Analysis Of X-ray Diffraction Data Research Articles

Oxygen distribution in the structure of YBa-=SUB=-2-=/SUB=-Cu-=SUB=-3-=/SUB=-O-=SUB=-7-delta-=/SUB=- thin films after vacuum exposure at 300 K

We have found out that vacuum exposure of YBa2Cu3O7-delta thin epitaxial films at 300 K for 24 hours decreases oxygen content and induces changes in their crystal structure depending on the films synthesis conditions. YBa2Cu3O7-delta films on SrTiO3 (100) substrates were synthesized by pulsed laser deposition. The crystal structure was studied using XRD technique. Additional maxima of diffraction peak (005) before and after vacuum exposure indicate the presence of regions with different oxygen content; and the change in the shape of the rocking curves indicate a change in the crystallites orientation. After vacuum exposure, the oxygen deficiency delta in the films increased from ~0.01 to ~0.6 for films with a crystallites size of 2-10 nm and from ~0.25-0.35 to ~0.6 for crystallites size of 500-1000 nm. The appearance of a residual resistance after the superconducting transition in the dependence R(T) may be explained by the fact that oxygen loss mainly in the boundary regions of the crystallites takes place, so that their boundaries become dielectric, while the crystallites themselves remain superconductive. Based on the data of X-ray diffraction analysis, as well as resistive measurements, we have come to the conclusion about oxygen loss through grain boundaries in films with nanocrystallites of 2-10 nm in size, and also through structural defects in films with larger crystallites. Keywords: pulsed laser deposition, surface relief, transport characteristics of films, film evolution, SrTiO3.

Кинетика формирования сверхструктуры L10 в сплаве Cu–56Au (ат. %): резистометрическое исследование

Due to the improved strength properties compared to the equiatomic Cu–50 at. % Au alloy, non-stoichiometric Cu–56 at. % Au alloy can be used both in dentistry and as a corrosion-resistant conductor of weak electrical signals in tool engineering. The work studies the kinetics of the disorder→order phase transformation in the Cu–56Au alloy, during which the disordered fcc lattice (A1-phase) is rearranged into an atomically ordered one with the L10 superstructure. The initial disordered state of the alloy was obtained in two ways: applying plastic deformation by 90 % or quenching at a temperature of above 600 °C (i. e., from the region of the A1-phase existence). To form the L10 superstructure, annealing was carried out at temperatures of 200, 225, and 250 °C. The annealing duration ranged from 1 h to 2 months. Resistometry was chosen as the main technique to study the kinetics of the disorder→order transformation. The temperature dependences of the electrical resistivity of the alloy in various structural states are obtained. The authors constructed the graphs of the electrical resistance dependence on the annealing time logarithm, based on which, the rate of the new phase formation was estimated. To evaluate the structural state of the alloy at various transformation stages, the authors used X-ray diffraction analysis (XRD). The crystal structure rearrangement during the transformation is shown by the example of splitting the initial cubic A1-phase peak (200) into two tetragonal ordered L10 phase peaks – (200) and (002). Based on the resistometry and X-ray diffraction analysis data, the authors carried out a quantitative assessment of the rate of the disorder→order phase transformation in the alloy under the study. It is established that the values of the converted volume fraction (resistometry) and the long-range order degree (X-ray diffraction analysis) are close. The study shows that in the temperature range of 200–250 °C, the rate of atomic ordering according to the L10 type in the nonstoichiometric alloy Cu–56 at. % Au is maximum at 250 °C. It is identified that the disorder→order transformation in the initially quenched specimens of the investigated alloy proceeds approximately an order of magnitude faster than in preliminarily deformed specimens.

Реакции пентафенил- и пента(пара-толил)сурьмы с ферроцендикарбоновой кислотой

In reactions of pentaphenyl- and penta(para-tolyl)antimony with ferrocene dicarboxylic acid (molar ratios 1:1 and 2:1) in toluene (20 С, 24 h), hydrogen in one or two carboxylate groups is replaced with formation of tetraarylantimony ferrocene carboxylates HOOС5H4FeС5H4C(O)OSbPh4 (1), HOOС5H4FeС5H4C(O)OSbTol4 (2), Ph4SbC(O)OC5H4FeС5H4C(O)OSbPh4 (3) and p-Tol4SbC(O)OC5H4FeС5H4C(O)OSbTol4 (4), yielding up to 83 %. Compounds 1–4 have been identified by elemental analysis, IR spectroscopy, and X-ray diffraction analysis for 4. X-ray diffraction analysis of complex 4 has been performed on a D8 Quest Bruker automatic four-circle diffractometer (Mo Kα radiation, λ = 0.71073 Å, graphite monochromator ) at 293 K. Crystallographic characteristics of compound 4: monoclinic system, space group P21/c, a = 17.227(17), b = 11.064(9), c = 30.59(3) Å, β = 100.00(4) deg., V = 5742(9) Å3, Z = 4, calc = 1.440 g/cm3, 2 6.02-49.08 deg., total reflections 124343, independent reflections 9436, number of refined parameters 684, Rint = 0.1051, GOOF 1.094, R1 = 0.0536, wR2 = 0.1309, residual electron density (max/min) 0.88/1.21 e/Å3. According to the X-ray diffraction analysis data, in crystal 4 coordination of the antimony atoms is distorted octahedral due to the fact that the carboxylate ligand is a bidentate chelating ligand. The diagonal angles in the two octahedra are 146.4(2), 154.0(3), 171.0(2) and 147.4(2), 154.8(2), 166.9(2). The SbO distances are 2.296(5), 2.502(5) Å and 2.289(5), 2.453(5) Å, the SbC bonds are significantly different (2.146(7)2.166(7) and 2.123(6)2.165(7) Å). The structural organization of the crystal is mainly due to the interactions of the СН•••-type.

Синтез и кристаллическая структура бис(2-метилкарборанил-карбоксилата) трис(3-фторфенил)сурьмы

Oxidation of tris(3-fluorophenyl)antimony with hydrogen hydroperoxide in the presence of 2-methylcarboranylcarboxylic acid leads to the formation of tris(3-fluorophenyl)antimony bis(2-methylcarboranylcarboxylate) (1), the structural features of which have been established by X-ray diffraction analysis. According to X-ray diffraction analysis performed at 293 K on an automatic four-circle diffractometer D8 Quest Bruker (two-coordinate CCD detector, Mo Kα-radiation, λ = 0.71073 Å, graphite monochromator), the crystals are characterized by: C26H38B20F3O4Sb, M 809.52; monoclinic system, space group С2/c; cell parameters: a = 19.050(13), b = 14.441(9), c = 14.568(9) Å;  = 90, β = 98.51(2),  = 90; V = 3964(4) Å3; Z = 4; crystal size 0.8 × 0.55 × 0.29 mm; index ranges –25 ≤ h ≤ 25, –18 ≤ k ≤ 18, –18 ≤ l ≤ 19; total reflections 37401; independent reflections 4709; Rint 0.0545; GOOF 1.108; R1 = 0.0578, wR2 = 0.1482; residual electron density –0.59/1.09 e/Å3. According to X-ray diffraction analysis data, in the molecules of compound 1, the antimony atoms have a distorted trigonal-bipyramidal coordination with the oxygen atoms of the carboxylate ligands in the axial positions. The Sb–C bonds (2.104(4)–2.114(8) Å) are shorter than the Sb–O distances (2.113(3) Å), the OSbО axial angle is 178.48(15)°, the CSbC angles are 109.7(2)°, 118.4(2)°, 131.8(3)°, while a significant increase in one of the angles is associated with the cis-conformation of the carboxylate ligands relative to the equatorial plane. The conformation of aryl ligands with respect to the equatorial plane [C3] is propeller. Structure 1 contains intramolecular Sb•••O=С contacts between the antimony and oxygen atoms of the carbonyl groups of the carboxylate ligands, which are 3.089(3) Å. The formation of a spatial network in the crystal of compound 1 is due to the presence of weak hydrogen bonds with the participation of boron atoms of carboxylate ligands and fluorine of aryl ligands: B•••H (3.19 Å) and F•••B (3.45 Å). Complete tables of atomic coordinates, bond lengths, and bond angles are deposited at the Cambridge Structural Data Center (no. 2178731; deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk/data_request/ cif).

Antisite disorder and Berry curvature driven anomalous Hall effect in the spin gapless semiconducting Mn2CoAl Heusler compound

Spin gapless semiconductors exhibit a finite band gap for one spin channel and a closed gap for another spin channel, and they have emerged as a new state of magnetic materials with a great potential for spintronic applications. The first experimental evidence for spin gapless semiconducting behavior was observed in an inverse Heusler compound ${\mathrm{Mn}}_{2}\mathrm{CoAl}$. Here, we report a detailed investigation of the crystal structure and anomalous Hall effect in ${\mathrm{Mn}}_{2}\mathrm{CoAl}$ using experimental and theoretical studies. The analysis of the high-resolution synchrotron x-ray diffraction data shows antisite disorder between Mn and Al atoms within the inverse Heusler structure. The temperature-dependent resistivity shows semiconducting behavior and follows Mooij's criteria for disordered metal. The scaling behavior of the anomalous Hall resistivity suggests that the anomalous Hall effect in ${\mathrm{Mn}}_{2}\mathrm{CoAl}$ is primarily governed by an intrinsic mechanism due to the Berry curvature in momentum space. The experimental intrinsic anomalous Hall conductivity (AHC) is found to be $\ensuremath{\sim}35$ S/cm, which is considerably larger than the theoretically predicted value for ordered ${\mathrm{Mn}}_{2}\mathrm{CoAl}$. Our first-principles calculations conclude that the antisite disorder between Mn and Al atoms enhances the Berry curvature and hence the value of intrinsic AHC, which is in very good agreement with the experiment.

Bis-(2-difluoroamino-2,2-dinitroethyl)nitramine – Energetic oxidizer and high explosive

• Bis-(2-difluoramino-2,2-dinitroethyl)nitramine ( 1 ) is synthesized. • 1 has a very high density of 2.032 g cm −3 at 298 K. • Thermochemical and kinetic data is reported. • Specific impulse is improved over standard AP-based formulations. • 1 reaches the detonation performance level of landmark CL-20. There is an urgent demand for novel energetic materials with improved performance to serve as oxygen suppliers (oxidizers) and high-energy additives. Synthesis and characterization of compound that combines both of the above roles, bis-(2-difluoroamino-2,2-dinitroethyl)nitramine ( 1 ), is reported. 1 was synthesized by difluoroamination of bis(2,2-dinitroethyl)nitramine in good yield. The analysis of X-ray diffraction data shows that NF 2 -groups has a significant contribution into a very high density of 1 , 2.032 g cm −3 at 298 K. The positive oxygen balance (+8%) makes it an attractive oxidizer, the rocket specific impulse is improved to 277 s vs 265 s for standard ammonium perchlorate-based formulation. Furthermore, the detonation performance of 1 reaches the level of most powerful explosive, CL-20. As a way to tune the melt-casting temperature and decrease the high friction sensitivity of 1 , its eutectics with trinitrotoluene were proposed.

Stabilised mechanical properties in Ni-based Hastelloy C276 alloy by additive manufacturing under different heat inputs incorporated with active interlayer temperature control

In this study, a Ni-based Hastelloy C276 alloy was prepared using cold metal transfer (CMT)-based directed energy deposition (DED) under different heat inputs with a zig-zag deposition path, integrated with active cooling and interlayer temperature control. Analogous mechanical properties were obtained for the fabricated alloys under different heat inputs (276, 368 and 553 J/mm) through effective interlayer temperature control. Such a broad processing window facilitates the large-scale industrial manufacturing and application of Hastelloy C276 by DED. Nevertheless, the lower heat input appears to slightly refine the microstructure and decrease the mechanical anisotropy of manufactured alloys, which is ascribed to combined effects of the manipulated bulk texture, refined dendrite arm spacing and reduced chemical segregation under lower heat input. Despite the variations of geometrically necessary dislocation (GND) densities with heat inputs, no significant change was observed in the average total dislocation density (TDD) in the microstructure of all samples as suggested by the peak profile analysis of Synchrotron X-ray diffraction data, which is advantageous for lowering the solidification cracking susceptibility. Moreover, all as-fabricated alloys present a typical strong fibre-type (200) crystallographic bulk texture measured by neutron diffraction, while such texture was relatively weaker in the lowest heat input condition. This work provides a reliable approach for stable additive manufacturing of Hastelloy C276 alloy, and innovatively presents rationales of stabilised properties based on the obtained insights into microstructure and bulk texture developments in a wide observation range by various techniques.

Zr3Mn3Sn4Ga: a new hexagonal Ti6Sn5-type quaternary intermetallic

The discovery of a new quaternary intermetallic compound of composition Zr3Mn3Sn4Ga during a survey of the Zr–Mn–Sn–Ga phase diagram is reported. Single-crystal X-ray diffraction reveals that the new compound crystallizes in a hexagonal lattice (space group P63/mmc, No. 194). The analysis of single-crystal X-ray diffraction data indicates that the atomic arrangement is an ordered variant of the high-temperature hexagonal Ti6Sn5 crystal structure. From a simple geometry point of view, the unit cell consists of GaZr3 octahedra chains and Mn chains growing along the sixfold symmetry axis c. The Mn chains are stacked within the ab basal plane in a kagome geometry, with large interatomic distances. The possible slight levels of Sn/Ga and Zr/Mn mixed occupancy based on additional results of electron probe microanalysis and single-crystal neutron diffraction are discussed. It is noteworthy that this compound is the first quaternary intermetallic discovered in this structure and the first Ti6Sn5 derivative bearing a magnetic metal, namely Mn, in the 6g position, which may give rise to interesting physical properties.

Structure and magnetic properties of (Mg1/6Zn1/6Mn1/6Co1/6Ni1/6Fe1/6)3O4 nanocrystalline high-entropy oxide synthesized using a sol-gel auto combustion approach

A sol–gel auto-combustion method is used in this study to synthesize a new class of single-phase high-entropy oxide (HEO) (Mg1/6Zn1/6Mn1/6Co1/6Ni1/6Fe1/6)3O4. The as-synthesized compound exhibits a single-phase spinel structure with an 8.3224 Å lattice parameter and an average crystallite size of 10 nm as determined by X-ray diffraction (XRD) data analysis. Raman and Fourier transform infrared results are in agreement with the XRD results. A scanning electron microscopy-based energy dispersed spectroscopy study suggests the formation of a porous structured morphology with a uniform elemental distribution. In addition, high-resolution transmission electron microscopy and surface analyses further confirm the formation of a pure spinel structure with a particle size of 12–20 nm and a mesoporous character with a pore size of 4.55 nm. X-ray photoelectron spectroscopy indicates mixed-valence states of elements (Mn, Fe, Co, and Ni) and their occupations over tetrahedral and octahedral sites. The temperature-dependent magnetization exhibited a bifurcation between zero-field-cooled and field-cooled magnetizations. From the M−H curves, the magnetization decreased monotonically with the increase in temperature (M is 22 emu/g at 2 K and 7.2 emu/g at 300 K). The coercivity decreased by approximately-one order of magnitude (HC = 1700 Oe at 2 K and HC = 200 Oe at 370 K). Finally, a comprehensive magnetic characterization of the as-synthesized HEO indicates their ferrimagnetic nature. The novel physical properties of the as-synthesized HEO could be useful in various potential applications.

Crystal structure, electric and microwave dielectric properties of La2Mg(Mg1/3Sb2/3)O6 novel double-perovskite with non-stoichiometric 1:1 cationic ordering

In this contribution, the novel double-perovskite La2Mg(Mg1/3Sb2/3)O6 has been successfully prepared by solid-state reaction method, and its structure has been determined for the first time by a combination of X-ray and neutron powder diffraction data analysis. The novel material exhibits a thermal expansion of ∼9.1 ppm/°C and a large optical band gap (4.23 eV). The complex impedance data analysis indicates that La2Mg(Mg1/3Sb2/3)O6 features a Debye-like behaviour, with a bulk conductivity, σb, varying between 10-7-10-4 S ‧cm-1 within 500–900 °C temperature range, and activation energy (Ea) of ∼ 1.36 eV. In addition, the microwave dielectric properties of La2Mg(Mg1/3Sb2/3)O6 sintered at 1625 °C display optimized quality factor (Q×f) of ∼ 28,700 GHz (f = 9.65 GHz), a dielectric constant (εr) of ∼ 20.2 and temperature coefficient of the resonant frequency (τf) of ∼ − 89 ppm/°C. This work widen the reduced number of A3+B2/32+B1/35+O3 compounds explored so far.

Self-Assembled glycerol monooleate demixes miscible liquids through selective hydrogen bonding to water

Water is miscible with dimethylsulfoxide (DMSO), with which it interacts through hydrogen bonds (H-bonds). Glycerol monooleate (GMO, 53 g/L) demixes water and DMSO, yielding kinetically stable DMSO in water emulsions with up to ≈75 % DMSO (relative to water, v/v), as demonstrated by Fourier Transform Infrared (FTIR) spectromicroscopy, ultra small angle X-ray scattering (USAXS) and light scattering experiments, and optical microscopy. With > 75 % DMSO (relative to water) emulsions reverse and DMSO becomes the continuous phase (as shown by electrical conductivity measurements). The size of emulsified droplets decreases with increasing DMSO ratios (relative to water), as demonstrated by USAXS. Synchrotron X-ray Diffraction (XRD) measurements conducted in the small (SAXS) and wide angle (WAXS) regions show that the DMSO:water ratio affects GMO self-assembly. GMO (53 g/L) self-assembles into cubic crystal mesophases with 40 % DMSO (relative to water) and into disordered lamellar phases with 50 % DMSO. At even higher DMSO percentages, GMO self-assembles into reverse micelles, which contain water and are surrounded by DMSO (as shown by analyzing XRD data with the Steubner and Strey model). Although GMO mainly partitions in the DMSO rich phase, attenuated total reflectance (ATR)-FTIR measurements show that GMO interacts with water through H-bonds. Importantly, it increases the proportion of single H-bond donors (SD, which structure water the most) relative to double donors (DD, which structure water less). H-bonding between the hydrophilic head of GMO and initiates separation between DMSO and water, which would be H-bonded to one another in the absence of GMO. While this study focuses on DMSO, GMO also emulsifies water and tetrahydrofuran (THF), dimethylformamide (DMF) and dioxane. Our findings redefine which solvents can be emulsified with water, and have potential implications for water treatment.

Domain Auto Finder (DAFi) program: the analysis of single-crystal X-ray diffraction data from polycrystalline samples.

This paper presents the Domain Auto Finder (DAFi) program and its application to the analysis of single-crystal X-ray diffraction (SC-XRD) data from multiphase mixtures of microcrystalline solids and powders. Superposition of numerous reflections originating from a large number of single-crystal domains of the same and/or different (especially unknown) phases usually precludes the sorting of reflections coming from individual domains, making their automatic indexing impossible. The DAFi algorithm is designed to quickly find subsets of reflections from individual domains in a whole set of SC-XRD data. Further indexing of all found subsets can be easily performed using widely accessible crystallographic packages. As the algorithm neither requires a priori crystallographic information nor is limited by the number of phases or individual domains, DAFi is powerful software to be used for studies of multiphase polycrystalline and microcrystalline (powder) materials. The algorithm is validated by testing on X-ray diffraction data sets obtained from real samples: a multi-mineral basalt rock at ambient conditions and products of the chemical reaction of yttrium and nitro-gen in a laser-heated diamond anvil cell at 50 GPa. The high performance of the DAFi algorithm means it can be used for processing SC-XRD data online during experiments at synchrotron facilities.

Two-step combustion synthesis of single-phase mesoporous ScFeO3 with bixbyite structure and magnetically soft behavior

In this paper, we consider the possibility of obtaining cubic bixbyite-type scandium ferrite in the form of phase-pure nanopowders. The samples were obtained by solution combustion method with either lack or excess of fuel and represented an X-ray amorphous phase according to the X-ray diffraction (XRD) results. To obtain cubic scandium ferrite, the samples were subjected to heat treatment at 700 °C, determined using DTA/TGA. The XRD data analysis confirmed the formation of cubic scandium ferrite with an average crystallite size of ∼20 nm for the sample obtained with a lack of fuel and 13 nm with an excess of fuel. According to the low-temperature nitrogen adsorption-desorption technique, the specific surface of the mesoporous samples decreased after annealing from 39.7 m2/g to 20.5 m2/g for the sample obtained with a lack of fuel and from 82.7 m2/g to 34 m2/g for the sample obtained with excess fuel. Scanning electronic microscopy (SEM) results demonstrated the foam-like morphology of nanopowders and no significant changes in their microstructure after heat treatment. The magnetic properties of powders that have undergone heat treatment have been studied. Narrow M-H hysteresis loops and low values of the coercive force indicate ferromagnetic behavior of the synthesized nanoparticles, which is supported by low values of the coercive force (Hc = 345 Oe and 769 Oe), remanent magnetization (Mr = 0.65 emu/g and 0.26 emu /g) and saturation magnetization (Ms = 1.69 emu/g and 0.26 emu/g) for lack and excess of fuel, respectively. The obtained materials are classified as magnetically soft and can potentially be used in the creation of transformers, magnetic screens, magnetic memory systems, radio engineering, and computer technology.

A study on the electrical properties of flux grown 0.91PZN-0.09PT single crystals for high-performance piezoelectric and pyroelectric device applications

In the present work, large-size piezoelectric single crystals of 0.91[Pb(Zn1/3Nb2/3)O3]-0.09PbTiO3 (PZN-9PT) have been grown by high-temperature flux method. Rietveld refinement analysis of X-ray diffraction data demonstrates the existence of monoclinic [Cm and Pm] phases, further supported by electron diffraction studies. PZN-9PT single crystal shows broad and diffused dielectric response peaks at 354 K and 443 K with noticeable frequency dispersion identified from temperature-dependent dielectric measurements. The 001 oriented PZN-9PT elements sliced from the grown single crystals display a remnant polarisation (Pr) of 30 µC/cm2, saturation polarization (Ps) of 33 µC/cm2, and an enhanced piezoelectric strain of 0.3 %. In addition, the piezoelectric coefficients d33, d31 and electric field-induced strain d33∗ measured by the direct method is 2100 pC/N, 1650 pC/N and 2500 pm/V, respectively. The mechanism behind the enhanced piezoelectric properties of PZN-9PT is explained with reference to the stabilization of the monoclinic phase and polarization rotation mechanisms. Further, the pyroelectric coefficient, p measured to be 11.31 × 10−4 C/m2 K at room temperature and 51.22 × 10−4 C/m2 K at the ferroelectric to the paraelectric phase transition temperature. The enhanced piezoelectric and pyroelectric properties of PZN-9PT make them suitable for high-performance piezoelectric transducers, actuators at ambient temperature and pyroelectric sensors at elevated temperature, respectively.

Hypoxylonone, a new oxa-bridged seven-membered ring analog from fungus Hypoxylon cf. subgilvum SWUF15-004

A new oxa-bridged seven-membered ring analog, hypoxylonone (1), and thirteen known compounds (2–14) were isolated from fungus Hypoxylon cf. subgilvum SWUF15-004. The structures were elucidated by the analysis of spectroscopic (IR, 1 D and 2 D NMR), HRESIMS and X-ray diffraction (MoKα) data. Several isolated compounds were evaluated for cytotoxicity against four human cancer cell lines (HeLa, HT29, MCF-7, A549). Compound 1 exhibited weak inhibitory effects of the nitric oxide production in RAW264.7 cells. Compounds 8 and 9 exhibited slight cytotoxicity.

Structural and electronic phase transitions in Zr1.03Se2 at high pressure

We have carried out a detailed high pressure investigation using x-ray diffraction, Raman spectroscopy, and low temperature resistivity measurements on 1T ${\mathrm{ZrSe}}_{2}$ having an excess of 3 at.% Zr. A careful x-ray diffraction data analysis shows that the sample undergoes a gradual structural transition to a monoclinic structure, with a mixed phase in the pressure range of 5.9 GPa to 14.8 GPa. We observe a minimum in the $c/a$ ratio as well as in the full width at half maximum of the ${A}_{1g}$ Raman mode at the same pressure in the parent 1T phase, which indicates an electronic phase transition. The sample shows a metallic characteristic in its low temperature resistivity data at ambient pressure, which persist until about 5.1 GPa and can be related to the presence of slight excess Zr. At and above 7.3 GPa, the sample shows a metal to semiconductor transition with the opening of a very small band gap, which increases with pressure. The low temperature resistivity data show an upturn, which flattens with the increase in pressure. The phenomenological analysis of the low temperature resistivity data indicates the presence of the Kondo effect in the sample, which may be due to the excess Zr.

Influence of nanocomposite (1-x)CdS/xCuS on optical characteristics of PVA/CMC/PEG blended polymer; effect of ratio (x)

PVA/CMC/PEG blended polymers loaded with (1-x)CdS/xCuS nanocomposites (x = 0, 0.3, 0.5, 0.7, 1) were formed applying the thermolysis and casting techniques. Rietveld analysis of synchrotron x-ray diffraction data measured for (1-x)CdS/xCuS manifested a single hexagonal phase CuS (x = 1.0) and biphasic structure, hexagonal and cubic, for CdS (x = 0.0); composite samples (x = 0.3, 0.5, and 0.7) exhibited the three phases with varied percentages. Average crystallite size for all nanofillers ranged 4–12 nm. The surface morphology and chemical compositions of the different blends were investigated using SEM and EDS techniques. The effect of loading PVA/CMC/PEG blends with multi phases CdS–CuS nanocomposite on the optical linear and nonlinear behaviors was explored using diffused reflectance technique. The direct and indirect optical band gaps (Eg) values determined for PVA/CMC/PEG are 5.62 and 5.18 eV, respectively, which reduced to (4.2, 4.5, 4.47, 4.56, 3.89) and (3.43, 3.9, 3.74, 3.98, 3.18) eV upon loading with (1-x)CdS-xCuS for x = 0, 0.3, 0.5, 0.7, and 1, respectively. The refractive index of all loaded blends increased non monotonically with (x) reached its highest value for λ ≥ 500 nm upon loading with x = 0.0 (CdS). The fluorescence (FL) intensity of the blended polymers nearly quenched upon loading with CuS (x = 1.0) and greatly enhanced for x = 0.5.

Microstructure, Optical and Electrical Properties of Cu-Cu<sub>2</sub>O Core-Shell Nanostructures

Composites of nanometre-sized copper core–copper oxide (Cu-Cu2O) shell with different diameters were synthesized by a facile one step co-solvent technique. By the analysis of X-ray diffraction (XRD) and transmission electron microscope (TEM) data, the resultant particles were confirmed to be pure and nanocrystalline in nature. The perfect core-shell structure of nanocrystalline Cu-Cu2O was confirmed by using high resolution TEM. The presence of pure Cu and Cu2O was further confirmed from optical absorbance spectrum and Fourier transform infrared (FT-IR) spectroscopy. The tailoring of position of optical absorption peaks, originating from Cu or Cu2O nanoparticles, is possible by modulating the oil to water ratio, which controls the size of the composite particles and thickness of Cu2O. Drastic change of electrical resistivity with change in thickness of shell, has been observed. Variation of resistivity with temperature delineates a semiconducting nature with two distinct activation processes. Results demonstrate that the activation energies for the core-shell nanostructure composites were found to be smaller than the bulk Cu2O. Photoluminescence spectrum further confirms the semiconducting nature of the composite. In addition, the kinetic of core-shell morphology formation is also discussed briefly.

STUDI ANALISIS DATA DIFRAKSI SINAR-X PADA MATERIAL ZIRCON PASIR ALAM MELALUI METODE RIETVELD

ZrSiO4 (zircon) material derived from natural sand has been successfully synthesized to produce single crystals. Structural analysis and phase change were studied by X-Ray diffraction. Rietveld analysis was carried out as a method of analyzing X-Ray Diffraction data. Zircon with a tetragonal crystal structure has been successfully synthesized to produce single crystals of ZrSiO4 with space group I41/amd. The results of the Rietveld analysis of single crystal ZrSiO4 samples with a tetragonal structure obtained lattice parameters a= 6.602727 (323) c= 5.978810 (317) with a crystal size distribution of 527.033 (0) nm and macrostrains of 0.001x10-4.

Tuning structure and magnetic properties of table-like magnetocaloric effect in Er6MnSb2 by zirconium substitution

In this study, zirconium (Zr) successfully substituted for erbium (Er) in Er6–xZrxMnSb2 (x = 0, 0.5, 1, 1.5) of the Fe2P type, with comprehensive characterizations on crystal structure, electronic structure and magnetic properties. According to synchrotron powder X-ray diffraction data analysis and density functional theory calculation, Zr does not randomly but preferentially occupy during the doping process and results in weaker magnetic exchange interactions and depressed ordering temperatures. The electronic structure data show that the doping of Zr can weaken interaction between Er and Mn atoms. Owing to multiple transitions, the Er6–xZrxMnSb2 (x = 0, 0.5, 1, 1.5) exhibit table-like magnetocaloric effect. Er6MnSb2 displays wide δTFWHM (full width at half maximum of the magnetic entropy change curve) of 116 K and high relative cooling power of 388.62 J/kg for 3 T. The maximum magnetic entropy change of Er6–xZrxMnSb2 is increased from 3.81 to 7.69 J/(kg·K) with the Zr content up from x = 0 to x = 1.5.