Powder X-ray Diffraction Profiles Research Articles

Hydrophobization of surfaces on cellulose nanofibers by enzymatic grafting of partially 2-deoxygenated amylose

Recently, attention has been paid to cellulose nanofibers, such as 2,2,6,6-tetramethylpiperidine-1-oxyl-oxidized cellulose nanofibers (TOCN), as new bio-based materials. In addition, hydrophobized surface on TOCNs can be expected to provide new applications. Based on our previous finding that partially 2-deoxygenated (P2D)-amylose, which was synthesized by GP-catalyzed enzymatic copolymerization of D-glucal with α-d-glucose 1-phosphate (Glc-1-P) as comonomers, was hydrophobic, in this study, hydrophobization of surfaces on TOCNs was investigated by the GP-catalyzed enzymatic grafting of P2D-amylose chains on TOCNs. After maltooligosaccharide primers were modified on TOCNs, the GP-catalyzed enzymatic copolymerization of D-glucal with Glc-1-P was performed for grafting of P2D-amylose chains. 1H NMR spectroscopic analysis confirmed the production of P2D-amylose-grafted TOCNs with different 2-deoxyglucose/Glc unit ratios. The powder X-ray diffraction profiles of the products indicated that the entire crystalline structures were strongly affected by the unit ratios and chain lengths of the grafted polysaccharides. The SEM images observed differences in nanofiber diameter in the reaction solutions and surface morphology after film formation, due to grafting of P2D-amylose chains from TOCNs. The water contact angle measurement of a cast film prepared from the product indicated its hydrophobicity.

Enhanced photocatalytic, photoluminescence and fingerprint properties of Dy3+ ions doped BaZrO3 nanopowders for multifunctional applications

In the present investigation photoluminescent, photocatalytic and advanced forensic applications of hydrothermally prepared BaZrO3:Dy3+ (1–9 mol%) nanopowders were studied in detail. Fresh green Aloe Vera (AV) gel was used as capping agent for the preparation of NPs. The pure cubic phase was observed by powder X-ray diffraction (PXRD) profiles. Fourier transform infrared (FTIR) was utilized to investigate the functional groups present in the prepared NPs. The modification in surface morphology was investigated by using Field emission scanning electron microscope (FESEM) images. The grain size was evaluated by utilizing transmission electron microscope (TEM) images and found to be around 48 nm. Further, with the help of high-resolution TEM (HR-TEM) images the interplanar distance was calculated and found to be 0.32 nm. Photoluminescence (PL) studies were carried out in detail using excitation and emission spectra. The maximum intensity was detected for peak 388 nm ascribed to 6H15/2 → 4I13/2 + 4F7/2 of Dy3+ transition under 574 nm emanation wavelength. The obtained emanation spectra consist of 3 characteristics peaks of Dy3+ ions at 480, 574 and 666 nm attributed to 4F9/2→ 6H15/2, 4F9/2→ 6H13/2 and 4F9/2→ 6H11/2 respectively. The PL intensity increases up to 7 mol% dopant ion weight and afterwards it decreases due to concentration quenching phenomena. The dipole–dipole interaction was responsible for this quenching. The color coordinates results in white emission witnessed from the Commission International de I'Eclairage (CIE) and correlated color temperature (CCT) diagrams. The average CCT value was observed around 4836 K. Further, the color purity (CP) and external quantum efficiency (QE) was estimated and found to be 86 % and 64 % respectively. The photocatalytic degradation activity was also studied for the prepared powders and found that, the optimum degradation was observed till 180 min. The kinetics studies revealed that, the present powders were in agreement with the 0th order with estimated ko = 0.015 with R2 value of 0.98 respectively. The powders were also explored for their latent fingerprint (LFP) visualization on various porous and non-porous surfaces and found that, the powders exhibited all types of fingerprint ridge details including the 3rd type such as sweat pores and scar. The observed all outcomes specify that, the prepared powders can be used as a potential candidate for the fabrication of white LEDs (wLEDs), excellent photocatalyst and fingerprint visualization.

Investigating the thermal behavior of acyclovir

Viruses are a significant health, economic and social issue. Acyclovir (ACV) is an antiviral agent analogous to the guanine nitrogenous base that acts by interrupting the multiplication of DNA of virus in infected cells. The thermal decomposition mechanism of ACV was evaluated by thermoanalytical techniques Thermogravimetry/derivative thermogravimetry (TG/DTG), differential thermal analysis (DTA), evolved gas analysis by thermogravimetry coupled to vibrational infrared spectrometry in gas phase (TG-FTIR), differential scanning calorimetry (DSC), hot stage microscopy (HSM) and mass spectrometry (MS). TG/DTG and DTA curves were performed under N2 and air atmospheres. Under N2, four stages of mass loss were observed from the TG curve between 523-1273 K, while under air decomposition occurred in a similar way, however, the additional burning of carbonaceous material was found in air. DSC curves were obtained in heat-cool-heat mode, from 233 to 543 K, under N2 atmosphere and presented two endothermic peaks related to water loss and phase transition followed by exothermic crystallization of a new form, followed by melting associated with decomposition in agreement with HSM images. Powder X-ray diffraction (PXRD) profiles confirmed the phase transitions. From the TG-FTIR characterization, it was suggested that decomposition undergoes by release of water, 1,3-dioxolane, isocyanic acid, carbon dioxide, carbon monoxide, and ammonia. MS spectrum of the residue collected at 543 K revealed the presence of guanine free base as decomposition product in agreement with the release of dioxolane ring in gas phase.

Defect rocksalt structures in the La-Na-N system.

Sodium azide (NaN3) is a versatile nitrogen source that can be used for the synthesis of new nitrides under high-pressure and temperature conditions. Reactions between lanthanum nitride (LaN) and sodium azide (NaN3) at 800°C under 8 GPa pressure have led to the discovery of two defect rocksalt phases which are the first reported ternaries in the La-Na-N system. Preliminary structure assignments have been made based on fits to powder X-ray diffraction profiles. One phase is La1-xNa3xN with vacancies at octahedral La sites and interstitial tetrahedral Na cations. This phase has a tetragonally distorted rocksalt structure (space group I4[Formula: see text]mmm, a = 3.8704(2) and c = 5.2098(3) Å for nominal x = 0.10) and the distortion decreases with increasing Na content (space group I4[Formula: see text]mmm, a = 3.8060(2) Å, c = 5.2470(3) Å for nominal x = 0.14), further giving a cubic phase (a = 5.3055(2) Å) for nominal x = 0.25. This coexists with another cubic [Formula: see text] phase (a = 5.1561 (5) Å), tentatively identified as rocksalt 'NaN1/3' stabilized by a small amount of La; NaLayN(1+3y)/3 with y ≈ 1%. These initial investigations reveal that the high-pressure La-Na-N phase diagram may be rich in defect rocksalt-type materials although further work using neutron diffraction will be needed to confirm the structures. This article is part of the theme issue 'Exploring the length scales, timescales and chemistry of challenging materials (Part 1)'.

Crystal Structure of Poly(7-heptalactone)

The crystal structure of poly(7-heptalactone) (PHL) is presented. PHL has been synthesized by a combination of ring-opening polymerization of η-heptalactone and reversible addition–fragmentation chain transfer polymerization using diphenyl phosphate as catalyst. The noncommercial available η-heptalactone monomer has been prepared by oxidation of cycloheptanone. The crystal structure of PHL has been determined by analysis of the X-ray powder diffraction profiles and of the electron diffraction patterns of single crystals and calculations of lattice energy. The structure has been refined with the Rietveld full-profile refinement. Chains in trans planar conformation are packed in an orthorhombic unit cell with axes a = 7.37 Å, b = 5.05 Å, and c = 10.07 Å according to the space group symmetry P21.

Investigation on electrical transport and dielectric relaxation mechanism in TbCrO3 perovskite orthochromite

Herein, the TbCrO3 (TCO) chromite was synthesized by the sol-gel auto-combustion route and sintered at 900 °C. The Rietveld analysis of the room temperature powder X-ray diffraction profile confirmed the single-phase formation of the material crystallized in the orthorhombic phase of the perovskite structure with Pbnm space group symmetry. The surface morphology, the elemental composition, and the chemical states of the compound were investigated by field emission scanning electron microscopy, energy dispersive X-ray analysis, and X-ray photoelectron spectroscopy, respectively. The electronic density of states, band structure, and electron density were analyzed by Density Functional Theory. The electrical transport and dielectric relaxation mechanism were investigated using complex impedance spectroscopy over the experimental frequency and temperature ranging from 40-1.2x106Hz and 138−273 K, respectively. Two semicircular arcs in the impedance complex plane plots were modeled to an equivalent circuit configured by RG∥QG+RGB∥QGB which were attributed to the contributions of the highly resistive grain boundaries and relatively conducting grains in the material. The electrical conductivity as a function of frequency followed Jonscher’s universal power law behavior and an increasing nature of the temperature-dependent frequency exponent suggested small polaron hopping as the electrical conduction mechanism of the material. The least capacitive response of the TCO system was investigated by the complex electrical modulus formalism and the frequency-dependent imaginary modulus spectra were modeled by the Kohlrausch–Williams–Watts function, which resolved the thermally activated peaks of bulk and interface effects to the dielectric relaxation mechanism. The dielectric constant exhibited Maxwell-Wagner interfacial polarization effects and the dielectric loss factor showed frequency dispersion at all temperatures.

Photocatalytic activity of sol-gel self-combustion derived MCr2O4 (M= Mg, Ni) spinel chromites for photodegradation of organic dyes

Herein, MCr2O4 (M= Mg, Ni) chromite photocatalysts were synthesized via sol-gel self-combustion route and sintered at 1000 °C. The Rietveld refined X-ray powder diffraction profiles confirmed the single-phase formation of MgCr2O4 (MCO) and NiCr2O4 (NCO) chromites crystalized in the face-centered cubic and tetragonal spinel structures having Fd3̅m and I41/amd space group symmetries, respectively. The polyhedral geometrical shape and sizes of the grains were determined by the surface micrographs obtained from the field emission scanning electron microscopy (FESEM). The oxidation states and cations distribution investigated by the x-ray photoelectron spectroscopic (XPS) analysis professed the charge balance in the compounds. The photocatalytic performance of the chromite nanoparticles was examined using malachite green (MG) and crystal violet (CV) organic dyes at 5 ppm in solutions irradiated under sunlight. The photodegradation studies revealed the degradation efficacy of 70% and 85% for MCO, and 90% and 95% for NCO catalysts for the degradation of the MG and CV dye pollutants within 120 min, without utilizing H2O2. Furthermore, the kinetic studies were carried out and the experimental equilibrium data were observed to follow the pseudo-second-order and intraparticle diffusion models which described the synergetic adsorption-photodegradation procedures. Thus, NCO exhibited a high percentage for the removal of MG and CV organic pollutants compared to MGO, indicating that the tetragonally distorted NiCr2O4 nanocatalyst is an efficient candidate for the potential environmental purification of toxic organic contaminants.

Magnetic characterization of La3+ and Li1+ co-substituted M-type strontium hexaferrite

Effects of stoichiometric La3+–Li1+ co-substitution on magnetic properties of M-type strontium hexaferrites Sr1-xLaxFe12-x/2Lix/2O19 (x = 0, 0.25, 0.4, 0.5, 0.6) have been studied by using crystallographic and magnetic measurements. Samples were prepared thru conventional ceramic technique and their powder X-ray diffraction profiles were checked by the Rietveld method using GSAS package. Field emission scanning electron microscopy images show that lithium addition derives the enhanced degree of grain separation, which significantly affects the coercivity and anisotropy constant as examined by vibrating sample magnetometer measurement. 57Fe Mössbauer spectra of the samples show that Li1+ ions preferentially occupy the 2a sites, which causes the decrease of MS with lithium addition.

Vine-Twining Inclusion Behavior of Amylose towards Hydrophobic Polyester, Poly(β-propiolactone), in Glucan Phosphorylase-Catalyzed Enzymatic Polymerization.

This study investigates inclusion behavior of amylose towards, poly(β-propiolactone) (PPL), that is a hydrophobic polyester, via the vine-twining process in glucan phosphorylase (GP, isolated from thermophilic bacteria, Aquifex aeolicus VF5)-catalyzed enzymatic polymerization. As a result of poor dispersibility of PPL in sodium acetate buffer, the enzymatically produced amylose by GP catalysis incompletely included PPL in the buffer media under the general vine-twining polymerization conditions. Alternatively, we employed an ethyl acetate-sodium acetate buffer emulsion system with dispersing PPL as the media for vine-twining polymerization. Accordingly, the GP (from thermophilic bacteria)-catalyzed enzymatic polymerization of an α-d-glucose 1-phosphate monomer from a maltoheptaose primer was performed at 50 °C for 48 h in the prepared emulsion to efficiently form the inclusion complex. The powder X-ray diffraction profile of the precipitated product suggested that the amylose-PPL inclusion complex was mostly produced in the above system. The 1H NMR spectrum of the product also supported the inclusion complex structure, where a calculation based on an integrated ratio of signals indicated an almost perfect inclusion of PPL in the amylosic cavity. The prevention of crystallization of PPL in the product was suggested by IR analysis, because it was surrounded by the amylosic chains due to the inclusion complex structure.

Preparation of Nanochitin Films with Oligochitin Graft Chains

Even nowadays, chitin is mostly unutilized as a biomass resource, although it is abundantly present in nature. To develop an efficient method to use chitin as the component in new functional bio-based materials, in this study, we investigated the preparation of a flexible nanochitin (chitin nanofiber, ChNF) film with oligochitin dihexanoate graft chains. The parent ChNF film was prepared by regeneration of a chitin ion gel with an ionic liquid, 1-allyl-3-methylimidazolium bromide (AMIMBr), using methanol and subsequent filtration. However, the obtained film showed a quite brittle nature, probably because of the high crystallinity of the chitin chains. To reduce the crystallinity, oligochitin dihexanoate, which was provided by partial depolymerization of the parent chitin dihexanoate under acidic conditions, was modified on the partially deacetylated ChNF film by reductive amination. The introduction of the oligochitin dihexanoate graft chains was supported by 1H NMR and IR measurements. The powder X-ray diffraction (XRD) profile of a film, which was obtained from an aqueous acetic acid suspension of the grafted product, indicated a reduction in chitin crystallinity, which contributes to the disappearance of nanofiber morphology and enhancement of flexibility. The removal of hexanoyl groups from the film was performed by treatment with aqueous NaOH. The IR and XRD measurements of the obtained film suggested the compete dehexanoylation and the reformation of the chitin crystalline structure, respectively. This study provides a method to fabricate new bio-based graft and soft materials entirely comprising chitin moieties.

Short-Chain Mono-Alkyl β-D-Glucoside Crystals-Do They Form a Cubic Crystal Structure?

Three-dimensional liquid crystal (LC) phases, cubic LC phases, have been extensively studied as fascinating molecular assembled systems formed by amphiphilic compounds. However, similar structures have only been seen in rare instances in lipid crystal states in glycolipid crystal studies. In this study, we prepared short-chain n-alkyl β-D-glucosides (CnG) with an alkyl chain length n ranging from 4 to 6 and investigated their crystal structures. First, differential thermal analysis (DTA) and thermogravimetric analysis (TG) measurements showed the formation of hydrated crystals for C4G and C5G, respectively. Second, the crystal structures of CnG (n = 4, 5, 6) in both anhydrous and hydrated states were examined using a temperature-controlled powder X-ray diffraction (PXRD) measurement. Both hydrate and anhydrous crystals of C4G and C5G with critical packing parameters (CPPs) less than 0.33 formed cubic crystal phases. Bilayer lengths, calculated from the main diffraction peaks in each PXRD profile, depended on crystalline moisture for C5G, but no significant change was confirmed for C4G, indicating that the properties of each hydrophilic layer differ. However, C6G with a CPP of 0.42 formed a crystal structure with a modulated lamellar structure similar to C7G and C8G with similar CPP values. Thus, a glycolipid motif concept with a cubic crystal structure was demonstrated.

Multivariate versus traditional quantitative phase analysis of X-ray powder diffraction and fluorescence data of mixtures showing preferred orientation and microabsorption.

In materials and earth science, but also in chemistry, pharmaceutics and engineering, the quantification of elements and crystal phases in solid samples is often essential for a full characterization of materials. The most frequently used techniques for this purpose are X-ray fluorescence (XRF) for elemental analysis and X-ray powder diffraction (XRPD) for phase analysis. In both methods, relations between signal and quantity do exist but they are expressed in terms of complex equations including many parameters related to both sample and instruments, and the dependence on the active element or phase amounts to be determined is convoluted among those parameters. Often real-life samples hold relations not suitable for a direct quantification and, therefore, estimations based only on the values of the relative intensities are affected by large errors. Preferred orientation (PO) and microabsorption (MA) in XRPD cannot usually be avoided, and traditional corrections in Rietveld refinement, such as the Brindley MA correction, are not able, in general, to restore the correct phase quantification. In this work, a multivariate approach, where principal component analysis is exploited alone or combined with regression methods, is used on XRPD profiles collected on ad hoc designed mixtures to face and overcome the typical problems of traditional approaches. Moreover, the partial or no known crystal structure (PONKCS) method was tested on XRPD data, as an example of a hybrid approach between Rietveld and multivariate approaches, to correct for the MA effect. Particular attention is given to the comparison and selection of both method and pre-process, the two key steps for good performance when applying multivariate methods to obtain reliable quantitative estimations from XRPD data, especially when MA and PO are present. A similar approach was tested on XRF data to deal with matrix effects and compared with the more classical fundamental-parameter approach. Finally, useful indications to overcome the difficulties of the general user in managing the parameters for a successful application of multivariate approaches for XRPD and XRF data analysis are given.

Deep reddish-orange emitting Sr3Gd(PO4)3: Sm3+ phosphors via modified citrate-gel combustion method

The photoluminescence properties of different concentrations of Sm3+ activated Sr3Gd(PO4)3 phosphors synthesized by modified citrate gel-combustion method were investigated for white light emitting diode (w-LED) applications. The studied phosphors were characterized through powder x-ray diffraction (PXRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), photoluminescence excitation, emission and lifetime studies. The PXRD profiles confirmed the body centred cubic structure of undoped and Sm3+ -doped phosphors. The SEM studies showed the distribution and agglomeration of particles. The characteristic emission transitions such as 4G5/2 → 6H5/2 (∼561 nm), 4G5/2 → 6H7/2 (∼598 nm), 4G5/2 → 6H9/2 (∼645 nm) and 4G5/2 → 6H11/2 (∼705 nm) were noticed at their respective positions when excited at 403 nm wavelength. The highest luminescence intensity was found for 1.0 mol% of Sm3+ doped phosphors at 403 nm excitation showing luminescence quenching and it was ascribed to dipole-dipole interaction type of energy transfer among the excited Sm3+ ions at higher concentrations. The reddish-orange color of emitted luminescence was examined by evaluating the chromaticity coordinates. The experimental results confirm the potentiality of studied phosphors for w-LED applications.

Conformation Selectivity and Disharmony of the Lattice Constant Depending on the Guest Size in Clathrate Hydrates

This study reports the guest molecular conformation selectivity of a clathrate hydrate and lattice shrunk by hydrogen bonds between the guest and host water frameworks. Cyclohexanol (CHnol) exhibited two conformations (equatorial and axial structures) with small energy differences. The Rietveld refinement results of the powder X-ray diffraction profiles of two structure II (sII) hydrates enclosing CHnol showed that encaged CHnol prefers equatorial conformation over axial conformation in the 51264 cage. In contrast, the hydrate samples were synthesized in both the equatorial and axial conformations in equal proportions. Generally, longer or larger guest molecules exhibit longer lattice constants of the hydrate structure. The equatorial CHnol was longer than cyclohexanone (CHnone), known as an sII former. Nevertheless, the sII (CH4 + CHnol) hydrate showed a smaller lattice constant than that of the sII (CH4 + CHnone) hydrate. The average radius of the 51264 cage in the sII (CH4 + CHnol) hydrate was smaller than that in the sII (CH4 + CHnone) hydrate. This disharmony was caused by the hydrogen bond between CHnol and the water framework of the 51264 cage.

Color tunable SrZrO3:Sm3+ nanopowders with satisfactory photoluminescent, band engineering properties for warm white LEDs and advanced forensic applications

In the present investigation, color tunable samarium ions incorporated SrZrO3 nanopowders fabricated by simple solution combustion technique by using Aloe vera gel as fuel studied. The thorough characterization of the synthesised SrZrO3 nano materials by different analytical techniques has been explored. The powder X-ray diffraction profiles authorizes the orthorhombic phase of SrZrO3. The band gap energies were evaluated by diffuse reflectance spectra profiles and it was found that the values were observed between 4.42-4.81 eV. The dumb-bell shaped morphology was confirmed by the scanning electron microscope images. The size of the particles was estimated by means of Transmission electron microscope and it was found to be around 30 nm. The photoluminescence properties were studied by means of emission spectra at room temperature. The three prominent peaks of Sm ions were observed at 555 (4G5/2→6H5/2), 609 (4G5/2→6H7/2) and 645 nm (4G5/2→6H9/2) respectively under 403 nm (6H5/2→4F7/2) excitation wavelength. The highest PL emission was observed for 5 mol% of Sm incorporated SrZrO3. The photoluminescence emission decreases beyond 5 mol% of dopant concentrations owing to the well-known concentration quenching mechanism. Commission international de I'Eclairage diagram unveils orange color due to (0.6362, 0.3633) lines and the average color purity of the fabricated powders was found to be ∼ 90%. Further, the average internal quantum efficiency was estimated and it was observed to be 36.46%. In addition to this, the optimized powders were utilized to detect the latent fingerprint on non-porous surface. The found results indicated that, the powders can simulate the clear ridge details including the 3 types such as sweat pores without any background hindrance. The achieved results recommend the prepared phosphors can be excellently employed in the production of the white light emitting diode applications as orange-red component and also used for the advanced forensic applications.

Nazarovite, Ni12P5, a new terrestrial and meteoritic mineral structurally related to nickelphosphide, Ni3P

Abstract Nazarovite, Ni12P5, is a new natural phosphide discovered on Earth and in meteorites. Terrestrial nazarovite originates from phosphide assemblages confined to pyrometamorphic suite of the Hatrurim Formation (the Mottled Zone), the Dead Sea basin, Negev desert, Israel. Meteoritic nazarovite was identified among Ni-rich phosphide precipitates extracted from the Marjalahti meteorite (main group pallasite). Terrestrial mineral occurs as micrometer-sized lamella intergrown with transjordanite (Ni2P). Meteoritic nazarovite forms chisel-like crystals up to 8 μm long. The mineral is tetragonal, space group I4/m. The unit-cell parameters of terrestrial and meteoritic material, respectively: a 8.640(1) and 8.6543(3), c 5.071(3), and 5.0665(2) Å, V 378.5(2), and 379.47(3) Å3, Z = 2. The crystal structure of terrestrial nazarovite was solved and refined on the basis of X-ray single-crystal data (R1 = 0.0516), whereas the structure of meteoritic mineral was refined by the Rietveld method using an X-ray powder diffraction profile (RB = 0.22%). The mineral is structurally similar to phosphides of schreibersite–nickelphosphide join, Fe3P-Ni3P. Chemical composition of nazarovite (terrestrial/meteoritic, electron microprobe, wt%): Ni 81.87/78.59, Fe <0.2/4.10; Co <0.2/0.07, P 18.16/17.91, total 100.03/100.67, leading to the empirical formula Ni11.97P5.03 and (Ni11.43Fe0.63Co0.01)12.07P4.94, based on 17 atoms per formula unit. Nazarovite formation in nature, both on Earth and in meteorites, is related to the processes of Fe/Ni fractionation in solid state, at temperatures below 1100 °C.

Spectroscopic investigation of ultrasound assisted sonochemical synthesis of BiOCl: Dy3+ nanophosphors for latent fingerprints visualization

A series of Dy3+ (1–9 mol%) doped BiOCl NPs were fabricated via ultrasound assisted sonochemical route using Aloe Vera (A.V.) gel as a bio-surfactant. Intense and sharp powder x-ray diffraction profiles confirm the matlockite-type tetragonal structure of BiOCl. The morphology of the nanophosphor was engineered by varying various experimental parameters, namely ultrasound irradiation time, pH level and A.V. gel concentration. The photoluminescence emission spectra of the prepared nanophosphor comprised of several intense peaks at ∼457, 549 and 614 nm, which are ascribed to 4F9/2→6H15/2 (Blue), 4F9/2→6H13/2 (Green) and 4F9/2→6H11/2 (Red) transitions of Dy3+ ions, respectively. The Judd–Ofelt intensity parameters Ωt (t = 2, 4) and other important radiative properties, such as total radiative transition probability, radiative life time and branching ratio of Dy3+ ions in the BiOCl were exploited using photoluminescent emission spectra. The photometric properties of the nanophosphors exhibit pure cool white light emission, which validate the potential applications of synthesized nanophosphor in phosphor converted white light emitting diodes. The optimized BiOCl:Dy3+ (5 mol%) nanophosphor was utilized as a powder dusting material to visualize LFPs on diverse surfaces. The stable optical properties and nano-regime of the nanophosphor permitted high resolution imaging enabling level I-III ridge arrangements details can be obtained. Therefore, the prepared nanophosphor has great potential for application in individual recognition.

The LiNiO2 Cathode Active Material: A Comprehensive Study of Calcination Conditions and their Correlation with Physicochemical Properties. Part I. Structural Chemistry

Following the demand for increased energy density of lithium-ion batteries, the Ni content of the Nickel-Cobalt-Manganese oxide (NCM) cathode materials has been increased into the direction of LiNiO2 (LNO), which regained the attention of both industry and academia. To understand the correlations between physicochemical parameters and electrochemical performance of LNO, a calcination study was performed with variation of precursor secondary particle size, maximum calcination temperature and Li stoichiometry. The structural properties of the materials were analyzed by means of powder X-ray diffraction, magnetization measurements and half-cell voltage profiles. All three techniques yield good agreement concerning the quantification of Ni excess in the Li layer (1.6%–3.7%). This study reveals that the number of Li equivalents per Ni is the determining factor concerning the final stoichiometry rather than the calcination temperature within the used calcination parameter space. Contrary to widespread belief, the Ni excess shows no correlation to the 1st cycle capacity loss, which indicates that a formerly overlooked physical property of LNO, namely primary particle morphology, has to be considered.

Green synthesis and characterisation of nanocrystalline NiO-GDC powders with low activation energy for solid oxide fuel cells

This work reports the preparation of nanocrystalline Ni-Gd0.1Ce0.9O1.95 (NiO-GDC) anode powders using a novel single-step co-precipitation synthesis method (carboxylate route) based on ammonium tartrate as a low-cost green precipitant. The thermogravimetric analysis (TGA) of the synthesised powder showed the complete calcination/crystallisation of the resultant precipitates to take place at 500 °C. The prepared NiO-GDC powder was coated on a GDC electrolyte disc and co-sintered at 1300 °C. A mixture of La0.6Sr0.4Co0.2Fe0.8O3−δ and GDC was used as the cathode material and subsequently coated onto the anode-electrolyte bilayer, resulting in the fabrication of a NiO-GDC|GDC|La0.6Sr0.4Co0.2Fe0.8O3−δ-GDC cell. The crystallite size of both NiO and CeO2 phases were estimated using the X-ray powder diffraction (XRD) profiles and were calculated to be ~14 nm. Applied H2 temperature-programmed reduction (H2-TPR) analysis indicated a synergetic effect among different anode composites' constituents, where an intense interaction between the dispersed NiO nanocrystalline particles and the GDC crystallite phase had weakened the metal-oxygen bonds in the synthesised anode composites, resulting in a strikingly high catalytic activity at temperatures as low as 300 °C. The electrochemical impedance spectroscopy (EIS) and the electrochemical performance of the fabricated cells were measured over a broad range of operating temperatures (500–750 °C) and H2/Ar-ratios of the anode fuel (e.g. 100%–15%). Quantitative analysis from the EIS data and the application of the distribution of relaxation times (DRT) method allowed for the estimation of the activation energies of the anodic high and intermediate frequency processes that were 0.45 eV and 0.76 eV, respectively. This is the first report of a NiO-GDC synthesis, where a considerable improvement in activation energy is observed at the low-temperature region. Such low activation energies were later associated with the adsorption/desorption process of water molecules at the surface of NiO-GDC composite, indicating a high activity towards hydrogen oxidation.

Bisindole [3]arenes—Indolyl Macrocyclic Arenes Having Significant Iodine Capture Capacity

Bisindole [3]arenes—Indolyl Macrocyclic Arenes Having Significant Iodine Capture Capacity