Constants Of Pt Research Articles

On the Rate of Interaction of Sodium Borohydride with Platinum (IV) Chloride Complexes in Alkaline Media

In this work, sodium borohydride was used as a strong reductant of traces of platinum complex ions. The investigations of the kinetics of redox reaction between platinum(IV) chloride complex ions and sodium borohydride were carried out. For the first time, the kinetic experiments were carried out in a basic medium (pH~13), which prevents NaBH4 from decomposition and suppresses the release of hydrogen to the environment. The rate constants of Pt(IV) reduction to Pt(II) ions under different temperatures and concentrations of chloride ions conditions were determined. In alkaline solution (pH~13), the values of enthalpy and entropy of activation are 29.6 kJ/mol and –131 J/mol K. It was also found that oxygen dissolved in the solution strongly affects kinetics of the reduction process. Using collected results, the reduction mechanism was suggested. For the first time, the appearance of diborane as an intermediate product during Pt(IV) ions reduction was suggested. Moreover, the influence of oxygen present in the reacting solution on the rate of reduction reaction was also shown.

Enhanced electrochemical performance of Pt–Sn–In/C nanoparticles for membraneless fuel cells

Carbon-supported ternary Pt70Sn10In20, Pt70Sn15In15 and Pt70Sn20In10/C electrocatalysts were synthesized by co-impregnation method for the electrooxidation of ethanol in membraneless fuel cells. The resulting catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX) analyses compared to Pt50Sn50, Pt50In50 and Pt100/C catalysts produced in the same way. The results revealed that all catalysts showed a similar particle morphology and the lattice constant of Pt–Sn–In was between Pt–Sn and Pt–In. Cyclic voltammetry (CV) and chronoamperometry (CA) showed that the Pt–Sn–In catalyst has improved electrocatalytic activity for ethanol oxidation compared to Pt–Sn and Pt–In catalysts, which is in agreement with the results of the single cell test. The improvement in activity is due to a greatly increased electrochemically active surface and the promoting function of indium.

Theoretical Analysis of Solvent Effect on the NMR Parameters in trans-(NHC)PtI2Py Complex: A Platinum-Based Anticancer Drug

In this study, quantum chemical calculations using MPW1PW91 method were applied to analyze the solvent effect on the NMR parameters for a platinum-based anticancer drug, namely complex trans-(NHC)PtI2Py. The solvent effects on isotropic magnetic shielding tensor data (σiso) for Pt and CNHC atoms and spin–spin coupling constants of Pt–C and Pt–N in the complex were studied by the self-consistent reaction field theory (SCRF) based on the Polarizable Continuum Model (PCM). The linear correlations between these parameters and dielectric constants of solvents were studied. The σiso (Pt) values in different solvents were correlated with the Kirkwood–Bauer–Magat equation (KBM).

Synthesis, characterization, HSA interaction, and antibacterial activity of a new water-soluble Pt(II) complex containing the drug cephalexin

A new water-soluble platinum(II) complex, [Pt(CEX)Cl(DMSO)]Cl (CEX is cephalexin), was synthesized and characterized by physicochemical, spectroscopic, and computational methods. Multispectroscopic techniques were used to investigate the interaction of Pt(II) complex with human serum albumin (HSA) under the physiological conditions. The results of fluorescence titration indicated that the binding of the Pt(II) complex to HSA induced fluorescence quenching through static quenching mechanism with binding constant of 1.24 × 104 M−1 at 298 K. The thermodynamic parameters at different temperatures indicated that van der Waals forces, hydrogen bonds, and electrostatic forces play major roles in the stability of Pt(II) complex–HSA association. The displacement experiments using the site probes warfarin and ibuprofen substantiated that Pt(II) complex could bind to both site I and II of HSA. Furthermore, UV–Vis and fluorescence spectra were used to investigate the conformational changes of HSA molecule with the addition of Pt(II) complex. The binding constant of Pt(II) complex is more than two orders of magnitude higher than the corresponding value of cephalexin. These results indicate that the binding affinity of Pt(II) complex is stronger than the free drug. In addition, the antibacterial study showed that the MIC of platinum complex of cephalexin for variety of organisms was lower than free cephalexin.

Pt/Alumina Hyperbolic Metafilms with High‐Temperature Stability, Wide Wavelength Tunability, and Omnidirectional Absorption

The authors report high‐temperature stable, spectrally tunable, Pt/alumina hyperbolic metafilms with broadband absorption. Two uniform pairs of Pt (10 nm)/alumina (100, 150, or 200 nm) multilayer films with a top alumina passivation layer and a bottom Pt mirror and are prepared on sapphire substrates by sputtering. These Pt/alumina multilayer films yielded strong light absorption at visible to near‐infrared wavelengths that are spectrally tunable by modulating the thickness of each alumina layer. Based on effective medium theory for 1D metafilms, such tuning behavior is well understood; the maximum absorption occurred at a specific range of wavelengths wherein the real part of the effective permittivity was near‐zero. The broadband absorption spectrum is only marginally altered over a wide range of incident angles from 0 to 70°, a finding supported by simulations using the transfer matrix method using the experimentally derived optical constants of Pt and alumina. The fabricated Pt/alumina multilayer films maintained their initial absorption spectra after a heating test at 1450 K for 12 h. Transmission electron microscopy images and fast Fourier transform diffraction patterns show pristine Pt/alumina interfaces, devoid of any features related to oxidation, interdiffusion, and deformation after the heating test. These pristine interfaces are further verified with the elemental mapping results obtained by energy dispersion X‐ray spectroscopy. This work demonstrates that a one‐dimensional stack of Pt and alumina layers with deep‐submicron thicknesses functions as a refractory hyperbolic metamaterial with a large absorption at specific wavelengths, which will be extensively utilized in a diverse range of thermal radiation‐engineered applications.

Bimetallic nanoparticles synthesized in microemulsions: A computer simulation study on relationship between kinetics and metal segregation

Computer simulations were carried out to study the origin of the different metal segregation showed by bimetallic nanoparticles synthesized in microemulsions. Our hypothesis is that the kinetics of nanoparticle formation in microemulsions has to be considered on terms of two potentially limiting factors, chemical reaction itself and the rate of reactants exchange between micelles. From the kinetic study it is deduced that chemical reduction in microemulsions is a pseudo first-order process, but not from the beginning. At the initial stage of the synthesis, redistribution of reactants between micelles is controlled by the intermicellar exchange rate, meanwhile the core and middle layers are being built. This exchange control has a different impact depending on the reduction rate of the particular metal in relation to the intermicellar exchange rate. For the case of Au/Pt nanoparticles, the kinetic constant of Au (fast reduction) is strongly dependent on intermicellar exchange rate and reactant concentration. On the contrary, the kinetic constant of Pt (slower reduction) remains constant. Therefore, the fact that the reaction takes place in a microemulsion affects more or less depending on the reduction rate of the metals. As a consequence, the final nanostructure not only depends on difference between the reduction rates of both metals, but also on the reduction rate of each metal in relation to the intermicellar exchange rate.

Charge optimized many body (COMB) potentials for Pt and Au

Interatomic potentials for Pt and Au are developed within the third generation charge optimized many-body (COMB3) formalism. The potentials are capable of reproducing phase order, lattice constants, and elastic constants of Pt and Au systems as experimentally measured or calculated by density functional theory. We also fit defect formation energies, surface energies and stacking fault energies for Pt and Au metals. The resulting potentials are used to map a 2D contour of the gamma surface and simulate the tensile test of 16-grain polycrystalline Pt and Au structures at 300 K. The stress–strain behaviour is investigated and the primary slip systems {1 1 1}〈1 0〉 are identified. In addition, we perform high temperature (1800 K for Au and 2300 K for Pt) molecular dynamics simulations of 30 nm Pt and Au truncated octahedron nanoparticles and examine morphological changes of each particle. We further calculate the activation energy barrier for surface diffusion during simulations of several nanoseconds and report energies of eV for Pt and eV for Au. This initial parameterization and application of the Pt and Au potentials demonstrates a starting point for the extension of these potentials to multicomponent systems within the COMB3 framework.

Pt(II) and Ni(II) complexes of octahydropyrrolo[3,4-c]pyrrole N-benzoylthiourea derivatives: Synthesis, characterization, physical parameters and biological activity

In this study, four novel Pt(II) and Ni(II) complexes of octahydropyrrolo[3,4-c]pyrrole, consisting of pyrrolidine fused to pyrrolidine-2,5-dione, N-benzoylthiourea derivatives were synthesized and their structural characterization was performed by NMR, FT-IR, MS, HRMS and elemental analysis techniques and single crystal X-ray diffraction studies. The octahydropyrrolo[3,4-c]pyrrole N-benzoylthiourea compound 3c crystallizes triclinic, with space group P-1. Pt(II) and Ni(II) ions created cis-complexes Pt(II) 4c and Ni(II) 5a forming distorted square-planar structures in orthorhombic space groups Pnma and Pbca, respectively. Furthermore, the ligands behave as bidentate and bind to the metal atom via the S and O atoms. Acid dissociation constants of the ligands were determined by potentiometric titration method in 25% (v/v) acetonitrile-water hydroorganic solvent at 25±0.1°C, at an ionic background of 0.1mol/L of NaCl using the HYPERQUAD computer program and at least three acid dissociation constants were determined for each ligand. Stability constants of Pt(II) and Ni(II) complexes of the ligands were determined by potentiometric titration under the same conditions as stated above. Determination of the stability constant studies show that the ligands tend to form with Pt(II) ion in acidic medium as 1:1 (M:L) and in basic medium as 1:2 (M:L), but the ligands tend to form with Ni(II) ion in both acidic medium and basic medium as 1:2 (M:L). Antibacterial activity of the ligands and their complexes was investigated against S. aureus, B. subtilis, A. hydrophila, E. coli and A. baumannii standard bacterial strains. The ligands and their Pt(II) and Ni(II) complexes exhibited antibacterial activity against mentioned bacterial strains in the range of 62.5–125μg/mL, 62.5–250μg/mL and 62.5–125μg/mL, respectively. Antimycobacterial activity of the compounds was investigated against the M. tuberculosis H37Rv strain. The compounds exhibit antimycobacterial activity in the range of 40–80μg/mL.

Effect of structure on the magnetic anisotropy ofL10FePt nanoparticles

We carry out a systematic theoretical investigation of Magneto Crystalline Anisotropy (MCA) of L10 FePt clusters with alternating Fe and Pt planes along the (001) direction. We calculate the structural relaxation and magnetic moment of each cluster by using ab initio spin-polarized density functional theory (DFT), and the MCA with both spin-polarized DFT (including spin-orbit coupling self-consistently) and the torque method. We find that the MCA of any composite structure of a given size is enhanced with respect to that of the same-sized pure Pt or pure Fe cluster as well as to that of any pair of Fe and Pt atoms in bulk L10 FePt. This enhancement results from the hybridization we observe between the 3d orbital of the Fe atoms and the 5d orbital of their Pt neighbors. This hybridization, however, affects the electronic properties of the component atoms in significantly different ways. While it somewhat increases the spin moment of the Fe atoms, it has little effect on their orbital moment; at the same time, it greatly increases both the spin and orbital moment of the Pt atoms. Given the fact that the spin-orbit coupling (SOC) constant of Pt is about 7 times greater than that of Fe, this Fe-induced jump in the orbital moment of the Pt atoms produces the increase in MCA of the composite structures over that of their pure counterparts. That any composite structure exhibits higher MCA than bulk L10 FePt results from the lower coordination of Pt atoms in the cluster, whether Fe or Pt predominates within it. We also find that bipyramidal clusters whose central layer is Pt have higher MCA than their same-sized counterparts whose central layer is Fe. This results from the fact that Pt atoms in such configurations are coordinated with more Fe atoms than in the latter. By thus participating in more instances of hybridization, they contribute higher orbital moments to the overall MCA of the unit.

Synthesis, Characterization, and DNA Binding Studies of a New Pt(II) Complex Containing the Drug Levetiracetam: Combining Experimental and Computational Methods

The water-soluble platinum(II) complex, [Pt(LV)(dmso)Cl]Cl (LV is Levetiracetam an anti-epileptic drug belonging to the pyrrolidine family) was synthesized and characterized using physico-chemical, spectroscopic and computational methods. Multi-spectroscopic methods used to study the interaction of Pt(II) complex with calf thymus (ct-DNA) in Tris-HCl buffer solution (pH 7.4). The Pt(II) complex was found to be a minor groove binder with a preference for the A-T region compared to the G-C region. This was substantiated by displacement studies with Hoechst 33258, a known minor groove binder. The mean binding constant obtained from the spectroscopic techniques was 7 × 10(4) M(-1). In comparison with the previous study, the binding constant of Pt(II) complex is 15 times greater than the corresponding value of levetiracetam. These results indicate that the binding affinity of Pt(II) complex is stronger than levetiracetam.

A highly active PtNi/C electrocatalyst for methanol electro-oxidation in alkaline media

A carbon supported PtNi/C electrocatalyst synthesized via a polyol process was characterized by XRD, TEM and voltammetry techniques. The XRD analysis showed a decreased lattice constant of Pt for the PtNi/C catalyst compared with the Pt/C. indicating partial PtNi alloy formed. The PtNi/C exhibited enhanced mass activity towards methanol oxidation reaction as well as decreased CO stripping currents in alkaline media compared with the Pt/C. Density functional theory studies revealed the electronic structure modification of Pt by Ni atoms and weakened CO adsorption energy on the Pt(3)Ni than on the Pt(4) clusters, which may account for the increased MOR activity. Crown Copyright (C) 2010 Published by Elsevier By. All rights reserved.

1J-2 Unusual Temperature Dependence of Elastic Constants of Pt and Pd Studied by Picosecond Ultrasounds and Ab initio Calculation(Physical Acoustics)

1J-2 Unusual Temperature Dependence of Elastic Constants of Pt and Pd Studied by Picosecond Ultrasounds and Ab initio Calculation(Physical Acoustics)

Relaxor/Ferroelectric Super-Lattice Films Fabricated on the Single Lattice Scale

Relaxor/ferroelectric super lattice films Pb(Sc 1/2 Nb 1/2 )O 3 /PbTiO 3 (PSN/PT) with different PT ratios are synthesized on the lattice cell scale by the pulsed laser deposition method. X-ray diffraction analyses reveal that fabricated and designed super-lattice (SL) periods coincide well within 6% error, and are uniform over thin film thickness of 100 nm. The lattice constant of PT in SL films shows an abrupt increase at a specific PT ratio of around 30%, which indicates the change in the a-axis to the c-axis domain configuration. The dielectric constant shows also the maximum at this PT ratio probably due to the dielectric anisotropy of PT, and it does not depend on the SL period.

Infrared reflection absorption spectral study for CO adsorption on Pd/Pt(1 1 1) bimetallic surfaces

Infrared reflection absorption spectroscopy (IRRAS) was used to investigate carbon monoxide (CO) adsorption on 0.15 nm-thick–0.6 nm-thick Pd-deposited Pt(1 1 1) bimetallic surfaces: Pd x /Pt(1 1 1) (where x is the Pd thickness in nanometers) fabricated using molecular beam epitaxial method at substrate temperatures of 343 K, 473 K, and 673 K. Reflection high-energy electron diffraction (RHEED) measurements for Pd 0.15–0.6 nm /Pt(1 1 1) surfaces fabricated at 343 K showed that Pd grows epitaxially on a clean Pt(1 1 1), having an almost identical lattice constant of Pt(1 1 1). The 1.0 L CO exposure to the clean Pt(1 1 1) at room temperature yielded linearly bonded and bridge-bonded CO–Pt bands at 2093 and 1855 cm −1. The CO–Pt band intensities for the CO-exposed Pd x /Pt(1 1 1) surfaces decreased with increasing Pd thickness. For Pd 0.3 nm /Pt(1 1 1) deposited at 343 K, the 1933 cm −1 band caused by bridge-bonded CO–Pd enhanced the spectral intensity. The linear-bonded CO–Pt band (2090 cm −1) almost disappeared and the bridge-bonded CO–Pd band dominated the spectra for Pd 0.6 nm /Pt(1 1 1). With increasing substrate temperature during the Pd depositions, the relative band intensities of the CO–Pt/CO–Pd increased. For the Pd 0.3 nm /Pt(1 1 1) deposited at 673 K, the linear-bonded CO–Pt and bridge-bonded CO–Pd bands are located respectively at 2071 and 1928 cm −1. The temperature-programmed desorption (TPD) spectrum for the 673 K-deposited Pd 0.3 nm /Pt(1 1 1) showed that a desorption signal for the adsorbed CO on the Pt sites decreased in intensity and shifted ca. 20 K to a lower temperature than those for the clean Pt(1 1 1). We discuss the CO adsorption behavior on well-defined Pd-deposited Pt(1 1 1) bimetallic surfaces.

A DFT study of pseudomorphic monolayer Pt and Pd catalysts for NO x storage reduction applications

Pseudomorphic monolayer catalysts involving Pd and Pt monolayers above late transition metal (TM) hosts (Cu, Ru, Rh, Ag, Ir and Au) were examined for the oxidation of NO with atomic oxygen. It is found that for systems in which the lattice constant of Pt (or Pd) is expanded, the reaction enthalpy is more endothermic and the reaction barrier is higher. Conversely, for systems under compression, NO 2 formation is more exothermic and has a lower barrier. These systems were also examined for their thermodynamic stability upon adsorption of NO and oxygen. Although, segregated systems with a pseudomorphic monolayer of Pt and Pd above a transition metal were found to be stable for systems involving Ru, Ir, Rh and Au even in the presence of adsorbates, oxygen was found to be capable of reversing the position of the supported monolayer and the host metal for systems involving Ag or Cu.

Polyol-synthesized PtRu/C and PtRu black for direct methanol fuel cells

PtRu/C and PtRu black catalysts with nominal Pt:Ru atomic ratio of 1:1 are prepared by a modified polyol process (co-reduction of metal precursor salts) as anode catalysts for direct methanol fuel cells (DMFCs). Without the carbon support, PtRu nanoparticles tend to agglomerate, while the PtRu nanoparticles in PtRu/C have a good dispersion as shown by TEM. Both PtRu black and PtRu/C have the almost same alloy degree indicated by XRD, but PtRu supported on carbon could improve the influence of Ru on Pt toward methanol oxidization as shown by cyclic voltammetry. The microstructure of PtRu/C is further studied by high-resolution transmission electron microscopy (HRTEM), and the results indicate that the lattice constant of Pt in PtRu electrocatalyst has contracted despite a few parts of Pt not alloyed with Ru due to the lattice constant of Pt without contracting, which is further proved by the results of temperature-programmed reduction (TPR). Such parts of unalloyed Ru are further proved to have ability to reduce the methanol oxidation potential on Pt by comparing the catalytic behaviors of Pt/C and Pt + Ru/C prepared by mixing carbon with separately prepared Pt and Ru colloids. Moreover, the catalytic behaviors of PtRu black and PtRu/C are also compared with those of commercial ones.

Single Molecule Observations of the Adsorption Sites of Methyl Isocyanide on Pt(111) by Low-Temperature Scanning Tunneling Microscopy

Scanning tunneling microscopy (STM) has been used to directly investigate the local structure of methyl isocyanide (CNCH3) adsorbed on Pt(111). At low coverages, CNCH3 is preferentially adsorbed at on-top sites, in agreement with earlier deductions based on vibrational spectroscopy. When dosed at low coverages at 50 K, the molecules tend to adsorb near other CNCH3 molecules with preferred distances of a and a, where a = 2.78 A is the lattice constant of Pt. Annealing the surface to 120 K, however, results in a more uniform separation of the molecules. At higher coverages, the CNCH3 molecules are observed to occupy both on-top and two-fold bridge sites. On the basis of STM image analysis, CNCH3 forms an ordered layer of (2 x 3) periodicity at 0.33 ML. Additional details on the structures of CNCH3 adsorbed at the on-top and two-fold bridge sites are provided by density functional theory (DFT) calculations. At a coverage that saturates the first layer (0.33 ML), the occupation ratio for the on-top and two-fold bridge bonded CNCH3 is 1:1, which is consistent with the results obtained from the combined use of experimental reflection absorption infrared spectroscopy (RAIRS) data and DFT calculations.

Structure and chemical composition of supported Pt–Sn electrocatalysts for ethanol oxidation

Carbon supported PtSn alloy and PtSnO x particles with nominal Pt:Sn ratios of 3:1 were prepared by a modified polyol method. High resolution transmission electron microscopy (HRTEM) and X-ray microchemical analysis were used to characterize the composition, size, distribution, and morphology of PtSn particles. The particles are predominantly single nanocrystals with diameters in the order of 2.0–3.0 nm. According to the XRD results, the lattice constant of Pt in the PtSn alloy is dilated due to Sn atoms penetrating into the Pt crystalline lattice. While for PtSnO x nanoparticles, the lattice constant of Pt only changed a little. HRTEM micrograph of PtSnO x clearly shows that the change of the spacing of Pt (1 1 1) plane is neglectable, meanwhile, SnO 2 nanoparticles, characterized with the nominal 0.264 nm spacing of SnO 2 (1 0 1) plane, were found in the vicinity of Pt particles. In contrast, the HRTEM micrograph of PtSn alloy shows that the spacing of Pt (1 1 1) plane extends to 0.234 nm from the original 0.226 nm. High resolution energy dispersive X-ray spectroscopy (HR-EDS) analyses show that all investigated particles in the two PtSn catalysts represent uniform Pt/Sn compositions very close to the nominal one. Cyclic voltammograms (CV) in sulfuric acid show that the hydrogen ad/desorption was inhibited on the surface of PtSn alloy compared to that on the surface of the PtSnO x catalyst. PtSnO x catalyst showed higher catalytic activity for ethanol electro-oxidation than PtSn alloy from the results of chronoamperometry (CA) analysis and the performance of direct ethanol fuel cells (DEFCs). It is deduced that the unchanged lattice parameter of Pt in the PtSnO x catalyst is favorable to ethanol adsorption and meanwhile, tin oxide in the vicinity of Pt nanoparticles could offer oxygen species conveniently to remove the CO-like species of ethanolic residues to free Pt active sites.

Metastable surface structures of the bimetallic Sn/Pt(100) system

An ordered Sn overlayer on Pt(1 0 0) and several metastable Sn/Pt(1 0 0) surface alloys were studied using scanning tunneling microscopy (STM), low energy electron diffraction (LEED), and Auger electron spectroscopy (AES). These surfaces were studied previously using alkali-ion scattering spectroscopy (ALISS), LEED, and CO chemisorption, in order to determine conditions for alloy formation [Surf. Sci. 330 (1995) 193]. In those earlier studies, structural transitions with increasing annealing temperatures from a c(2 × 2)-Sn overlayer to a c(2 × 2)-Sn/Pt(1 0 0) surface alloy and finally to a (3√2×√2)R45° alloy structure were observed. Here STM is used to determine surface morphologies and atomic scale structures of these alloys. Sn (0.67 ML) deposited on the reconstructed Pt(1 0 0)-hex surface and annealed to 550 K formed a c(2 × 2)-Sn overlayer with compact, monolayer-high islands with step edges oriented along the [1 0 0] and [0 1 0] azimuths. Annealing the sample to 750 K initiated alloying and a c(2 × 2) surface alloy formed locally. However, the c(2 × 2) alloy structure does not appear to be stable even at this early stage of alloying and narrow channels along the 〈1 0 0〉 crystallographic directions form. For higher annealing temperatures, these channels evolve to form a two-domain structure with almost equidistant channels along the [1 0 0] and [0 1 0] directions, respectively. A dominant channel separation of 3√2 times the surface-lattice constant of Pt(1 0 0) is observed. This channel separation gives rise to a streaky (3√2×√2)R45° LEED pattern. The channels are characterized by three missing atomic rows. Between these channels are narrow terraces that are predominantly three-atomic-rows wide. The step edges of these terraces are Pt-terminated, while Sn is alloyed in the center of these terraces. A local p(2 × 2) ordering of alloyed Sn is often observed for wider terraces. Annealing to 1000 K results in “fragmentation” of the narrow terraces to form small, often square, islands with side-lengths as small as √2 times the surface-lattice constant of Pt(1 0 0). The structural characterization of these Sn/Pt(1 0 0) surfaces is used to interpret previous chemical adsorption studies.

Metastable surface structures of the bimetallic Sn/Pt(1 0 0) system

An ordered Sn overlayer on Pt(1 0 0) and several metastable Sn/Pt(1 0 0) surface alloys were studied using scanning tunneling microscopy (STM), low energy electron diffraction (LEED), and Auger electron spectroscopy (AES). These surfaces were studied previously using alkali-ion scattering spectroscopy (ALISS), LEED, and CO chemisorption, in order to determine conditions for alloy formation [Surf. Sci. 330 (1995) 193]. In those earlier studies, structural transitions with increasing annealing temperatures from a c(2 × 2)-Sn overlayer to a c(2 × 2)-Sn/Pt(1 0 0) surface alloy and finally to a (3√2×√2)R45° alloy structure were observed. Here STM is used to determine surface morphologies and atomic scale structures of these alloys. Sn (0.67 ML) deposited on the reconstructed Pt(1 0 0)-hex surface and annealed to 550 K formed a c(2 × 2)-Sn overlayer with compact, monolayer-high islands with step edges oriented along the [1 0 0] and [0 1 0] azimuths. Annealing the sample to 750 K initiated alloying and a c(2 × 2) surface alloy formed locally. However, the c(2 × 2) alloy structure does not appear to be stable even at this early stage of alloying and narrow channels along the 〈1 0 0〉 crystallographic directions form. For higher annealing temperatures, these channels evolve to form a two-domain structure with almost equidistant channels along the [1 0 0] and [0 1 0] directions, respectively. A dominant channel separation of 3√2 times the surface-lattice constant of Pt(1 0 0) is observed. This channel separation gives rise to a streaky (3√2×√2)R45° LEED pattern. The channels are characterized by three missing atomic rows. Between these channels are narrow terraces that are predominantly three-atomic-rows wide. The step edges of these terraces are Pt-terminated, while Sn is alloyed in the center of these terraces. A local p(2 × 2) ordering of alloyed Sn is often observed for wider terraces. Annealing to 1000 K results in “fragmentation” of the narrow terraces to form small, often square, islands with side-lengths as small as √2 times the surface-lattice constant of Pt(1 0 0). The structural characterization of these Sn/Pt(1 0 0) surfaces is used to interpret previous chemical adsorption studies.