Izabela Sosnowska

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• Prof. Dr.
• Professor of Physics at University of Warsaw

The gradual ferromagnetic spin reorientation in hexagonal close packed cobalt (hcp-Co) phase between 230∘C and 330∘C reported for a Co single crystal [Bertaut et al., Solid State Commun. 1, 81 (1963)] suggests that this phase could not have a hexagonal symmetry. This hypothesis is verified positively by synchrotron radiation diffraction and neutron...

The structure and the physical phenomena that occur in a crystal can be described by using a suitable set of symmetry-adapted modes. The classification of magnetic modes in crystals presented in Fabrykiewicz et al. [Acta Cryst. (2021), A77, 327–338] is extended to a classification of electric and toroidal (anapole) modes in crystals. These three cl...

The structural and magnetic properties of the room-Temperature multiferroic bulk a-BiFeO3 are described by using the magnetic superspace group formalism. The antiferromagnetic cycloid with its propagation vector along the hexagonal [1,1,0] direction cannot be described with trigonal magnetic superspace groups derived from R3c. This disagreement sho...

A classification of magnetic point groups is presented which gives an answer to the question: which magnetic groups can describe a given magnetic mode? There are 32 categories of magnetic point groups which describe 64 unique magnetic modes: 16 with a ferromagnetic component and 48 without. This classification focused on magnetic modes is helpful f...

A classification of magnetic superspace groups compatible with the helical and cycloidal magnetic modulations is presented. Helical modulations are compatible with groups from crystal classes 1, 2, 222, 4, 422, 3, 32, 6 and 622, while cycloidal modulations are compatible with groups from crystal classes 1, 2, m and mm2. For each magnetic crystal cl...

The structural and electronic properties of the rutile-type oxide β−PbO2 (plattnerite) are studied by neutron and synchrotron radiation diffraction and first-principles density functional theory (DFT) calculations. Both diffraction measurements and DFT calculations show that β−PbO2 has a CaCl2-type orthorhombic structure (space group Pnnm) instead...

A hitherto unrecognized resolution effect in neutron Larmor diffraction (LD) is reported, resulting from small-angle neutron scattering (SANS) in the sample. Small distortions of the neutron trajectories by SANS give rise to a blurring of the Bragg angles of the order of a few hundredths of a degree, leading to a degradation of the momentum resolut...

The symmetry lowering from tetragonal to orthorhombic is demonstrated using high-resolution diffraction and also justified by using the magnetic superspace groups formalism for the rutile-type compound β-MnO2. The (lower) orthorhombic symmetry is observed at temperatures both below and above the Néel temperature. The magnetic ordering of β-MnO2 is...

The crystal structures of several transition metal oxides, Ti2O3, V2O3, Cr2O3, Al2O3 and α-Fe2O3, are studied using synchrotron radiation X-ray powder diffraction. The observed angular dependence of the integral breadths is described by two models: (i) the distorted corundum-type structure model described by the space group C2/c and (ii) the Stephe...

The symmetry of materials which undergo a continuous spin reorientation has been analysed. It is shown that continuous spin reorientation is possible only in materials with triclinic or monoclinic crystal structure symmetry, i.e. other symmetries – orthorhombic, tetragonal, trigonal, hexagonal and cubic – are forbidden.

Over the first three years (1997 – 1999) of the original project of the 'European Physics Education Network' (EUPEN), Working Group 3 (WG3) has looked at the Organization of Physics Studies at both undergraduate and doctoral level. This was mainly done by means of questionnaires, which were sent to the members of the EUPEN network. The results from...

After concentrating on th first-degree Physics course, in the first ywo years of the EUPEN project, in the third year we extended this work to the doctoral degree. A questionnaire on this subject was prepared and sent out to the EUPEN partner institutions in early 1999. We received 93 completed questionnaires from a total of 117 sent out. In this p...

The modulated spin density wave magnetic orderings observed in chromium suggests that the crystal structure of chromium cannot be described by the cubic space group Im3¯m. Our experimental studies of polycrystalline and nanocrystalline chromium by synchrotron radiation (SR) and neutron powder diffraction show a hkl-dependent Bragg peak broadening w...

High-resolution synchrotron radiation powder diffraction patterns of α-Fe2O3 measured between room temperature and 1100 K, i.e. above the Néel temperature TN = 950 K, have been analyzed. The integral breadths of the Bragg peaks show a hkl-dependent anisotropy, both below and above TN. This anisotropy can be quantitatively described by using a stati...

High resolution synchrotron radiation powder diffraction shows that the average crystal structure of calcite at ambient conditions is described with the trigonal space group but there is a systematic hkl-dependent Bragg peak broadening. A modelling of this anisotropic peak broadening with the microstrain model from [Stephens, J. Appl. Cryst., 1999,...

Behind every improvement there is a story . The early history of the TOF neutron powder diffraction technique is presented. Successes and problems in the application of this technique in material science are reported. Powder diffraction technique is very useful when materials, in a single crystal form, reveal complicated electric and magnetic domai...

The crystal structure of α-Fe2O3 and α-Cr2O3 is usually described with the corundum-type trigonal crystal structure based on the space group . There are, however, some observations of the magnetic ordering of both α-Fe2O3 and α-Cr2O3 that are incompatible with the trigonal symmetry. We show experimental evidence based on X-ray powder diffraction an...

Lineshape analysis of high resolution synchrotron radiation diffraction patterns of polycrystalline α-Fe2O3 powders show distortions from trigonal (space group R-3c) symmetry. The symmetry lowering is observed for α-Fe2O3 polycrystalline powders from several commercial vendors. The experimental observations can be explained by assuming a monoclinic...

The rhombohedral CaMn7O12 manganite is an important material which shows magnetoelectrioc coupling with very high values of the electric polarization [1]. These outstanding properties motivated many experimental studies and also theoretical analysis. The mechanism which leads to these extraordinary properties has not been explained up to now. A fun...

The crystal structure of CaCu3Ti4O12 has been studied using high resolution synchrotron radiation based x-ray powder diffraction. The observed x-ray diffraction patterns show pronounced Bragg peak asymmetries which should not be present assuming the commonly accepted cubic crystal structure of CaCu3Ti4O12 described by the space group Im-3. Several...

Ultra-high-resolution neutron diffraction studies of BiFe0.8Co0.2O3 show a transition from a cycloidal space modulated spin structure at T = 10 K to a collinear G-type antiferromagnetic structure at T = 120 K. The model of antiparallel directions of Fe(3+) and Co(3+) magnetic moments at the shared Wyckoff position describes well the observed neutro...

The modulated magnetic ordering in the multiferroic manganite CaMn7O12 has been studied by using the neutron powder diffraction technique. The relative orientation of the magnetic moments of Mn4+ and Mn3+ ions located in Mn3 sublattice at (0,0,1/2) and Mn2 sublattice at (1/2,0,1/2) is shown to be antiparallel, i.e. their relative orientation angle...

A systematic study of the atomic position modulation in polycrystalline CaMn7O12 with different particle sizes (determined from scanning electron microscopy) and crystallite sizes (determined from X-ray diffraction) is reported. The morphology and phase composition are characterised by scanning electron microscopy, selected area electron diffractio...

The modulated magnetic ordering and the atomic position modulation are studied in the case of the multiferroic CaCuxMn7-xO12 by neutron and SR powder diffraction methods. Below the magnetic transition temperature of TN2=50 K both orderings are described by using the magnetic superspace group R31'(00γ)ts. For the magnetic ordering two different inco...

The modulated crystal structure and modulated magnetic ordering of the multiferroic CaCuxMn7−xO12 is studied by analysing neutron and synchrotron-radiation (SR) powder diffraction data with a model based on the magnetic superspace group R31′(00γ)ts. Both atomic position modulations and magnetic modulations are described with the modulation vector (...

Lineshape analysis of high resolution synchrotron radiation (SR) diffraction patterns of polycrystalline α-BiFeO3 is presented. The observations can be explained by assuming a symmetry lowering from the rhombohedral R3c to the monoclinic Cc. The lattice constants for the monoclinic Cc group are given. The symmetry lowering is observed with four dif...

High-resolution time-of-flight neutron diffraction studies of the magnetic ordering in the multiferroic BiFeO3 are presented. Our results show that the cycloidal modulated ordering proposed earlier [ I. Sosnowska, T. Peterlin-Neumaier and E. Steichele J. Phys. C 15 4835 (1982)] is stable between 10 and 295 K. The concept of the anharmonic character...

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Low temperature atomic position modulations and magnetic moment modulations are reported for CaCu(x)Mn(7 - x)O(12) (x = 0.0, 0.1 and 0.23) using neutron powder diffraction. Both modulations are described with propagation vectors (0, 0, q) parallel to the c-axis in the hexagonal setting. The present neutron diffraction studies confirm the quantitati...

The crystal and magnetic structure of BiFeO 3 have been studied with the use of high resolution neutron diffraction between 5 K and 300 K. The atomic coordinates in BiFeO 3 are almost unchanged between 5 K and 300 K.

Application of the neutron scattering technique in the study of crystal and magnetic properties of multiferroic BiFeO3 is presented. The crucial role of the neutron scattering technique, complementary to X-ray diffraction method and transmission electron microscopy, is shown. Especially the ultra high-resolution time-of-flight (TOF) neutron diffrac...

The modulation of atomic positions in CaCuxMn7−xO12 (x = 0 and 0.1) was studied using synchrotron radiation powder diffraction below 250 and 220 K, respectively. The copper-rich member CaCuxMn7−xO12 (x = 0.23) does not show any modulation of the atomic positions at temperatures as low as 10 K. Using low-temperature neutron powder diffraction the mo...

The magnetization of polycrystalline ceramic BiFeO3 has been studied with pulsed magnetic fields up to 58 T. We observe a magnetic transition in both, increasing and decreasing magnetic fields. The critical field of the transition decreases with temperature. It is observed at 18.1 T at 80 K and 16.1 T at 235 K for increasing fields, whereas with de...

We report the crystal structure evolution of CaCu0.2Mn6.8O12 as a function of temperature between 10 K and 290 K. The analysis of the diffraction data is carried out with the Rietveld method applied to the average trigonal structure of CaCu0.2Mn6.8O12. The x = 0.2 member shows similar low temperature extrema for the unit cell parameter evolution as...

The crystal structure of CaMn7O12 and CaCu0.1Mn6.9O12 has been studied by synchrotron radiation (SR) based powder x-ray diffraction and neutron powder diffraction in the temperature range from 10 K up to 290 K. The lattice parameter a exhibits a minimum at 45 K in CaMn7O12. The c lattice parameter in CaMn7O12 and CaCu0.1Mn6.9O12 has a maximum at th...

The parameters of the crystal structure of BiFeO3, described within the space group R3c, have been determined by high-resolution neutron powder diffraction for temperatures from 293 to 923 K. It was found that there is a local minimum for the rhombohedral angle αrh, near the Néel temperature TN ≃ 640 K, a gradual rotation of the FeO6 octahedra and...

The kinetics of thermal evolution of the microstructure of nanocrystalline chromium (nano-Cr) has been studied by time-resolved synchrotron radiation techniques: high-resolution powder diffraction and small-angle X-ray scattering (SAXS). The as-prepared electrodeposited nano-Cr with average grain size of 27 nm shows the same bcc structure as alpha-...

The crystal structure of NdFeO3 has been studied by high resolution synchrotron powder X-ray diffraction in the range from 10 K to 750 K and laboratory X-ray powder diffraction in the range from 700 K to 1200 K. The refined a and c lattice parameters are monotonically increasing, whereas the b parameter goes through a maximum at around 40 K and a b...

High resolution synchrotron radiation (SR) diffraction does not show any sign of charge ordering nor any crystal symmetry breaking in BiFeO3 at temperatures from 5 K up to 1000 K. The temperature dependence of the BiFeO3 lattice parameters shows a local minimum of the rhombohedral angle αrh around TN suggesting a strong spin–lattice coupling. Mössb...

The energy splitting of Nd nuclear levels and Nd nuclear polarization in NdFeO3 have been studied by using high resolution inelastic neutron backscattering with simultaneous neutron diffraction at temperatures between 100mK and 15K. Inelastic peaks are observed below 4.5K with a corresponding energy splitting ΔE=1.24μeV below 0.9K. The Nd nuclear m...

We present several modulated magnetic ordering models which all describe the high resolution neutron powder diffraction patterns of BiFeO3 with the same accuracy as the circular cycloid one proposed in [J. Phys. C 15 (1982) 4835]. These orderings are: the elliptical cycloid and the spin density wave (SDW). The ambiguity of the magnetic ordering in...

A phase diagram for CaCu{sub x}Mn{sub 7-x}O{sub 12} for x=<0.7 is presented. At room temperature CaCu{sub x}Mn{sub 7-x}O{sub 12} with x=0.10 and 0.20 crystallizes in the trigonal space group R3-bar and shows the same charge ordering of Mn{sup 3+} and Mn{sup 4+} ions as has been found for undoped CaMn{sub 7}O{sub 12}. The x=0.10 and 0.20 compounds b...

A phase diagram for CaCuxMn7-xO12 for x <= 0.7 is presented. At room temperature CaCuxMn7-xO12 with x = 0.10 and 0.20 crystallizes in the trigonal space group R (3) over bar and shows the same charge ordering of Mn3+ and Mn4+ ions as has been found for undoped CaMn7O12. The x = 0.10 and 0.20 compounds both show an apical-type Jahn-Teller distortion...

We contend that the anomalies observed in the magnetization, specific heat, and thermal expansion of CaMn7O12 at T S = 89 K and T M = 49 K reported in O. Volkova et al., Pis’ma v ZhETF 82, 498 (2005) [JETP Lett. 82, 444 (2005)] and mentioned in Pis’ma v ZhETF 82, 724 (2005) [JETP Lett. 82, 642 (2005)] are both of magnetic origin.

High resolution neutron powder diffraction has been applied to verify the model of distorted cycloidal magnetic modulation proposed on the basis of NMR studies of the multiferroic BiFeO3 in Zalesskii et al (2000 Europhys. Lett. 50 547). Our experimental results do not support the model of magnetic modulation given by Zalesskii et al for BiFeO3 at 4...

The crystal structure and the Fe3+ magnetic moment ordering in NdFeO3 have been studied by high-resolution neutron powder diffraction at temperatures ranging from 1.5 to 300 K. Between 100 and 200 K a spin reorientation transition is observed with gradual changes of the directions of the Fe3+ ordered magnetic moments. The spin reorientation tempera...

The magnetic long range ordering (LRO) and short range ordering (SRO) in beta-MnO2 has been studied by neutron powder diffraction. Below TN=92.5(1) K beta-MnO2 has an incommensurate modulated magnetic LRO with temperature dependent propagation vector length kz. The values of kz show a maximum, corresponding to kz = (2/7) + 0.0120(1), near 90 K. The...

The magnetic ordering of α-Mn2O3 has been studied by neutron powder diffraction measurements. An antiferromagnetic ordering occurs with the magnetic unit cell equivalent to the crystalline unit cell. Our results are compared with the results of previous works. The main antiferromagnetic Bragg peaks have different temperature dependence of their int...

The crystal structure of CaMn7O12 has been studied by high-resolution neutron and synchrotron radiation diffraction between 10 and . The unusual geometrical properties of the Mn–O bonds network in CaMn7O12 are discussed. The thermal lattice expansion is anisotropic—the hexagonal lattice parameter c has a local maximum around and a local minimum at...

DOI:https://doi.org/10.1103/PhysRevB.69.029901

The magnetic ordering of α-Mn2O3 has been studied by neutron powder diffraction measurements. An antiferromagnetic ordering occurs with the magnetic unit cell equivalent to the crystalline unit cell. Our results are compared with the results of previous works. The main antiferromagnetic Bragg peaks have different temperature dependence of their int...

The crystal structure of the distorted perovskite manganite system CaCuxMn7−xO12 has been investigated by using high resolution synchrotron and neutron powder diffraction for x=0.38 and 0.7. The measurements show a cubic phase at room temperature. For the system with smaller Cu content (x=0.38), there is a phase coexistence phenomenon: below 300 K...

The structural phase transition in annealed CaMn7O12 has been investigated by using high resolution synchrotron radiation powder diffraction. There is a phase coexistence phenomenon: two different crystallographic phases coexist in the material between 410 and 458K. The first one is trigonal and it has a charge ordering (CO) of the Mn3+ and Mn4+ io...

Neutron powder diffraction has been performed on polycrystalline BiMnxFe1-xO3 (x=0, 0.1 and 0.2). The structures of the doped compounds are described by the space group R3c of ferroelectric BiFeO3. Refined structure parameters are presented. Mn doping generates microstructural changes manifested by broadening in the diffraction patterns. The lattic...

The magnetic ordering in the distorted perovskite system CaMn7O12 has been studied by powder neutron diffraction. The magnetic ordering in CaMn7O12 consists of two phases: α, which is ferrimagnetic and β, which is modulated. The magnetic peaks due to both phases disappear at the same temperature near 90 K. The temperature dependence of the value of...

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The magnetic ordering and thermal lattice expansion of nanocrystaline chromium (n-Cr) are studied by neutron powder diffraction. Nanocrystalline Cr with a volume-averaged crystallite size of 27 nm has been obtained by electrodeposition. Between room temperature and 240 K there is a simple antiferromagnetic ordering. At 240 K the magnetic ordering c...

The structural phase transition in CaMn7O12 has been investigated by using high-resolution synchrotron and neutron powder diffraction. Both measurements show a phase coexistence phenomenon: between 409 and 448 K two different crystallographic phases coexist in the material. The first one is trigonal and it has a charge ordering (CO) of the Mn3+ and...

The crystal and magnetic structures of the CaCuxMn3-xMn4O12 compounds with x = 0.3 and 0.7 were investigated by means of x-ray and neutron powder diffraction. The crystal structure parameters of the x = 0.3 compound at 60 K have been refined within the trigonal space group R3̄. The magnetic moments of Mn ions in the x = 0.3 sample become ordered be...

Changes in the crystal and magnetic structures of BiFeO3 produced by substitution of some Fe ions by Mn ions are considered. For BiMnxFe1-xO3 with x = 0.1 and 0.2, the refinements of the crystal and magnetic structure parameters from time-of-flight (TOF) neutron diffraction data collected at 293 K are presented. The magnetic ordering temperatures a...

High-temperature proton conductors with perovskite structures are a class of well-known systems with high protonic conductivity, which is of high technological interest in view of the possible applications in solid oxide fuel cells. We present neutron and X-ray diffraction studies of the crystal structure of the Ba3Ca1.18Nb1.82O9−δ+zD2O (BCN18) sys...

The Debye-Waller factors of polycrystalline As, Sb and Bi, obtained by neutron diffraction in the temperature range of 5K up to almost the melting point, are compared with lattice dynamics model calculations and results from X-ray and Mossbauer effect measurements. Within experimental accuracy the thermal motions appear to be isotropic and almost h...

The temperature dependence of structural and magnetic order parameters of ferroelectric-antiferromagnetic BiFeO3 with rhombohedral perovskite structure is investigated by means of neutron diffraction on a powder sample. The tilt angle of oxygen octahedra decreases from 12.5 degrees at 4.2K to 11.4 degrees at 878K. Associated with ferroelectricity t...

New information on the magnetic ordering of the iron ions in bismuth ferrite BiFeO3 was obtained by a study with a high-resolution time-of-flight neutron diffractometer. The observed splitting of magnetic diffraction maxima could be interpreted in terms of a magnetic cycloidal spiral with a long period of 620+or-20 AA, which is unusual for perovski...

The mixed valence manganite CaMn7O12 system has a modulated magnetic ordering below 90 K which gives magnetic satellite reflections at Q < 0.2 Angstrom(-1). The results of small-angle neutron scattering (SANS) measurements on polycrystalline CaMn7O12 with and without external magnetic fields are discussed. It was found that near 50 K there is a sec...

Changes in the crystal and magnetic structure of BiFeO3 produced by substitution of some Fe ions by Mn ions are considered. Neutron diffraction patterns of BiMn0.2Fe0.8O3 were obtained at RT and at 700K at neutron wavelengths 1.12 and 2.33Å by using the DAS diffractometer. Refinement of the crystal and magnetic structure of BiMn0.2Fe0.8O3 is presen...

Recently, a new long-range order was observed in the Ba3Ca1.18Nb1.82O9- delta+xD2O proton conductor, where x!=0. In order to get more information concerning atomic arrangements in these complex perovskite oxides systematic neutron and X-ray diffraction studies of the stoichiometric and non-stiochiometric compound with and without D2O were performed...

The results of neutron powder diffraction experiments on a mixed valence oxide system CaMn7O12 with a distorted perovskite structure are discussed. Below 86 K long-range magnetic ordering of the magnetic moments of Mn3+ and Mn4+ ions was observed. Between 50 and 86 K there are two different ordered magnetic phases: one ferrimagnetic and the second...

We shall review some results in a few areas of material science in which neutron scattering and X-ray synchrotron scattering have exercised complementary (if not competitive!) roles. Three areas are selected: magnetism and the determination of magnetic structures; crystallography at high pressure; lattice dynamics and the phonon dispersion relation...

We discuss the properties of synchrotron radiation (SR) and neutron powder diffraction investigations of the crystal and magnetic structure of solids. Special emphasis is paid to the analysis of the full width at half maximum (FWHM) of the observed Bragg reflections and its relation with the size of the coherently ordered regions of the material. T...

The role of the neutron scattering technique in investigations of the proton conducting perovskite-oxides is briefly presented. Some applications of neutron scattering in the studies of crystal structure and dynamics of the proton conducting materials are given. Investigations of perovskite-oxides structures by very high-resolution neutron diffract...

We shall review some results from several areas of oxide science in which neutron scattering and X-ray synchrotron scattering exercise a complement-ary role to high-resolution transmission electron microscopy. The very high-resolution time-of-flight neutron diffraction technique and its role in studies of the magnetic structure of oxides will espec...

The magnetic structure of CaMn7O12 was investigated by neutron powder diffraction measurments in temperatures from 1.7 K to RT. We observed several magnetic reflections which appear around 86 K. Their 2theta positions shift considerably and get broader between 30 and 50 K, where an anomaly in magnetic susceptibility exists. These phenomena can be d...

Slow neutrons have been used in materials science for about 50 years. The principal reason for this is that neutrons are neutral particles and penetrate deep into materials. The principal cross-section of the slow neutron scattering is nuclear in origin. In particular, the neutron scattering cross-section for hydrogen is much greater than that for...

We describe we role of neutron and synchrotron radiation (SR) diffraction methods in the investigations of the crystal and magnetic structure of polycrystalline materials. Several examples of neutron and synchrotron radiation diffraction studies are presented. We discuss the structural properties of the following materials: cellular random systems...

The magnetic structure of CaMn7O12 was investigated by neutron powder diffraction measurements in temperatures from 1.7 K to RT. We observed several magnetic reflections which appear around 86 K. Their 2θ positions shift considerably and get broader between 30 and 50 K, where an anomaly in magnetic susceptibility exists. These phenomena can be due...

Very high resolution neutron diffraction of polycrystalline materials and the role of the TOF diffraction method as a unique tool for investigations of physical properties of materials, such as magnetism and proton conductivity, especially in slightly distorted perovskites, are discussed.

We observe magnetic contributions in the neutron diffraction patterns of BaSn2Fe4O11 at 10 K and of BaTi2Fe4O11 at 240, 165 and 10 K. In the former, we see evidence for a short-range Fe3+ antiferromagnetic ordering, while in the latter we observe contributions due to both long-and short-range magnetic orderings which may confirm the re-entrant spin...

Precious opals are built up from closest-packed silica spheres of about 200 nm diameter. The inelastic neutron scattering by ‘wet’ opal sample with 6 wt% water and by ‘dry’ opal sample 0.8 wt% water was investigated at different temperatures. The comparison between the opal water signal and the ice signal shows substantial differences, indicating a...

Refinement of the crystal structure of BaSn2Fe4O11 was made by using neutron diffraction data at 10 and 240 K, and high-resolution SR diffraction data at RT. Our data are best described by the space group P63/mmc. We determine the Fe/Sn distribution among crystallographic positions.

The temperature variation of the (100) and (010) neutron diffraction peak intensities, related only to the Nd magnetic moments, have been measured on a NdFeO3 single crystal, at temperatures down to 70 mK. The (100) peak becomes noticeable below 25 K while the (010) peak only gives an appreciable contribution below 1 K. Above TN2≈1 K the (100) peak...

We observe magnetic contributions in the neutron diffraction patterns of BaSn2Fe4O11 at 10 K and of BaTi2Fe4O11 at 240, 165 and 10 K. In the former, we see evidence for a short-range Fe3+ antiferromagnetic ordering, while in the latter we observe contributions due to both long- and short-range magnetic orderings which may confirm the re-entrant spi...

The high-temperature proton conductor (HTPC) Ba3Ca1.18Nb1.82O9−δ + yD2O was investigated at RT, 423 and 573 K by neutron diffraction. This HTPC, containing D2O, shows extra diffraction maxima. A new long-range order in the sample is observed.

Polycrystalline materials obtained from the around single crystals of BiFe03 and Bi0.93La0.07Fe03, reported as not having superstructure, show superstructure reflections in X-rays and neutron diffraction patterns. The determined magnetic moment of antiferromagnetically ordered Fe3+ ions is μFe = (3.70 ± 0.03)μBand μFe = (3.79 ± 0.03)μB for BiFe03 a...

Refinement of the crystal structure of BaTi2Fe4O11 was performed using neutron diffraction data collected at 10, 165 and 240 K. The Shiojiri model is proposed for the crystal structure. New structural parameters refined for these temperatures are presented. The neutron diffraction patterns show the existence of a long-range order of the magnetic mo...

Magnetic ordering of Nd3+ and Fe3+ ions in orthoferrite, NdFeO3, was investigated by neutron diffraction. Neutron diffraction patterns of polycrystalline NdFeO3 at 70 mK, 1.1 K and 4 K were obtained at neutron wavelength λ = 2.38 Å. C-type ordering for Nd3+ magnetic moments was confirmed. A deviation from the pure Gz-type configuration for Fe3+ mag...

The Time-of-Flight (TOF) method is used nowadays as a standard method for crystal structure investigations of polycrystalline materials at pulsed neutron sources. However, as was pointed out in the invited talk [1] at the ICNS'94 in Sendai, Japan, there is very little magnetic powder diffraction workdone at spallation neutron sources (see [1] and r...

Refinement of the crystal structure of BaSn2Fe4O11 was made using neutron-diffraction data collected at 10 K and 240 K, as well as the Shiojiri model of the crystal structure. New structural parameters were found for both temperatures. The neutron diffraction pattern at 10 K shows a new magnetic ordering of Fe3+ ions.

Refinement of the crystal structure of CaNdAlO4 was performed using neutron diffraction data collected at 10 and 240 K, and the structure parameters were determined for both temperatures. No order-disorder magnetic or structural phase transition occurred in the substance between RT and 10 K.

The ferroelectric-antiferromagnet BiFeO3 shows long period modulated magnetic structure with . The origin of this spatially modulated structure can be explained in terms of existence of relativistic Lifshitz invariants. By minimizing the free energy of the crystal and taking the Lifshitz invariants into account the spatially modulated spin structur...

We present inelastic magnetic neutron scattering spectra of polycrystalline Dy2Fe14B measured between 2 and 650 K employing different time-of-flight spectrometers. At the lowest temperatures we can identify in the magnetic excitation spectra the following features: (i) a dominant line at Δ = 12 meV with a shoulder at 11.1 meV, and (ii) two weak lin...

The complete crystalline electric field (CF) spectrum of Nd3+ (4I93) in NdFeO3 has been determined at T = 18 K by using inelastic neutron scattering. The four excited energy levels (doublets) are at 10.4, 22.7, 45.4 and 60.8 meV. A set of crystal field parameters was found that describes the CF peak positions and intensities very well.

The orthoferrite NdFeO3 crystallizes in space group Pbnm. At T = 1.5 K the ordering of Fe3+ ions is antiferromagnetic Gz with a small ferromagnetic component Fx. The ordering of Nd3+ ions is antiferromagnetic of the C type. The ordered magnetic moment of the Nd3+ ions at T = 1.5 K equals μNd = (1.14 ± 0.17) μB.