Synthesis, characterization and electrochemical properties of S-doped carbon aerogels

Heteroatom doping in carbon aerogels is critical for improving the surface areas and electronic properties of these aerogels. This paper demonstrates doping sulfur (S) atom into carbon aerogels. S-doped carbon aerogels (S-CAs) were prepared via a sol-gel process using phloroglucinol (P), resorcinol (R) and formaldehyde as the polymerization precursors with sodium carbonate (Na2CO3) as the basic catalyst and sodium 4-hydroxybenzenesulfonate (HBS) as the surfactant. The as-synthesized products were dried in normal temperature and carbonized with temperature-programmed. The effects of S-doping on the surface area and electronic properties of the S-CAs were studied by a surface area analyzer and electrochemical workstation. When the S loading was up to 1.38%, the corresponding S-CA exhibited the most optimal surface area and specific capacitance. The textural properties were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), a surface area analyzer, an X-ray diffraction spectrometer, a Raman spectrometer, the X-ray photoelectron spectroscopy (XPS) spectra, an elemental analyzer and an EDX detector, and the electrochemical properties were measured using cyclic voltammetry, galvanostatic charge–discharge measurements and electrochemical impedance spectroscopy (EIS). When the molar ratio of HBS/(P + R) was 0.05, the S loading was 1.38%, the specific surface area of the as-synthesized CA was 831 m2/g, and its specific capacitance was 105 F/g.

Microstructure and Properties of Semi-solid ZCuSn10P1 Alloy Processed with an Enclosed Cooling Slope Channel

Semi-solid ZCuSn10P1 alloy slurry was fabricated by a novel enclosed cooling slope channel (ECSC). The influence of pouring length of ECSC on the microstructures of ZCuSn10P1 alloy semi-solid slurry was studied with an optical microscope an optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). Liquid squeeze casting and semi-solid squeeze casting were performed under the same forming conditions, and the microstructure and properties were compared. The results show that primary α-Cu phase gradually evolved from dendrites to worm-like or equiaxed grains under the chilling action of the inner wall of the ECSC. The mass fraction of tin in the primary α-Cu phase increased from 5.85 to 6.46 after the ECSC process, and intergranular segregation was effectively suppressed. The finest microstructure can be obtained at 300 mm pouring length of ECSC; the equivalent diameter is 46.6 μm and its shape factor is 0.73. The average ultimate tensile strength and average elongation of semi-solid squeeze casting ZCuSn10P1 alloy reached 417 MPa and 12.6%, which were improved by 22% and 93%, respectively, as compared to that of liquid squeeze casting.

Self-adaptive MoS2-Pb-Ti film for vacuum and humid air

Space equipment is stored in terrestrial environments before launch, where the water vapor is detrimental to the tribological performance of molybdenum disulfide (MoS2). To meet the requirement of the storage on the earth and the use in space, a new kind of MoS2-Pb-Ti film was designed. Both vacuum and air tests demonstrated that its tribological performance was much better than that of MoS2 film. To explore the origin of the excellent tribological performance, MoS2, MoS2-Ti and MoS2-Pb films were also studied as references. The composition, mechanical properties, surface morphologies and microstructures of as-deposited films were investigated with energy dispersive spectrometer (EDS), nanoindenter, scanning electron microscopy (SEM), atomic force microscopy (AFM), glancing angle X-ray diffraction (GIXRD) and Raman spectrometer. The tribological tests were performed in vacuum and air under different relative humidity. The superior tribological properties of MoS2-Pb-Ti film in vacuum were mainly attributed to MoS2 dominated contact interfaces, the increased elastic modulus and an improved transfer layer. Moreover, the significantly improved tribological performance in humid air was mainly due to the sacrificial effect of doped metals, which protected the MoS2 from the attack of H2O and O2. Furthermore, the potential application of MoS2-Pb-Ti film for alternative humid air and vacuum was explored.

Effect of adding of SiC particulate on the microstructure and shear strength of SiC ceramic joint brazed with Si-24Ti alloy

In order to refine the grain size of TiSi2 silicide and reduce the formation of micro-defects in the joint, and thereby increasing the joint strength of SiC ceramic brazed with Si-24Ti (wt.%), a small amount of SiC particulates were added in the brazing alloy. The microstructure and mechanical strength of SiC joints was investigated by using field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction spectrometer, and shear strength test. The results indicated that SiC particulates enhanced the nucleation and grain refinement of the TiSi2 and Si phase. The adding of appropriate content of SiC (<1 wt.%) could effectively refine the size of TiSi2 phase and increase the fraction of Si-TiSi2 eutectic zone. However, excess addition of 1.5 wt.% SiC caused the coarsening of TiSi2 phase due to the clustering of added fine SiC particulates. With the increasing of SiC particulate content, the shear strength of the joints increased at first and then decreased. The maximum shear strength of 106.3 MPa of SiC joint was obtained for the joint brazed with 1 wt.% SiC addition, which was ~19% higher than that of the joint brazed without SiC particulates.

Preparation of amorphous NiP-based catalysts for hydrogen evolution reactions

Amorphous alloy NiP and its carbon composite catalysts NiP/C and NiP/reduced graphene oxide (RGO) were successfully one-pot synthesized using NaH2PO2 and NiSO4 as phosphorus and nickel source, respectively. The electrocatalysts were characterized with transmission electron microscope (TEM), X-ray diffraction spectrometer (XRD), inductively coupled plasma analysis (ICP) and thermogravimetric analysis (TG), respectively. The hydrogen evolution reactions (HER) performance of the electrocatalysts was evaluated with a linear sweep voltammetry method in both acidic and alkaline solution. Among them, NiP/RGO elctrocatalyst exhibited 89.0 mV onset overpotential and Tafel slope 135.1 mV/decade in acidic solution, as well as 116.1 mV onset overpotential and Tafel slope 122.4 mV/decade in alkaline solution with excellent long-term stability. Results indicated that the NiP/RGO was a very active catalyst.

Synthesis and Characterization of ZNO/MN Nanocomposite by using Sol-Gel Method

Zink oxide doped Mn nanocomposites were synthesized by simple sol-gel method at low temperature by using combination of aquadest with methanol as the solvent and ethylene glycol as the additive. Zink acetate dehydrate and manganese chloride tetrahydrate were used as the precursors. Composition dopants were 1,3,5,and 7%. The crystals were formed by drying at 110°C for 1 hour, after which they were heated at ± 500°C for 2 hours. The as-prepared ZnO/Mn nanocomposites were characterized by X-ray diffraction (XRD) and UV Diffuse Reflectance Spectrometer (UVDRS). The XRD patterns of the ZnO nanocrystals showed that they are mostly hexagonal wurtzite with specific peaks at 2θ = 31, 34, 36, 47, 56, 63, 66 dan 69. The sizes of the ZnO doped Mn particles produced with 1%, 3%, 5% and 7% were18-95; 17-87; 18-96 19-98 nm, respectively. UVDRS analysis showed that the band gap of the ZnO were 2,60; 2,90; 2,99 dan 3,01 eV for 1%, 3%, 5% and 7% Mn respectively.

STUDY ON ITO THIN FILMS PREPARED BY MULTI-ANNEALING TECHNIQUE

Indium tin oxide (ITO) thin films have been successfully prepared by a solution process followed by a multi-annealing method. In this study, we focus on the use of multi-annealing method, for which each layer was annealed at a suitable temperature, instead of a conventional annealing way, by means of a rapid thermal annealing system, in order to improve the film quality. The crystalline structure and surface morphology of the ITO thin films were investigated by using X-ray diffraction (XRD) spectrometer, atomic force microscope (AFM) and scanning electron microscope (SEM). It has been obtained that all of ITO films exhibit a single phase with (222)- and (440)-preferred orientations. The AFM and SEM observations show that the particle size of ITO films was about 10 nm and the ITO film thickness was 180 nm, respectively. In sequence, the electrical properties of ITO thin films were evaluated by using four-point probe and Hall effect measurement methods, and the optical properties were investigated by UV/VIS spectrometer. The results show that the best ITO films have electrical resistivity of 2.6 × 10-3 Ω.cm and transparency higher than 90 %, which strongly supports to the application of electrode in solar cell, LED or transistor devices from viewpoints of low-cost production and low-energy consumption.

Effects of TiO2 addition on microwave dielectric properties of Li2MgSiO4 ceramics

Silicates have been widely studied for substrate applications in microwave integrated circuits owing to their low dielectric constant and low tangent loss values. Li2MgSiO4 (LMS) ceramics are synthesized through solid-state reaction route using TiO2 as an additive to the pure ceramics. Variations in dielectric properties of LMS upon TiO2 addition in different weight percentages (0.5, 1.5, 2) are studied by keeping the sintering parameters constant. Crystalline structure, phase composition, and microstructure of LMS and LMS-TiO2 ceramics were studied using x-ray diffraction spectrometer and High Resolution Scanning electron microscope. Density was measured through Archimedes method and the microwave dielectric properties were examined by Cavity perturbation technique. LMS achieved relative permittivity (εr) of 5.73 and dielectric loss (tan δ) of 5.897 × 10−4 at 8 GHz. In LMS-TiO2 ceramics, 0.5 wt% TiO2 added LMS showed comparatively better dielectric properties than other weight percentages where εr = 5.67, tan δ = 7.737 × 10−4 at 8 GHz.

Investigation of the graphene oxide and asphalt interaction and its effect on asphalt pavement performance

Previous studies have shown that graphene oxide (GO) could improve the mechanical and rheological properties of polymers. However, the GO-asphalt interaction and the effects of GO on asphalt pavement performance are still not clear. In this paper, the GO modified asphalt binders were prepared by melt blending method, the GO-asphalt interaction was investigated by the Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and gas chromatography-mass spectrometer (GC-MS). The GO effects on the pavement performance of asphalt binders were also studied. In addition, the thermal properties of GO modified asphalt were studied by thermo gravimetric (TG) analysis. The results show that the gas released from GO modified asphalt is the CO2. There is no chemical reaction between the GO and asphalt binders, as much as the CO2 is produced by the decomposition of GO. After being mixed with asphalt binders, the lamella structure of GO is completely stripped, and scattered to a single layer in asphalt binders. The GO has many advantages in improving the pavement performance.