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ThMn12 nitrides are good candidates for high performance permanent magnets. However, one of the remaining challenges is to transfer the good properties of the powder into a useful bulk magnet. Thus, understanding the denitrogenation process of this phase is of key importance. In this study, we investigate the magnetic and structural stability of the (Nd0.75,Pr0.25)1.2Fe10.5Mo1.5Nx compound (x=0 and 0.85) as function of temperature by means of neutron powder diffraction. Thermal dependence of the lattice parameters, formation of α-(Fe,Mo), as well as the nitrogen content in the nitrides are investigated by heating the compounds up to 1010 K. The decomposition takes place mainly via the formation of the α-(Fe,Mo) phase, which starts at around 900 K, whereas the nitrogen remains stable in the lattice. Additionally, we show that the magnetic properties of the nitrides [M(4T)=90Am2/kg and Hc=0.55 T] are maintained after the thermal treatments up to 900 K. This study demonstrates that the ThMn12 nitrides with the Mo stabilizing element offer good prospects for a bulk magnet provided an adequate processing route is found., The authors acknowledge the project “SpINS: Spanish Initiatives on Neutron Scattering,” funded by the Spanish Ministry of Science and Innovation, and the CSIC for the neutron beam time granted on the “CRG-D1B.” Institut Laue-Langevin (ILL) is also acknowledged. We are also thankful for technical and human support provided by SGIker (UPV/EHU) and particularly the services of X-Ray Molecules and Materials (Dr. Aitor Larrañaga Varga) and Magnetic Measurements (Dr. Iñaki Orue). This work has received funding from the European Union’s Horizon 2020 research and innovation program under Grant Agreement No. 686056 (NOVAMAG).

On the nanoscale, CoO can have different polymorph crystal structures, zinc blende and wurtzite, apart from rock salt, which is the stable one in bulk. However, the magnetic structures of the zinc blende and wurtzite phases remain virtually unexplored. Here we discuss some of the main parameters controlling the growth of the CoO wurtzite and zinc blende polymorphs by thermal decomposition of cobalt (II) acetylacetonate. In addition, we present a detailed neutron diffraction study of oxygen deficient CoO (CoO0.70–0.75) nanoparticles with zinc blende (∼15 nm) and wurtzite (∼30 nm) crystal structures to unravel their magnetic order and its temperature evolution. The magnetic order of the zinc blende nanoparticles is antiferromagnetic and appears at the Néel temperature TN ∼ 203 K. It corresponds to the 3rd type of magnetic ordering in a face-centered cubic lattice with magnetic moments aligned along a cube edge. The magnetic structure in the wurtzite nanoparticles turned out to be rather complex with two perpendicular components. One component is incommensurate, of the longitudinal spin wave type, with the magnetic moments confined in the ab-plane. In the perpendicular direction, this magnetic order is uncorrelated, forming quasi-two-dimensional magnetic layers. The component of the magnetic moment, aligned along the hexagonal axis, is commensurate and corresponds to the antiferromagnetic order known as the 2nd type in a wurtzite structure. The Néel temperature of wurtzite phase is estimated to be ∼109 K. The temperature dependence of the magnetic reflections confirms the reduced dimensionality of the incommensurate magnetic order. Incommensurate magnetic structures in nanoparticles are an unusual phenomenon and in the case of wurtzite CoO it is probably caused by structural defects (e.g., vacancies, strains and stacking faults)., This work was supported by the Russian grant RFBR 16-02-00058, the MAT2016-79455-P and MAT2015-68200-C2-2-P projects of the Spanish MINECO and by the 2017 SGR 292 and 2017 SGR 776 projects of the Generalitat de Catalunya. The ICN2 is supported by the Severo Ochoa Centres of Excellence programme funded by the Spanish Research Agency(AEI, grant no. SEV-2017-0706). ALO acknowledges the Juan de la Cierva Program (MINECO IJCI-2014-21530).

${\mathrm{CePd}}_{2}{\mathrm{Al}}_{2\ensuremath{-}x}{\mathrm{Ga}}_{x}$ compounds crystallizing in the tetragonal ${\mathrm{CaBe}}_{2}{\mathrm{Ge}}_{2}$-type structure (space group $P4/nmm$) and undergoing a structural phase transition to an orthorhombic structure ($Cmme$) at low temperatures were studied by means of neutron scattering. The amplitude-modulated magnetic structure of ${\mathrm{CePd}}_{2}{\mathrm{Al}}_{2}$ is described by an incommensurate propagation vector $\stackrel{P\vec}{k}=({\ensuremath{\delta}}_{x},\frac{1}{2}+{\ensuremath{\delta}}_{y},0)$ with ${\ensuremath{\delta}}_{x}=0.06$ and ${\ensuremath{\delta}}_{y}=0.04$. The magnetic moments order antiferromagnetically within the $ab$ planes stacked along the $c$ axis and are arranged along the direction close to the orthorhombic $a$ axis with a maximum value of 1.5(1) ${\ensuremath{\mu}}_{\mathrm{B}}/{\mathrm{Ce}}^{3+}$. ${\mathrm{CePd}}_{2}{\mathrm{Ga}}_{2}$ reveals a magnetic structure composed of two components: the first is described by the propagation vector $\stackrel{P\vec}{{k}_{1}}=(\frac{1}{2},\phantom{\rule{0.16em}{0ex}}\frac{1}{2},\phantom{\rule{0.16em}{0ex}}0)$, and the second one propagates with $\stackrel{P\vec}{{k}_{2}}=(0,\frac{1}{2},0)$. The magnetic moments of both components are aligned along the same direction---the orthorhombic [100] direction---and their total amplitude varies depending on the mutual phase of magnetic moment components on each Ce site. The propagation vectors $\stackrel{P\vec}{{k}_{1}}$ and $\stackrel{P\vec}{{k}_{2}}$ describe also the magnetic structure of substituted ${\mathrm{CePd}}_{2}{\mathrm{Al}}_{2\ensuremath{-}x}{\mathrm{Ga}}_{x}$ compounds, except the one with $x=0.1.\phantom{\rule{0.28em}{0ex}}{\mathrm{CePd}}_{2}{\mathrm{Al}}_{1.9}{\mathrm{Ga}}_{0.1}$ with magnetic structure described by $\stackrel{P\vec}{k}$ and $\stackrel{P\vec}{{k}_{1}}$ stays on the border between pure ${\mathrm{CePd}}_{2}{\mathrm{Al}}_{2}$ and the rest of the series. Determined magnetic structures are compared with other Ce 112 compounds. Inelastic neutron scattering experiments disclosed three nondispersive magnetic excitations in the paramagnetic state of ${\mathrm{CePd}}_{2}{\mathrm{Al}}_{2}$, while only two crystal field (CF) excitations are expected from the splitting of ground state $J=\frac{5}{2}$ of the ${\mathrm{Ce}}^{3+}$ ion in a tetragonal/orthorhombic point symmetry. Three magnetic excitations at 1.4, 7.8, and 15.9 meV are observed in the tetragonal phase of ${\mathrm{CePd}}_{2}{\mathrm{Al}}_{2}$. A structural phase transition to an orthorhombic structure shifts the first excitation up to 3.7 meV, while the other two excitations remain at almost the same energy. The presence of an additional magnetic peak is discussed and described within the Thalmeier-Fulde CF-phonon coupling (i.e., magnetoelastic coupling) model generalized to the tetragonal point symmetry. The second parent compound ${\mathrm{CePd}}_{2}{\mathrm{Ga}}_{2}$ does not display any sign of additional magnetic excitation. The expected two CF excitations were observed. The development of magnetic excitations in the ${\mathrm{CePd}}_{2}{\mathrm{Al}}_{2\ensuremath{-}x}{\mathrm{Ga}}_{x}$ series is discussed and crystal field parameters determined.

4 pags., 5 figs., 2 tabs., Ultra-microindentation was used to measure the microhardness and modulus of silk (Bombyx mori) membranes, cast from 20 to 80°C. The microhardness and modulus were determined from the loading/unloading curves. The membranes exhibit microhardness of about 400 MPa which is larger than the values for most common synthetic polymers (50-300 MPa) implying a greater scratch resistance. The moduli are of the order of those measured by the other means for B. mori silk membranes (5 GPa), and fibers (7-11 GPa). There is some correlation between microhardness and the dimensions of the grains/nanofibrils, but none with surface roughness. The results extend the range of an empirical correlation between microhardness and modulus. The present data together with previous data from other polymers fit the equation, H=0.55E0.74, with a correlation coefficient of 0.94. Finally, it is shown that elastic recovery of the silk membranes is an increasing function of the maximum load applied. © 2004 Elsevier Ltd. All rights reserved., This work was supported in part by Air Force Office of Scientific Research (AFOSR) Award number F49620-03-1-0169. Grateful acknowledgement is due to MCYT (grantBFM2000-1474) for the support of this investigation. Oneof us, I.P.O., also acknowledges the support of the FPIProgramme of MCYT (Spain).

Studies of the liquid state present an obvious fundamental interest and are also important for technological applications since the molten state is an essential stage in various industrial processes (e.g. glass making, single crystal growing, iron and steel making). Most of the physical properties of a high-temperature liquid are related to its atomic structure. Thus it is important to develop devices to probe the local environment of the atoms in the sample. At very high temperature, it is difficult to use conventional furnaces, which present several problems. In particular, physical contact with the container can contaminate the sample and/or modify its structural properties. Such problems encouraged the development of containerless techniques, which are powerful tools to study high-temperature melts. By eliminating completely any contact between sample and container, it is possible to study the sample with a very high degree of control and to access very high temperatures. An additional advantage of levitation methods is that it is possible to supercool hot liquids down to several hundred of degrees below their equilibrium freezing point, since heterogeneous nucleation processes are suppressed.

Procedures based on equilibrium conditions (stress and bending moment) have been used to obtain an unstressed lattice spacing, d0, as a crucial requirement for calculating the residual stress (RS) profile across a joint conducted on a 10 mm thick plate of age-hardenable AA2024 alloy by friction stir welding (FSW). Two procedures have been used that take advantage of neutron diffraction measurements. First, equilibrium conditions were imposed on sections parallel to the weld so that a constant d0 value corresponding to the base material region could be calculated analytically. Second, balance conditions were imposed on a section transverse to the weld. Then, using the data and a genetic algorithm, suitable d0 values for the different regions of the weld have been found. For several reasons, the comb method has proved to be inappropriate for RS determination in the case of age-hardenable alloys. However, the equilibrium conditions, together with the genetic algorithm, has been shown to be very suitable for determining RS profiles in FSW joints of these alloys, where inherent microstructural variations of d 0 across the weld are expected. © Published by Elsevier Ltd. All rights reserved., Support from Projects MAT-05-0527 and MAT-09-09545 from MICINN, and PIE 200960I076 from C.S.I.C., Spain, is gratefully acknowledged. Financial help from the ILL to conduct the neutron diffraction measurements on SALSA, experiments 1-02-6 and 1-02-10, is recognized. Support from Spanish Government Grants TIN 2008-00508 and MEC CONSOLIDER CSD00C-07-20811 and from Spanish MINECO (projects MAT2011-23455 and MAT2011-25991) is also acknowledged by J.I.H. and I.P.O., respectively.

The breathing of the flexible metal organic framework MIL-53(Cr) has been widely explored by both experimental and modeling approaches upon the inclusion of different guest molecules within its porosity. This spectacular phenomenon has been only partially tackled by force field based simulations mainly due to the complexity of deriving a set of accurate potential parameters able to capture the associated structural transition implying a unit cell volume change up to 40%. Here, a new parametrization of a flexible force field for the MIL-53(Cr) framework is realized from an iterative procedure starting with the experimental structural data collected in the presence of CO 2 as the guest molecule. Hybrid osmotic Monte Carlo simulations based on this refined force field are then successfully conducted to reproduce for the first time the complex shape of the CO 2 adsorption isotherm in the whole range of pressures. The structural behavior of the MIL-53(Cr) under a wide range of applied temperature and pressure is then followed by molecular dynamics simulations. It is established that these two stimuli also induce a similar reversible structural transition toward a contracted phase, with the presence of a hysteresis. Each of these predictions is confirmed by experimental evidence issued from either the literature for the impact of the temperature or from our own high pressure neutron diffraction measurements. This permanent experimental/modeling interplay allows a full validation of the derived flexible force field, a prerequisite for further understanding the microscopic key features that govern the spectacular breathing of such a material. © 2012 American Chemical Society.

9 páginas, 9 figuras, 4 tablas.-- PACS number(s): 71.20.Lp, 75.25.−j, 75.30.Gw, We report on the magnetic structures in the TbNiAl1−xInx compounds as determined by powder neutron diffraction. These compounds belong to a large family of ternary rare-earth intermetallics crystallizing in the ZrNiAl-type hexagonal structure. All studied compounds order magnetically with magnetic structures characterized by k1=(0,0,0) and k2=(1/2,0,1/2) propagation vectors and magnetic moments aligned along or perpendicular to the hexagonal c axis. The magnetocrystalline anisotropy changes from uniaxial in the In-poor compounds (x≤0.4) to planar in the In-rich compounds (x≥0.5). The change of magnetocrystalline anisotropy type is a consequence of the development of structural parameters in the studied series. The Tb moments are oriented along the c axis when the nearest Tb-Tb distances between the planes are large compared to those within the planes, whereas Tb moments lie within the basal planes in the opposite case. This picture relating the structural parameters and anisotropy type can be generalized to the whole group of Tb-based compounds with the ZrNiAl type of structure., This work is a part of Research Project No. LG11024 financed by the Ministry of Education of the Czech Republic. The work was also supported by the Czech Science Foundation under Grant No. 202/09/1027. The work of M.K. was supported by Grant No. SVV-2011-263303.

17 pags., 7 figs., The present work is concerned with the study of the development of the crystalline structure of poly(ethylene terephthalate) in multilayered films of poly(ethylene terephthalate)/polycarbonate (PET/PC) prepared by means of layer multiplying coextrusion. Small angle X-ray scattering patterns were recorded during isothermal crystallization experiments and evaluated by means of Ruland's interface distribution function. Thus, structural parameters describing the thickness distribution of crystalline and amorphous layers were determinated. It is shown that the crystallization of PET is delayed with increasing confinement. However when the crystallization process comes to an end, the values of the nanostructural parameters of the lamellar system are nearly the same for the confined and non-confined PET. © 2009 Elsevier Ltd.

European Discussion Meeting on Polymer Physics; Semicrystalline Polymers: Structure Formation and Properties, Alemania, 24 September 2003, he microhardness H of multilayered poly(ethylene terephthalate) (PET)/polycarbonate (PC) films, produced by continuous layer multiplying coextrusion has been determined. These materials present rather uniform laminates up to thousands of layers in the micrometre and submicrometre range. The micromechanical properties have been investigated as a function of layer thickness of the single polymer components, the total number of layers, the film thickness and the influence of heat treatment. The microhardness of the microlayered structure has also been determined across the profile in the parallel direction to the packing of the layers. The hardness in the vicinity of the PET/PC phases has been examined. Results reveal that the influence of the interphase on the H values for the samples with a large number of layers is rather small. The most important parameter in determining the final hardness of the multilayered films is the ratio of the penetration depth to the thickness of the layer. Upon heating, a microhardness increase is observed as a consequence of a double contribution: the crystallization of the PET layers, on the one hand, and the physical ageing of the PC zones on the other.

D1B is a medium resolution high flux powder diffractometer located at the Institut Laue Langevin, ILL. D1B a suitable instrument for studying a large variety of polycrystalline materials. D1B runs since 1998 as a CRG (collaborating research group) instrument, being exploited by the CNRS (Centre National de la Recherche Scientifique, France) and CSIC (Consejo Superior de Investigaciones Cientificas, Spain). In 2008 the Spanish CRG started an updating program which included a new detector and a radial oscillating collimator (ROC). The detector, which has a sensitive height of 100mm, covers an angular range of 128°. Its 1280 gold wires provide a neutron detection point every 0.1°. The ROC is made of 198 gadolinium- based absorbing collimation blades, regular placed every 0.67°. Here the present characteristics of D1B are reviewed and the different experimental performances will be presented.