We report on an investigation of the low-temperature structural, thermal, and magnetic properties of the binary trifluoride VF3 by temperature-dependent magnetization, heat capacity, electron paramagnetic resonance, and synchrotron powder and neutron powder diffraction measurements. At room temperature the crystal structure of VF3 features V3+ spin S = 1 regular triangular layers. At similar to 120 K VF3 undergoes a structural phase transition, and at similar to 18 K it undergoes an antiferromagnetic phase transition. The structural phase transition involves a minute orthorhombic distortion of the regular octahedral fluorine coordination shell of the trivalent V cations, effecting a distortion to the monoclinic crystal system. The magnetic phase transition generates a weak ferromagnet with V magnetic moments essentially confined to the trigonal planes of the room temperature structure described in the space group R - 3c. The ordered magnetic moments of the V3+ cations amount to approximate to 1 & micro;B and is thus distinctly reduced from the spin-only magnetic moment of 2 & micro;B. This finding and the weak ferromagnetic moment are discussed in view of the low-symmetry structure and spin-orbit effects on the 3T1 cubic ground term of the V3+ d2 system.

We report on an investigation of the low-temperature structural, thermal, and magnetic properties of the binary trifluoride VF 3 by temperature-dependent magnetization, heat capacity, electron paramagnetic resonance, and synchrotron powder and neutron powder diffraction measurements. At room temperature the crystal structure of VF 3 features V 3 + spin S = 1 regular triangular layers. At ∼ 120 K VF 3 undergoes a structural phase transition, and at ∼ 18 K it undergoes an antiferromagnetic phase transition. The structural phase transition involves a minute orthorhombic distortion of the regular octahedral fluorine coordination shell of the trivalent V cations, effecting a distortion to the monoclinic crystal system. The magnetic phase transition generates a weak ferromagnet with V magnetic moments essentially confined to the trigonal planes of the room temperature structure described in the space group R − 3 c . The ordered magnetic moments of the V 3 + cations amount to ≈ 1 μ B and is thus distinctly reduced from the spin-only magnetic moment of 2 μ B . This finding and the weak ferromagnetic moment are discussed in view of the low-symmetry structure and spin-orbit effects on the 3 T 1 cubic ground term of the V 3 + d 2 system.

Data mining for materials science and structure prediction is growing rapidly. Such an approach relies a lot on the available published and unpublished crystal structure. In this contribution, we are using the experimental pattern reported in the PDF entry 00-058-0728 for the experimental data used to solve the previously unreported crystal structure of RbCdVO 4 . Contrary to the reported literature, the title compound crystallizes in the monoclinic system P2 1 with Z = 4. The lattice parameters are a = 12.53678(16) Å, b = 5.82451(7) Å, c = 12.47733(17) Å, β = 105.6169(10)°, and V = 877.47(2) Å 3 . Its crystal structure type is new and quite complex as it exhibits 28 atoms in the asymmetric unit.

Data mining for materials science and structure prediction is growing rapidly. Such an approach relies a lot on the available published and unpublished crystal structure. In this contribution, we are using the experimental pattern reported in the PDF entry 00-058-0728 for the experimental data used to solve the previously unreported crystal structure of RbCdVO4. Contrary to the reported literature, the title compound crystallizes in the monoclinic system P21 with Z = 4. The lattice parameters are a = 12.53678(16) & Aring;, b = 5.82451(7) & Aring;, c = 12.47733(17) & Aring;, beta = 105.6169(10)degrees, and V = 877.47(2) & Aring;3. Its crystal structure type is new and quite complex as it exhibits 28 atoms in the asymmetric unit.

The effect of specimen displacement in X-ray powder diffraction experiments with laboratory diffractometers has been revisited and new expressions have been derived for several commonly used experimental configurations, including Bragg–Brentano parafocusing geometry and flat-plate transmission geometry. The results presented in this work allow the analysis of data from samples with relatively large displacements. This may open the possibility to study samples with dimensions that are difficult to accommodate with the sample-handling capabilities of standard laboratory diffractometers.

For long time, naproxen salts were believed to be the exception to the rule about polymorphism in active pharmaceutical ingredient. This unusual absence of polymorphism in naproxen salts triggered us recently to synthetize and characterize new naproxen salts. In this contribution, we are reporting the newly synthetized β polymorph of cadmium naproxen trihydrate exhibiting the formula Cd[C14H13O3]2(H2O)2.H2O. The water content and the absence of inversion center are being confirmed by DSC/TGA and second harmonic generation data. This work confirms the existence of polymorphism in naproxen salts, calling for further investigation in related salts.

We have investigated the in-situ heating of MgSiF6.6H2O using self-generated atmosphere to attempt synthetizing new phases of general formula MgSi(OH,F)6.xH2O. We are presenting our results with the synthesis and structure determination of the new fluoride MgSi(OH,F)6.2H2O. Our results demonstrate that insitu diffraction experiment using self-generated atmosphere with quartz capillaries is a good technique for investigating new hydroxyfluoric hydrated phases.

A new polymorphic form of sodium selenite pentahydrate is reported in this contribution. We determined its crystal structure from laboratory powder diffraction data recorded at room temperature. It crystallizes in the monoclinic system P 2 1 / n with Z = 4. The lattice parameters are a = 15.01473(16) Å, b = 7.03125(7) Å, c = 8.13336(10) Å, β = 98.4458(10)°, and V = 849.345(16) Å 3 . The crystal structure exhibits a layered structure with isolated 1D chains running along the b -axis.

Sodium naproxen is widely used as a non-steroidal anti-inflammatory active pharmaceutical ingredient (API).The crystal structure of this API has been reported back in 1990 [1].Despite 3 decades of research on this API, only one single polymorph has been reported.On the other hand, physicochemical stability may become a serious problem during new drug development and thus pseudo-polymorphism have been widely investigated for sodium naproxen.So far, 4 hydrates have been reported and characterized [2].So, while the pseudo-polymorphism is rather rich, polymorphism is unusually simple with only one known representative.This is a rather unusual case as polymorphism for APIs tends to be rather rich [3].With that in mind, we have started exploring other salts of naproxen, which could have been within Severus Snape's potion class: lead and cadmium salts.While cadmium exhibits only one hydrated form, lead naproxen exhibits a very rich polymorphism with one hydrate as illustrated in Fig. 1.All polymorphic structures have been determined using high resolution powder diffraction and are discussed in light of the already exhibiting sodium naproxen.Figure 1.Temperature dependence of Pb[C14H13O3]2.xH2O illustrating the temperature stability range of the 4 polymorphs and of its dihydrate (x = 2).

We report on the synthesis and structural characterization of a new naproxen salt. In-situ heating X-ray diffraction experiment allows us to determine the phase stability of the various polymorphic phases. Slow heating rate and repetitive scans strategy were essential to probe all phases in presence. Contrary to previously reported absence of polymorphic forms for naproxen salt, this new salt exhibits one metastable dihydrate form and five anhydrous phases. The crystal structures of all phases were determined using the in-situ X-ray powder diffraction data.

Several metal-organic frameworks (MOFs) excel in harvesting water from the air or as heat pumps as they show a steep increase in water uptake at 10-30 % relative humidity (RH%). A precise understanding of which structural characteristics govern such behavior is lacking. Herein, CAU-10-H and CAU-10-CH3 are studied with H, CH3 corresponding to the functions grafted to the organic linker. CAU-10-H shows a steep water uptake ≈18 RH% of interest for water harvesting, yet the subtle replacement of H by CH3 in the organic linker drastically changes the water adsorption behavior to less steep water uptake at much higher humidity values. The materials' structural deformation and water ordering during adsorption with in situ sum-frequency generation, in situ X-ray diffraction, and molecular simulations are unraveled. In CAU-10-H, an energetically favorable water cluster is formed in the hydrophobic pore, tethered via H-bonds to the framework μOH groups, while for CAU-10-CH3, such a favorable cluster cannot form. By relating the findings to the features of water adsorption isotherms of a series of MOFs, it is concluded that favorable water adsorption occurs when sites of intermediate hydrophilicity are present in a hydrophobic structure, and the formation of energetically favorable water clusters is possible.

A phase of silver iodate, gamma-AgIO3, has been obtained at ambient temperature by compressing alpha-AgIO3 to 1.60(5) GPa. The gamma-AgIO3 crystal structure was identified via Rietveld refinement of high-pressure powder synchrotron x-ray diffraction. The gamma-AgIO3 reflections were indexed to an orthorhombic lattice (Pbca) with unit-cell dimensions of a = 7.2945(12), b = 15.0013(24), c = 5.3904(9) angstrom, and V = 589.85(29) angstrom(3) at 2.20(5) GPa. Density-functional theory calculations predict that gamma-AgIO3 is more stable than alpha-AgIO3 above 0.15 GPa. The alpha -> gamma -phase transition is characterized by a decrease in the volume per formula unit of approximately 2% and it is reversible on decompression. Single-crystal optical-absorption measurements and density-functional theory calculations reveal the electronic band gap to decrease monotonically with increasing pressure in both alpha and gamma phases, however the alpha -> gamma-phase transition (indirect -> indirect) is characterized by an abrupt band-gap energy increase of approximately +0.18 eV. This pressure induced band-gap evolution is rationalized based on the I-O bond lengths. The. phase may correspond to an intermediate step between the previously known alpha and beta phases.

Synthetic and naturally occurring forms of tricopper orthotellurate, CuII3TeVIO6 (the mineral mcalpineite) have been investigated by 3D electron diffraction (3D ED), X-ray powder diffraction (XRPD), Raman and infrared (IR) spectroscopic measurements. As a result of the diffraction analyses, CuII3TeVIO6 is shown to occur in two polytypes. The higher-symmetric CuII3TeVIO6-1C polytype is cubic, space group Ia3, with a = 9.537 (1) Å and V = 867.4 (3) Å3 as reported in previous studies. The 1C polytype is a well characterized structure consisting of alternating layers of CuIIO6 octahedra and both CuIIO6 and TeVIO6 octahedra in a patchwork arrangement. The structure of the lower-symmetric orthorhombic CuII3TeVIO6-2O polytype was determined for the first time in this study by 3D ED and verified by Rietveld refinement. The 2O polytype crystallizes in space group Pcca, with a = 9.745 (3) Å, b = 9.749 (2) Å, c = 9.771 (2) Å and V = 928.3 (4) Å3. High-precision XRPD data were also collected on CuII3TeVIO6-2O to verify the lower-symmetric structure by performing a Rietveld refinement. The resultant structure is identical to that determined by 3D ED, with unit-cell parameters a = 9.56157 (19) Å, b = 9.55853 (11) Å, c = 9.62891 (15) Å and V = 880.03 (2) Å3. The lower symmetry of the 2O polytype is a consequence of a different cation ordering arrangement, which involves the movement of every second CuIIO6 and TeVIO6 octahedral layer by (1/4, 1/4, 0), leading to an offset of TeVIO6 and CuIIO6 octahedra in every second layer giving an ABAB* stacking arrangement. Syntheses of CuII3TeVIO6 showed that low-temperature (473 K) hydrothermal conditions generally produce the 2O polytype. XRPD measurements in combination with Raman spectroscopic analysis showed that most natural mcalpineite is the orthorhombic 2O polytype. Both XRPD and Raman spectroscopy measurements may be used to differentiate between the two polytypes of CuII3TeVIO6. In Raman spectroscopy, CuII3TeVIO6-1C has a single strong band around 730 cm-1, whereas CuII3TeVIO6-2O shows a broad double maximum with bands centred around 692 and 742 cm-1.

Molecular sieving membranes with uniform pore size are highly desired for carbon dioxide separation. All-silica zeolite membranes feature well-defined micropores, but the size-exclusion effect is significantly compromised by the non-selective macro-pores generated during detemplation. Here we propose a template modulated crystal transition (TMCT) approach to tune the flexibility of Decadodecasil 3 R (DD3R) zeolite to prepare ultra-selective membranes for CO 2 /CH 4 separation. An instantaneous overheating is applied to synchronize the template decomposition with the structure relaxation. The organic template molecules are transitionally converted to tight carbon species by the one-minute overheating at 700 °C, which are facilely burnt out by a following moderate thermal treatment. The resulting membranes exhibit CO 2 /CH 4 selectivity of 157~1,172 and CO 2 permeance of (890~1,540) × 10 −10 mol m −2 s −1 Pa −1 . The CO 2 flux and CO 2 /CH 4 mixture selectivity reach 3.6 Nm 3 m −2 h −1 and 43 even at feed pressure up to 31 bar. Such strategy could pave the way of all-silica zeolite membranes to practical applications.