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The composition-dependent properties and their correlation with the phase stability of Fe75+xPd25-x (-10:0 ≤ x ≤ 10:0) alloys are systematically investigated by using first-principles exact muffin-tin orbitals (EMTO)-coherent potential approximation (CPA) calculations. It is shown that the martensitic transformation (MT) from L12 to body-centered-tetragonal (bct) occurs in the ordered alloys with about -5:0 ≤ x ≤ 10:0. In both the L12 and bct phases, the evaluated a and c/a agree well with the available experimental data; the average magnetic moment per atom increases whereas the local magnetic moments of Fe atoms, dependent on both their positions and the structure of the alloy, decrease with increasing x. The tetragonal shear elastic constant of the L12 phase (C') decreases whereas that of the bct phase (Cs) increases with x. The tetragonality of the martensite (|1 - c/a|) increases whereas its energy relative to the austenite with a negative value decreases with Fe addition. All these effects account for the increase of MT temperature (TM) with x. The MT from L12 to bct is finally confirmed originating from the splitting of Fe 3d Eg and T2g bands upon tetragonal distortion due to the Jahn-Teller effect. [ABSTRACT FROM AUTHOR]

We have studied three-dimensional shapes and distribution of FePd nanoparticles, prepared by electron beam deposition and postdeposition annealing, by means of single-axis tilt tomography using atomic number contrasts obtained by high-angle annular dark-field scanning transmission electron microscopy. Particle size, shape, and locations were reconstructed by weighted backprojection (WBP), as well as by simultaneous iterative reconstruction technique (SIRT). We have also estimated the particle size by simple extrapolation of tilt-series original data sets, which proved to be quite powerful. The results of the two algorithms for reconstruction have been compared quantitatively with those obtained by the extrapolation method and those independently reported by electron holography. It was found that the reconstructed intensity map by WBP contains a small amount of dotlike artifacts, which do not exist in the results by SIRT, and that the particle surface obtained by WBP is rougher than that by SIRT. We demonstrate, on the other hand, that WBP yields a better estimation of the particle size in the z direction than SIRT does, most likely due to the presence of a “missing wedge” in the original data set. [ABSTRACT FROM AUTHOR]

The long-range order (LRO) parameter (S) of single isolated L10-FePd nanoparticle was determined by quantitative analysis of nanobeam electron diffraction (NBD) intensities and intensity calculations considering the multiple scattering of electrons. The obtained order parameters of the nanoparticles larger than 8 nm are distributed around the mean LRO parameter (S =0.79) which was determined by selected area electron diffraction intensity analysis, while the parameters slightly decreased gradually as the particle size decreased below about 8 nm (S=0.60–0.73). The low degree of order in very small particles is responsible for the coercivity decrease of the L10 nanoparticles in smaller-sized regions. Quantitative NBD intensity analysis is quite useful for the determination of the LRO parameter of individual L10-FePd single crystalline nanoparticle. Experimental conditions required for NBD analysis are presented in detail and the possible experimental errors of the determined LRO parameters are discussed. [ABSTRACT FROM AUTHOR]

Martensitic phase transition in an aged Fe–Pd–Rh alloy was studied using transmission electron microscopy (TEM) and x-ray diffraction. Both TEM and x-ray diffraction reveal the appearance of an intermediate structure between the fcc→L10 martensitic transformation. The intermediate phase, denoted L1m, has a monoclinic structure with lattice parameters of a=3.193 Å, b=3.684 Å, c=3.141 Å, and β=92.042°, and the normal L10 martensitic phase has an ordered structure with lattice parameters of a=3.876 Å, c=3.684 Å, and c/a=0.950, as confirmed by TEM and x-ray diffraction. [ABSTRACT FROM AUTHOR]

We have investigated the influence of twin boundary properties on the damping behavior of single crystalline Fe-31.2Pd (at%) alloy, which exhibits a weak first-order martensitic transformation. Different static tensile stress was applied by dynamic mechanical analyzer to adjust the twin boundary density and hydrogen was doped to modify the twin boundary mobility. A high damping capacity (tan δ > 0.1) in a wide temperature range from about 140 K to 230 K was observed under a low static stress of about 0.3 MPa. Hydrogen doping further increased the maximum value of the damping capacity by introducing a relaxation tan δ peak. The damping capacity decreased with increasing static stress probably due to the decrease in twin boundary density. [ABSTRACT FROM AUTHOR]

Elastocaloric effects of a Ni50Fe19Ga27Co4 alloy exhibiting a typical first‐order martensitic transformation (MT) and an Fe‐31.2Pd (at.%) alloy exhibiting a weak first‐order MT, respectively, have been compared using their single crystals. A flat region appears in the temperature dependence of elastocaloric effect in the Ni50Fe19Ga27Co4 alloy, while such region is missing in the Fe‐31.2Pd alloy. The elastocaloric effect of the Ni50Fe19Ga27Co4 alloy originates essentially from the latent heat released by the stress‐induced MT, while that in the Fe‐31.2Pd alloy originates essentially from the entropy change caused by elastic deformation of the parent and martensite phases. Although the Young's modulus in the [001] direction at Ms is nearly the same for the two alloys (E ∼ 2 GPa), its slope dE/dT is largely different between the two alloys. It is approximately 0.003 GPa K−1 for the Ni50Fe19Ga27Co4 alloy and 0.2 GPa K−1 for Fe‐31.2Pd alloy. [ABSTRACT FROM AUTHOR]

Structure and magnetic properties of FePd thin films substrate on the glass with SiN to player have been investigated. The results suggested that ceramic SiN component distributed around the FePd nanograins, which inhibits the growth of the FePd particles and refined grain size of FePd films. Compared with the pure FePd thin films the coercivity and remanence ratio of FePd/SiN films reached to the maximum value of 3.3 and 0.98 kOe, respectively. With further increase of the annealing time, magnetic properties of FePd/SiNfilms do not drop rapidly, but keep high magnetic properties at a relatively wide temperature range. Defects, inclusions and intermixing phenomena occurred between the FePd layers and the SiN top layers promoted the improvement of L1 ordered phase transformation. [ABSTRACT FROM AUTHOR]

Fe 7 Pd 3 structured thin films were synthesized using GLAD, motivated by the high potential of such structures in magnetically-controlled bioapplications. GLAD was carried out on prestructured gold templates to obtain Fe-Pd structures of several hundred nanometers in width by up to 1.5 μm in length, depending on template and growth parameters. The resulting polycrystalline microstructure was in the body centred cubic (bcc) phase with a composition near Fe 7 Pd 3 , determined by energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). Annealing at 900 °C resulted in the appearance of signatures of the face centred tetragonal (fct) martensitic phase within XRD measurements. Therefore, fct structures could be achieved if measures for structural preservation are taken, such as by ultra rapid annealing or lift-off before annealing. The cellular response to the structured films was investigated using human brain microvascular endothelial cells (HBMEC) and revealed consistent cell adhesion, morphologies and proliferation compared to control Fe-Pd and Si substrates. Only trace amounts of palladium and iron were released from the films into the growth medium during culture, regardless of the structures. Overall, this method is highly promising for the development of biocompatible, submicron structured films and shape-anisotropic ferromagnetic micro- and nanostructures, with applicability to a range of other alloys. [ABSTRACT FROM AUTHOR]

Depending on Pd content, disordered Fe-Pd alloys take various crystal structures: body-centered cubic (BCC), body-centered tetragonal (BCT), face-centered tetragonal (FCT) and face-centered cubic (FCC) structures. We have measured specific heat of Fe-Pd alloys to understand the lattice stability and electronic state of the alloys. At the phase boundary between FCT and FCC phases, electronic specific heat coefficient shows a local maximum and the Debye temperature shows a local minimum. A local maximum of electronic specific heat coefficient also appears in the BCC region with Pd content of near 10 at.%. [ABSTRACT FROM AUTHOR]

The characterization of the magnetic switching behavior of heat assisted magnetic recording (HAMR) media at near Curie temperature ( T c ) is important for high density recording. In this study, we measured the magnetic property of FePt granular media (with room temperature coercivity ~25 kOe) at near T c with a home built HAMR testing instrument. The local area of HAMR media is heated to near T c by a flat-top optical heating beam. The magnetic property in the heated area was in-situ measured by a magneto-optic Kerr effect (MOKE) testing beam. The switching field distribution (SFD) and coercive field ( H c ) of the FePt granular media and their dependence on the optical heating power at near T c were studied. We measured the DC demagnetization (DCD) signal with pulsed laser heating at different optical powers. We also measured the T c distribution of the media by measuring the AC magnetic signal as a function of optical heating power. In a summary, we studied the SFD, H c of the HAMR media at near T c in a static manner. The present methodology will facilitate the HAMR media testing. [ABSTRACT FROM AUTHOR]

The isothermal section of the Fe-Pd-Nd ternary system at 773 K was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and energy dispersion spectroscopy (EDS) techniques. It is found that the isothermal section consists of 15 single-phase regions, 28 two-phase regions and 14 three-phase regions. The highest solubilities of Nd in FePd and FePd 3 , Pd in Fe 17 Nd 2 and Fe 17 Nd 5 and Fe in Pd 5 Nd, Pd 2 Nd, Pd 3 Nd 2 , Pd 4 Nd 3 and PdNd are all less than 1 at.%. Whereas the maximum solubilities of Fe in Pd 3 Nd and Pd 3 Nd 7 are approximately confirmed to be 1.0 and 4.1 at.% Fe, respectively. In the present work, a new ternary compound Nd 6 Fe 13 Pd with Pr 6 Fe 13 Ag structure, space group I 4/ mcm and lattice parameters a = 0.8076(2) and c = 2.2373(7) nm is observed. [ABSTRACT FROM AUTHOR]

The elastocaloric effect under tensile stress along the [001] direction has been investigated in an Fe-31.2Pd (at.%) alloy, which exhibits a weak first-order martensitic transformation at 230 K from a face-centered cubic structure to a face-centered tetragonal ( c/a < 1) structure. A stable temperature variation of 1.9 K was observed at room temperature (∼288 K) up to 10000 cycles of sinusoidal tensile stress (200 MPa). The stress-strain curve shows a macroscopic strain of 1.2% under 200 MPa with a negligible stress hysteresis. The macroscopic strain coincides with the lattice strain obtained by in situ X-ray diffraction. A significant extension of the 200 reflection, perpendicular to the tensile direction, was observed. This peak extension could be the way the specimen realizes a high elastic strain, even under tensile stress. [ABSTRACT FROM AUTHOR]

Developing high-efficient non-platinum (Pt) catalysts for oxygen reduction reaction (ORR) is the key to reduce the usage of Pt and the palladium (Pd)-based catalyst is a promising alternative. Here, we presented a facile approach to core/shell FePd/Pd nanoparticle (NP) catalyst with the FePd core in chemically ordered face-centered tetragonal (fct-) structure and the shell in controlled thickness from 0.32 to 0.81 nm via the thermal annealing of FePd NP followed by an electro-anodization process. With a 0.71 nm-thick Pd shell, the fct-FePd/Pd shows a robust catalytic activity and durability for ORR with the mass activities at 0.85 and 0.90 V reaching 453 and 96.7 A/mg, respectively, which are about 3.0 and 2.1 times higher than those of commercial Pt in alkaline media. This work presents a new class of non-Pt catalyst with superior performance to Pt for ORR catalysis, and the strategy demonstrated here can be extended to design high-efficient catalysts for other chemical reactions. [ABSTRACT FROM AUTHOR]

From first-principle calculations with the generalized gradient approximation (GGA) method, the structural, electronic and magnetic properties of the hexagonal PdFeTe ( x = 0, 0.0625, 0.125) compound have been studied. Three kinds of doping models corresponding to above the Fe-doped concentration x were proposed and further verified to be rational. On these models, the calculation of energy minimization manifests that the ferromagnetic (FM) phase is more stable than the nonmagnetic (NM) phase. And, the analysis of the density of states (DOS) indicates that the electronic properties are largely determined by the Pd-d, Te-p, and Fe-d electronic states and that the total DOS at the Fermi Level increases with the concentration x. Furthermore, the calculation of magnetic properties shows that the Fe-d electrons are responsible for the ferromagnetism of both PdFeTe and PdFeTe, that the more the spin splitting of the Fe-d states is, the larger the induced magnetic moment is, and also that the total magnetic moment of PdFeTe increases with the concentration x. [ABSTRACT FROM AUTHOR]

A disordered Fe-31.2Pd (at.%) alloy exhibits a weak first-order martensitic transformation (MT) from a face-centered cubic structure to a face-centered tetragonal structure. We employed a Dynamic Mechanical Analysis (DMA) to understand the transformation behavior. As the temperature decreases, the storage modulus E ′ decreases in the parent phase and increases in the martensite phase. The loss tangent (tan δ ) shows a slight increase when approaching M s (=225 K), suggesting the formation of movable interfaces even above M s . The value of tan δ is nearly proportional to (1 − c/a ) 2 below M s , meaning that highly mobile twinned interfaces are essential for internal friction below M s . The so-called transitory term of tan δ is negligibly small for the MT of this alloy. [ABSTRACT FROM AUTHOR]

Magnetic properties and structure of sputter-prepared FePd thin films on the glass substrates by underlayering with refractory elements M (M = Nb, Mo, and W) have been studied. The structural analysis shows that FePd films have a (111) preferred orientation. All studied FePd films exhibit in-plane magnetic anisotropy. For single-layer FePd films, the coercivity ( Hc) and magnetic energy product [(BH) \mathrm {max}] are increased with annealing temperature ( Ta) and reached the maximum value of 1.3 kOe and 3.8 MGOe in the sample annealing at 600 °C. With the further increase of Ta , magnetic properties drop rapidly. Dependence of magnetic hardening on Ta can be explained by dominant solid reactions in different region of Ta including ordering and grain growth. Interestingly, magnetic properties of L10-FePd are largely improved by underlayering with 5 nm-thick Nb, Mo, and W layers. Both the coercivity and energy product are significantly increased to 1.6 kOe and 4.9 MGOe for M = Nb, 2.5 kOe and 6.4 MGOe for M = Mo, and 3.3 kOe and 8.7 MGOe for M = W, respectively. Structural analysis suggests that this magnetic enhancement is related to both higher ordering degree and refined microstructure. [ABSTRACT FROM AUTHOR]

FePd alloy films of 1 to 500 nm thicknesses are prepared on MgO(001) single-crystal substrates by employing a two-step method consisting of low-temperature deposition at 200 °C followed by high-temperature annealing at 600 °C. The influences of film thickness on the crystallographic orientation, the degree of L10 ordering, the magnetic property, and the surface roughness are systematically investigated. FePd(001) single-crystal films with disordered structure grow epitaxially on the substrates at 200 °C. The in-plane lattice is expanded to accommodate the lattice misfit between the film and the substrate (−9%). The distortion is decreased with increasing the thickness. When the films are annealed at 600 °C, transformation to L10 phase occurs. The films thinner than 40 nm consist of L10(001) variant with the c-axis normal to the substrate surface, where the transformation along the perpendicular direction is preferentially taking place. On the contrary, the films thicker than 100 nm involve L10(100) and L10(010) variants whose c-axes lie in the film plane and are rotated around the film normal by 90° of each other. The volume ratio of L10(001) variant decreases to 0.22, as the thickness increases up to 500 nm. The order degrees of films thinner than 40 nm are 0.6–0.7. With further increasing the thickness, the order degree decreases. The lattice deformation in the disordered FePd film before annealing is effective in enhancing L10 ordering and aligning the c-axis perpendicular to the substrate surface. The easy magnetization direction varies from perpendicular to in-plane, as the thickness increases from 100 to 500 nm. The magnetic anisotropy is affected by the crystal orientation and the order degree. The films thinner than 2 nm have island-like surfaces, where condensation of deposited atoms on substrate is taking place during the annealing process. When the thickness is increased beyond 10 nm, a flat surface is kept before and after annealing. [ABSTRACT FROM AUTHOR]

Using electrodeposition into anodic aluminum oxide (AAO) membranes, we have successfully fabricated near-equiatomic Fe48±3Pd52±3 nanowires (NWs) with the diameter of \approx 200 nm and the length of \approx 3.5~\mu{\rm m} . X-ray diffraction and transmission electron microscopy/selected-area electron diffraction analyses revealed that the as-deposited NWs are isotropic and polycrystalline with an average crystal size of 5 nm and have an fcc crystal structure. Magnetic force microscopy (MFM) on a single Fe–Pd NW revealed its single-domain behavior with the easy axis of magnetization along the long axis of the NW. The magnetizationswitching behavior of a single Fe–Pd NW studied with the MFM suggested a square-shaped magnetization curve (M/Ms = 1)$ with H_{C\Vert} \approx 3.2 kA/m. In addition, using in-field MFM techniques, the effects of dipolar interactions in an Fe–Pd array of NWs still embedded in the AAO were determined. It was found that the dipolar interactions greatly reduce the parameters of the magnetization hysteresis loop, such as the coercivity, the remanence, and the switching-field distribution of the Fe–Pd NW array. [ABSTRACT FROM AUTHOR]

CuTlBaCaCuO/(Fe-Pd 0, 0.5, 1.0, 1.5 %) superconductors are prepared at normal pressure by using three-step method. Alloy of CuTlBaCa CuO/(Fe-Pd 1 %) have shown maximum increase in the magnitude of superconductivity. Cu Tl BaCa Cu O/(Fe-Pd 0, 0.5, 1.0, 1.5 %) samples have shown T( R= 0) around 106, 105.3, 102, and 100 K and the onset of diamagnetism around 113, 110, 102, and 105 K, respectively. A comparison of X-ray diffraction (XRD) scans of Fe-Pd nanoparticles with CuTlBaCaCu O/(Fe-Pd 0.5, 1.0, 1.5 %) superconducting samples have shown that the nanoparticles of Fe-Pd are quite stable in the matrix of CuTlBaCaCu O samples even after repeated firing at 890 C. With increase addition of Fe-Pd nanoparticles, the axes length increases, showing some inclusion of nanoparticle into the unit cell of CuTlBaCaCu O samples from the termination ends of crystal.The inclusion of Fe-Pd in the superconducting CuTlBaCaCu O grains is also evidenced in Fourier transform infrared spectroscopy (FTIR) absorption measurements. The Fe-Pd nanoparticles added in CuTlBaCaCu O samples have been found to decrease the population of inter-grain voids that is found to increase the coherence length along the c-axis and the inter-layer coupling J. The FIC analysis of conductivity data haveshown the Fe-Pd nanoparticles diffusing into the inter-grain sites promoted an increase of penetration depth λ and Ginzburg-Landau parameter, κ. Due to the this possible diffusion of the Fe-Pd nanoparticles in the superconducting grains, the T( R= 0), B( T), B( T), and J(0) values are suppressed in CuTlBaCaCu O samples. [ABSTRACT FROM AUTHOR]

The effect of an external magnetic field B on the martensite phase transformation temperature T 0 was studied for single crystalline Fe 72 Pd 28 thin films. From in-plane and out-of-plane aligned magnetic field dependent resistance measurements under various fields up to 9 T, T 0 was determined. The relation between T 0 and B is explained quantitatively by the Clausius–Clapeyron equation. The calculated value of 0.62 K/T is close to the values of the linear fits of 0.79 K/T and 0.76 K/T obtained from measurements with B aligned in-plane and out-of-plane. [ABSTRACT FROM AUTHOR]

The thermal stability of FePdB thin films was studied using nonisothermal and isothermal analyses. X-ray diffraction (XRD) patterns indicated that Fe 40 Pd 40 B 20 and Fe 60 Pd 20 B 20 films with thicknesses in the range 25–75 Å were amorphous, whereas Fe 40 Pd 40 B 20 and Fe 60 Pd 20 B 20 films with thicknesses in the range 100–200 Å exhibited a nanocrystalline FePd (111) structure. The crucial glass forming ability index ( γ and γ m ) was determined using the differential scanning calorimetry (DSC) results of amorphous FePdB films. The Kissinger formula was applied to calculate the activation energy ( Q ) of crystallization for determining the resistance of the films to crystallization. Thermal analysis showed that the thermal stability and incubation time of Fe 40 Pd 40 B 20 are more favorable than those of Fe 60 Pd 20 B 20 . [ABSTRACT FROM AUTHOR]

Near equiatomic Fe52±3Pd48±3 nanowires (NWs) with the length of 3.5 \mu \textm and diameter of \approx 200 nm were potentiostatically deposited at −1.1 V for 900 s into a porous anodic aluminum oxide template. Cylindrical NWs with a consistent composition along their length were obtained after introducing two additional steps prior to the electrodeposition (ED) of the Fe–Pd NWs, i.e., template wetting and pre-ED of Au NWs. The as-deposited Fe–Pd NWs were isotropic and nanocrystalline with an fcc crystal structure and were magnetically soft. The influence on the development of the coercivity with annealing temperature and time due to the {L}1_{\mathrm { {0}}} transformation was investigated. For this purpose, the as-deposited NWs were annealed at temperatures from 400 °C to 700 °C for 1-5 h in Ar + H2 and the phase transformation, microstructure and magnetic properties were analyzed. The coercivity was found to increase by increasing the annealing temperature, as the {L}1_{\mathrm { {0}}} ordering becomes more complete. A maximum in the coercivity of H{{ {C\vert \vert }}} = 267 kA/m and {M}{{ {r}}} / {M}{{ {s\vert \vert }}}=0.85 was achieved upon annealing at 600 °C for 4 h. The high remanence is attributed to the exchange coupling between the nanosized grains and/or the coupling between the soft [ \alpha -Fe, \gamma -(Fe,Pd), fcc-FePd] and hard L1\mathrm { {0}} phases. The effect of the deposited Au NWs prior to the Fe–Pd NWs’ deposition on the L1\mathrm { {0}} ordering was evaluated as well; however, the magnetic properties were significantly decreased due to the formation of soft-magnetic phases, i.e., (Au, Fe) and (Au, Pd). [ABSTRACT FROM PUBLISHER]

Conductivity in Fe7Pd3 is characterized by an anomalous increase when traversing the face-centered-cubic (fcc) austenite to face-centered-tetragonal (fct) martensite transition, contrary to most other conventional and ferromagnetic shape memory alloys. Experiments on molecularbeam-epitaxy-grown single crystals indicate a resistivity change of ≈20% during the transformation on top of a quadratic temperature dependence reaching up to room temperature. The physical foundations of residual resistivity changes along the full Bain path are addressed by a Kubo- Greenwood approach within the framework of density functional theory. To do so, a concept to reliably extract the DC conductivities is proposed that yields reproducible results consistent with experiments. Finding that conductivity peaks in the fct phase, we identify a large density of states paired with high velocities at the Fermi level in the majority spin sub-bands in presence of minimum s-d electron scattering as underlying physical origin. [ABSTRACT FROM AUTHOR]

We have examined the transformation strain, Δε, in the [0 0 1] direction of an Fe-31.2Pd (at.%) shape memory alloy under compressive stress applied in the same direction. When the stress is absent, the alloy exhibits a cubic to tetragonal martensitic transformation at 230 K with |Δε| of 1.4%. As the stress increases, the transformation temperature increases linearly and |Δε| decreases linearly and vanishes at 40 MPa (280 K). This point is the critical point of this transformation at which the first-order nature disappears, and the critical exponentβis evaluated to be 0.47 ± 0.04. [ABSTRACT FROM AUTHOR]

In typical shape memory alloys, significant elastocaloric effects appear in association with stress-induced martensitic transformations. However, we report here that in an Fe-31.2Pd (at.%) alloy, a significant elastocaloric effect appears due to lattice softening, which causes a weak first-order martensitic transformation at T 0 (∼230 K). We found that in a wide temperature range of between 175 K (< T 0 ) and 335 K (> T 0 ), the alloy exhibits an adiabatic temperature decrease of more than 1.5 K when a compressive stress of 200 MPa applied in the [0 0 1] direction is removed. The refrigeration capacity calculated in this temperature range is 5 MJ/m 3 . [ABSTRACT FROM AUTHOR]

This research paper mainly presents an investigation of the microstructures and magnetic properties of bulk ferromagnetic shape memory (FSM) FePdNi (Ni = 4, 8 at.%) alloys, by transmission electron microscopy (TEM), a magnetostrictive-meter setup, and a superconducting quantum interference device (SQUID) magnetometer. The FSM alloys were homogenized through hot and cold strain forging (SF) to a ∼38 % reduction in thickness, solution-treated (ST) with annealing recrystallization at 1100 °C or 8 h, quenched in ice brine, and then aged at 500 °C for 100 h (5 HTA). The investigation of the microstructures and magnetic properties indicated that the higher Ni content (N = 8 at.%) in the FePdNi alloy SF and ST reduced the saturation magnetostriction at RT. However, with higher Ni content in the FePdNi alloy, the decomposition of L1 + L1 twin phases into stoichiometric L1 + L1 + α structures was suppressed after the alloy was ST and aged at 5 HTA, as confirmed by TEM investigation. The result was that the FSM FePdNi alloy maintained a high saturation magnetostriction and magnetization after the alloy was ST and aged at 5 HTA. This magnetic property of the FePdNi FSM alloy makes it suitable for application in high-temperature ( T < 500 °C) and high-frequency environments. However, low Ni content FSM FePdNi (N = 4 at.%) alloy SF, ST, and aged at 5 HTA underwent decomposition of the L1 + L1 twin phases into the stoichiometric L1 + L1 + α structures, as confirmed by TEM, leading to a decrease of saturation magnetostriction and magnetization. This magnetic property of the FePdNi FSM alloy is not suitable for application in high-temperature ( T < 500 °C) environments. [ABSTRACT FROM AUTHOR]

The methods of scanning electron microscopy, differential scanning calorimetry and x-ray diffraction are used to study the morphological and thermal characteristics of cooling-induced martensite in alloy Fe - 30% Ni - 3% Pd. It is shown that the kinetics of the martensitic transformation is athermal and the morphology is lamellar. The mean values of the parameters of the austenite and martensite lattices are 0.35704 and 0.28614 nm respectively. The thermocycling leaves the points A and A invariable. [ABSTRACT FROM AUTHOR]

The existence of an L1 0 –L1 2 hybrid ordered phase for face-centered cubic (fcc) crystal symmetry was first theorized by William Shockley in 1938, but has not been verifiably observed to date. Ordered magnetic thin films of Fe 38.5 Pd 61.5 , the expected L1 0 –L1 2 eutectoid composition, grown epitaxially on MgO(0 0 1) substrates by pulsed laser deposition, are shown to exhibit the first empirical confirmation of L1′ type ordering. A formal treatment of L1′ ordering requiring the definition of two independent ordering parameters is discussed in conjunction with the crystallographic and magnetic characterization of the Fe 38.5 Pd 61.5 thin films. Two theories regarding origination of the unique metastable ordering behavior induced by the non-equilibrium strain conditions are proposed. [ABSTRACT FROM AUTHOR]

Ribbons of Fe-Pd ferromagnetic shape memory alloys were prepared by rapid solidification via the melt-spinning technique. The effect of moderate and high temperature heat treatments on the martensitic transformation and the related changes of the magnetic behavior was analyzed by X-ray diffraction, differential scanning calorimetry and temperature, and field-dependent magnetometry. In addition, information about magnetic easy axis and magnetically field-induced strains (MFIS) were achieved from linear thermal expansion measurements performed under cooling at different applied fields. The observed low values of MFIS in the as-prepared ribbons are due, besides to the small size and random orientation of the grains, to the high atomic disorder inside the crystalline grains. The anisotropy field is enhanced by the reduced atomic disorder, as reflected by the increased MFIS values after thermal treatments. [ABSTRACT FROM AUTHOR]

L10 films formed on (001)-oriented underlayers or substrates may involve (100) crystal with the $c$ -axis lying in the film plane in addition to (001) crystal with the c$ -axis normal to the film surface. In this paper, FePt, CoPt, and FePd alloy films with c$ -axis orientation is accurately controlled to be perpendicular by introducing a thin MgO cap layer on magnetic films with disordered structure prepared by low-temperature deposition at 200 °C and by annealing the bilayer films at 600 °C. The phase transformation preferentially occurs along the perpendicular direction in the MgO/(FePt, CoPt, FePd)/MgO sandwich structures. Furthermore, the cap layer promotes L10 ordering. The order degrees of FePt, CoPt, and FePd films with and without cap layers, ( , S_{\rm w/o}), are (0.82, 0.58), (0.36, 0.30), and (0.72, 0.62), respectively. The FePt film with cap layer shows a strong perpendicular magnetic anisotropy and a very low in-plane coercivity because of which the film does not include L10 (100) crystal and possesses a high-order degree. [ABSTRACT FROM AUTHOR]

Nanoporous PdFe (NP-PdFe) alloy with uniform structure size and controllable bimetallic ratio was easily fabricated by one-step mild dealloying from PdFeAl precursor alloy. NP-PdFe consisted of nanoscaled interconnected network skeleton with bicontinuous hollow channels extending in all three dimensions. Compared with NP-Pd and commercial Pt/C catalysts, the NP-PdFe exhibits superior electrocatalytic activity for oxygen-reduction reaction (ORR) with enhanced specific and mass activities. Electrocatalytic measurements indicated that NP-PdFe possesses higher catalytic durability than Pt/C with the less loss of ORR activity and electrochemical active surface area upon long term potential scan. NP-PdFe alloy also shows higher methanol tolerance relative to Pt/C catalyst. XPS and DFT calculations suggest that the downshift of Pd d-band center after alloying with Fe makes favorable reaction kinetics for ORR with decreased adsorption energy of O and OH on Pd surface. [ABSTRACT FROM AUTHOR]

High-quality L10 ordered 20nm-thick FePd epitaxial thin films with a large perpendicular magnetic anisotropy were fabricated using a SrTiO3 substrate. The uniaxial crystalline magnetic anisotropy constant Ku evaluated for the films annealed above 500 °C was 14 Merg/cm³. A very low effective damping constant, aeff = 0.007, was observed for FePd thin films annealed at 500 °C. This value is smaller than that of other Fe-based ordered alloys with a large perpendicular magnetic anisotropy. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the evolution of the recrystallization texture and microstructure was investigated after annealing of 50% and 90% cold-rolled FePd alloy at 530°C. The FePd alloy was produced by vacuum arc melting in an atmosphere of 97% Ar and 3% H2. The specimens were cold rolled to achieve 50% and 90% reduction in thickness. Electron backscatter diffraction measurements were performed on the rolling direction–normal direction section. With increased deformation from 50% to 90%, recrystallized texture transition occurs. For the 50% cold-rolled alloy, the preferred orientation is (0 1 0) [11 0 1], which is close to the cubic orientation after 400h of annealing. For the 90% cold-rolled alloy, the orientation changes to (0 5 4) [22–4 5] after 16h of annealing. [Copyright &y& Elsevier]

Abstract: We have employed quasi-chemical approximation to study the concentration dependence of bulk thermodynamic properties of two liquid alloys, Co–Fe and Fe–Pd at temperatures of 1863K and 1873K, respectively, at fixed atmospheric pressure. In order to investigate the surface structure in the alloys we have also performed a comparative study of surface tension using two statistical models. The study of the alloys indicates a positive deviation from the Raoultian behaviour with a higher degree of segregation in Fe–Pd system than that in the Co–Fe system. The surface tension is found to increase, both in Co–Fe and Fe–Pd alloys, with the addition of Fe-component. Furthermore, the surface segregation of the atoms of the metal with lower surface tension (Pd atoms in Fe–Pd alloy and Co atoms in Co–Fe alloy) is pronounced. Maximum surface segregation is expected to occur in the Co–Fe and Fe–Pd alloys around the compositions xCo =0.5 and xFe =0.8, respectively. [Copyright &y& Elsevier]

Novel reactive materials for catalytic degradation of chlorinated organic compounds in water at ambient conditions have been prepared on the basis of silica-supported Pd-Fe nanoparticles. Nanoscale Fe-Pd particles were synthesized inside porous silica supports using (NH4)3[Fe(C2O4)3] and [Pd(NH3)4]Cl2 or Pd acetate as reaction precursors. According to temperature programmed reduction (TPR) studies, Pd introduction decreased the reduction temperature of the supported Fe n+ species and nearly complete reduction with H2 was observed at 400 °C. The successful surface loading with Pd was confirmed by X-ray photoelectron spectroscopy (XPS) analysis. Characterization of the samples by X-ray diffraction (XRD) and X-ray absorption near-edge structure + extended X-ray absorption fine structure (XANES + EXAFS) verified the presence of highly dispersed Pd0, Pd x Fe1- x and Fe0 phases. Reduction of the supported precursors in hydrogen resulted in materials that were highly active in perchloroethene (PCE) degradation and 2-chlorobiphenyl (2-ClBP) dechlorination. It was found that highly dispersed amorphous Fe-Pd bimetallic nanoparticles on silica support showed superior catalytic activity against PCE dechlorination in comparison to the free-standing Fe-Pd nanoparticles. For the samples with the same Fe content, the conversion of chlorinated organics as well as the stability increased with the Pd loading, e.g., the most effective degradation of PCEs and 2-ClBP was achieved at a Pd loading of 2.3-3.2 wt. %. [ABSTRACT FROM AUTHOR]

Highlights: [•] NP-PdFe alloy is fabricated by a simple dealloying method. [•] NP-PdFe possesses open three-dimensional bicontinuous spongy morphology. [•] NP-PdFe shows high electrochemical sensing activities towards H2O2 and glucose. [•] NP-PdFe shows good long-term stability for H2O2 and glucose detection. [•] NP-PdFe shows good reproducibility for H2O2 and glucose detection. [Copyright &y& Elsevier]

Highlights: [•] The laser irradiations transformed FePdCu multilayers, into chemically ordered L10 phase. [•] The (111) crystallites have elliptical shape elongated in direction perpendicular to surface. [•] The (002) crystallites have shape of disks with the longer axis of symmetry parallel to the sample surface. [Copyright &y& Elsevier]

Highlights: [•] Size-selected FePt clusters have been deposited under vacuum on carbon nanotubes. [•] The ability of clusters to diffuse on the nanotube surface is put into evidence. [•] The behavior on different carbon based surfaces is compared. [•] A local organization of the FePt clusters on nanotubes is obtained. [ABSTRACT FROM AUTHOR]

Highlights: [•] Monodispersed 4.1nm FePt nanoparticles were successfully synthesized by the chemical polyol process. [•] High temperature (usually higher than 550°C) annealing is necessary to obtain L10 ordered structure. [•] Annealing causes the surfactant start to decompose and sintering of particles take place. [•] MnFe2O4 shell were used as the shell around of each FePt core particles to prevent them from sintering. [•] MnFe2O4 shell with magnetic behavior exposed exchange-coupled interaction with the magnetic core particles. [ABSTRACT FROM AUTHOR]

Highlights: [•] Hindered diffusion of Fe3+ and Pd2+ complexes in an AAO template. [•] Same kinetics of Fe and Pd ions and constant DFe/DPd ratio irrespective of the WE. [•] Alloy composition is independent of working electrode's geometry. [ABSTRACT FROM AUTHOR]

Abstract: An Fe–55Pd (at.%) alloy exhibits a disorder–order transformation from the A1-type disordered cubic phase to the L10-type ordered tetragonal phase. We have investigated the influence of the magnetocrystalline anisotropy energy on the selective formation of a variant of the ordered phase during heat treatment. We found that the strength of the magnetic field required to produce a single variant decreases from approximately 4T to approximately 0.4T when the ordering heat-treatment temperature is decreased from 673 to 603K. The magnetocrystalline anisotropy energy was evaluated at these temperatures as a function of magnetic field. The nucleation ratio between different variants was evaluated through the magnetocrystalline anisotropy. It is revealed that a single variant state is obtained during the growth process when the nucleation ratio of the dominant variant exceeds approximately 1.1. [Copyright &y& Elsevier]

Attainment of perpendicular coercivity higher than 900 Oe and accurate calculation of the degree of long-range order in an FePd alloy thin film is essential in the realization of the perpendicular magnetic recording media. Here, we prepared the off-stoichiometric FePd films through the multilayer growth of [Fe(2 nm)/Pd(2 nm)] × 30 deposited on MgO(001) substrates by magnetron sputtering. The effects of post-annealing these films at 700 °C for 1 and 10 h on their surface morphologies, and crystallographic and magnetic characteristics were investigated. The results show that, with increasing annealing time, the FePd thin films are predominantly (001)-oriented with a progressive increase of the grain size and surface roughness, as well as the improved crystallinity and reduced micro-strain. Accordingly, the perpendicular coercivity is significantly increased to the value of 1.5 kOe, and Pd loses its 4d electrons upon alloying. Furthermore, analysis of X-ray absorption data elucidates some structural details of the Fe scattering phase in addition to the dominant tetragonal FePd phase. We also present a way of determining the long-range order parameter for the FePd alloy thin film, using the combined information of the tetragonality ratio extracted from extended x-ray absorption fine-structure spectroscopy and the stoichiometric deviation of the thin film. [ABSTRACT FROM AUTHOR]

Abstract: Fe–Pd alloy nanowires have been fabricated successfully by alternating current (AC) pulse electrodeposition in the porous anodic aluminum oxide (AAO) template at room temperature. AFM and TEM analysis show that the pore diameter of Fe–Pd nanowires is about 30–40nm, the line spacing is 60–80nm, and the aspect ratio is more than 100. Moreover, Fe–Pd nanowires in AAO also exhibits obvious magnetic anisotropy, that is, they magnetized along the nanowires length direction other than the nanowires diameter direction, and there have been exchanged anisotropy speculate in nanowires stochastically through asymmetrical hysteresis loop. [Copyright &y& Elsevier]

\Fe52{\Pd}48 thin films with thickness of 10 nm were deposited on the glass substrate at room temperature and subsequently annealed at 600\-900\ ^\circ\C through three different heat treatment procedures: (A) furnace heating as well as quenching in the ice water; (B) furnace heating and then natural cooling in a furnace; and (C) rapid thermal annealing (RTA). The results show that the FePd films annealed at 800 ^\circ\C with procedures (A) and (B) present magnetic isotropy behaviors, whereas magnetic anisotropy is gradually switched to perpendicular with procedure (C). Further RTA of the FePd films with different temperatures, the film morphology is a continuous structure with well connected magnetic grains in as-deposited state, and it starts to agglomerate at 600 ^\circ\C and then turns into particle-like structure as the temperature is higher than 700 ^\circ\C. The magnetic behavior also switches from in-plane, through isotropy, and into out-of-plane directions. The heating rate and annealing temperature are the key effects on formation of \mbiLl0\ {\FePd} (001), but not for the cooling rate and annealing time. In this study, the RTA process is an effective way to induce the tensile stress in biaxial \mbia and \mbib, resulting the shrinkage along \mbic-axis and ordered \FePd\,\mbiLl0 (001) planes on glass. This paper shows a nonepitaxial method for \mbiLl0\ {\FePd} (001) orientation growth on amorphous glass substrates. [ABSTRACT FROM PUBLISHER]

Abstract: Magnetic force microscope (MFM) tips are prepared by coating Si tips of 4nm radius with FePd, FePt, and CoPt films of 80nm thickness at room temperature followed by annealing at 600°C. The spatial resolution and the switching field are investigated. The resolution of about 9nm is realized for all the tips. On the contrary, the switching fields of FePd-, FePt-, and CoPt-coated tips are 117.4, 37.8, and 268.6 kA/m, respectively. The crystal structure and the magnetic properties of coated magnetic thin films prepared on flat Si substrates are measured and the interrelationships with the MFM tip characteristics are briefly investigated. [Copyright &y& Elsevier]

Abstract: Thermoelastic strain in a polycrystalline Fe–Pd thin film due to shape memory effect was determined from Hooke's law using the measured residual stress and the elastic modulus obtained by the wrinkling method, and the variation in the thermoelastic strain was discussed in terms of thermally induced phase transformation. The measurement of thermoelastic strain from Hooke's law and the wrinkling method was in good quantitative agreement with previously reported data obtained from a digital camera. The variation of thermoelastic strain of the Fe-28.1at.% Pd thin film was associated with the martensitic transformation between the high-temperature face-centered cubic austenite and the low-temperature face-centered tetragonal martensite during a thermal cycle. [Copyright &y& Elsevier]

Structural and magnetic transitions of Ni 47.5-xCo xMn 37.5Sn 15 ( x = 0, 1, 2 and 3.5) alloys were confirmed and studied by magnetic and resistivity measurements. Though a large magnetic entropy change ( ΔSM) ~ 9.5 J/kg K was obtained for x = 3.5 due to a change of only 1.5 T magnetic field, hysteresis losses limited its refrigerant capacity to a significant extent. A maximum –69% magnetoresistance was obtained due to a structural transition in the same sample in presence of 8 T field. It was found that the same material can be used for practical applications within a wide range of temperature as it shows large magnetoresistance at remote temperatures far below from its structural transition point. [ABSTRACT FROM AUTHOR]

FePd nanowires (NWs) with different compositions have been grown into anodized aluminum oxide templates (AAO) by AC electrodeposition at room temperature. The effects of nanowire composition and morphology on the hysteresis properties of the ordered array of NWs are investigated. All the NWs are polycrystalline; the Fe-rich wires have a bcc structure while the Pd rich ones are fcc. FePd NWs are ferromagnetic and the spontaneous magnetization is found to be parallel to the nanowire long axis (out of plane easy axis) and both, the saturation polarization and the coercive field increase with the iron content. [ABSTRACT FROM PUBLISHER]

Highlights: [•] Full degradation of p-chlorophenol by B/Fe/Pd nanoparticles and Bacillus fusiformis. [•] p-CP was dechlorinated by B/Fe/Pd and the formation of the phenol. [•] Phenol was biodegraded by BF Bacillus fusiformis. [•] A integrated approach using both B–Fe/Pd nd sequential biodegradation. [Copyright &y& Elsevier]