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The room temperature aerosol deposition method is especially promising for the rapid deposition of ceramic thick films, making it interesting for functional components in energy, mobility, and telecommunications applications. Despite this, a number of challenges remain, such as an enhanced electrical conductivity and internal residual stresses in as-deposited films. In this work, a novel technique that integrates a sacrificial water-soluble buffer layer was used to fabricate freestanding ceramic thick films, which allows for direct observation of the film without influence of the substrate or prior thermal treatment. Here, the temperature-dependent chemical and structural relaxation phenomena in freestanding BaTiO3 films were directly investigated by characterizing the thermal expansion properties and temperature-dependent crystal structure as a function of oxygen partial pressure, where a clear nonlinear, hysteretic contraction was observed during heating, which is understood to be influenced by lattice defects. As such, aliovalent doping and atmosphere-dependent annealing experiments were used to demonstrate the influence of local chemical redistribution and oxygen vacancies on the thermal expansion, leading to insight into the origin of the high room temperature conductivity of as-deposited films as well as greater insight into the influence of the induced chemical, structural, and microstructural changes in room temperature deposited functional ceramic thick films. Graphical abstract

A novel Ruddlesden–Popper-related compound, Gd3Ba2Fe4O12, was discovered and its crystal structure was determinedviasingle-crystal X-ray diffraction. The structure has an ordered structure of octahedra and pyramids along thecaxis. Gd3Ba2Fe4O12belongs to the tetragonal systemP42/ncm, witha= 5.59040 (10) Å andc= 35.1899 (10) Å. TheA-site ions in the Ruddlesden–Popper structure,i.e.Gd3+and Ba2+, exhibit an ordering along thecaxis. The perfect oxygen deficiency is accommodated at the GdO layers in the proper Ruddlesden–Popper structure. Using the bond-valence-sum method, the Fe ions in the FeO6octahedra and FeO5pyramids represent valence states of +3 and +2.5, respectively, demonstrating a two-dimensional charge disproportionation. The corner-sharing FeO6octahedra and FeO5pyramids are tilted in opposite directions, with the neighbours around one axis of the simple perovskite configuration, which, using Glazer's notation, can be represented asa−b0c0/b0a−c0. In the perovskite blocks, the facing FeO5pyramids across the Gd layer rotate in the same sense, which is a unique rotation feature related to oxygen deficiency.

Ferrochiral transition, i.e., a transition involving an emergence of chirality, provides an unique opportunity to achieve a nonvolatile reversible control of chirality with external fields. However, materials showing pure ferrochiral transitions, which are accompanied by no other types of ferroic transition, are exceedingly rare. In this study, we propose that a pure ferrochiral transition is achieved by a combination of antipolar and antiferroaxial orderings of structural units, and substantiate this proposal through a study of the chiral compound Ba(TiO)Cu4(PO4)4. Single crystal X-ray diffraction measurements have revealed that this material undergoes a second order ferrochiral transition whose order parameter is described by an antiferroaxial (staggered) rotation of antipolar structural units, thus demonstrating our proposal. Furthermore, by measuring spatial distributions of optical rotation, we successfully visualized a temperature evolution of ferrochiral domains across the transition temperature and demonstrated the relationship between chirality and optical rotation. This work provides a guide to find a pure ferrochiral transition, thus providing an opportunity to achieve a ferroic control of chirality.

We report the successful synthesis, crystal structure, and electrical properties of Sr3Re2O9, which contains Re6+ with the 5d1 configuration. This compound is isostructural with Ba3Re2O9 and shows a first-order structural phase transition at ∼370 K. The low-temperature (LT) phase crystallizes in a hettotype structure of Ba3Re2O9, which is different from that of the LT phase of Sr3W2O9, suggesting that the electronic state of Re6+ plays an important role in determining the crystal structure of the LT phase. The structural transition is accompanied by a sharp change in the electrical resistivity. This is likely a metal-insulator transition, as suggested by the electronic band calculation and magnetic susceptibility. In the LT phase, the ReO6 octahedra are rotated in a pseudo-a0a0a+ manner in Glazer notation, which corresponds to C-type orbital ordering. Paramagnetic dipole moments were confirmed to exist in the LT phase by muon spin rotation and relaxation measurements. However, the dipole moments shrink greatly because of the strong spin-orbit coupling in the Re ions. Thus, the electronic state of the LT phase corresponds to a Mott insulating state with strong spin-orbit interactions at the Re sites.

Quasi-zero-dimensional antiferromagnets with weakly coupled clusters of multiple spins can provide an excellent platform for exploring exotic quantum states of matter. Here, we report the synthesis and the characterization of a copper-based insulating antiferromagnet, K(NbO)Cu4(PO4)4. Single-crystal X-ray diffraction measurements reveal that the crystal structure belongs to the tetragonal space group P4/nmm, in which Cu2+ ions align to form a quasi-two-dimensional layer of spin-1/2 coupled square tetramers. The structure is quasi-isostructural to recently reported magnetoelectric antiferromagnets, A(TiO)Cu4(PO4)4 (A = Ba, Sr, and Pb) with the P4212 space group. Despite their structural similarities, whereas the antiferromagnetic transition in A(TiO)Cu4(PO4)4 produces conventional anomalies in magnetization and heat capacity, that in K(NbO)Cu4(PO4)4 has several unusual features such as an upturn in magnetic susceptibility and a very weak specific heat anomaly that corresponds to a spin entropy release as small as 3%. These results indicate that the magnetism of K(NbO)Cu4(PO4)4 is far different from that of A(TiO)Cu4(PO4)4 and suggest that the ground state is very close to a quantum nonmagnetic singlet state. The origin of the distinct magnetism in K(NbO)Cu4(PO4)4 is discussed in terms of structural modifications of a Cu4O12 unit forming a square tetramer. Our study demonstrates that the present material family, represented by an extended chemical formula A(BO)Cu4(PO4)4 (AB = KNb, BaTi, SrTi, and PbTi), has broad chemical controllability of their magnetism. This makes this system an attractive material platform to study the physics of quantum spin-1/2 coupled square tetramers.

The spin dimer magnet NaCu2VP2O10 was discovered, and its crystal structure was determined using single-crystal X-ray diffraction and electron diffraction. Maximum magnetic susceptibility was observed at ∼60 K and NaCu2VP2O10 became non-magnetic upon further cooling., The crystal structure of the spin dimer magnet NaCu2VP2O10 was determined using single-crystal X-ray diffraction and electron diffraction. NaCu2VP2O10 displayed a non-centrosymmetric orthorhombic C2221 structure with a = 6.13860 (10) Å, b = 14.4846 (3) Å and c = 8.2392 (2) Å. The layered structure comprised CuO4 plaquettes, VO6 octahedra and PO4 tetrahedra. A pair of CuO4 plaquettes formed Cu2O6 structural dimers through edge sharing. The Cu–Cu network formed a distorted puckered-layer structure with pseudo-one-dimensional characteristics. Maximum magnetic susceptibility was observed at ∼60 K and NaCu2VP2O10 became non-magnetic upon further cooling. The spin gap between the spin-singlet non-magnetic ground state and triplet excited state was estimated to be 43.4 K. Thus, NaCu2VP2O10 was assumed to be an alternating chain system with a singlet ground state of dimer origin. The V5+ ions in the VO6 octahedra showed large off-centre displacements along the [110] direction in the primitive perovskite structure, which were attributed to the pseudo-Jahn–Teller distortion of d 0 transition metals.

Superconductors are influenced by high-entropy alloys (HEAs); these have been investigated in various functional materials. REOBiS$_2$ (RE = La, Ce, Pr, Nd, Sm, and Gd in different combinations) single crystals with HEAs at the RE-site were successfully grown using the flux method. The obtained crystals were plate-shaped (1 mm$^2$) with a well-developed c-plane. Ce was present in both trivalent (Ce$^{3+}$) and tetravalent (Ce$^{4+}$) electronic configurations; the concentration of Ce$^{4+}$ at the RE-site was approximately 10 at% in all single crystals. The single crystals showed superconducting transition temperature with zero resistivity within 1.2-4.2 K. The superconducting transition temperature, superconducting anisotropy, electronic specific heat coefficient, and Debye temperature of the crystals were not correlated with the mixed entropy at the RE-site. Except for the electronic specific heat coefficient, the variation of these parameters as a function of mixed entropy showed different trends for equivalent and non-equivalent RE element compositions. Thus, the configuration of RE elements influences the superconducting properties of REOBiS$_2$ single crystals, alluding to a method of modulating transition temperatures.

X-ray fluorescence holography (XFH) measurements were carried out for multiferroic $\mathrm{Pb}({\mathrm{Fe}}_{1/2}{\mathrm{Nb}}_{1/2}){\mathrm{O}}_{3}$ (PFN) single crystal to investigate variations in the local structures around Nb ions with decreasing temperature from 300 to 100 K, in combination with single-crystal x-ray diffraction (XRD) experiments. We find that the Nb--Pb correlation is more significantly changed by cooling than the average structure derived from the single-crystal XRD experiments, indicating a mobile feature of Nb ions. Also, we analyze previously obtained XFH results around Fe ions in detail for comparison with those around Nb ions. In contrast to the case of Nb ions, the variation in the Fe--Pb correlation with decreasing temperature is well explained by the average structure from 300 K down to the N\'eel temperature of about 150 K. On the other hand, a remarkable positional fluctuation between Fe and Pb ions is observed at 100 K, which is evaluated to be 90% larger than that between Nb and Pb ions. This observation strongly indicates the presence of spin-lattice coupling in PFN. The present study clearly elucidates the differences of local environment around the Nb ions from that around the Fe ions located at the same $B$-site.

We have for the first time clarified the incommensurately modulated crystal structure as well as the photoluminescence properties of Eu2+-activated Ca2SiO4 solid solution, the chemical formula of which is (Ca1.88Eu2+0.01□0.11)(Si0.78P0.22)O4, where □ denotes vacancies in Ca sites with the replacement of Si4+ by P5+. The emission spectrum upon the 335 nm excitation showed a relatively broad band centered at ca. 490 nm and a full width at half-maximum of ca. 80 nm. The crystal structure was made up of the four types of β-Ca2SiO4-like layers with one type of interlayer. The incommensurate modulation with superspace group Pnma(0 β 0)00 s was induced by the long-range stacking order of these layers. The modulation wavevector was 0.27404(2) × b*, with the basic unit-cell dimensions being a = 0.68355(2) nm, b = 0.54227(2) nm, and c = 0.93840(3) nm ( Z = 4). The basic structure contained two nonequivalent Ca sites. One site was fully occupied by Ca2+ and free from Eu2+ in the overall incommensurate structure. The occupational modulation at the other site was so significant that the sum of site occupation factors for Ca2+ and Eu2+ as low as 0.5 was seen at the interlayer. This site was too large for accommodation of Ca2+ but was suitable for Eu2+. Thus, the Eu2+ ions would exclusively concentrate at the relevant site, which would cause the emission peak of the incommensurate phase to be shifted to the shorter wavelength ranges as compared with those of the other commensurate phases such as β and α'L.

A novel Ruddlesden-Popper-related compound, Gd

Ferrochiral transition, i.e., a transition involving an emergence of chirality, provides an unique opportunity to achieve a nonvolatile reversible control of chirality with external fields. However, materials showing pure ferrochiral transitions, which are accompanied by no other types of ferroic transition, are exceedingly rare. In this study, we propose that a pure ferrochiral transition is achieved by a combination of antipolar and antiferroaxial orderings of structural units, and substantiate this proposal through a study of the chiral compound Ba(TiO)Cu

We report the successful synthesis, crystal structure, and electrical properties of Sr

Quasi-zero-dimensional antiferromagnets with weakly coupled clusters of multiple spins can provide an excellent platform for exploring exotic quantum states of matter. Here, we report the synthesis and the characterization of a copper-based insulating antiferromagnet, K(NbO)Cu

TmFe

We have determined the crystal structure of U-phase, which is one of the calcium-aluminate layered double hydroxides (Ca–Al LDHs). Based on X-ray powder diffraction data, we derived the hydrogen-free structural model with space group R3 and hexagonal unit-cell dimensions a ​= ​0.99404(1) and c ​= ​3.00791(4) nm. The location of hydrogen sites was determined by calculation methods. The final structural model, with structural formula [3Ca2Al(OH)6][Na(H2O)6(SO4)2‧6H2O] (Z ​= ​3, a ​= ​0.99372 and c ​= ​2.82658 ​nm), was composed of [Ca2Al(OH)6]+ layers and [Na(H2O)6(SO4)2‧6H2O]3– interlayers. They were alternately stacked in c-axis direction and connected by hydrogen bonds to build the overall structure. The positions of Ca2+ in Ca(OH)64− octahedra were significantly shifted from the centroids of octahedra. Considering the coordination environment of divalent cations in Mn2+-Al LDH and Fe2+-Al LDH, the remarkable displacements of Ca2+ sites in the relevant octahedra would be one of the common structural characteristics of Ca–Al LDHs.

The strontium tungstate compound Sr3W2O9was prepared by a high-pressure synthesis technique. The crystal structure was determined by single-crystal X-ray diffraction and transmission electron microscopy. The structure was found to be a hettotype structure of the high-pressure phase of Ba3W2O9, which has corner-sharing octahedra with a trigonal symmetry. Sr3W2O9has a monoclinic unit cell ofC2/csymmetry. One characteristic of the structure is the breaking of the threefold rotation symmetry existing in the high-pressure phase of Ba3W2O9. The substitution of Sr at the Ba site results in a significant shortening of the interlayer distances of the [AO3] layers (A= Ba, Sr) and causes a distortion in the crystal structure. In Sr3W2O9, there is an off-centre displacement of W6+ions in the WO6octahedra. Such a displacement is also observed in the high-pressure phase of Ba3W2O9.

A new polymorphism of Ba3W2O9 is discovered with the use of a high-pressure synthesis technique and its crystal structure is determined by single-crystal X-ray diffraction and transmission electron microscopy. The crystal structure was isostructural with that of Ba3Re2O9, having a hexagonal unit cell of R3m symmetry with a = 0.574060(10) nm and c = 2.08256(4) nm. The high-pressure (HP) phase is obtained from a transformation of an ambient-pressure (AP) phase of the compound, which has the Cs3Tl2Cl9-type structure. The most notable change in the transformation is the connection of WO6 octahedra. The HP phase has corner-sharing octahedra, which form a bilayer structure, while the AP phase has face-sharing octahedra of isolated [W2O9] dimers. This type of the structural phase transition is unreported although it is possibly that a sequence of high-pressure structural transformations occurs for similar chemical compositions. The HP phase has W ions in WO6 octahedra with an unusual off-center displacement; al...

Ce1−xPrxOBiS2 (0. 1 ≤ x ≤ 0.9) single crystals were grown using a CsCl flux method. Their structural and physical properties were examined by X-ray diffraction, X-ray absorption, transmission electron microscopy, and electrical resistivity. All of the Ce1−xPrxOBiS2 single crystals with 0.1 ≤ x ≤ 0.9 exhibited tetragonal phase. With increasing Pr content, the a-axis and c-axis lattice parameters decreased and increased, respectively. Transmission electron microscope analysis of Ce0.1Pr0.9OBiS2 (x = 0.9) single crystal showed no stacking faults. Atomic-resolution energy dispersive X-ray spectrometry mapping revealed that Bi, Ce/Pr, O, and S occupied different crystallographic sites, while Ce and Pr randomly occupied the same sites. X-ray absorption spectra showed that an increase of the Pr ratio increased the ratio of Ce4+/Ce3+. All of the Ce1−xPrxOBiS2 crystals showed superconducting transition, with a maximum transition temperature of ~4 K at x = 0.9.

We investigated the correlation between the crystal structure and magnetism in ${\mathrm{Sr}}_{2}{\mathrm{Co}}_{2}{\mathrm{Fe}}_{28}{\mathrm{O}}_{46}$ using magnetic measurements and transmission electron microscopy. With changing temperature, the magnitude of the magnetization along the $[2\overline{1}\overline{1}0]$ and $[01\overline{1}0]$ directions changed drastically at $\ensuremath{\sim}340$ K, whereas that along the [0001] direction remained almost unchanged, suggesting a spin reorientation transition. The field dependence of the magnetization along $[2\overline{1}\overline{1}0]$ exhibited characteristic stepwise behavior below 150 K, whereas that along $[01\overline{1}0]$ did not exhibit this behavior, which suggests unusual magnetic anisotropy within the (0001) plane. Evaluation of the magnetic domain structures revealed that ${\mathrm{Sr}}_{2}{\mathrm{Co}}_{2}{\mathrm{Fe}}_{28}{\mathrm{O}}_{46}$ exhibits strong axial magnetocrystalline anisotropy with the axis along the direction tilted by $\ensuremath{\sim}{60}^{\ensuremath{\circ}}$ from the [0001] direction toward the $[01\overline{1}0]$ direction at low temperatures. This anisotropy along a nonunique crystallographic direction results in multiaxial anisotropy because of the crystal symmetry.

We have for the first time clarified the incommensurately modulated crystal structure as well as the photoluminescence properties of Eu

Understanding and controlling atomic motions in solid are essential in ionic materials, such as ion conductors, electrolyte and electrodes of batteries, and gas separators. Although photoinduced proton transport in solid materials has been demonstrated, photoinduced transport of heavier ions, such as the oxide ion, in solid materials remains entirely elusive. Herein, we apply ultrafast time-resolved electron diffraction to observe the large displacement of oxide ions in a strongly correlated material, EuBaCo2O5.39, under near-ultraviolet photoexcitation at room temperature. The mechanism of the photoinduced transport of oxide ions is revealed via the combination of ultrafast optical spectroscopy and density functional theory calculations. Our findings show that photoexcitation induces ionic motions in a ceramic crystal at room temperature through the charge transfer that strongly couples with large ionic displacement under the nonequilibrium condition.

The crystal structure and the magnetoelectric (ME) effect were investigated in highly c-axis oriented polycrystalline samples of Y-type hexaferrite, BaSrCo2Fe11AlO22, fabricated using a rotating magnetic field. A detailed crystal structure was determined using a combination of scanning transmission electron microscopy and single crystal x-ray diffraction. It was revealed that Co and Al ions, which play important roles in the performance of the ME effect, reside mainly on the Fe site in the S block of the Y-type hexaferrite. In the oriented samples, electric polarization induced by applying a magnetic field reached 140 μC/m2 at 200 K and 51 μC/m2 at 300 K; consequently, the ME coefficient αH was estimated to be 7200 ps/m at 300 K. The ME performance of the oriented samples is superior to that of nonoriented polycrystalline samples and comparable with that of single crystals. Furthermore, the oriented samples allow the control of magnetization by an electric field up to 325 K. These results facilitate further investigations on room-temperature multiferroics and their practical applications.

TmFe2O4 is one kind of multiferroic material in which equivalent amounts of Fe2+ and Fe3+ occupy a two-dimensional triangular lattice, leading to charge and spin frustrations. The spin frustration is expected to be increased as the fraction of Fe2+ (Fe3+) becomes larger than that of Fe3+ (Fe2+). We have grown single-crystalline TmFe2O4-δ with oxygen vacancies by using floating zone melting method and examined its magnetic properties. On cooling the compound, a long-range magnetic ordering develops around ∼240 K. With further cooling, a maximum of zero-field-cooled (ZFC) magnetization is observed at 186.2 K. The ac magnetic susceptibility obtained by ZFC process also manifests a maximum in its temperature dependence, and the variation of spin-freezing temperature with frequency of ac magnetic field is explainable in terms of the dynamic scaling law with the critical component of 8.68(8). This value suggests that the spin glass transition occurs at 186.2 K. The effect of external dc magnetic field on the irreversible transition temperature is coincident with the de Almeida-Thouless (AT) line. Aging-memory and rejuvenation effect is also observed below the spin-freezing temperature. These facts support the idea that TmFe2O4-δ undergoes spin glass transition below the ferrimagnetic transition temperature. In other words, TmFe2O4-δ can be regarded as a reentrance spin glass. It is thought that the oxygen vacancies bring about unequal number of Fe2+ and Fe3+ ions and thereby strengthen the magnetic frustration among the iron ions coupled with antiferromagnetic interactions, leading to the spin glass behavior.

The crystal structures of a perovskite-related layered compound ${\mathrm{Sr}}_{3}{\mathrm{W}}_{2}{\mathrm{O}}_{9}$ are investigated within a broad range of temperatures using x-ray diffraction and transmission electron microscopy. We observe successive structural phase transitions from the high-temperature ($R\overline{3}m$) to the middle-temperature ($R\overline{3}c$), and then to the low-temperature ($C2/c$) phases. The order parameter between the high- and middle-temperature phases can be regarded as the tilt angle of ${\mathrm{WO}}_{6}$ octahedra. In the middle-temperature phase, with increasing temperature, the tilt angle of ${\mathrm{WO}}_{6}$ octahedra decreases and approaches that of the high-temperature phase (zero tilting angle). In the low-temperature phase, an additional monoclinic distortion, which breaks the threefold symmetry that is observed in the high- and middle-temperature phases, appears. The successive structural phase transitions in ${\mathrm{Sr}}_{3}{\mathrm{W}}_{2}{\mathrm{O}}_{9}$ are attributed to the tilting of ${\mathrm{WO}}_{6}$ octahedra and subsequent octahedral distortion related to the layered structure.

A new polymorphism of Ba

The crystal structure of an X-type hexaferrite Sr2Co2Fe28O46 was investigated by the x-ray and neutron diffraction methods for a single crystal. Sr2Co2Fe28O46 has the crystal structure described as...

Well-faceted and chemically homogeneous single crystals of BaO-doped lanthanum silicate oxyapatite were grown by a BaCl2 flux method. They were characterized by optical microscopy, scanning electron microscopy, electron probe microanalysis (EPMA), X-ray diffractometry (XRD), and electrochemical impedance spectroscopy. The developed faces were identified for the two types of single crystals with different habit. The face indices were {100}, {101}, {110}, and {210} for the prismatic crystals, and {100}, {101}, {111}, and {001} for the isometric ones. With prismatic crystals, the general formula was derived from the numbers of cations determined by EPMA and structural data refined by XRD to be (La10−xBax)Σ=10(Si5.5+0.25x□0.5−0.25x)Σ=6O26 (1.78 ≤ x ≤ 1.81), where □ denotes a vacancy in Si site. We determined the oxide-ion conductivity (σ) of the prismatic single crystal of (La8.22Ba1.78)(Si5.94□0.06)O26 (x = 1.78) along the elongation direction, which is parallel to the c-axis. The σ-value steadily increased from 7.69 × 10−3 to 5.30 × 10−2 S cm−1 with increasing temperature from 823 to 1073 K. When compared at the same temperature, the σ-values were >230 times higher than those of the randomly grain-oriented polycrystal with the same chemical composition, the latter of which ranged from 1.74 × 10−5 S cm−1 at 823 K to 2.24 × 10−4 S cm−1 at 1073 K. The remarkable difference in conductivity between the single crystal and randomly grain-oriented polycrystal was found to be principally induced by the marked conduction anisotropy in the crystal structure.

We investigate the composition dependence of the magnetic properties in X-type hexaferrites Sr2CoxFe30−xO46. We prepared single crystals including various contents of cobalt ions using a flux method. The samples with x ≥ 1.58 exhibited a different behavior in the 2 1 ¯ 1 ¯ 0 and 01 1 ¯ 0 directions at 100 K, which was observed by magnetic measurements and Lorentz transmission electron microscopy. Such anisotropy was not observed in the sample that included slightly less cobalt ions (x = 1.32). In contrast, the Curie temperature was independent of the cobalt content. It was concluded that such strong magnetocrystalline anisotropy was caused by the cobalt ions especially at low temperature.

We investigated the correlations between the crystal structures and electrical properties of the double-perovskite GdBaFe2O5 over a broad range of temperatures. We examined the successive phase transitions and determined the crystal structures of four crystallographic phases of GdBaFe2O5 using electron diffraction and synchrotron radiation X-ray powder diffraction (SRXRD). The valence states of the Fe sites in the respective phases were deduced from the SRXRD data. We observed two types of charge-ordered states caused by charge and orbital orderings at Fe ions. The electrical resistivity displayed a metal-insulator transition, which is compatible with charge-ordered states. The structural phase transitions in GdBaFe2O5 were observed to be related to the charge-, magnetic-, and orbital-ordered states.

We performed X-ray fluorescence holography measurements on a Pb(Fe1/2Nb1/2)O3 (PFN) multiferroic material in order to investigate the temperature dependence of three dimensional local structure around Fe atoms. It was found that the atomic image intensity of the nearest neighbor Pb atom abruptly decreases when the temperature becomes lower than the Neel temperature (T N) of about 150 K, while the intensity of the atomic image at nearest Fe/Nb position remains almost unchanged. These observations show that the magnetic transition at T N induces static positional shifts of Pb atoms but does not strongly influence the Fe/Nb atoms, which suggests the involvement of Pb ions into the superexchange interaction between Fe ions and its contribution to the spin-lattice coupling in PFN.

Crystal structure of Ca1-x/2AlSi(N3-xOx):Eu2+(x∼ 0.11) has been characterized using an X-ray powder diffractometer and a transmission electron microscope equipped with an energy dispersive X-ray analyzer (EDX) and an electron energy loss spectrometer (EELS). The title compound is orthorhombic with space groupCmc21,Z= 4, unit-cell dimensionsa= 0.979780(7) nm,b= 0.565197(4) nm,c= 0.506356(3) nm, andV= 0.280404(3) nm3. The atom ratio Al:Si was determined to be 1:1 by EDX, and the presence of O atoms in the crystal structure was confirmed by EELS. Thex-value and the atomic coordinates of the final structural model were determined by the Rietveld method. The maximum-entropy methods-based pattern fitting (MPF) method was used to confirm the validity of the structural model, in which conventional structure bias caused by assuming intensity partitioning was minimized. The reliability indices calculated from MPF areRwp= 9.18%,S= 1.17,Rp= 6.77%,RB= 1.91%, andRF= 0.86%. Atomic arrangements of the final structural model are in an excellent agreement with the three dimensional electron-density distributions determined by MPF.

A new aluminum silicon oxycarbonitride, (Al 5.8 Si 1.2 )(O 1.0 C 3.5 N 1.5 ), has been synthesized and characterized by X-ray powder diffraction (XRPD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) and electron energy loss spectroscopy (EELS). The title compound is hexagonal with space group P 6 3 / mmc and unit-cell dimensions a =0.322508(4) nm, c =3.17193(4) nm and V =0.285717(6) nm 3 . The atom ratios of Al:Si and those of O:C:N were, respectively, determined by EDX and EELS. The initial structural model was successfully derived from the XRPD data by the direct methods and further refined by the Rietveld method. The crystal is most probably composed of four types of domains with nearly the same fraction, each of which is isotypic to Al 7 C 3 N 3 with space group P 6 3 mc . The existence of another new oxycarbonitride (Al 6.6 Si 1.4 )(O 0.7 C 4.3 N 2.0 ), which must be homeotypic to Al 8 C 3 N 4 , has been also demonstrated by XRPD and TEM.