Time Differential Perturbed Angular Correlation Spectra Research Articles

Temperature dependence of the local electromagnetic field at the Fe site in multiferroic bismuth ferrite

In this paper, we present a study of the temperature-dependent characteristics of electromagnetic fields at the atomic scale in multiferroic bismuth ferrite (${\mathrm{BiFeO}}_{3}$ or BFO). The study was performed using time differential perturbed angular correlation (TDPAC) spectroscopy on implanted $^{111}\mathrm{In}$ ($^{111}\mathrm{Cd}$) probes over a wide temperature range. The TDPAC spectra show that substitutional $^{111}\mathrm{In}$ on the ${\mathrm{Fe}}^{3+}$ site experiences local electric polarization, which is otherwise expected to essentially stem from the ${\mathrm{Bi}}^{3+}$ lone pair electrons. Moreover, the TDPAC spectra show combined electric and magnetic interactions below the N\'eel temperature ${T}_{N}$. This is consistent with simulated spectra. X-ray diffraction (XRD) was employed to investigate how high-temperature TDPAC measurements influence the macroscopic structure and secondary phases. With the support of ab initio DFT simulations, we can discuss the probe nucleus site assignment and can conclude that the $^{111}\mathrm{In}$ ($^{111}\mathrm{Cd}$) probe substitutes the Fe atom at the B site of the perovskite structure.

Electron beam irradiation induced changes in local structure of simulated waste bearing sodium borosilicate glasses

Time differential perturbed angular correlation (TDPAC) and Extended X-ray absorption fine structure (EXAFS) studies have been carried out on electron beam (EB) irradiated sodium borosilicate (NBS) and simulated waste oxide loaded sodium borosilicate (SNBS) glasses with a view to investigate the effect of self β-irradiation in vitrified high level waste. NBS and SNBS glasses were synthesized and doped with 1.5% HfO2. For TDPAC studies the glasses were doped with 181Hf probe, while for EXAFS studies measurements were carried out at and around Hf LIII edge. TDPAC and EXAFS acquisition were performed before and after electron beam irradiation doses up to 10 MGy for both NBS and SNBS glasses. Fourier transforms of the TDPAC spectra show broad frequency distribution reminiscent of the disordered glass matrix, with increase in hyperfine interaction frequency in irradiated glasses with respect to unirradiated ones as well as with increasing EB dose. On the other hand, the width of the frequency distribution was found to decrease with EB dose. No change in asymmetry of the electric field gradient was observed in irradiated glasses with respect to unirradiated ones. These observations indicate that while there is no indication of appearance of micro-crystallinity in the glasses up to EB dose of 10 MGy, local structural changes around Hf do take place with EB irradiation in both the glasses. No change in metric parameters (Hf-O bond distance and coordination number of Hf) was observed from EXAFS measurements on both NBS and SNBS glasses up to EB dose of 10 MGy.

Implantation of cobalt in SnO2 thin films studied by TDPAC

Here we report time differential perturbed angular correlation (TDPAC) results of Co-doped SnO2 thin films. Making use of stable Co and radioactive 111In implanted at the Bonn Radioisotope Separator with energies of 80 keV and 160 keV, respectively, it was possible to study the dopant incorporation and its lattice location during annealing. The hyperfine parameters have been probed as a function of temperature in vacuum. Two quadrupole interactions were observed. At high temperatures the dominant fraction for the probe nuclei can be assigned to the Cd-incorporation at the cation substitutional site in a highly disordered structure, obtained after implantation, to high crystallinity for the measurements at 873 K and 923 K. The similarity in TDPAC spectra obtained in undoped SnO gives indirect evidence that In and Co diffuse to different depths during the annealing process. Other interpretations will be discussed.

Thermal stability of nonmagnetic Cd and In impurities in Fe3O4

Magnetite (Fe3O4) was doped with radioactive 111mCd and 111In ions as impurities, and their residence sites and thermal stability were investigated by means of time-differential perturbed angular correlation (TDPAC) spectroscopy. Well-defined TDPAC spectra unequivocally show their sites: Cd ions are stably located only in the tetrahedral A site in all the temperature range of the present observation (77 K–873 K); In ions also specifically occupy the A site at low temperature, but at high temperature part of them select the B site in a reversible fashion. The energy difference between the A and B sites for the accommodation of In was experimentally determined to be 0.119 (9) eV by assuming a Boltzmann distribution for the populations of the 111In probe in the respective sites. The element-dependent thermal stabilities observed for Cd and In were well corroborated by density functional theory calculations. The successful observation of thermally activated site-to-site displacement of impurity In ions in Fe3O4 is reported.

Investigation of gamma radiation induced changes in local structure of borosilicate glass by TDPAC and EXAFS

Gamma radiation induced changes in local structure around the probe atom (Hafnium) were investigated in sodium barium borosilicate (NBS) glass, used for immobilization of high level liquid waste generated from the reprocessing plant at Trombay, Mumbai. The (NBS) glass was doped with 181Hf as a probe for time differential perturbed angular correlation (TDPAC) spectroscopy studies, while for studies using extended X-ray absorption fine structure (EXAFS) spectroscopy, the same was doped with 0.5 and 2 % (mole %) hafnium oxide. The irradiated as well as un-irradiated glass samples were studied by TDPAC and EXAFS techniques to obtain information about the changes (if any) around the probe atom due to gamma irradiation. TDPAC spectra of unirradiated and irradiated glasses were similar and reminescent of amorphous materials, indicating negligible effect of gamma radiation on the microstructure around Hafnium probe atom, though the quaqdrupole interaction frequency (ω Q) and asymmetry parameter (η) did show a marginal decrease in the irradiated glass compared to that in the unirradiated glass. EXAFS measurements showed a slight decrease in the Hf-O bond distance upon gamma irradiation of Hf doped NBS glass indicating densification of the glass matrix, while the cordination number around hafnium remains unchanged.

Local structures at In impurity sites in ZnO probed by the TDPAC technique

Local structures in zinc oxide (ZnO) doped with In ions were investigated by means of the time-differential perturbed angular correlation (TDPAC) method with the 111Cd(← 111In) probe. Indium-concentration dependence of the TDPAC spectra suggests that the local structures formed by the impurities are sensitive to their population in the system: In ions occupy defect-free Zn sites when doped with a trace amount; they locally form microscopic unique structures widely dispersed in ZnO at 0.05 at. % or higher; and other compounds are formed at the In concentration as high as 10 at. %. Their characteristic structures are discussed based on the hyperfine-interaction parameters.

Thermal stability of locally-associated Al and In impurities in zinc oxide

The stability of locally-associated Al and In impurities in zinc oxide (ZnO) was investigated by means of the time-differential perturbed angular correlation (TDPAC) method with the 111Cd(←111In) probe. We found that Al and In impurities associate with each other by their thermal diffusion in air, and the association process irreversibly proceeds at high temperature. In vacuum, however, it was revealed that the rigid bonding between Al and In ions dissociates by heat treatment at temperatures higher than 873 K, and this dissociation process is enhanced with increasing annealing temperature. The contrastive atmosphere dependence of the stability of the association between Al and In in ZnO is discussed based on the variation of the TDPAC spectra against heat-treatment temperature.

Studies of interaction between He and elements with mass number 140 in Fe by time-differential perturbed-angular-correlation measurements

Room-temperature time-differential perturbed-angular-correlation (TDPAC) spectra of 140Ce arising through 140Ba-140La from 140Cs in He-doped Fe, unannealed and annealed in vacuum at various temperatures, were obtained in order to examine whether Ce (or rather, La and Ba) and He form complexes having a definite geometrical structure in Fe, as suggested by first-principles density-functional theory calculations. No clear signal of such complexes was observed in the TDPAC spectra. However, the TDPAC spectra indicate that Ce and He form complexes having a variety of geometrical structures. Comparison with reported TDPAC results on 111Cd arising from 111In in He-doped stainless steel shows that the parent atoms (La and Ba) of 140Ce trap He atoms more efficiently than In atoms do, indicating stronger bonding of He to the former atoms, while different from the present case, 111Cd (In)–He complexes form a unique geometrical structure.

Recoil Induced Room Temperature Stable Frenkel Pairs in a-Hafnium Upon Thermal Neutron Capture

Ultrapure hafnium metal (110 ppm zirconium) was neutron activated with a thermal neutron flux of 6:6 · 1012 cm-2s-1 in order to obtain 181Hf for subsequent time differential perturbed angular correlation (TDPAC) experiments using the nuclear probe 181Hf(β-) 181Ta. Apart from the expected nuclear quadrupole interaction (NQI) signal for a hexagonal close-packed (hcp) metal, three further discrete NQIs were observed with a few percent fraction each. The TDPAC spectra were recorded for up to 11 half lives with extreme statistical accuracy. The fitted parameters vary slightly within the temperature range between 248 K and 373 K. The signals corresponding to the three additional sites completely disappear after ‘annealing’ at 453 K for one minute. Based on the symmetry of the additional NQIs and their temperature dependencies, they are tentatively attributed to Frenkel pairs produced by recoil due to the emission of a prompt 5:694 MeV -ray following thermal neutron capture and reported by the nuclear probe in three different positions. These Frenkel pairs are stable up to at least 373 K.

Characteristic local association of In impurities dispersed in ZnO

Local environments in 0.5 at.$%$ In-doped ZnO were investigated by means of the time-differential perturbed angular correlation (TDPAC) method. In a comparative study, using the ${}^{111}$Cd probe nuclei as the decay products of different parents, ${}^{111}$In and ${}^{111\mathrm{m}}$Cd, we found that ${}^{111}$In microscopically forms a unique structure with nonradioactive In ion(s) dispersed in ZnO, whereas ${}^{111\mathrm{m}}$Cd has no specific interaction with the In impurities. The spectral damping of the TDPAC spectra is attributed to the aftereffect following the EC decay of ${}^{111}$In. It was demonstrated from the aftereffect that the local density and/or mobility of conduction electrons at the ${}^{111}$In probe site in the In-doped ZnO is lowered due to the characteristic structure locally formed by the dispersed In ion(s).

Strong Affinity between In and Al Impurities Doped in ZnO

In recent years, zinc oxide (ZnO) doped with group 13 elements (Al, Ga, In) as impurity donors is strongly expected for application to functional devices as n-type II–VI compound semiconductors. It is known that the electric conductivity of the semiconductor drastically changes depending on the type, concentration, and introduction methods of impurities. For the precise control of conductivity, therefore, it is essential to investigate the physical and chemical states of the impurities. With respect to the study of the electromagnetic field in the vicinity of dilute impurities, nuclear techniques with radioactive probes are very suited because of their high sensitivity. Taking this advantage, we have applied the timedifferential perturbed angular correlation (TDPAC) method to the investigation of local fields at donor sites in ZnO, employing Cd disintegrated from In, symbolized as 111Cdð 111InÞ hereafter, as the nuclear probe expecting the behavior of In as a donor impurity. In our previous TDPAC studies, we found that local fields at the probe nucleus in ZnO doped with dilute In, Ga and Al ions are distinctly different from that for undoped ZnO. Especially for the Al-doped ZnO, in addition, the doping effect on the 111Cdð 111InÞ probe is prominent even at as low Al concentration as 0.05 at.% (500 ppm). This observation implies a high probability for the local association of the 111Cdð 111InÞ probe and Al ion(s) as a result of their thermal diffusion in ZnO. Directing our interest to the probability of their association, we investigated the dilute limit of Al concentration at which their association presumed above can be observed. The present paper proves the presence of a strong attractive force between In and Al ion(s) in ZnO matrix by showing an experimental evidence that the 111Cdð 111InÞ probe can be locally associated with extremely dilute Al ion(s). Zinc oxide samples doped with various Al concentrations were separately synthesized by a solid-state reaction following our previous work. For the synthesized samples, we found from powder X-ray diffraction patterns that the lattice constants were unchanged from pure ZnO even for the 5000 ppm at.% Al-doped ZnO and new phases were not detected. TDPAC measurements were performed for the 111Cdð 111InÞ probe doped in each sample at the concentration of 100 ppt on the cascade rays with the intermediate state of I 1⁄4 5=2 having a half-life of 85.0 ns. In the present work, observation of TDPAC was made for the directional anisotropy, A22G22ðtÞ, as a function of the time interval between the cascade -ray emissions, t, during which the probe is perturbed by the outer surrounding field. Here, A22 denotes the angular correlation coefficient depending only on the nuclear properties and G22ðtÞ is the time-differential perturbation factor. For easy understanding of the effect of the Al doping on the present perturbation pattern, the TDPAC spectra of 111Cdð 111InÞ in undoped and 500 ppm Al-doped ZnO are firstly cited in Fig. 1 from our previous studies. The spectrum for the undoped ZnO in Fig. 1(a) exhibits an oscillatory structure typical of the electric quadrupole interaction between the probe nucleus and the extranuclear field (hereafter denominated Component A). Although the oscillating pattern reproducible with a single component is not clearly discernible due to the damped structure reflecting a wide distribution of the field at the probe, the static perturbation pattern for the Al-doped ZnO in Fig. 1(b) (denominated Component B) is also ascribable to the electric quadrupole interaction because the sample consists of no magnetic materials; accordingly, the distinct perturbation should be attributed to the change in the charge distribution around the probe by the Al doping. We thus performed least squares fits to the spectra in Fig. 1 with G22ðtÞ expressed as G22ðtÞ 1⁄4 G 22ðtÞ 2;0 þ X3

Electric field gradient at the 111Cd(←111In) site in Ga-doped ZnO

Abstract The time-differential perturbed angular correlation (TDPAC) method was applied to a study of the local environment at the 111Cd(←111In) probe nucleus introduced in 0.5 at. % Ga-doped ZnO. The TDPAC spectrum obtained at room temperature suggests that the doped Ga ions reside at the substitutional Zn site and they are locally associated in immediate proximity to the probe, reflecting strong attractive force between the probe and the dopants. The relative width of the magnitude of the electric field gradient produced at the probe nucleus shows that the doped Ga ion(s) adjacent to the probe is/are diversely distributed compared with doped In ion(s).

The time differential perturbed angular correlation study of binding of hafnium to humic acid and its model compound

Time differential perturbed angular correlation (TDPAC) spectroscopy has been used to study the binding of hafnium to mandelic acid, which is a model compound of humic acid. The Fourier transform of TDPAC spectrum of Hf–mandelate complex showed two ω values, namely, ω Q 1 = 77 (±0.4) Mrad/s and ω Q 2 = 111 (±3.1) Mrad/s. The asymmetry parameters for the two sites were found to be 0.7 and 0.3, respectively. The electric field gradient (EFG) around the metal ion was theoretically calculated using the computer code GAMESS. The calculated EFG value was found to be in reasonable agreement with that deduced from experiment. Contrary to Hf–mandelate, the TDPAC spectrum of Hf–humate system did not show characteristic features of discrete binding sites.

Temperature-Dependent Behavior of Impurity Atoms Implanted in Highly Oriented Pyrolytic Graphite –An Application of a New Online TDPAC Method–

The behavior of impurity atoms in graphite is one of the most intriguing subjects in current materials science. It is well known, for graphite intercalation compounds, that the type and concentration of intercalated impurities control their physical and chemical properties. It is thus of great importance to investigate the behavior of intercalants in the two dimensional layers for further understanding of their interacting nature with the graphite matrix. In order to investigate such interactions, it is essential to introduce impurities of interest into graphite; and, for that purpose, the ion-implantation method would be the simplest method. Nuclear techniques with radioactive probes are highly suited to such studies on the behavior of dilute impurities because of their high sensitivity. In our recent study, we developed a new detection apparatus for radioactive impurities: an online time-differential perturbed angular correlation (TDPAC) measurement system. The TDPAC method is a spectroscopy using unstable nuclei as the probe; by observing the time-variant angular correlation of rays successively emitted in the disintegration process of the excited nucleus of the probe, we can obtain direct information on the local field in the vicinity of the probe nucleus through electromagnetic interactions between the probe nucleus and extranuclear field. The newly developed system enables the application of shortlived unstable nuclei to the spectroscopy as the parents of probes; they are implanted in samples of interest at high energy immediately after their production by acceleratorbased nuclear reactions. In our previous paper, we demonstrated the applicability of the present online system and reported on the residence site of F( O) implanted in highly oriented pyrolytic graphite (HOPG). In comparison with the previous data obtained at 18K, we here discuss the displacement of the F( O) nuclei at room temperature on the basis of the damping trend of the TDPAC spectra. The online TDPAC experiment was carried out at the RIKEN Nishina Center. Ionized Ne was accelerated by a two-stage acceleration with the AVF cyclotron and the ring cyclotron up to 110MeV/u at a beam intensity of 150 pnA. A variety of radioactive nuclides were produced at a Be production target by projectile-fragmentation reactions; the secondary beam of interest, O (t1=2 1⁄4 26:9 s), was separated out of these heavy ions at a purity of 98% or higher by the RIKEN projectile-fragment separator (RIPS). A wellfocused pulsed beam of O was implanted deep in an HOPG sheet at a beam intensity of 10 s . The online TDPAC measurements were performed at room temperature on the 1357–197 keV cascade rays from F nuclei, whose 197 keV intermediate state with nuclear spin of I 1⁄4 5=2 has a half-life of 89.3 ns. In the present work, the time evolution of the angular correlations of the cascade rays was observed at =2 and directions. In order to obtain better counting statistics, we used sixteen BaF2 detectors. They were arranged in four independent detector planes for the investigation of the sample-to-detector configuration dependence of perturbation patterns for a single-crystalline sample. All the events were taken in a list mode using a CAMAC system so that we could work on off-line data processing searching for the optimum conditions on energy gates for the detected rays of interest. The experimental details are described elsewhere. The TDPAC spectra of F( O) implanted in the HOPG sheet at room temperature are shown in Fig. 1 together with the previous data obtained at 18K. In the present experiment, we derive the time evolution of the angular correlation as a function of the time interval between the cascade -ray emissions, RðtÞ, from the following simple arithmetic operation: -0.2

Online time-differential perturbed angular correlation study with an 19O beam – Residence sites of oxygen atoms in highly oriented pyrolytic graphite

The online time-differential perturbed angular correlation (TDPAC) method was applied to a study of the physical states of a probe 19F, the β− decay product of 19O (t1/2=26.9s), implanted in highly oriented pyrolytic graphite. The observed magnitude of the electric field gradient at the probe nucleus, ∣Vzz∣=2.91(17)×1022Vm−2, suggests that the incident 19O atoms are stabilized at an interlayer position with point group C3v. Exhibiting observed TDPAC spectra having a clear sample-to-detector configuration dependence, we demonstrate the applicability of the present online method with a short-lived radioactive 19O beam.

<SUP>111</SUP>Cd(←<SUP>111</SUP>In) Time Differential Perturbed Angular Correlation (TDPAC) Spectroscopy in Fe/Ag Films

We have investigated the magnetic properties of Cd atoms decayed from 111 In at the interfaces of Fe/Ag evaporated films. In order to determine the magnetic properties of the films, we have measured 111 Cd( 111 In) time differential perturbed angular correlation (TDPAC) spectra at room temperature as a function of distance from the interface. Fe and Ag were evaporated using electron beam evaporation, and small amounts of radioactive 111 In were evaporated by resistance-heating. The evaporated films had the following stacking orders on kapton polyimide film substrate: (1) polyimide/Fe 50 nm/ 111 In/Fe x nm/Ag 20 nm (x¼ 0:2; 0:3; 1; 3; 5; 10), (2) polyimide/Fe 50 nm/Ag x nm/ 111 In/Ag 20 nm (x¼ 0; 0:2; 1). We used an Ag layer as a cap layer in order to prevent oxidation in air. TDPAC spectra were measured using a four-detector arrangement. The hyperfine magnetic field tends to be slightly larger when 111 In is close to the interface of the Fe/Ag layer. The intensity of perturbation damps rapidly as 111 In is close to the interface of Fe and Ag. These behaviors are thought to depend on electric field gradients and the influence of the surface roughness.

111Cd Time Differential Perturbed Angular Correlation Study of Deformed Ni

Using a time differential perturbed angular correlation (TDPAC) method with 111 In which decays to 111 Cd, the lattice defects induced by cold rolling in Ni metal at 77 K have been studied by the magnetic hyperfine fields observed at the 111 Cd probe nuclear sites. To investigate the dependence of annealing temperature, we have measured TDPAC spectra at 298 K during 1 hour isochronal annealing up to 1273 K in Ar + 7%H 2 gas atmosphere. After 1273 K annealing, only one component which shows ω L = 98.0 ± 0.5 Mrad/s corresponding to magnetic hyperfine field of 6.68 ± 0.02 T has been observed at 300 K. This frequency is interpreted as a hyperfine field at 111 Cd nucleus which occupies substitutionally the Ni lattice sites. We have also investigated the interaction between probe nucleus and lattice defects from the measurements of 111 Cd TDPAC spectra. After deformation, distinctive changes have not been observed. But after 473 K annealing, ω L = 40.60 ± 1.03 Mrad/s corresponding to magnetic hyperfine field of 2.77 ± 0.07 T was observed in addition to the component originating from the substitutional 111 Cd atoms. This frequency seems to be due to the component from the trivacancy trapping site. Because 111 In-V 3 site might transform immediately to 111 In - V 4 complex, and shows the cubic environment. This component disappeared after anneal ing above 873 K, and after 1273 K annealing the spectrum completely returned to the original substitutional 111 Cd spectrum before the cold rolling.

<SUP>140</SUP>Ce (←<SUP>140</SUP>La) Time-Differential Perturbed Angular Correlation Study of CeRu<SUB>2</SUB>Ge<SUB>2</SUB>

The hyperfine interaction at 140Ce nucleus in CeRu2Ge2 has been investigated, using the 140Ce Time-Differential Perturbed Angular Correlation (TDPAC) method. 140Cs ions, which are fission products from 235U, have been implanted into a single crystal of CeRu2Ge2 at room temperature. 140Cs decays to 140Ce 4+ intermediate state through 140Ba with the life-time of 12.752 days and 140La with a life-time of 1.6781 days. TDPAC spectrum at 4.2 K clearly shows the existence of the magnetic perturbation, which is absent at room temperature. Larmor frequency observed at 4.2 K is 1.32(1) Grad/s corresponding to the hyperfine magnetic field of 24.2(2) T at 140Ce nucleus. Magnetization measurements of CeRu2Ge2 performed by using the SQUID magnetometer revealed the magnetic moment of 1.848 μB which indicates that the hyperfine coupling constant of Ce is 13.1(3) T/μB.

Extended X-ray absorption fine structure and time differential perturbed angular correlation study of hafnium(IV) sorbed onto amorphous silica

Sorption of Hf(IV) onto amorphous silica at pH values between 1 and 7 is investigated by extended X-ray absorption fine structure (EXAFS) and time differential perturbed angular correlation (TDPAC) spectroscopies. Hafnium(IV) is studied as a chemical analogue for understanding the speciation of tetravalent actinides. In addition, 181Hf is a frequently investigated TDPAC probe nuclide. Spectra obtained from both techniques show that there is a change in Hf-species with sample preparation pH. Results from TDPAC measurements show that two similar surface binding sites exist for Hf(IV) on the silica surface at low pH values. At a pH above 3, a third, unspecific surface binding site for Hf(IV) begins to dominate. EXAFS investigations do not detect the presence of polynuclear surface species. Both TDPAC and Hf L3 edge EXAFS spectra of the sorption samples differ from that of a Hf(IV) solution or a Hf(IV) hydrolysis product. This indicates that the sorbed species are different from solution or simple hydrolysis species. Short Hf-O distances are obtained from theoretical fits to the EXAFS oscillations for all samples. This suggests that the primary interaction of Hf(IV) with the silica surface occurs via silanol groups. Differences in the electric field gradient surrounding sorbed Hf(IV) cations as a function of pH, observed in the TDPAC spectra, must result from changes in overall species geometry rather than a change in the primary Hf-silica surface interaction.

Combined TDPAC and EXAFS Study of InPt/FER Catalysts

Time Differential Perturbed Angular Correlation (TDPAC) experiments using 111In as probe were performed in order to determine the nature of In-sites in In-ferrierite (In/FER), before and after the incorporation of Pt through the hyperfine interaction between the nuclear quadrupole moment of the probe's nucleus and the extranuclear electric field gradient (EFG). Extended X-ray Absorption Fine Structure (EXAFS) measurements were performed to measure the absorbance above the Pt's LIII absorption edge in the transmission mode in order to determine the local environment of Pt atoms in Pt/FER and In Pt/FER catalysts. TDPAC spectra of 111In in In/FER and InPt/FER taken at 500°C in air indicated that there are no changes in the indium surroundings after the incorporation of Pt. Three sites were found for indium in both samples. Two of them correspond to the two sites of indium in ln2O3 and the third one is attributed to In in exchange sites of the zeolites. Their population, quadrupole frequencies and asymmetry parameters didn't change with the incorporation of Pt. EXAFS experiments showed similar near neighborhood Pt-0 distances and Pt coordination number in Pt/FER and In Pt/FER samples. There is no evidence of the presence of any In-Pt bimetallic entity in In Pt/FER catalyst.