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In this investigation, highly crystalline and mesoporous Zinc oxide (ZnO) nanoparticles with the large surface area were synthesized without calcination. Furthermore, the effects of different pH values on structural, physicochemical and textural properties of ZnO nanoparticles were comprehensively investigated. Rietveld refinement implied that the pH variation had significant effects on the crystal structure of ZnO nanoparticles. The phase, molecular and elemental structures confirmed the formation of ZnO as a major phase in all nanopowders. The morphology of ZnO nanoparticles was irregular with an average size of 45 ± 9 nm. Both phase and atomic structures confirmed the polycrystalline arrangement of ZnO nanoparticles. Moreover, isotherms confirmed the mesoporous structure of all ZnO nanoparticles with superior specific surface area and porosity volume. Thus, owing to the concoction of high crystallinity, superior surface area and porosity volume, resultant ZnO nanoparticles can be effectively employed for diverse multifunctional therapeutic applications. [ABSTRACT FROM AUTHOR]

Studies suggest that feitknechtite (β-MnOOH) is a prevalent, and perhaps necessary, intermediate phase during the synthesis of birnessite-like phases, the abiotic oxidation of Mn2+, and the transformation of biogenic hexagonal phyllomanganates to more complex Mn oxides in laboratory and natural systems. Researchers have generally described feitknechtite as consisting of pyrochroite-like (or cadmium iodide-like) Mn-O octahedral layers, but a detailed crystal structure has not been reported. We used TEM/SAED and powder XRD and Rietveld refinements to derive the unit cell and, for the first time, report a complete structure description for feitknechtite (β-MnOOH). Rietveld refinements were also completed for three natural feitknechtite/hausmannite samples, and time-resolved synchrotron XRD experiments were used to follow the thermal transformation of feitknechtite to hausmannite. Additionally, we identified and report the structure for a second, and perhaps novel, MnOOH polymorph (proposed designation ε-MnOOH), mixed with the synthetic feitknechtite, that is similar to β-MnOOH but with a different layer stacking. [ABSTRACT FROM AUTHOR]

The manganates Sm1.5–xSr1 + xBa0.5Mn2O7 for x = 0, 0.1, and 0.3 were successfully synthesized by the co-precipitation route. The compounds' crystalline structures were analyzed through powder X-ray diffraction using the refinement Rietveld method. The refined structure parameters are entirely in agreement with those expected in the case of An + 1BnO3n + 1 for n = 2 corresponding to the iso-structural Sr3Ti2O7 type. Magnetic measurements of Sm1.5–xSr1 + xBa0.5Mn2O7 (x = 0, 0.1, and 0.3) revealed the existence of a predominant antiferromagnetic ordering. Furthermore, isothermal magnetization shows that magnetization saturation is not fully attained at high fields, which can be explained by a strong super-exchange interaction of the antiferromagnetic state. The electrical resistivity at zero field shows that these compounds are electrically insulating materials, which can be explained by the predominance of the antiferromagnetic ordering. [ABSTRACT FROM AUTHOR]

Magadiite from Lake Magadi was structurally analyzed based on X‑ray powder diffraction data. The idealized chemical composition of magadiite is Na16[Si112O224(OH)16]∙64H2O per unit cell. The XRD powder diffraction pattern was indexed in orthorhombic symmetry with lattice parameters a0 = 10.5035(9) Å, b0 = 10.0262(9) Å, and c0 = 61.9608(46) Å. The crystal structure was solved from a synthetic magadiite sample in a complex process using 3D electron diffraction combined with model building as presented in an additional paper. A Rietveld refinement of this structure model performed on a magadiite mineral sample in space group F2dd (No. 43) converged to residual values of RBragg = 0.031 and RF = 0.026 confirming the structure model. Physico-chemical characterization using solid-state NMR spectroscopy, SEM, TG-DTA, and DRIFT spectroscopy further confirmed the structure. The structure of magadiite contains two enantiomorphic silicate layers of, so far, unknown topology. The dense layers exhibit no porosity or micro-channels and have a thickness of 11.5 Å (disregarding the van der Waals radii of the terminal O atoms) and possess a silicon Q4 to Q3 ratio of 2.5. 16 out of 32 terminal silanol groups are protonated, and the remaining groups compensate for the charge of the hydrated sodium cations. Bands of edge-sharing [Na(H2O)6/1.5] octahedra are intercalated between the silicate layers extending along (110) and (110). The water molecules are hydrogen bonded to terminal silanol groups with O···O distances of 2.54–2.91 Å. The structure of magadiite is slightly disordered, typical for hydrous layer silicates (HLS), which possess only weak interactions between neighboring layers. In this respect, the result of the structure refinement represents a somewhat idealized structure. Nevertheless, the natural magadiite possesses a higher degree of structural order than any synthetic magadiite sample. The structure analysis also revealed the presence of strong intra-layer hydrogen bonds between the terminal O atoms (silanol/siloxy groups), confirmed by 1H MAS NMR and DRIFT spectroscopy. The surface zone of the silicate layers, as well as the interlayer region containing the [Na(H2O)6/1.5] octahedra, are closely related to the structure of Na-RUB-18. [ABSTRACT FROM AUTHOR]

The crystal structures of (CH3NH3)2Cu(Cl1-xBrx)4 compounds have been investigated by means of synchrotron powder X-ray diffraction and pair distribution function analysis at room temperature. As a result, new insights are gained about the structural properties of these compounds, suggesting a monoclinic symmetry (space group No. 14: P21/c - C52h) induced by the cooperative orbital ordering produced by the Jahn-Teller distortion characterizing the 3d9 Cu2+ ion. In contrast to previous studies, a significant amount of vacancies is found at halogen positions, a feature that can be likely ascribed to the synthesis technique adopted in the present study. Br atoms preferentially occupy axial positions, likely on account of reduced steric hindrance at these sites. [ABSTRACT FROM AUTHOR]

Psilocybin {systematic name: 3‐[2‐(dimethylamino)ethyl]‐1H‐indol‐4‐yl dihydrogen phosphate} is a zwitterionic tryptamine natural product found in numerous species of fungi known for their psychoactive properties. Following its structural elucidation and chemical synthesis in 1959, purified synthetic psilocybin has been evaluated in clinical trials and has shown promise in the treatment of various mental health disorders. In a recent process‐scale crystallization investigation, three crystalline forms of psilocybin were repeatedly observed: Hydrate A, Polymorph A, and Polymorph B. The crystal structure for Hydrate A was solved previously by single‐crystal X‐ray diffraction. This article presents new crystal structure solutions for the two anhydrates, Polymorphs A and B, based on Rietveld refinement using laboratory and synchrotron X‐ray diffraction data, and density functional theory (DFT) calculations. Utilizing the three solved structures, an investigation was conducted via Rietveld method (RM) based quantitative phase analysis (QPA) to estimate the contribution of the three different forms in powder X‐ray diffraction (PXRD) patterns provided by different sources of bulk psilocybin produced between 1963 and 2021. Over the last 57 years, each of these samples quantitatively reflect one or more of the hydrate and anhydrate polymorphs. In addition to quantitatively evaluating the composition of each sample, this article evaluates correlations between the crystal forms present, corresponding process methods, sample age, and storage conditions. Furthermore, revision is recommended on characterizations in recently granted patents that include descriptions of crystalline psilocybin inappropriately reported as a single‐phase 'isostructural variant.' Rietveld refinement demonstrated that the claimed material was composed of approximately 81% Polymorph A and 19% Polymorph B, both of which have been identified in historical samples. In this article, we show conclusively that all published data can be explained in terms of three well‐defined forms of psilocybin and that no additional forms are needed to explain the diffraction patterns. [ABSTRACT FROM AUTHOR]

The ferrierite crystal structure has often been subject to discussion because of the possible lowering of symmetry from the space group Immm. It mainly occurs in nature with a fibrous crystal habit, and because of the existence of line/planar defects in the framework, texture and preferred orientation effects it has been difficult to obtain an exact crystallographic model based only on the results from powder diffraction data. Therefore, nano‐single‐crystal diffraction and tomography data have been combined in order to improve the refinement with a meaningful model. High‐quality single‐crystal data, providing reliable structural information, and tomography images have been used as input for a Rietveld refinement which took into account a phenomenological description of stacking disorder and the analytical description of the preferred orientation, by means of spherical harmonics for strong texture effects. This is one of the first examples of application of synchrotron nano‐diffraction for the structure solution of fibrous minerals of micrometre to nanometre size. The high quality of the crystals allowed collection of single‐crystal X‐ray diffraction data of up to 0.6 Å resolution, leading to an unambiguous solution and precise anisotropic refinement. Nano‐single‐crystal diffraction and phase contrast tomography data were collected at ID11 and the high‐resolution powder diffraction patterns at ID22 of the European Synchrotron Radiation Facility. This detailed crystallographic characterization provides a basis for understanding the potential of ferrierite for toxicity and carcinogenicity. [ABSTRACT FROM AUTHOR]

The single crystals of Na 2 Mn 2 (MoO 4) 3 were successfully grown using the solid-state synthesis method. This compound crystallizes in a triclinic system with space group P 1 ‾ (C i). Its structure can be described as a three-dimensional anionic framework of Mn 2 O 10 double octahedra units sharing edges with the MoO 4 tetrahedra. The Na+ ions are disordered and located in the voids forming infinite channels running along the [100], [010] and [001] directions. The structural model was validated by the bond valence sum (BVS) and charge distribution (CHARDI) methods. The polycrystalline powder of Na 2 Mn 2 (MoO 4) 3 was prepared as well using citrate process. The obtained sample was characterized by powder X-ray diffraction, infrared spectroscopy and Raman scattering at room temperature. The vibrational study confirms the existence of the MoO 4 2− functional groups. Thermal stability of the studied material was analyzed using differential scanning calorimetry. The Na 2 Mn 2 (MoO 4) 3 compound is thermally stable up to 500 °C. Magnetic susceptibility measurements reveal that the title compound is antiferromagnetic with Néel temperature T N = 6.5 (5) K. At higher temperatures, its susceptibility follows a Curie–Weiss law. Electrical measurements of this material were studied by means of the impedance spectroscopy technique, in 0.1 Hz–4 MHz frequency and in 443–691 K temperature ranges. The conductivity of Na 2 Mn 2 (MoO 4) 3 is 2.30 μScm−1 at 691 K and it is thermally activated with energy of 0.47 eV. The sodium migration pathways in the crystal structure were investigated using the bond valence sum pathways (BVSP) analysis and the bond valence site energy (BVSE) model. Image 1 • A new single crystal of Na 2 Mn 2 (MoO 4) 3 was grown by solid state reaction. • The structure was determined by single-crystal X-ray diffraction. • Magnetic susceptibility measurements revel that Na 2 Mn 2 (MoO 4) 3 is antiferromagnetic. • Na+ ionic conductivity was studied by complex impedance spectroscopy. [ABSTRACT FROM AUTHOR]

The temperature dependence of the crystal structure of Potassium Hexaiodoplatinate(IV) between 80 and 500 K is described. Below 410 K, K 2 PtI 6 adopts a monoclinic structure described in space group P 2 1 / n due to the presence of tilting of the PtI 6 octahedra. Heating the sample to above 410 K results in the loss of the out-of-phase tilts and a transition to the previously described tetragonal structure in space group P 4/ mnc. The remaining in-phase tilts are lost upon heating to above 460 K where the structure is cubic in space group F m 3 ‾ m. It is anticipated that the identification of accurate structures for the three polymorphs of K 2 PtI 6 will stimulate further theoretical and practical studies. [Display omitted] • The structure of K 2 PtI 6 at room temperature is shown to be monoclinic P 2 1 / n. • Structural Phase Transitions in K 2 PtI 6 described. • Rb 2 PtI 6 and Cs 2 PtI 6 have cubic structures at room temperature reflecting their larger tolerance factor. [ABSTRACT FROM AUTHOR]

Lanthanum (La) modified BFO crystallize to an impurity free crystal structure and enhance the multiferroic properties in BFO. The Bi 0.850 La 0.150 FeO 3 is found to be optimized composition to have very good multiferroic properties. It is also reported that the Ti 4+ substitution significantly reduces the leakage current in BFO. Moreover, the Ti 4+ substitution is more effective than that of magnetic cations to increase the magnetization. Hence, Bi 0.850 La 0.150 Fe 1-x Ti x O 3 (x = 0.000, 0.025, 0.050, 0.100) polycrystalline samples were synthesized by the tartaric acid modified sol gel method and the effect of non-magnetic Ti substitution at the Fe-site of Bi 0.850 La 0.150 FeO 3 on crystal structure and magnetic properties has been studied. The Rietveld refinements of X-ray diffraction patterns indicate the structural transition from rhombohedral ( R3c ) to orthorhombic ( Pbnm ) with the increase in the substitution concentration. A gradual shift in the frequency of Fe-O stretching modes toward higher frequency in the FTIR spectra indicates a composition-driven structural transition. Magnetic properties of Bi 0.850 La 0.150 Fe 1-x Ti x O 3 polycrystalline samples were measured at room temperature with the applied field range of ±7 T. A significant increase in the magnetization with Ti substitution is observed from the magnetic hysteresis loops. The highest magnetic moment was observed for 2.5% Ti substitution at the Fe-site in Bi 0.850 La 0.150 FeO 3 . [ABSTRACT FROM AUTHOR]

Nanostructured Ni2 As2 O7 semiconductor samples were synthesized by a solid state method among As2 O3 and Ni(NO3 )2.6H2 O raw materials at 650 °C (S1 ) and 750 °C (S2 ) as reaction temperatures. The synthesized nanomaterials were characterized by powder X-ray Diffraction (PXRD) technique and Fourier-Transform Infrared (FTIR) spectroscopy. The Rietveld analysis showed that the obtained materials were crystallized well in the triclinic crystal structure with the space group P1 . The data of Rietveld analysis showed that the purity of the synthesized nanomaterials was increased by increasing the reaction temperature. The morphologies of the synthesized materials were studied by field emission scanning electron microscope (FESEM). It was found that the morphology of the obtained materials was changed from homogeneous sponge to particles and somewhat porous structure, by increasing the reaction temperature. Besides, the average particle sizes were increased considerably by increasing the reaction temperature. Ultraviolet-visible spectra analysis showed that the synthesized Ni2 As2 O7 nanomaterials had strong light absorption in the ultraviolet light region. The direct optical band gap energies were 3.20, 3.90, 4.80 eV and 2.9, 3.40, 4.70 eV for S1 and S2 , respectively. The data showed that the band gaps were decreased by increasing the reaction temperature that can be due to the increasing the crystallite sizes of the targets. [ABSTRACT FROM AUTHOR]

The search for thermoelectric materials has been incredibly increased due to the increase in global energy demand. Hence the present work focus on preparation and characterization of thermal transport phenomena of pure and Ba/Ca substituted perovskite LaFeO 3 orthoferrite system. The conventional solid state reaction technique is utilized for the preparation of LaFeO 3 and La 0.9 M 0.1 FeO 3 (M = Ca and Ba) compounds. Crystal structure analyses of the prepared samples are analyses using Rietveld refinement process which confirms the orthoferrite crystal structure of all the prepared compounds with induced distortion in position of atoms by the incorporation of substituent atoms. The electronic structure calculations are performed by VASP. As the LaFeO 3 compound is a strongly energy correlated system, the Density Functional Theory (DFT) calculations are performed by DFT + U (Hubbard function) method. The computed band gap values are compared with the energy gap values calculated from UV–Vis spectral analysis. Electrical conductivity measurement and Arrhenius behavior for the temperature range of room temperature to 650 K are analyzed and the drift increase in conductivity with respect to temperature is due to the thermally activated mobility of charge carriers. Temperature dependent thermopower analysis is also examined using homemade seebeck coefficient measurement system. The calculation of thermoelectric power factor reveals that the Ba substituted LaFeO 3 compound show highest power factor value of 3.73 μW/K 2 cm at higher temperature and the superior power factor values observed in the Ba substituted compound determine the material's capability in power generating devices based on thermoelectric effect. [ABSTRACT FROM AUTHOR]

Three novel mixed alkali borate-nitrates Na3− x K x[B6O10]NO3 ( x=0.5, 0.6, 0.7) were synthesized hydrothermally; their crystal structures were determined through Rietveld analyses, and supported through EDX as well as vibrational spectroscopy. The phases represent solid solutions of the alkali borate-nitrate Na3(NO3)[B6O10], which was reported in 2002 as a 'New type of boron-oxygen framework in the Na3(NO3)[B6O10] crystal structure' (O. V. Yakubovich, I. V. Perevoznikova, O. V. Dimitrova, V. S. Urusov, Dokl. Phys. 2002, 47, 791). Only two of the three crystallographically independent Na+ positions in the new structures are partially substituted by K+; a pure potassium borate-nitrate was not formed until now. The cell parameters of the novel phases vary from a=1261.72(5)-1267.12(5), b=1004.19(5)-1007.96(4), c=770.55(3)-774.38(3) pm, and V=0.97630(6)-0.98905(6) nm3 in the orthorhombic space group Pnma (no. 62), in alignment with increasing K+ content. [ABSTRACT FROM AUTHOR]

The crystal structure of a synthetic AB-type carbonate apatite sample was analyzed by Rietveld refinement including a model with carbon atom not fixed in the B-site of the apatite structure. Only one constraint was applied to this model: the fractional occupancies of the atoms in the CO3 ion plus PO4 ion were equal 1.0 per phosphate site with six sites per unit cell. Rietveld refinement of the crystal structure with space group P6(3)/m results in cell parameters a = 9.3583(1) Å and c = 6.9226(5) Å; Z =1; Rwp = 0.0824 and 9.5 wt. (%) of carbonate in this structure. The use of simple geometry formulas showed that the C atom is not located at the center of the equilateral triangle of oxygen O2, O3 and O3', but to a distance 0.18 Å of this triangle. The results seem to indicate a new 3-D crystal structure of the carbonated apatite in PO4 groups.

Strontium (Sr) substituted cobalt ferrite i.e. Co 1− x Sr x Fe 2 O 4 ( x =0.00, 0.01, 0.015, 0.02, 0.05, 0.1) have been synthesized by the citric acid modified sol–gel method. Crystal structure and phase purity have been studied by the X-ray powder diffraction technique. The Rietveld refinement of XRD pattern using the space group F d 3 ¯ m shows monotonically increasing of lattice parameter with the increase in Sr concentration. Magnetic hysteresis loops measurement has been carried out at room temperature using a vibrating sample magnetometer (VSM) over a field range of ±1.5 T. Magnetocrystalline anisotropy constant were calculated by employing the Law of Approach (LA) to the saturation. It is observed that magnetocrystalline anisotropy has anomaly for x =0.01 (Co 0.99 Sr 0.01 Fe 2 O 4 ) sample. Strain mediated modification of magnetic properties in Sr substituted cobalt ferrite has been observed. The saturation magnetization for doping concentration i.e. x =0.01 abruptly increase while for x >0.01 decreases with the increase in Sr concentration. A correlation between lattice strain and magnetic behavior in non-magnetic Sr- substituted nano-crystalline cobalt ferrite has been reported. [ABSTRACT FROM AUTHOR]

Two different crystalline structures corresponding to a zinc adipate and a zinc succinate were determined combining: X-ray powder and single-crystal diffraction, infrared spectroscopy, thermal analysis, and true densities experiments. The zinc succinate crystal structure was determined by single-crystal X-ray diffraction. This compound crystallizes in the orthorhombic space-group Cccm with unit-cell parameters a = 4.792(1) Å, b = 21.204(6) Å, c = 6.691(2) Å, V = 679.8(3) Å3, and Z = 8. Zinc adipate crystal structure was refined from the laboratory X-ray powder diffraction data by the Rietveld method. It crystallizes in the monoclinic space group P2/c with unit-cell parameters, a = 16.2037(17)Å, b = 4.7810(2)Å, c = 9.2692(6)Å, β = 90.329(3)°, V = 718.07(9) Å3, and Z = 4. The thermal expansion of it was estimated in 5.40 × 10−5 K−1. This contribution is a step on the way to systematize the regularities in the coordination diversity between linear dicarboxylates and transition metal–inorganic buildings units of metal–organic frameworks. [ABSTRACT FROM AUTHOR]

Fifteen lead white-containing painting samples, about 1–3 μg in weight, from a selection of easel painting masterpieces of the Louvre and other French museums, dating from the Renaissance to the late 19 th century, were investigated using synchrotron diffraction on the ESRF high resolution XRD beamline ID22. The Rietveld analysis revealed the nature of the pigments through the cerussite:hydrocerussite (PbCO 3 :Pb 3 (CO 3 ) 2 (OH) 2 ) ratios, the approximate dimensions of the crystallites and the presence of crystalline extenders. This first insight into a still widely unknown domain gives some hints, but also raises questions about the artists' preferences for selecting, preparing and post-treating white pigments. A significant increase of the crystallites size over five centuries also suggests an evolution of these processes. [ABSTRACT FROM AUTHOR]

Two new crystalline polymorphs of the widely used antifungal drug griseofulvin (phases II and III), which originate from the crystallization of the melt, have been detected recently. The crystal structure of phase II of griseofulvin {systematic name: (2S,6′R)‐7‐chloro‐2′,4,6‐trimethoxy‐6′‐methyl‐3H,4′H‐spiro[1‐benzofuran‐2,1′‐cyclohex‐2‐ene]‐3,4′‐dione}, C17H17ClO6, has been solved by powder X‐ray diffraction (PXRD). The PXRD pattern of this new phase was recorded at room temperature using synchrotron radiation. The starting structural model was generated by a Monte Carlo simulated annealing method. The final structure was obtained through Rietveld refinement with soft restraints for interatomic bond lengths and angles, except for the aromatic ring, where a rigid‐body constraint was applied. The symmetry is orthorhombic (space group P212121) and the asymmetric unit contains two molecules. [ABSTRACT FROM AUTHOR]

Synchrotron X-ray powder diffraction methods have been used to obtain accurate structures of the lanthanoid tantalates, Ln TaO 4 , at room temperature. Three different structures are observed, depending on the size of the Ln cation: P 2 1 / c (Ln = La, Pr), I 2/ a (Ln = Nd-Ho), and P 2/ c (Ln = Tb-Lu). BVS analysis indicated that TaV is six-coordinate in these structures, with four short bonds and two longer bonds. Synchrotron X-ray powder diffraction methods were also used to observe the impact of Ta doping on the orthoniobates, Ln (Nb 1- x Ta x)O 4 (Ln = Pr, Nd, Sm, Gd, Tb, Dy, Ho, Yb, and Lu). Where both the niobate and tantalate oxide were isostructural (fergusonite structure, space group I 2/ a), complete solid solutions were prepared. In these solid solutions, the unit cell volume decreases as the Ta content increases. The subtle interaction evident between the Ln O 8 and B O 6 sublattices in the fergusonite-type oxides was not observed in the related pyrochlore oxides. A combined synchrotron X-ray and neutron powder diffraction study of the series Ho(Nb 1- x Ta x)O 4 was used to determine accurate atomic positions of the anions, and hence, bond lengths. This revealed a change in the (Nb/Ta)-O bond lengths, reflective of the difference in the valence orbitals of Nb(4 d) and Ta(5 d). Examination of the partial density of states demonstrates differences in the electronics between Nb and Ta, leading to a difference in the bandgap. This study highlights the importance of the long B -O contacts in the fergusonite structures, and its potential impact on the I 2/ a to I 4 1 / a phase transition. [Display omitted] • An integrated experimental and theoretical investigation of orthoniobates and orthotantalates is presented. • Combined synchrotron X-ray and neutron diffraction detail subtle differences between NbV and TaV. • There are long Ta-O bonds in the fergusonite structure that potentially impacting the I 2/ a to I 4 1 / a phase transition. • The pDOS reveal differences between NbV and TaV, leading to the experimentally observed difference in bandgap. [ABSTRACT FROM AUTHOR]

Two series of A-site and B-site Eu 3+ doped (Sr x Ba 1− x ) 2 CaW y Mo 1− y O 6 double perovskite phosphor materials were prepared via a modified Pechini sol–gel route; (Sr x Ba 1− x ) 1.96 Eu 0.02 K 0.02 CaW y Mo 1− y O 6 and (Sr x Ba 1− x ) 2 Ca 0.96 Eu 0.02 Li 0.02 W y Mo 1− y O 6 (x and y =0, 0.25, 0.50, 0.75, 1). The Sr/Ba ratio was the main determinant for the crystal symmetry of the series, while variation in the W/Mo ratio did influence the crystal symmetry significantly. The crystal structure evolved with Sr/Ba ratio from cubic Fm 3 ¯ m for x =0, via tetragonal I 4 / m for x =0.25, to monoclinic P 2 1 / n for x≥0.5, as verified by Rietveld refinement of X-ray diffractograms as well as by Raman spectroscopy. The reported boundaries for the compositionally induced phase transitions are in very good agreement with reported optical properties. [ABSTRACT FROM AUTHOR]

Tetragonal and cubic zirconia nanoparticles were hydrothermally prepared and calcinated at different temperature. X-ray diffraction via Rietveld refinement is used to study the crystalline structure of nanoparticles. Results show that as-prepared tetragonal nanoparticles exhibit a crystalline structure with distorted lattice; the crystalline structure evolutes with the increasing calcination temperature and the distorted lattice is recovered after nanoparticles were calcinated at temperature higher than 900 °C. The cause for lattice distortion of tetragonal nanoparticles is discussed and is explained in term of the incorporations of hydroxyls into its lattice during preparation. [ABSTRACT FROM AUTHOR]

We report on the crystal structure refinements in the novel electron-transfer-active Prussian Blue analogs (PBA) KMn 4 II [ Co 1 − x III Fe x III ( CN ) 6 ] 3 · n H 2 O ( n ≃ 12 ). The series of novel PBA with the end members of KMn 4 [ Co ( CN ) 6 ] 3 · 11.8 H 2 O and KMn 4 [ Fe ( CN ) 6 ] 3 · 10.5 H 2 O have been synthesized for the first time, all showing a number of extra-reflections incompatible with ordinary face-centered cell of the Fm-3m symmetry group. We have analyzed the Rietveld patterns for x = 0 , 0.53 , 1 and found that the extra-reflections could be well fitted using several primitive (P) cell symmetries. The best fitting quality was obtained using the noncentrosymmetric space group (S.G.) P 4 ¯ 3 m ( Z =1) with the origin of coordinate system shifted into a zeolitic site. In this structure model, the Co–CN–Mn entities are bent owing to the charge introduced by the K + insertion that induces also the electron transfer between Mn and Fe. Using Mössbauer spectroscopy the electron transfer activity is identified with the appearance of unsplit resonance at the isomer shift of typically −0.15 mm/s evidencing the low-spin state for Fe 3+ and Fe 2+ species. In the same P 4 ¯ 3 m phases doped with Fe 2 + 57 into the Mn site, a sequence of discrete values of quadrupole splitting (0 mm/s, 0.9 mm/s, 1.8 mm/s) is observed and attributed to different conformations of the polyhedra, in which the ground states are orbital triplet, doublet and singlet, respectively. [ABSTRACT FROM AUTHOR]

The crystal structure of rilpivirine has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. Rilpivirine crystallizes in space group P21/c (#14) with a = 8.39049(3), b = 13.89687(4), c = 16.03960(6) Å, β = 90.9344(3)°, V = 1869.995(11) Å3, and Z = 4. The most prominent features of the structure are N–H···N hydrogen bonds. These form a R2,2(8) pattern which, along with C1,1(12) and longer chains, yield a three-dimensional hydrogen bond network. The powder pattern has been submitted to International Centre for Diffraction Data, ICDD, for inclusion in future releases of the Powder Diffraction File™. [ABSTRACT FROM PUBLISHER]

Structural and magnetic properties have been investigated for Co x Fe 3− x O 4 nanoferrites ( x =0.5–1.2, with a step increment of 0.1) prepared by a citrate-precursor autocombustion method. X-ray diffraction patterns (XRD) and Fourier-transform infrared (FTIR) spectra prove the formation of a cubic spinel phase of CoFe 2 O 4 , besides x -dependent FeCo 2 O 4 spinel for samples with x ≥0.7. Size of the formed nano-crystals ranges from 34 to 45 nm, which is further confirmed with a TEM micrograph. Investigating magnetic parameters such as saturation magnetization, coercivity, and remanence field, through vibrating sample magnetometry (VSM) data, revealed a strong dependence of the magnetic properties of each sample on its own cation distribution being suggested according to the experimental results of XRD, VSM, and IR data. [ABSTRACT FROM AUTHOR]

The crystal structure of folic acid dihydrate has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. Folic acid dihydrate crystallizes in space group P212121 (#19) with a = 7.275 78(3), b = 8.632 17(4), c = 32.417 19(22) Å, V = 2035.985(18) Å3, and Z = 4. The structure is dominated by a three-dimensional network of hydrogen bonds. The dicarboxylic acid side chain occurs in a bent conformation, helping explain the ability of folate derivatives to coordinate metal cations. The powder pattern has been submitted to ICDD for inclusion in future releases of the Powder Diffraction File™. [ABSTRACT FROM AUTHOR]

Almost a century has passed since the pioneering work of Debye, Scherrer, and Hull and their first powder X-ray diffraction experiments in 1916/17. Although these pioneers and many others discovered most of the fundamental concepts in the field of powder diffraction within the first few years, nobody at that time could foresee the development of the computer and its calculating power in the 21st century. The general availability of computing power changed the field of powder diffraction, as Hugo Rietveld showed with his computer-assisted whole powder pattern fitting concept around fifty years after the first powder diffraction patterns were observed. Nowadays, much more complex algorithms are used to solve and identify crystal structures from powders. The intention of this historical review is to show some of the most important developments from the viewpoint of the authors in the field of powder diffraction in the last century, from the beginnings of the first transmission experiments and the determination of simple cubic crystal structures to the techniques of today allowing for the refinement of thousands of atoms within one unit cell. [ABSTRACT FROM AUTHOR]

The structural and magnetic properties of Bi1-xNdxFe1-xMnxO3 ceramics prepared by the tartaric acid modified sol-gel technique have been studied to understand the effect of structural modification on the magnetic Properties of BiFeO3. The co-substitution of Nd and Mn at Bi and Fe sites respectively in BiFeO3 significantly suppress the impurity phases (Bi25FeO40, Bi2Fe4O9 etc.). The Rietveld analysis of X-ray diffraction (XRD) patterns indicates the existence of compositional driven crystal structure transformation from rhombohederal (R3c space group, higher crystal symmetry) to the orthorhombic (Pbnm space group, lower crystal symmetry) with the increase in substitution concentration due to excess chemical pressure (lattice strain). The quantitative crystallographic phase analysis has been carried out by Rietveld analysis of all the XRD patterns. Magnetic measurements reveal that co-substituted BiFeO3 nanoparticles for x=0.050 have enhanced remnant magnetization about 21 times as compared to pure one. The remnant magnetization reaches a maximum value at the morphological phase boundary (x=0.050) and further increase (x>0.050) in substitution concentration results in the reduction of remnant magnetization due to the appearance of complete antiferromagnetic ordering in the orthorhombic structure because of the significant contribution from the crystallographic phase of Pbnm space group (as obtained from the quantitative crystallographic phase contribution by the Rietveld analysis). [ABSTRACT FROM AUTHOR]

Commercial dutasteride crystallizes in the orthorhombic space group P212121 (#19), with a = 7.587 44(3), b = 9.960 80(5), c = 33.500 42(12) Å, V = 2531.862(17) Å3, and Z = 4. The structure was solved and refined using synchrotron powder diffraction data, Rietveld, and density functional techniques. The most prominent feature of the structure is a zigzag chain of strong N–H···O = C hydrogen bonds along the a-axis. The powder pattern has been submitted to ICDD for inclusion in future releases of the Powder Diffraction File™. [ABSTRACT FROM PUBLISHER]

Commercial atomoxetine hydrochloride crystallizes in the orthorhombic space group P212121 (#19), with a = 7.362 554(12), b = 13.340 168(27), c = 16.701 887(33) Å, V = 1640.421(5) Å3, and Z = 4. The structure was solved and refined using synchrotron powder diffraction data, and Rietveld and density functional techniques. The most prominent feature of the structure is zigzag chains of N–H···Cl hydrogen bonds along the a-axis. The powder pattern has been submitted to the ICDD for inclusion in future releases of the Powder Diffraction File™. [ABSTRACT FROM PUBLISHER]

Ho3+ion-substituted nanocrystalline cobalt ferrite materials with the chemical formula CoFe2−xHoxO4forx = 0.0, 0.025, 0.05, 0.075 and 0.1 have been synthesised by standard citrate precursor method. Crystal structure and phase purity have been studied by powder X-ray diffraction (XRD) method by employing Rietveld refinement technique. The distribution of cations between the tetrahedral site (A-site) and octahedral site (B-site) has been estimated by Rietveld analysis. The refinement result shows that Ho3+ion has a strong preference for octahedral sites (B-sites). The lattice constants decrease with the Ho3+concentration up tox = 0.05. Crystallite size decreases with the Ho3+concentration. The magnetic hysteresis loop measurements have been carried out at room temperature using a vibrating sample magnetometer (VSM) over a field range of ±2 T. The magnetisations in saturation have been analysed by employing the ‘law of approach (LA)’ technique. The magnetocrystalline anisotropy constant and saturation magnetisation are found to decrease with the Ho3+concentration up tox = 0.05. The coercivity decreases with the Ho3+concentration. The vibrational modes of the octahedral and tetrahedral metal complex in the sample have been carried out using Fourier transform infrared spectroscopy (FT-IR). The FT-IR spectra of the samples have been analysed in the wave number range of 350–1000 cm−1. We have observed two prominent absorption bands which are assigned to tetrahedral and octahedral metal complexes. The elemental analysis has been carried out using energy dispersive spectroscopy (EDS) with the help of field emission scanning electron microscope (FE-SEM) and the results reveal that, elements are as per the stoichiometric ratio in all the samples. [ABSTRACT FROM AUTHOR]

The Rietveld method is a versatile tool to parameterize the fine structure of crystallites analyzed by diffraction. The method relies on a crystallographic model representing what is known a priori, and free coefficients determined from fits to experimental data. This article provides an introduction to Rietveld analysis of celluloses from higher plants that are adequately described by the cellulose Iβ crystal structure. Possibilities of Rietveld analysis have been recently enhanced by a tailored crystallographic model and computational algorithm, named Cellulose Rietveld Analysis for Fine Structure (CRAFS). From each two-dimensional diffraction pattern, CRAFS automated analysis outputs unit cell parameters, crystallite sizes, peak profile functions, integrated crystalline intensity (proportional to cellulose degree of crystallinity), and crystallite orientation distribution function. Two of the major hurdles for analysis of plant cellulose-overlapping of diffraction peaks and preferred crystallite orientation-are consistently treated by the two-dimensional Rietveld analysis. Hence, the method is a unique tool to explore cellulose fine structural variability, with differences arising from specimen conditioning, processing, and biological origins. [ABSTRACT FROM AUTHOR]

Abstract: At mild hydrothermal conditions triclinic modifications of BaMP2O7 (M = Mn and/or Cu) have been succeeded. The method offers cheap, one step, impurity free and chemical flexible fabrication of family of metal phosphates that are potential low-dimensional quantum magnets. Partial isomorphous substitution of the Mn2+ by Cu2+ resulted into mixed-metal solid that has been structurally and magnetically characterized. Rietveld refinement study confirmed the structures and revealed the influence of transition metal substitution. The temperature-dependent magnetic measurements revealed that the system is paramagnetic in almost all temperature range and an apparent antiferromagnetic phase transition occurs around 5 K. Using the Curie–Weiss law, a Curie–Weiss temperature, θ P = −11.0 K, and a Curie constant C = 3.39 emu K mol−1 was obtained. The small negative θ P value and the χT behavior as a function of temperature reveal a weak antiferromagnetic interaction between the Cu2+/Mn2+magnetic centers. [Copyright &y& Elsevier]

Two morphological types of the synthetic analogue of the mineral natisite NaTiSiO have been prepared in the system NaO-TiO-SiO-HO. The crystal structures of the obtained pillow ( A)- and coin ( B)-shaped particles have been refined with similar parameters by the method of Rietveld, compared to each other and to the available single crystal X-ray diffraction data. Sample B showed bigger unit cell with longer a = b and shorter c-axis when compared with phase A. The shorter a = b axes in phase A led to compensative elongation of the c-axis and notably longer terminal bond distance in the TiO semi-octahedra. Analysis of the refined structural parameters showed that Ti-O bond of the unshared apical oxygen is the most responsive to the lattice strain. Additionally, the overall mechanism of structural response to the observed microstructural distortions is discussed. Graphical Abstract: The possible influence of different particle morphology on the Rietveld refinement results of synthetic natisite has been evaluated[Figure not available: see fulltext.]. [ABSTRACT FROM AUTHOR]

Abstract: Li4ZnTeO6 has been prepared by solid-state reactions and characterized by powder X-ray and neutron diffraction. It is monoclinic, C2/m, a=5.2114(3), b=8.9288(4), c=5.1768(3)Å, β=110.783(3)°. The material is structurally analogous to Li3Zn2SbO6 with LiTe substitution for ZnSb. The structure is based on honeycomb [(Li,Zn)2TeO6]3− layers interleaved with Li+ layers. Minor substitution of Zn in Li layers was detected. It is shown that Li3Cu2SbO6 known as C2/c actually belongs to the same C2/m type with halved unit cell volume. [Copyright &y& Elsevier]

Abstract: A new solid electrolyte Na2LiFeTeO6 has been prepared by solid-state reactions in air at 700°C and characterized by powder X-ray diffraction, redox titration and impedance measurements on ceramic samples. It is a new superstructure type of the well-known hexagonal layered P2 type with complete ordering of Li, Fe and Te in octahedral brucite-like layers: orthorhombic, P212121, a=5.2109(1), b=8.9791(2), c=11.2389(2)Å, Z=4. At room temperature, sodium ions in the interlayer gap are concentrated in two of the six non-equivalent trigonal prisms; at elevated temperatures, they exhibit high ionic conductivity, e.g., 4S/m at 300°C. Orthorhombic distortion decreases on heating, presumably due to sodium movement, and vanishes at ca. 400°C giving rise to the hexagonal Na2Co2TeO6-type structure. Analogous Na2LiRTeO6 (R=Al or Ga), Na2LiFeWO6, Na2Mn2TeO6, Na2M2WO6 (M=Ni or Cu), Na2NiMSbO6 (M=Al or Fe) and Na2NiAlTO6 (T=Nb or Ta) could not be prepared. [Copyright &y& Elsevier]

Abstract: The structural and magnetic properties of the spinel ferrite system Co1+x Fe2−2x Sn x O4 (x=0.0–1.0) have been studied. Samples in the series were prepared by the ceramic technique. The structural and microstructural evolutions of the nanophase have been studied using X-ray powder diffraction and the Rietveld method. The refinement result showed that the type of the cationic distribution over the tetrahedral and octahedral sites in the nanocrystalline lattice is partially an inverse spinel. Far infrared absorption spectra show two significant absorption bands, around 600cm−1 and 425cm−1, which are respectively attributed to tetrahedral (A) and octahedral [B] vibrations of the spinel. Scanning Electron Microscopy (SEM) was used to study surface morphology. SEM images reveal particles in the nanosize range. The transmission electronic microscope (TEM) reveals that the grains are spherical in shape. TEM analysis confirmed the X-ray results. The magnetic properties of the prepared samples were characterized by using a vibrating sample magnetometer. [Copyright &y& Elsevier]

The core mathematics, goodness-of-fit parameters of Rietveld refinement technique is introduced for structural analysis of crystalline materials not available as single crystals. X-ray diffraction (XRD) patterns of PbTiO compound prepared by following solid-state route, suggests it to be in single crystal form. All the observed peaks could be indexed to P4 mm space group with tetragonal symmetry. XRD pattern is analysed by employing Rietveld method. The unit cell parameters are found to be a = b = 38987 (0.0008) Å and c = 4·1380 (0·0009) Å. The axial ratio c/a and unit cell volume are found to be 1·0614 and 62·896 (0.023) Å. Bond lengths and angles are calculated using the cell parameters. Using the Rietveld refinement parameters a stable PbTiO structure is suggested. [ABSTRACT FROM AUTHOR]

Abstract: Aluminium substituted cobalt ferrite nanocrystalline materials with chemical formula CoFe2−x Al x O4 (x=0.0−0.4) have been synthesised by citrate precursor method. The crystal structure and phase purity were studied by powder X-ray diffraction (XRD). All the XRD patterns have been analysed by Rietveld refinement technique using the space group. The unit cell volume, average crystallite size, effective bond lengths and lattice parameters decrease with Al3+ concentration. Magnetic hysteresis loop measurements were carried out at room temperature using a vibrating sample magnetometer over a field range of ±2T. The saturation magnetisation, coercivity and Remanent magnetisation decrease with Al3+ concentration. The magnetic data in saturation have been analysed by employing the law of approach technique. The anisotropy constants are found to decrease with Al concentration. The saturation magnetisation, coercivity, remanent magnetisation and anisotropy constant increase with crystallite size. [Copyright &y& Elsevier]

Magnetoelectric Aurivillius phase Bi6Ti3Fe2O18 is obtained by molten salts synthesis (MSS). A description of the experimental conditions for preparing the compound is given. Scanning electron microscopy observation reveals that obtained crystallites show plate-like shape, with small size dispersion. MSS allows efficient control of crystallites' size. The crystal structure of the investigated phase is analyzed at the Stanford synchrotron powder diffractometer. Results of Rietveld structure analysis are given. Space group is F2mm. Cell parameters (in Á) are: a = 5.4967(2), b = 5.4655(2), c = 49.342(1). Iron ions tend to concentrate in perovskite octahedra far from the bismuth oxide layers. [ABSTRACT FROM AUTHOR]

Molten salt synthesis (MSS) of ceramics is an alternative to sol-gel and ceramic methods. Phase purity, as well as particle shape and size, may be effectively controlled by MSS. In the present study, magnetoelectric Aurivillius phase Bi 5 Ti 3 FeO 15 is obtained by MSS. Experimental setting for reaction control is described. Typical crystallites exhibit plate-like shape with noteworthy size uniformity and aspect ratio. The crystal structure of the investigated phase is analyzed by synchrotron x-ray powder diffraction. Rietveld refinement results for crystal symmetry, cell parameters and atomic positions are given. Space group is Fmm2. Cell parameters (in Å) are: a = 41.157(1), b = 5.4420(2), c = 5.4759(2). [ABSTRACT FROM AUTHOR]

Cadmium exchange on clinoptilolite is performed and structurally studied for different durations of the ion exchange process (2 h, 24 h, 72 h, 168 h, 12 days, 22 days) at room temperature and 90 °C. The distribution of Cd2+ ions in all samples is elucidated after exchange on clinoptilolite using powder XRD data processed by Rietveld structural software. Clinoptilolite is not selective for cadmium cations, but at 90 °C the exchange is ~2.5 cations per unit cell. At RT it reaches ~1.25 cations per unit cell being twice as low. The obtained maximum exchanged sample for 22 days 90 °C was structurally refined in order to find the cadmium positions in the clinoptilolite voids. The structural refinements of the occupations of the incoming and outgoing cations give an idea of how the intracrystalline diffusion is processed. A good correlation between results obtained by structural refinement of the Cd-exchanged samples and the data of the EDS measurements was achieved. [ABSTRACT FROM AUTHOR]

• Dy3+-doped Y 3 Al 5 O 12 (YAG) nanomaterials were successfully synthesized via facile solution route at 600 °C. • Rietveld refinement data confirmed the cubic unit cell with Ia3̅d (2 3 0) space group for the focused materials. • CIE color coordinates values were calculated to compare the intensity of prepared nanophosphors. • The suitable CIE color coordinates and CCT values in white region of chromaticity chart claim YAG:Dy3+ as promising candidate for WLEDs. Dy3+-doped Y 3 Al 5 O 12 (YAG) nanophosphors have been effectively synthesized via facile solution technique at 600 °C using urea as a fuel and calcined at 950 and 1050 °C for further analysis. Powder X-ray diffraction (PXRD), Fourier transformation infrared (FTIR), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) and photoluminescence (PL) studies were employed to confirm the synthesis, structural and luminescence properties of the phosphors. PXRD patterns of Y 3 Al 5 O 12 and Y 3 Al 5 O 12 :Dy3+ corresponds to JCPDS card No. 73–1370 having cubic unit cell and Ia3̅d space group, which were also confirmed by Rietveld refinement analysis. TEM images display the homogeneously disseminated nanocrystals with smooth morphology and particle size in 50–85 nm range. Energy dispersive X-Ray analysis (EDAX) proposed the pure synthesis of materials with presence of only elements integrated within host lattice. The photoluminescence emission (PL) spectra of YAG:Dy3+ nanophosphors exhibit strong emission owing to 4F 9/2 →6F 15/2 (480 nm) and 4F 9/2 →6F 13/2 (577 nm) under 352 nm excitation. Critical distance confirmed that the energy transfer occurs via multipolar interaction mechanism. CIE chromaticity diagram displays the intense white light emission for the phosphors. These investigations suggest the potential applications of YAG:Dy3+ nanocrystals in white light emitting diodes (WLEDs). [ABSTRACT FROM AUTHOR]

In this paper, we investigate the structural and magnetic properties of the GdHoRuO (0≤ x≤2) pyrochlores. X-ray diffractograms of all samples studied presented a cubic pyrochlore type crystal structure with lattice parameters varying linearly in accordance to Vegard's law. It is shown that by substituting Gd by Ho one can tune the magnetic order of this system moving from antiferromagnetic (in the absence of Ho) to ferromagnetic (in the absence of Gd). [ABSTRACT FROM AUTHOR]