X-ray Powder Diffractometer Research Articles

Visible light enhanced NO2 sensing performance of Au nanoparticles modified SnS2 hierarchical structure at room temperature

High-performance NO2 gas sensor at room temperature is vital in daily life. Herein, the performance of SnS2 hierarchical structure modified by Au nanoparticles was explored as a NO2 sensing material at room temperature. The samples were synthesized by solvothermal method and subsequent in-situ reduction method which could be confirmed by the analysis results of X-ray powder diffractometer (XRD), field-emission scanning electronic microscope (FESEM), transmission electron microscopy (TEM) and X-ray photoelectron spectra (XPS). Through a series of gas sensing measurements, the sensor based on Au-SnS2 possesses outstanding NO2 sensing properties under visible light at room temperature, including high response at trace concentration (14.24/5 ppm), excellent response/recovery time (29/148 s), low detection limit (36 ppb), satisfactory selectivity and repeatability. Combined with the first-principles calculations, the enhanced sensing performance can be contributed to the modification of Au with rich charge transfer (−0.5153 e) and the local surface plasmon resonance (LSPR) between Au and visible light with the enhanced optical absorption capacity and carrier density of the material. This work proffers opportunities for real-time NO2 detection in daily life.

Ti3C2OH MXene supported NiPtP nanoparticles with low noble metal content as hydrazine dehydrogenation catalysts

BackgroundHydrazine hydrate is widely used in hydrogen production due to its high hydrogen content and good room temperature stability. However, the decomposition pathway of hydrazine hydrate is related to the type of catalyst, therefore, it is necessary to develop efficient and good selective catalysts. Methodswe have developed a method for preparing NiPtP NPs on MXene using NaH2PO2 as a non-metallic phosphorus source by a one-pot reduction method. The structure and chemical composition of catalysts were studied by Scanning electron microscope (SEM), Energy dispersive spectroscopy (EDS), Transmission electron microscope (TEM), X-ray powder diffractometer (XRD), Inductively coupled plasma-atomic emission spectrometry (ICP-AES), and X-ray photoelectron spectroscopy (XPS). Significant findingsThe results show that the P doping significantly improved the catalytic hydrogen production activity of the Ni0.74Pt0.2P0.06@MXene catalysts in alkaline hydrazine hydrate solutions. The Ni0.74Pt0.2P0.06@MXene catalyst had good catalytic activity for the catalytic production of hydrogen from alkaline hydrazine hydrate solutions under mild conditions, with 100% selectivity for H2 and a TOF value of 794 h−1 at 323 K. This facile synthetic method for the preparation of transition metal phosphides, combined with the high catalytic activity, high hydrogen selectivity and low cost of Ni0.74Pt0.2P0.06@MXene catalysts, may facilitate the practical application of MXene in the field of chemical hydrogen storage, and further fill the gap in the application of transition metal phosphide materials in the field of hydrogen production.

A Study on the Sintering Mechanism of High-Strength Light Bricks Manufactured from Coal Gasification Slag

In this article, we report a way to produce sintered bricks from industrial coal gasification slag. Subsequently, we studied the impact of the addition of coal gasification slag and heat treatment on the density and compression strength of sintered materials with controlled variables. In addition, we implemented thermogravimetric analysis-differential scanning calorimetry (TG-DSC), an X-ray powder diffractometer (XRD), and a scanning electron microscope (SEM), as well as optical and thermal measurement devices, to analyze the microscopic structures of sintered materials; this revealed the action mechanism of coal gasification slag on the microscopic morphology and performance of sintered bricks. The volumetric density and compression strength of the sintered bricks were found to be negatively correlated with the amount of coal gasification slag introduced, but positively correlated with the sintering temperature. When the firing temperature was 1150 °C and the addition amount of coal gasification slag was 45%, the sintered brick products, with a predominant crystalline phase of anorthites, could achieve a density of 1.5 g/cm3 and a compression strength of 30 MPa; this met the requirements of the China National Standard GB/T 5101-2017 for MU30 bricks. This report may help with the implementation of coal gasification slag.

Comparative Study on Gemmological Characteristics and Luminescence of Colorless and Yellow Scapolites

The orange fluorescence of scapolite has been confirmed to be caused by (S2)−, but the frequent blue fluorescence in gem-quality scapolite has not been well explained. An energy dispersive X-ray fluorescence spectrometer (XRF), electron probe microanalyzer (EPMA), X-ray powder diffractometer (XRD), Fourier transform infrared spectrometer (FTIR), Raman spectrometer, ultraviolet-visible spectrophotometer, fluorescence spectrometer, and conventional gemological test methods were used to study the gemological characteristics, chemical composition, coloration mechanism, spectral characteristics, and luminescence of colorless and yellow scapolite. The results show that both yellow and colorless scapolites are mizzonite and that they share the same gemological and spectroscopic characteristics. The results of XRD, FIRT, and Raman spectra show that the yellow scapolite has the same structure as the colorless scapolite. The yellow color of scapolite is caused by Fe3+ and when the Fe content is low it is colorless. Yellow scapolite has about three times the Fe content of colorless scapolite. Under the excitation of long-wave and short-wave ultraviolet light, scapolite forms a strong and wide excitation peak in the blue-violet region centered at approximately 410 nm, which is due to the 4f1 → 5d1 of Ce3+, resulting in blue fluorescence.

Achieving Good Bonding Strength of the Cu Layer on PET Films by Pretreatment of a Mixed Plasma of Carbon and Copper.

Cu layers were fabricated on PET films with and without pretreatment by a mixed plasma composed of carbon and copper using a magnetron sputtering technique for potential application as the flexible copper-clad laminate (FCCL) in 5G technology. In order to evaluate the effect of carbon plasma on the composited layer, the graphite target current was adjusted from 0.5 to 2.0 A. The microstructures and properties of Cu layers on PET films with different treatments were measured by an X-ray powder diffractometer, X-ray photoelectron spectroscope, Raman spectroscope, scanning electron microscope, transmission electron microscope, scratching test, indentation test, and four-probe detector. The results showed that the organic polymer carbon structure on the surface of PET films was changed to inorganic amorphous carbon due to the effect of the carbon plasma. At the same time, the active free radicals formed in the transition process react with metal copper ions to form organometallic compounds. Under the treatment of a mixed plasma of carbon and copper, the C/Cu mixed layer was formed on the PET film at the top of the substrate. Due to the presence of C/Cu mixed interlayers, the bonding strengths between the final Cu layers and the PET film substrates were improved, and the strongest bonding strength appeared when the graphite target current was 1.0 A. In addition, the presence of the C/Cu mixed interlayer enhanced the toughness of the Cu layer on PET film. It was proposed that the good bonding strength in combination and the enhanced toughness for the Cu layer on a PET film was due to the formation of a C/Cu mixed interlayer induced by the pretreatment of a mixed plasma of carbon and copper.

Visible active narrow/narrow band gap CuO/Cu2SnS3 nanoheterostructures as efficient nanophotocatalysts.

Binary metal oxide/ternary metal sulphide based nanoheterostructures, such as CuO/Cu2SnS3, were prepared via a modified hydrothermal route. The prepared nanoheterostructures were characterized using scanning electron microscopy, x-ray powder diffractometer, XPS, ultraviolet-visible spectroscopy, isoelectric point, and Brunauer-Emmett-Teller techniques. The XPS results revealed the successful incorporation of Cu+/Cu2+ with different ratios. The prepared heterostructures were tested as solar active photocatalysts for Methylene Blue (MB) photodegradation. The CuO/Cu2SnS3 (20% Cu2SnS3/80% CuO) photocatalytic results exhibited a high photodegradation efficiency (90%) after 60min. In addition, the photonic efficiency values (ζ) were calculated to be 15.9%, 44%, and 61.4% for CuO, Cu2SnS3, and CuO/Cu2SnS3 nanoheterostructures, respectively. In addition, the reactive oxidative species were detected by the trapping experiments to get a clear insight about the photocatalytic reactivity factors. Total organic carbon (TOC) was conducted to confirm the safe photodegradation of MB dye without the formation of colorless hazardous (95.5% TOC removal). Based on the electronic band structure, the mechanism of photodegradation was investigated. The currently investigated heterostructure system is narrow/narrow bandgap, which fulfills the two contradictory conditions in terms of high solar photocatalytic activity and overcomes the rapid recombination process.

Synthesis of new heterocyclic N'-(2‑hydroxy-3-methoxybenzylidene)-4-oxopiperidine-1-carbohydrazide and its mononuclear metal (II) complexes: Spectroscopic characterization, fluorescence, DFT, thermo-kinetic, and antimicrobial studies

New hydrazone Schiff base N'‑(2‑hydroxy-3-methoxybenzylidene)-4-oxopiperidine-1-carbohydrazide (H2L), synthesized by the condensation reaction of 2‑hydroxy-3-methoxybenzaldehyde (HMB) and 4-oxopiperidine-1-carbohydrazide (CPH), form mononuclear complexes, [Mn(HL)(Cl)(H2O)2], [Co(HL)(Cl)(H2O)2], [Ni(HL)(Cl)(H2O)2] and [Cu(HL)(Cl) (H2O)2]. The formation of ligand was confirmed by elemental analysis, melting point, IR, 1H and 13C NMR, and ESI-Mass spectroscopy, Cu(II) complex was further examined by ESR spectroscopy. Other properties, like, molar conductance, IR, electronic spectra, magnetic susceptibility, DFT, powder X-ray diffractometer, fluorescence and thermal analysis have also been studied. Powder X-ray diffraction patterns inferred that compounds are nanocrystalline nature. Surface morphology further support this observation. All compounds show good absorption properties and in excited state at (λ334nm), the fluorochromes of the ligand and its metal (II) complexes emitted a good fluorescence emission with the resonation of 0.2 nm in (λ527–545 nm) region. The DFT B3LYP/6–311G+(d,p) calculations were carried out for the determination of the optimized structure of ligand (H2L) and its metal complexes. The frontier MOs energies data indicated good charge transfer (CT) from HOMO to LUMO. Thermal study of complexes monitored under nitrogen atmosphere led us to determine the activation parameters of various decomposition steps. On the basis of activation energy evaluated by Coat-Redfern relation, thermal stability order was found to be Ni(II)<Cu(II)<Mn (II)<Co(II). The ligand and complexes have also been screened for their antibacterial and antifungal potency and metal complexes showed higher activity against multi-stranded microorganisms viz. gram -ve bacteria (Escherichia coli and Salmonella. typhi), gram + ve bacteria (Staphylococcus aureus, Bacillus substilis) and fungal species (Candida albicans, Aspergillus niger).

The preparation and smart electrorheological behavior of MOF-Ti@PANI core-shell nanoparticles

In this paper, a kind of core–shell composite nanoparticles for electrorheological (ER) fluid was successfully prepared and showed good ER effect. The material possesses the high specific surface area and low density of metal organic frameworks (MOFs), and combines with the excellent dielectric properties of polyaniline (PANI). PANI precursors were prepared by a rapid mixing method, and then MOF-Ti (an MOF containing Ti) grew in situ on PANI under the solvothermal conditions. The MOF-Ti@PANI composite nanoparticles with core–shell structure were generated. These characteristics of PANI and MOF-Ti are conducive to stronger interfacial polarization of nanoparticles, which in turn leads to a good ER effect. The nanoparticle morphology as well as its ER and dielectric properties was modulated by using different amounts of PANI addition. The addition amount of PANI had a certain effect on the particle morphology, which was proved by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). We also determined particle size at the nanoscale in this process. The measured results of the X-ray powder diffractometer (XRD) are consistent with the characteristic peaks of MIL-125 (a kind of MOF-Ti). The internal chemical structure of the material and the chemical environment of the elements were analyzed using Fourier infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). Finally, the ER and dielectric properties of the nanoparticles in ER Fluids were investigated using high-speed rotational rheometry and broadband dielectric spectroscopy. The analysis revealed that the MOF-Ti@PANI core–shell nanoparticles have good ER properties under proper coating. For the core–shell modified MOFs, it is expected to be a promising development direction in the field of ER materials.

Synthesis and up-conversion luminescence of Er3+ and Yb3+ co-doped La14W8O45 phosphors

Pure phase orthorhombic Er3+ and Yb3+ co-doped La14W8O45 up-conversion luminescent materials were successfully prepared by the hydrothermal method combined with calcination treatment. The structures, morphology, and optical properties of the samples were analyzed by X-ray powder diffractometer (XRD), scanning electron microscope (SEM), ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS), and up-conversion photoluminescence spectroscopy (UPL) with a 980 nm laser. XRD results indicated that the obtained samples are single-phase orthorhombic Er3+ and Yb3+ co-doped La14W8O45 crystals. SEM results showed that the prepared sample exhibits an irregular and melted polyhedral-like morphology with agglomeration in submicron size of particles approximately 50–200 nm. UV–vis DRS results revealed that the La14W8O45 crystal is a direct semiconductor with an optical band gap of 3.84 eV. The prepared Er3+ and Yb3+ co-doped La14W8O45 crystals exhibit strong up-conversion emission peaks at about 526 nm, 548 nm, and 660 nm under 980 nm laser excitation. The intensity of up-conversion luminescence is affected by the Er3+ doping concentration, and concentration quenching will be observed due to the cross-relaxation (CR) process when the Er3+ doping content is above 1%. The pumping power dependence of the luminescence indicated that the up-conversion emissions of samples are excited by a two-photon absorption process. The color coordinates of the samples are located in the green light region.

Self-powered photodetector based on direct vapour transfer (DVT) method grown tin selenide (SnSe) crystals

The 2D-TMDC (transition metal dichalcogenides) formed thin films have attracted more attention due to their tuneable optoelectronic properties that improved the application of the photo-sensing device. SnSe single crystals were grown in the current work utilising the direct vapour transfer (DVT) technique. The elemental proportion and 2D surface structural analysis of grown crystal SnSe are carried out using Energy-dispersive X-ray analysis (EDAX) and Scanning electron microscopy (SEM). The orthorhombic crystal system of grown SnSe confirmed by high resolution transmission electron microscopy (HRTEM), and Powder X-ray diffractometer (XRD), the regular spot patter of HRTEM and Sharp pick in XRD graph indicated that the SnSe are highly crystalline in nature. The X-ray photoelectron spectroscopy (XPS) is carried out for confirming the binding states and chemical composition of grown SnSe single crystal. The A1g, β3g and A2g vibration mode of SnSe single crystal confirmed using Raman Spectroscopy. In the application part, SnSe exhibits high photodetection capability under the monochromatic and polychromatic light sources at self-bias mode (photoresponsivity of 71.20 µA/W and photo-detectivity of 3.45 × 108 Jones). The optoelectronic characteristics of SnSe devices including dependent photo-responses have also been carried out. Additionally, the important factors affecting photodetection characteristics are assessed, including photocurrent (Iph), sensitivity (S), photoresponsivity (R), Specific detectivity (D*), rise time, and decay time.

Fabrication of Selective and Sensitive Hydrazine Sensor Using Sol-Gel Synthesized MoSe2 as Efficient Electrode Modifier

Due to its hazardous nature, the determination of hydrazine is of great significance. This study designed and fabricated a hydrazine electrochemical sensor. Two-dimensional (2-D) molybdenum diselenide (MoSe2) has been synthesized by using the sol-gel method. The phase purity and formation of MoSe2 was determined by a powder X-ray diffractometer. The surface morphological characteristics of the MoSe2 were studied by scanning electron microscopy. The presence of Mo and Se elements in the synthesized MoSe2 was checked by energy dispersive X-ray spectroscopy. The glassy carbon (GC) electrode (3 mm) was modified with the prepared MoSe2 via a drop-cast approach. This MoSe2-glassy carbon (MoSe2-GC) electrode was used as the working electrode for the hydrazine sensing application. The electrochemical sensing properties of the fabricated MoSe2-GC were analyzed by linear sweep voltammetry and cyclic voltammetry. The MoSe2-GC has shown a sensitivity of 0.68 µA/µMcm2 and a detection limit of 0.091 µM. In addition, MoSe2-GC also has good selectivity toward hydrazine determination in the presence of various interfering compounds. The excellent electro-catalytic behavior of MoSe2 is solely responsible for this enhanced sensing performance of MoSe2-GC.

Synthesis, structural and morphological characterization of α-Bi2O3 nanostructure for photocatalytic hydrogen production and degradation of organic pollutants

This study used a solution combustion approach to develop α-Bi2O3 nanostructure with tunable structural phase and surface morphology for photocatalytic hydrogen production and methylene blue (MB) photodegradation under artificial visible light (50 W LED light). Powder X-ray diffractometer (PXRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), UV–Visible diffuse reflectance spectroscopy (DRS UV–Vis), and Fourier transform infrared (FTIR) spectroscopy were used to investigate the structural, morphological, and optical properties of the prepared α-Bi2O3 photocatalysts. XRD patterns and FTIR analysis showed excellent crystalline structure and high purity of the prepared samples. SEM images demonstrated the morphological transformation of α-Bi2O3 from nanoball to nanosheet with increasing the fuel and oxidizer ratios. DRS UV–Vis analysis revealed excellent optical properties of the prepared α-Bi2O3 nanostructures. Under 50 W LED light irradiation, the as-prepared α-Bi2O3 demonstrated 92% photodegradation of MB in 30 min and 45 μmol of photocatalytic hydrogen production in one hour. The result indicates a morphological-dependent photocatalytic efficiency. This study paves the way for developing photocatalytic semiconductors with various morphologies via a solution combustion route for efficient photocatalysts.

Synthesis, structural, morphological, functional, optical and particle size enhanced cadmium oxide nanoparticles on electro-chemical applications

The co-precipitation technique of cadmium oxide (CdO) nanoparticles in aqueous solutions at high temperatures was employed in this investigation. The potential for electrochemical activity was studied. Thus, a powder X-ray diffractometer was used to quantitatively evaluate the Scherer-calculated crystallite grain size and dislocation density. Scanning electron microscopy imaging and analysis revealed the distinct shape and structure of CdO nanoparticles. The above-mentioned nanoparticles were sorted into their respective functional groups by FTIR spectroscopy. The CdO nanoparticle size was measured in the nanometre range using a dilution-based particle size analyzer. There was a significant improvement in the CdO nanoparticles' ability to absorb UV-visible light. Their unique colours of light were made visible in the spectrum of their fluorescence emission, which allowed them to be clearly authenticated. An electrochemical probe into the phenomenon of super capacitance has revealed its fundamental characteristics. This CdO nanomaterial might be useful for scientific investigation.

Microstructure and mechanical properties of 3D-printed dental Co-Cr alloys, produced by selective laser melting

Purpose The aim of present work was to investigate microstructure and mechanical properties of 3D printed by selective laser melting (SLM) Co- Cr alloys, intended for additive manufacturing in dentistry. Methods A scanning electron microscope (SEM), equipped with an integrated Energy-Dispersive X-Ray Spectroscopy (EDS) system was used for investigation of the surface morphology and elemental composition of the 3D- printed Co-Cr sample. The X-ray structural analysis of the 3D - printed Co-Cr sample was made with a Bruker D8 Advance powder X-ray diffractometer. An Atomic force microscopy (AFM) was used for investigation of the surface topography of the sample. Tensile test, a three-point bending test, and nanoindentation experiments were used for investigation of mechanical properties of the 3D-printed Co-Cr sample.The influence of two different strain rates (1 mm/min and 60 mm/min) on the flexural strength was investigated as well. Results Higher values of indentation hardness (6.76 GPa), tensile strength (1016 MPa), yield strength (636.5 MPa) and flexural strength (1908 and 1891 MPa) of the produced by selective laser melting Co-Cr alloys have been obtained compared to cast Co-Cr and Cr-Ni alloys. It was found that increasing the strain rate from 1 mm/min to 60 mm/min caused a proportional increase in recorded flexural strength of ~0.9%. Conclusions The obtained results showed that the laser-sintered Co-Cr alloy can fully replace the cast Co-Cr alloy in dentistry, regards as of its good mechanics properties, as well as the high precision of the final product.

Peculiarities of BaTiO3 in electronic and X-Ray analysis

We have studied the most promising material of semiconductor nanotechnology BaTiO3. Barium titanate, a compound of barium and titanate oxides, was studied in three dimensional varieties: in the form of powder with a diameter of 1÷1.5 mm, solid BaTiO3 target with a diameter of 76 mm and thin films obtained by ion-plasma sputtering with a thickness d ≈ 10÷50 nm, on the Si (III) surface. The spectra were recorded at room temperature on an XRD-6100 powder X-ray diffractometer, and spectra were taken from room temperature to 673 K, and the amorphous and crystalline phases of this substance were determined based on the obtained X-ray diffraction spectrograms. The peaks of the spectrogram based on the Miller indices and interplanar distances dhkl show complex compounds that are newly formed on the basis of barium titanate.

Green synthesis of silver nanoparticles from peel extract of Chrysophyllum albidum fruit and their antimicrobial synergistic potentials and biofilm inhibition properties.

Current methods for green synthesis of metal nanoparticles often require continuous harvesting of fresh bio-materials for every synthesis cycle. Practices and procedures that economize bio-materials need to be employed if green synthesis could become a sustainable and eco-friendly method for synthesizing metal nanoparticles. This study explores Chrysophyllum albidum peels (mostly regarded as waste) to prepare silver nanoparticles (Alb-AgNPs). The technique employed in the synthesis allows repeated use of the peels, thus, reducing the heavy dependence on bio-materials. The optical and structural properties of the Alb-AgNPs were studied with Scanning electron microscope, Fourier transform infrared spectrometer, UV-Vis spectrophotometer and powder X-ray diffractometer. The antimicrobial properties of the Alb-AgNPs were studied with selected microorganisms namely; S. aureus, E. coli, K. pneumoniae, B. subtilis, S. mutans, P. aeruginosa, S. typhi, and Candida albicans. High inhibitory activity against the microorganisms were exhibited with MICs ranging from 15.62 to 1000µg/mL. Again, the Alb-AgNPs showed the ability to enhance the efficacy of standard antimicrobial agents. The results of the combined interaction with standard antibacterial and antifungal agents ranged from synergistic to antagonistic effects against the tested microorganisms. In addition, the Alb-AgNPs could serve as a biofilm inhibitor with the highest percent inhibition of about 92% against methicillin-resistant Staphylococcus aureus. The results from this study thus provide access to the simple, sustainable, economic and eco-friendly synthesis of silver nanoparticles with efficient antimicrobial properties as drug candidates as a means of overcoming the prevailing antibiotic resistance menaces.

Synthesis, morphological, structural, functional, optical and computational properties of nickel oxide nanoparticles using hydrothermal method

In this work, hydrothermal synthesis of NiO nanoparticles in aqueous solutions at higher temperatures was used. An investigation of its optical and electrical capabilities might be done in many ways. As a result, the size and structure of NiO nanoparticles were characterised using a scanning electron microscope. A powder X-ray diffractometer was used to measure experimentally the crystallite grain size and dislocation density, which were computed using the Scherer formula. The functional groups of the title nanoparticles were easily distinguishable in the FTIR spectrum. After optical absorption analyses, NiO nanoparticles were shown to have optimised UV-Visible transmittance. The density functional theory (B3LYP) was used to compute the bonding of molecular properties of NiO in the ground state using the basis sets 6-311+G (d, p) and 6-311++G (d, p). There is evidence of charge transfer in molecules based on the computed molecular electrostatic potential (MESP), Thermodynamic properties, HOMO and LUMO energies determined. The scientific applications of this NiO nanomaterial would be well served by this material.

Adhesion Performance between Solid Waste and Bitumen Based on Surface Energy Theory

Natural aggregates are gradually experiencing resource shortages and price accumulations with the rapid development rate of the highway construction industry. Therefore, new materials with social and economic benefits must be identified to replace natural aggregates. Limestone was selected as the representative of natural aggregates, and waste glass and waste ceramics were chosen as the representatives of solid waste in this article. This was undertaken to compare their physical and mechanical properties and the adhesion performance between bitumen and aggregates and to investigate the applicability of solid waste in asphalt pavement. The chemical and mineral compositions of these materials were tested by an X-ray fluorescence spectrometer and an X-ray powder diffractometer. The adhesion performance between bitumen and aggregates was analyzed by establishing adhesion and spalling models based on surface energy theory. Results show that the sizes of glass and ceramics must be small, characteristics which are unsuitable for use in high-grade roads. Glass and ceramics are more adhesive to bitumen than limestone and are suitable for areas with a considerable amount of rainfall and insufficient drainage systems. This article can promote the recycling of glass and ceramics and also provide a research idea for verifying the suitability of other solid waste in asphalt pavement.

The synthesis of Er3+/Yb3+/K+ triple-doped NaYF4 phosphors and its high sensitivity optical thermometers at low power

Optical Thermometry is popular among researchers because of its non-contact, high sensitivity, and fast measurement properties. In the present experiment, Er3+/Yb3+/K+ co-doped NaYF4 nanoparticles with different K+ concentrations were synthesized by solvothermal method, and the samples showed bright upconversion green emission under the excitation of a 980 nm laser. The powder X-ray diffractometer and transmission electron microscope were used to characterize the crystal structure and its surface morphology, respectively. The spectral characteristics of nanoparticles with K+ doping concentration from 10% to 30% (Molar ratio) were investigated by fluorescence spectroscopy, and it was observed that the fluorescence intensity reached the maximum at the K+ concentration of 20%, after which the intensity weakened when the K+ content continued to increase. According to the dependence between the luminescence intensity of the sample and the laser power density and fluorescence lifetime, the intrinsic mechanism was carefully investigated. Temperature-dependent spectra of the samples were recorded in the temperature range of 315–495 K， and the maximum values of absolute sensitivity (Sa) and relative sensitivity (Sr) were measured at 0.0041 K−1 (455 K) and 0.9220%K−1 (315 K). The experimental results show that K+/Er3+/Yb3+ triple-doped NaYF4 green fluorescent nanoparticles (GFNs) have good prospects for applications in display devices, temperature sensing, and other fields.

Mechanochemically activated microscale zero-valent iron with carboxymethylcellulose for efficient sequestration of phosphate in aqueous solution

This study modified microscale zero valent iron (mZVI) using hydrophilic sodium carboxymethyl cellulose (CMC) via mechanical ball milling method, which was donated as CMC-mZVI, and compared the phosphate removal performance of mZVI and CMC-mZVI. Characterization results of X-ray powder diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), EDS-mapping images of CMC-mZVI demonstrated that the dominant crystalline structure of mZVI did not alter significantly after the ball-milling process and CMC could be adsorbed on the surface of mZVI. Further phosphate (PO43-) removal experimental results revealed that the PO43- removal percentage of CMC-mZVI within 360 min was 99.99 %, which was much higher than that of mZVI (75.23 %). Subsequently, this study analyzed the concentration of ferrous ions and total iron ions dissolved by mZVI and CMC-mZVI, compared the high resolution X-ray photoelectron spectroscopy (HR-XPS) of mZVI and CMC-mZVI before and after the phosphate removal, and characterized the affinity of CMC-mZVI (or mZVI) to water by testing the static contact angle between CMC-mZVI (or mZVI) and water. The above results suggested that the existence of CMC on the surface of mZVI could promote the hydrophilic property of mZVI, resulting the enhancement of ferrous ions and total iron ions dissolution by 8 and 8.78 times than that of mZVI, and the rapid co-precipitation of phosphate. This study provided an environmentally friendly and effective method to improve the reactivity of commercial mZVI powder, and contributed to the wide application of mZVI technology in the field of environmental remediation.