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In this work, we report a facile method via electric field-assisted assembly of graphene oxide sheets to produce 3D graphene network. As expected, high specific capacitance (∼238 F g−1 at 0.5 A g−1) and well rate capability (the specific capacitance retained 60% at 10 A g−1) have been achieved in 3D graphene network-based supercapacitor. The significantly improved performances are due to large electrolyte accessible surface (257 m2 g−1) and high electrical conductivity (12.58 S cm−1). Furthermore, the electric field-assisted assembly method is a simple and promising way to fabricate 3D graphene network, compared to chemical vapor deposition, freeze drying, etc., which could efficiently reduce the production cost and promote its industrial production.

In this work, we study a Bronsted acid, p-Toluenesulfonic acid, as an effective TiO2/perovskite interface layer for high efficiency perovskite solar cell. The results show that p-Toluenesulfonic acid TiO2/perovskite interface layer-modified perovskite solar cell can significantly improve the power conversion efficiency to 19.29% under illumination of AM 1.5G (100 mW cm−2), in contrast to 17.91% of reference perovskite solar cell. It can be concluded that the p-Toluenesulfonic acid TiO2/perovskite interface layer-modified perovskite solar cell exhibits significantly enhanced device performance and reduced interface losses are due to the fact that the p-Toluenesulfonic acid TiO2/perovskite interface layer can induce preferential growth of perovskite crystals to form near-perfect perovskite film with bigger grain sizes and fewer interface defects, and effectively passivate the TiO2/perovskite interface, which favors to balance the electrons and holes transfer.

The subsolidus phase relations of the Dy-Fe-Al system have been investigated by means of X-ray powder diffraction. There are 5 ternary compounds, 10 binary compounds, and 21 three-phase regions in this system. The solid-solution regions of Dy(Fe1−xAlx)2, DyFe3−xAlx, Dy2(Fe1−xAlx)17, and DyFe12−xAlx have been determined based on the dependence of their unit-cell parameters on the Al content.

The structure transitions and phase relationships of DyFe3−xAlx compounds have been investigated by X-ray powder diffraction. Our XRD results show that each of the compounds with x≤0.45 crystallizes in the rhombohedral PuNi3-type structure with space group R3¯m and Z=9; for the 0.8≤x3 type with space group P63/mmc and Z=6; and each of the samples with 0.45

Double perovskite compounds (Sr{sub 2-x}Eu{sub x})FeMoO{sub 6} (0{

The structural and magnetic properties of the Nd2Co7-xFex compounds related to Rm+nT2m+5n series (R = rare earth, T = transition metal) were investigated by means of X-ray diffraction and magnetic measurements. The compounds crystallize in the Ce2Ni7-type structure with the space group P6(3)/mmc between x = 0.0 and 2.1. For higher Fe content the Nd-2(CoFe)(7) either coexists with the Nd(CoFe)(3) phase (x > 2.1) or decomposes to Nd(CoFe)(3) + Nd-2(CoFe)(17) (x > 2.4). The single phase Nd2Co7-xFe2 compounds exhibit two spin-reorientation transitions (SRT) for x 1.5. A magnetic phase diagram is constructed based on the magnetic measurements, thermogravimetry analysis under a low magnetic field and X-ray diffraction of magnetically aligned samples. The saturation magnetization of the compounds increases gradually first with the Fe content for x 1.5, which can be elucidated by a depletion effect of d band electrons due to the substitution of Fe for Co and the spin-flipping due to an enhanced d band splitting. (C) 2010 Elsevier B.V. All rights reserved.

Crystal structure of the compounds Co40V60−2xLax has been investigated by means of X-ray powder diffraction (XRD). The compounds crystallize in the tetragonal σ phase structure with the space group P42/mnm and form a solid solution with a solubility limit of x = 9.52. The lattice parameters a, c and the unit cell volume V of the compounds decrease linearly with the La content. A structure model with a preferential substitution of La for V atoms on the 8j sites accompanied by the presence of vacancies on these sites is proposed for Co40V44La8. The proposal structure model gives a satisfactory fitting to the XRD data and a reasonable La content close to the nominal composition as well as a coincidence of the calculated density with the experimentally measured one. The preferential occupation of La atoms on the 8j site is discussed based on a consideration of geometric constrain and thermodynamics.

The crystal structure and physical properties of Bi1−xGdxFeO3 ceramics with x ≤ 0.5 have been studied by X-ray diffraction, differential scanning calorimetry, dielectric and magnetic measurements. Bi1−xGdxFeO3 compounds crystallize at room temperature in R3c structure for x

Zn1−x Cr x O (0≤x≤0.15) nanoparticles were synthesized by an auto-combustion method and characterized by x-ray diffraction and Raman scattering techniques. The solubility limit for Cr in ZnO was determined as x≈0.03. Room-temperature ferromagnetism (RT-FM) was observed in lightly Cr-doped ZnO nanoparticles with x=0.01 and 0.02. Raman scattering spectra of the lightly Cr-doped and Co-doped ZnO were studied and compared. The enhancement of both the magnetization and the intensity of Raman scattering peak associated with donor defects (Zni and/or VO) and carriers indicates that light Cr doping in ZnO could be an effective way to achieve pronounced RT-FM and the ferromagnetism is closely related to the dopant-donor hybridization besides the ferromagnetic Cr–O–Cr superexchange interactions.

A novel hexaborate, Na2ZnB6O11, has been successfully synthesized by solid-state reaction and ab initio crystal-structure analysis has been completed using powder X-ray diffraction data. The compound crystallizes in the monoclinic space group Cc with lattice parameters a=10.7329(2) Å b=7.4080(3) Å, c=11.4822(2) Å, and β=112.16(2)°. The number of chemical formula per unit cell is Z=4 and the calculated density is 2.768(3) g/cm3. It represents a new structure type in which double-bridge-ring [B6O11]4− groups were found as fundamental building units. The infrared spectrum confirms the presence of both [BO3]3− groups and [BO4]5− groups.

Electron doped double perovskite compound (Sr 2− x Sm x )FeMoO 6 (0≤ x ≤0.25) has been synthesized by solid-state reaction at high temperature. Crystal structure and magnetic properties of the compounds have been investigated by X-ray powder diffraction (XRD) and magnetic measurements. XRD revealed that all the compounds were of single phase and belonged to a I4/m lattice. The degree of cationic ordering on the B site was decreased pronouncedly by the electron doping. Different from the results of La- and Nd-doped Sr 2 FeMoO 6 , Curie temperature ( T C ) of (Sr 2− x Sm x )FeMoO 6 decreased first with the doping and then increased beyond x =0.15, indicating that steric effect was enhanced as the radius of rare-earth ions decreased. Saturation magnetization ( M S ) of the compounds decreased with the doping level and anti-site (AS) concentration. Sm moment showed a considerable contribution to M S at low temperature, leading to an abrupt drop of M S between x =0.1 and 0.15.

Polycrystalline Nd(Mn(1-x)Fe(x))(2)Ge(2) (0

Two series of (In{sub 1-x}Fe{sub x}){sub 2}O{sub 3} were prepared by a solution combustion method using different fuel-to-oxidizer (i.e. glycine/metal nitrate, G/N) ratios. The crystal structure and magnetic properties of the compounds were investigated by means of X-ray diffraction, transmission electron microscopy and magnetic measurements. Detailed structural analysis shows the solubility limits of Fe in In{sub 2}O{sub 3} are x=0.08 and 0.45 for the G/N ratios of 5/4 and 5/6, respectively. Crystallite size of the samples prepared with the G/N ratio of 5/6 is much smaller than that of the samples prepared with the G/N ratio of 5/4. At room temperature, the sample with x=0.01 prepared with the G/N ratio of 5/4 is paramagnetic and those with x=0.03-0.07 are ferromagnetic, whereas the samples with x=0.15-0.45 prepared with the G/N ratio of 5/6 show superparamagnetic behavior and those samples with x

The crystal structure of K2Zn(PO3)4 was determined and refined using the Rietveld method based on the isostructure model of K2Cu(PO3)4. This compound belongs to the monoclinic system with space group Cc and lattice parameters of a=11.0941(2) Å, b=12.5215(3) Å, c=7.6597(2) Å, and β=102.47(2)°. The chemical formula unit per unit cell is Z=4 and the calculated density is 2.938(3) g∕cm3. Zigzag [PO3]∞ chains formed along the a axis, and their period contains eight PO4 tetrahedrons.

Polycrystalline GdGa compound was prepared by arc-melting method. X-ray powder diffraction reveals that GdGa crystallizes in the CrB-type structure. The Curie temperature of the compound is 183 K. A distinct peak associated with spin reorientation transition was shown around 100 K on the magnetization versus temperature Curve measured in a field of 0.05T. Isothermal magnetic entropy change (vertical bar Delta S(M)vertical bar) was estimated based on the magnetization isotherms. The maximum value of vertical bar Delta S(M)vertical bar is 4.81 J kg(-1) K(-1) under the apphed field changing from 0T to 5.0 T. The relative cooling power (RCP(S)) of GdGa compound is about 576 J kg(-1) under an applied field change of 5 T. The specific heat of the compound has been estimated within the framework of Debye and mean field approximations to evaluate the adiabatic temperature change (Delta T(ad)). (C) 2008 Elsevier B.V. All rights reserved.

Spin-dependent varistor-like electrical transport was observed in Sr-doped Nd(2/3)Sr(1/3)MnO(3-delta) perovskites for delta > 0.05, in which magnetic grain or phase boundaries is likely to be responsible. In addition to the varistor-like phenomena below a characteristic temperature, we also present evidence for electrical-field-induced magnetic order-order precursor transition at even lower temperature in regions close to highly insulating boundaries where larger electrical fields can be placed. This electrical-field-induced metamagnetic transition was understood by the competition among double exchange, superexchange interactions and external electrical or magnetic field. (c) 2008 Elsevier B.V. All rights reserved.

K2Zn3(P2O7)2was synthesized by solid state reaction and its crystal structure was determined byab initiomethod from powder X-ray diffraction (XRD) data. The title compound was determined to be orthorhombic with space groupP212121,Z=4, and lattice parametersa=12.901(8) Å,b=10.102(6) Å, andc=9.958(1) Å. Values of lattice parameters from 303 to 573 K were measured by temperature-dependent XRD. Thermal expansion coefficientsα0, lattice parameters, and cell volume at 0 K were determined to beα0(a)=1.62327×10−4/K,a0=12.855(4) Å,α0(b)=1.17921×10−4/K,b0=10.070(8) Å,α0(c)=2.62364×10−4/K,c0=9.880(4) Å, andα0(V)=6.599×10−2/K,V0=1278.967(0) Å3. The specific heat equation as a function of temperature was determined to beCp=0.77115+0.00231T−1241.60027T−2−1.4133×10−6T2(J/K g), for temperatures from 198 to 710 K. The melting point estimated from theμ-DTA heating curve is 795 °C.

In order to experimentally check the recent theoretical prediction regarding the Mn- or Fe-doped cubic ZrO(2) as potential spintronic materials and to search for high-temperature ferromagnetic spintronic material, a series of Zr(1-x)Mn(x)O(2) (x = 0.15-0.35) and Zr(1-x)Fe(x)O(2) (x = 0.15-0.40) nanoparticles were prepared by a coprecipitation method. The crystal structure and magnetic properties of the compounds were investigated by means of X-ray diffraction, transmission electron microscopy (TEM) and magnetic measurements. Detailed structural analysis confirmed that single phase of Mn- and Fe-stabilized cubic zirconia was obtained. The solubility limit of Mn (or Fe) in ZrO(2) is about x = 0.27 (or 0.36). Magnetic measurements showed that all the samples were paramagnetic at room temperature and 5 K. Existence of anti ferromagnetic interactions in the samples was inferred from the fitting of magnetization data to the Curie-Weiss law. The absence of ferromagnetism could plausibly be attributed to an excess of oxygen vacancies in the Mn- or Fe-stabilized cubic zirconia. (C) 2008 Elsevier B.V. All rights reserved.

Phase diagram of the pseudo-binary system Bi2O3-Cr2O3 has been reconstructed based upon X-ray diffraction measurement and differential thermal analysis. Four intermediate phases have been determined in this system: Bi14CrO24-based solid solution (beta(1), space group 14/m), Bi10Cr2O21 -based high-temperature solid solution (beta(2), orthorhombic symmetry), a new compound Bi2CrO6 (X, monoclinic symmetry) and the stoichiometric compound Bi6Cr2O15 (eta phase, orthorhombic symmetry, space group Ccc2). (C) 2008 Elsevier B.V. All rights reserved.

Strontium doped perovskite-type manganite Nd0.7Sr0.3MnO3 is synthesized by high-energy ball milling. Nd0.7Sr0.3MnO3 single phase with perovskite structure is formed completely after milling 4 h and the perovskite phase decreases gradually and changes into amorphous state with increasing ball milling time up to 12 h. The interesting point in this work is that the Nd0.7Sr0.3MnO3 perovskite can be formed again from the amorphous with subsequent 6 h ball milling. In addition, the re-obtained perovskite seems to be more stable than Nd0.7Sr0.3MnO3 compound prepared using solid-state reaction method.

Anti ferromagnetic Co3O4 nanoparticles with diameter around 30nm have been synthesized by a solution-based method. The phase identification by the wide-angle X-ray powder diffraction indicates that the CO3O4 nanoparticle has a cubic spinel structure with a lattice constant of 0.80843(2) nm. The image of field emission scanning electron microscope shows that the nanoparticles are assembled together to form nanorods. The magnetic properties of Co3O4 fine particles have been measured by a superconducting quantum interference device magnetometer. A deviation of the Neel temperature from the bulk is observed, which can be well described by the theory of finite-size scaling. An enhanced coercivity as well as a loop shift are observed in the field-cooled hysteresis loop. The exchange bias field decreases with increasing temperature and diminishes at the Neel temperature. The training effect and the opening of the loop reveal the existence of the spin-glass-like surface spins. (C) 2008 Elsevier B.V. All rights reserved.

The subsolidus phase relations of the ternary system ZnO-B2O3-P2O5 were investigated by means of X-ray diffraction (XRD). Seven binary compounds, 1 ternary compound and 10 three-phase regions were determined in this system. The phase diagrams of the pseudo-binary systems Zn-3(BO3)(2)-ZnO, Zn-3(PO4)(2)-ZnO and Zn3BPO7-ZnO were also determined through XRD and differential thermal analysis (DTA) methods. They all form eutectic systems with eutectic temperature about 1000 degrees C. Zn-3(BO3)(2) and Zn-3(PO4)(2) are not suitable fluxes, while Zn3BPO7 might be a suitable flux for ZnO crystal growth. (C) 2007 Elsevier B.V. All rights reserved.

Phase relations of BiFeO 3 –LaFeO 3 system at room temperature were investigated by X-ray powder diffraction. A rhombohedral ( R 3c) phase exists in the composition range of 0 ≤ x ≤ 0.1 and an orthorhombic ( P bnm) phase in the range of 0.6 x ≤ 1.0. Thermal expansion of single-phase samples with x = 0, 0.1, 0.7, 0.9 and 1.0 was studied by temperature-dependent X-ray diffraction. The temperature dependences of expansion coefficients of the samples were obtained. Specific heat capacity of the samples with x = 0, 0.1, 0.8 and 1.0 was measured in the temperature range of 200–760 K by a modulated-temperature differential scanning calorimeter. The phase boundaries of the antiferromagnetic–paramagnetic transition were determined.

A thermodynamic assessment of the Cu-Ga system was carried out by the CALPHAD approach (CALculation of PHase Diagram). The liquid phase, the solid solution phases of fcc (alpha-Cu) bcc (beta) and, hcp (zeta), the Solution compounds of Cu(9)Ga(4)_0 (gamma(o)), Cu(9)Ga(4)_1 (gamma(1)), Cu(9)Ga(4)_2 (gamma(2)) and Cu(9)Ga(4)_3 (gamma(3)), the stoichiometric compounds Of Cu(0.778)Ga(0.222) (zeta') and CuGa(2), and the terminal phase of orthorhombic-Ga were taken into consideration in the optimization. The substitutional solution model was used for the liquid phase and the solid solution phases of fcc, bcc and hcp. The solution compounds related to Cu(9)Ga(4) were described with the sublattice model. The order-disorder transformation between CugGa(4)_0 (gamma(0)) and Cu(9)Ga(4)_1 (gamma(1)) was considered. In the model description of Cu(9)Ga(4)_2 (gamma(2)) and Cu(9)Ga(4)_3 (gamma(3)), vacancies were considered. Differential scanning calorimetric analysis was conducted to obtain phase transformation temperatures and the enthalpies of fusion of Cu-Ga alloys. A set of self-consistent thermodynamic parameters were obtained and the calculated phase diagram and thermodynamic properties were presented and compared with experimental data. (C) 2008 Elsevier Ltd. All rights reserved.

Subsolidus phase relations in the ternary system SnO2 - TiO2 - Y2O3 have been investigated by means of X-ray powder diffraction. The samples are prepared by solid-state chemical reaction method at 1400 degrees C. The solid solution miscibility gap at room temperature for the TiO2 - SnO2 system was determined to be content 22 - 68 mol% SnO2, based on accurate determination of lattice parameters as functions of composition. The Y2Ti2 - xSnxO7 forms a complete solid solution with pyrochlore-type structure. (c) 2007 Elsevier B.V. All rights reserved.

We present a systematic investigation on the structural and magnetic properties of Zn1-xCoxO nanoparticles synthesized by an auto-combustion method. The single-phase Zn1-xCoxO crystallize in the wurtzite-type structure with a homogeneity range as large as x approximate to 0.30, which enables the observation of some anomalies. The lattice parameter a and the unit cell volume V increase with the Co content, and anomalies are discernable around x = 0.15 on the a-x and V-x curves. The magnetization data show no evidence of ferromagnetic ( FM) ordering in our samples down to T 5K, and the magnetization at 5K and 5T exhibits a maximum around x 0.125. Based on the detailed analysis of the magnetization data and the donor impurity band exchange model, the anomalies on composition dependence of both the lattice parameters and magnetization can be associated with an occurrence of cation percolation around the threshold x(p) (approximate to 1.5/Z = 0.125 for three-dimensional lattice with coordination number Z = 12). Within the framework of the donor impurity band exchange model, the absence of FM in the well-characterized Zn1-xCoxO can be attributed to insufficient donor electron concentration. (c) 2008 Elsevier B. V. All rights reserved.

Zn(1-x)Co(x)O (x = 0-0.04) nanoparticles were synthesized by an auto-combustion method. X-ray diffraction and Raman scattering studies confirmed the incorporation of Co into the ZnO lattice. Hysteresis loops were observed at 300 K in the samples with x = 0.01-0.04, and the coercivity decreased with increasing Co content x. Temperature dependence of magnetization showed a usual steep upturn for transition metals doped ZnO at low temperature, however a simultaneous rapid decrease of coercivity below 50 K was observed in this work. Both of the features could be associated with the localization and the low density of the carriers at low temperature. (C) 2008 Elsevier Ltd. All rights reserved.

Polycrystalline samples of Gd(Co1-xMnx)(2) have been prepared by arc-melting method. The compounds form a complete solid solution with the MgCu2-type structure and the lattice constant varies monotonically as a function of the Mn content with a negative deviation from the Vegard's law. The Curie temperatures of the compounds have been determined by thermomagnetic measurements and the thermogravimetric analysis. Isothermal magnetic entropy change (vertical bar Delta S-M vertical bar) of the samples with x = 0.65, 0.7, 0.8, and 0.9 have been calculated by the magnetization isotherms. In the four samples, the addition of Mn decreases the Curie temperature, while the vertical bar Delta S-M vertical bar increases. (c) 2007 Elsevier Ltd. All rights reserved.

A series of RFe 11 Mo compounds (R=Y, Nd, Gd, Tb, Dy, Ho and Er) with the ThMn 12 -type structure have been synthesized. The structural and magnetic properties of the compounds have been investigated by means of X-ray diffraction (XRD) and magnetic measurements. The lattice parameters a, c and the unit-cell volume V of the compounds decrease with decreasing the atomic radius of the rare earth element due to the lanthanide contraction. The spin-reorientation transition (SRT) was investigated in detail. For HoFe 11 Mo, no SRT was observed. For NdFe 11 Mo, TbFe 11 Mo and ErFe 11 Mo one SRT was observed, while for DyFe 11 Mo two SRTs were observed. By minimizing the magnetocrystalline anisotropy energy, theoretical SR temperatures of the compounds are derived, which show a reasonable agreement with the experimental values.

A solid solution with formula (Y1-xTbx)(3)GaO6 (x = 0-0.5) was prepared by solid-state reaction method. Powder X-ray diffraction (XRD) shows that Y3GaO6 is isostructural to Gd3GaO6 (Cmc2(1)), and the lattice parameters are a = 8.8364(1) angstrom, b = 11.0899(1) angstrom and c = 5.3937(1) angstrom. Atomic parameters were derived by Rietveld refinement of the XRD pattern. Photoluminescence (PL) spectra show a strong green emission of 543 nm from the D-5(4) -> F-7(5) transition of Th3+ at room and liquid nitrogen temperature. There is a wide saturation range of the PL intensity for the Th3+ content from x = 0.04-0.20, and a long life time about 1200 mu s for the green 543 nm emission at room temperature. (c) 2006 Elsevier B.V. All rights reserved.

The crystal and magnetic structures of Sr-2(Fe1-xVx)MoO6 (0.03

The crystal and magnetic structures of the Laves phase compound NdCo2 in the temperature range from 9 to 300K are determined by Rietveld refinement technique, using high-resolution neutron powder diffraction data. The compound crystallizes in space group Fd (3) over barm above the magnetic ordering temperature T-C (approximate to 100K), in space group I4(1)/amd below T-C and in space group Imma below the tetragonal-orthorhombic structural/magnetic transitions at T-M approximate to 42 K. The assignment of the space groups to the crystal structures of NdCo2 in different temperature ranges complies with the reported Mossbauer studies. Detailed information of the crystal and magnetic structures of NdCO2 at different temperatures are reported. (c) 2005 Elsevier B.V. All rights reserved.

The crystal structure and magnetic properties of mixed rare earth Nd2-xErxFe17 compounds (0

Hole-doped double perovskite compounds (Sr,Na)2FeMoO6 with the Na content of x=0,0.02,0.03,0.07 and 0.17 have been synthesized by sol–gel method. Effects of hole doping on the crystal structure and magnetic properties of Sr2FeMoO6 have been investigated by means of X-ray powder diffraction (XRD) and magnetic measurements. The XRD pattern indicates that all the samples are of single phase and belong to the space group I4/m. Due to the smaller ionic radius of Na+ than that of Sr2+ ions, the lattice constants and unit cell volume of the compound decrease slightly with x. The degree of cation ordering in the Na-doped Sr2FeMoO6 compounds shows a non-monotonic variation with the doping level, increasing from x=0 to x=0.03 and decreasing slightly with further increase of the doping. In contrast to the composition dependence of the degree of ordering, the Curie temperature of the compound decreases at low doping level and increases at high doping level. The saturation magnetization of the compound increases with x for x

The structural and magnetic properties of Nd1-xTbxFe10.5Mo1.5 (x = 0, 0.2. 0.4, 0.6, 0.8, 1.0) compounds have been investigated by means of X-ray diffraction and magnetic measurements. All the investigated compounds crystallize in the tetragonal ThMn12-type structure with 14/mmm space group. The lattice parameters a, c and the unit-cell volume V decrease with increasing x. The Curie temperatures T-C are almost independent x. There exists a unique spin-reorientation transition for the end compositions of Nd1-xTbxFe10.5Mo1.5 compounds with x = 0 and x = 1, while two spin-reorientation transitions are observed for x = 0.2-0.8. The room-temperature magnetocrystalline anisotropy of Nd1-xTbxFe10.5Mo1.5 compounds changes from uniaxial to planar with increasing x content. Based on magnetic measurements, a magnetic phase diagram of Nd1-xTbxFe10.5Mo1.5 compounds is constructed. By minimizing the magnetocrystalline anisotropy energy, a theoretical magnetic phase diagram for the Nd1-xTbxFe10.5Mo1.5 System is derived, showing a reasonable agreement with the observations. (c) 2005 Elsevier B.V. All rights reserved.

Two serials of Eu3+ doped AlN films are prepared by means of magnetron RF reactive sputtering under different RF powers and N-2/(N-2 + Ar) ratios. XRD analysis indicates that the films change from amorphous to c-axis oriented crystalline as the RF power increases or as the N-2/(N-2 + Ar) ratio decreases. Lower N-2/(N-2 + Ar) ratio and higher RF power enhance the deposition rate and crystallinity. The grain size and surface roughness observed by SEM and AFM increase with the increase of the RF power. The emission from 5 Do to F-7(J) (J = 0-4) of Eu3+ is observed in the PL spectra for all the crystalline films, and the D-5(0) to F-7(2) transition of the films grown at 300 W has double exponential decays, 38 and 161 mu s. The crystalline quality of the films improves the photoluminescence intensity. (C) 2005 Elsevier B.V. All rights reserved.

Crystal structure, magnetic and electrical-transport properties of the rare-earth-doped compounds (Sr(1.85)Ln(0.15))FeMoO6 (Ln = Sr, La, Ce, Pr, Nd, Sin and Eu) have been investigated by means of X-ray diffraction, magnetic and electric measurements. All the samples are single phase and belong to the I4/m space group. Due to the competing contributions of electron doping and steric effects, the unit-cell volume of the doped compounds changes slightly and does not vary systematically with the ionic radius of the rare-earth ions. The temperature dependence of the magnetization of (Sr(1.85)Ln(0.15))FeMoO6 indicates that the Curie temperature of the doped compounds has increased upon doping, except for the Eu-doped compound. The saturation magnetization of the compounds at 5 K cannot be explained simply by considering the ferrimagnetic arrangement of the magnetic sublattices of Fe and Mo because of the magnetic contribution of rare-earth ions. However, the saturation magnetization at 100 K of the doped compounds exhibits a linear decrease with the increase of the anti-site defect concentration. Comparison of the saturation magnetization of the compounds at 5 and 100 K suggests that at 5 K the magnetic moments of Ce, Pr, Nd and Sin align parallel with that of Fe, while the magnetic moment of Eu is anti-parallel with that of Fe. The normalized resistivities of the parent and the La- and Sm-doped compounds exhibit a semiconductor-metal transition, while the Pr-, Nd- and Eu-doped compounds exhibit semiconducting behavior. (c) 2006 Elsevier B.V. All rights reserved.

The crystal structure of double perovskite Sr2FeMoO6 synthesized via solid-state reaction at 1280 degrees C under a reduction atmosphere is refined by Rietveld technique based on X-ray powder diffraction (XRD) data in 2 theta range of 15-140 degrees. An antisite content (AS), i.e. Fe on the Mo sites (=Mo on the Fe sites), of 12.1 (1)% is derived. In reference to the refinement results, a series of X-ray and neutron powder diffraction (NPD) data with different antisite contents, ranging from 0 (completely ordered) to 50% (completely disordered), are generated with a Poisonian noise added and subjected to Rietveld refinements with the same initial values for the refinable parameters. The AS is reproduced satisfactorily from the refinement of XRD data and the combined refinement of XRD and NPD data with a relative deviation smaller than 4%, whereas the relative deviation of AS derived from the refinement of NPD data can be as large as 50%. However, the atomic occupancies and isotropic temperature factors of all the atoms can be reasonably reproduced from the refinement of NPD data and the combined refinement of XRD and NPD data, whereas these data can be reproduced only for cations (Sr, Fe, Mo) from the refinement of XRD data. The present simulation studies shed light on understanding the controversial statements derived from XRD and NPD work regarding the antisite defects in Sr2FeMoO6, which in turn is indispensable for understanding the mechanism of large room temperature low-field magnetoresistance of the compound. (c) 2006 Elsevier Ltd. All rights reserved.