Platinum Metals Rev., 2001, 45, (2), 92
ABSTRACTS: April 2001
of current literature on the platinum metals and their alloys
The Tin-Rich Part of the Au-Pt-Sn System
a. n. torgersen, l. offernes, a. kjekshus and a. olsen, J. Alloys Compd ., 2001, 314, (1–2), 92–95
Condensed phases, tie-lines and tie-triangles for an isothermal section of the Sn-rich part (≥ 50 at.%) of the Au—Pt—Sn phase diagram at 400°C are presented. There is a limited solid-solubility exchange between Au and Pt in most of the binary phases; however, for AuSn and Pt2Sn3 the ranges of homogeneity are appreciable. AuPt2Sn4 was also found.
Grain-Boundary Segregation of Impurities in Iridium and Effects on Mechanical Properties
l. heatherly and e. p. george, Acta Mater ., 2001, 49, (2), 289–298
Impurites of Fe, Ni, Cr, Al and Si (50–5000 ppm) were added to Ir-0.3 W-0.006 Th-0.005 Al to examine their effects. Fe, Ni, Cr and Al do not segregate to the grain boundaries of Ir, even when present at bulk levels of 3000–5000 ppm. Very low levels of Si (50 ppm) in the bulk segregate to Ir grain boundaries and at bulk levels of Si (< 200 ppm), both Th and Si segregate to the Ir grain boundaries. Fe, Ni, Cr, Al (and Si at low levels) do not embrittle Ir, whereas high levels of Si cause severe embrittlement.
Peculiarities of K2PdCl4 and K2PtCl4 Complexation with Polymer-Supported Dibenzo-18-crown-6
g. g. talanova, k. b. yatsmrskii and o. v. kravchenko, Ind. Eng. Chem. Res ., 2000, 39, (10), 3611–3615
Dibenzo-18-crown-6 supported on a styrene-divinylbenzene copolymer matrix (PDB18C6) is an efficient sorbent of Pt(II) and Pd(II) from aqueous K2PtCl4 and K2PdCl4 solutions, respectively. The sorption proceeds via coordination of K+ with the crown ether O atoms accompanied by the complex cation association with [PtCl4]2- and [Pdn Cl2n +2]2-. PDB18C6 shows stronger binding of Pt than of Pd.
Determination of Absolute Configuration of (π-Allyl)Palladium Complexes by NMR Spectroscopy and Stereoselective Complexation
a. gogoll, c. johansson, a. axÉn and h. grennberg, Chem. Eur. J ., 2001, 7, (2), 396–403
The (S,S )- and (R,R)-enantiomers of the chiral chelating ligand N,N ′-bis(phenylethyl)bispidine form complexes with (π-allyl)Pd species with high stereoselectivity. In the1H NMR spectra of the resulting complexes, signals of “antenna” protons were easily identified. Interligand nuclear Overhauser effects involving these protons enabled the absolute stereochemistry of the (π-allyl)Pd complex to be determined.
Characterization of the Inorganic/Organometallic Osmium(IV) Compound [Cp*2OsIVCl]2[OsIVCl6] as Formed by the Reaction of 0sCl3 with Pentamethylcyclopentadiene in Air
t. sixt, w. kaim and w. preetz, z. Naturforsch ., 2000, 55b, (3/4), 235–237
OsCl3 was reacted with pentamethylcyclopentadiene in EtOH in air to give the ionic Os(TV) compound [Cp*2OsCl]2[OsCl6], which contains two Os(IV) ions. Under similar conditions the RuCh homologue gave the Ru(III) compound [Cp*2RuCl2]2, confirming the more facile oxidation of trivalent Os to the tetravalent state.
Ruthenium Terpyridine Complexes with Mono-and Bi-Dentate Dithiolene Ligands
h. sugimoto, k. tsuge and k tanaka, J. Chem. Soe., Dalton Trans ., 2001, (1), 57–63
[Ru(CO)2Cl(terpy)]PF6 (1) (terpy = 2,2′:6,″-terpyridine) reacts with Na2mnt (mnt = S2C2(CN)2) to give initially [Ru(CO)2(mnt-KS)(terpy-K3NN′N″)], which then rearranges to [Ru(CO)2(mnt-K2SS′)(terpy-K2NN′)] in solution. (1) reacts with 3,4-toluenedithiol (H2tdt) to give [Ru(CO)2(tdt-K2SS′) (terpy-K2NN′)].
Analysis of the Activation Mechanism of Hydrogen Storage Alloy Negative Electrodes Containing Palladium Ion-Adsorbed Carbon Powder
s. morishita, k. fujita, k. itoh, s. towata and k. abe, Nippon Kagaku Kaishi, 2000, (11), 773–778
Pd2+/C powder (1) has been used to promote the initial activation of the H2 storage alloy negative electrodes in Ni—MH batteries. Electrode impedance values, and TEM and XRD of (1) were taken after cathodic polarisation. A mechanism is proposed: Pd2+ is reduced to fine Pd particles during the first charge. The fine Pd particles act as active sites for charge/discharge reactions. The alloy particles are pulverised due to volume expansion on H2 absorption; new active sites are formed on the fresh alloy surface.
Zeolitic Inorganic-Organic Polymer Electrolyte Based on Oligo(ethylene glycol) 600 K2PdCl4 and K3Co(CN)6
v. dinoto, J. Phys. Chem. B, 2000, 104, (44), 10116–10125
Aqueous solutions of K2PdCl4 and K3Co(CN)6 were combined separately with poly(ethylene glycol) 600 and then reacted together to give a zeolitic polymer electrolyte, [Cox Pdy (CN)z Clv (CH2n H4n +2On +1)Kl (1). (1) conducts ionically by two distinct conductivity regions which follow Arrhenius-type equations. At 25°C (1) has conductivity ∼3 x 10 -5 S cm-1.
Low-Lying Electronic States and Photophysical Properties of Organometallic Pd(II) and Pt(II) Compounds. Modern Research Trends Presented in Detailed Case Studies
h. yersin and d. donges, Top. Curr. Chem ., 2001, 214, 81–186
A review of photophysical research is presented, using two homologous organometallic compounds Pd(2-thpy)2 (1) and Pt(2-thpy)2 (2) (2-thpy- = 2-(2-thienyl)-pyridinate) as representative compounds. The triplets of (1) and (2) are marked by differences of nearly two orders of magnitude in metal/MLCT character. Highly resolved spectra are obtained in n- octane, at low temperature (1.3 K) and by laser spectroscopy, allowing detailed analysis. (191 Refs.)
New Luminescent and Redox-Active Homometallic Dinuclear Iridium(III), Ruthenium(II) and Osmium(II) Complexes Prepared by Metal-Catalyzed Coupling Reactions
p. m. griffiths, f. loiseau, f. puntoriero, s. serroni and s. campagna, Chem. Commun ., 2000, (23), 2297–2298
Complexes [(ppy)2Ir(phen-phen)Ir(ppy)2]2+ (ppy = monoanion of 2-phenylpyridine; phen—phen = 5,5′-bis(1,10-phenanthroline)), [(bpy)2Ru(phen—phen)-Ru(bpy)2]4+, [(bpy)2Os(phen-phen)Os(bpy)2]4+ and [(Me2bpy)2Os(phen-phen)Os(Me2bpy)2]4+(Me2bpy = 4,4′-dimethyl-2,2′-bipyridine) were prepared. They exhibit relatively intense room temperature luminescence which can be attributed to 3MLCT levels.
Rapid Synthesis of New Emitting Ir(III) Polypyridine Complexes
n. yoshkawa, y. masuda and t. matsumura-inoue, Chem. Lett. Jpn ., 2000, (10), 1206–1207
Microwave-assisted synthesis of Ir(III) polypyridine complexes, such as [Ir(bpy)3](PF6)3, has been achieved in ethylene glycol in a 500 W microwave oven of frequency 2450 MHz. The OH group of ethylene glycol was activated. These complexes were characterised by intense phosphorescence emission (505–630 nm).
On the Photochemical Behavior of the [Ru(NH3)4(N0)nicotinamide]3+ Cation and the Relative Stability of Light-Induced Metastable Isonitrosyl Isomers of Ru Complexes
c. kim, i. novozmlova, m. s. goodman, k. a. bagley and p. coppens, Inorg. Chem ., 2000, 39, (25), 5791–5795
Low-temperature IR experiments on crystalline samples of trans -[Ru(NH3)4(NO)nicotinainide]3+ salts (1) show a light-induced absorption band typical for isonitrosyl MS1 NO linkage isomers upon exposure to 300–500 nm light from a Xe source. The formation of a metastable species was confirmed by DSC measurement on (1) irradiated at low temperature with 457 nm light from an Ar+ laser. The light-induced species decays at 250–260 K.
APPARATUS AND TECHNIQUE
Electrochemical Sensing of Glucose at a Platinum Electrode with a Chitin/Glucose Oxidase Film
k. sugawara, h. fukushi, s. hoshi and k. akatsuka, Anal. Sci ., 2000, 16, (11), 1139–1143
An electrochemical glucose sensor, which can detect glucose in liquids, uses a Pt electrode covered with a chitin/glucose oxidase film. Glucose oxidase having a negative charge was immobilised on a pro-tonated chitin film in 0.1 mol dm-3 acetate buffer (pH 5.0) via an electrostatic interaction. An oxidation peak of H2O2 from the enzyme reaction occurs at +0.5 V (vs. Ag/AgCl) in 0.1 mol dm-3 acetate buffer (pH 6.2). The calibration curve of glucose was linear from 5 x 10-7-3 x 10-5 mol dm-3.
Reagentless Biosensor for Isocitrate Using One Step Modified Pt-Ir Microelectrode
a. c. pereira, f. l. fertonani, g. de oliveira neto, l. t. kubota and h. yamanaka, Talanta, 2001, 53, (4), 801–806
An isocitrate biosensor (1) had the isocitrate-dehy-drogenase-ICDH enzyme, the NADP+ coenzyme and Meldola’s Blue mediator immobilised on the surface of a Pt-lr microelectrode. Catalytic currents were proportional to isocitrate concentrations: 7.7 x 10-6-1.04 x 10-4 mol I-1. The detection limit of (1) was 3.50 x 10-6 mol 1-1. The response time < 20 s, the lifetime ∼ 30 determinations and no significant interference was noticed from sugars or citric acid.
Sensing Properties of Palladium-Gate MOS (Pd-M0S) Hydrogen Sensor-Based on Plasma Grown Silicon Dioxide
d. dwtvedi, r dwtvedi and s. k. srtvastava, Sens. Actuators B, Chem ., 2000, 71, (3), 161–168
A Pd-gate MOS H2 sensor (1) was fabricated on a n -type (100) Si wafer having resistivity of 1–6 Ω cm using plasma technology. The response-recovery time and sensitivity of (1) were studied for H2 concentrations of 1480–11,840 ppm at signal frequencies of 500 Hz, 10 and 100 kHz at room temperature. H2-induced interface-trapped density was evaluated as a function of gas concentration using a bias scan conductance method. (1) has improved performance: high sensitivity and low response recovery time.
Gas-Sensing Properties of PdO-Modified SnO2-Fe2O3 Double-Layer Thin-Film Sensor Prepared by PECVD Technique
m. s. tong, g. r dai and d. s. gao, Vacuum, 2000, 59, (4), 877–884
SnO2-Fe2O3 double-layer thin films were fabricated onto Si and ceramic substrates by using the plasma-enhanced CVD technique. The SnO2 surface was then coated with PdO and CO sensing properties were tested. Pd was deposited onto the films by dipping them into a solution of PdCl2, followed by reducing the Pd2+ with formaldehyde and SnCl2. The films have high sensitivity and selectivity to CO.
Heterogeneous Catalysis on the Atomic Scale
g. ertl, Chem. Rec ., 2001, 1, (1), 33–45
The progress of catalytic reactions on an atomic scale was observed using NH3 oxidation and other reactions as examples and by utilising scanning tunnelling microscopy and other surface techniques. CO oxidation on a Pt(111) surface proceeds preferentially along the boundaries between adsorbed O and CO patches. Ru is practically inactive for the same reaction under lower pressures but is transformed into RuO2 at atmospheric pressure, where some of the surface Ru atoms function as coordinatively unsaturated sites. In the H2 oxidation reaction on Pt(111), an autocatalytic reaction step occurs.
Investigation of the Operation Time Dependence of the Yield of Ammonia Conversion to Nitrogen(II) Oxide by Platinum Catalyst Sets
p. a. kozub, n. v. trusov, g. i. gryn and v. v. prezhdo, J. Chem. Technol. Biotechnol, 2001, 76, (2), 147–152
The origins of changes in the catalytic activity of Pt catalysts used for the NH3 oxidation reaction were studied. A general mathematical model for the dependence of the catalyst activity upon the operation time of a single Pt gauze is proposed. The model can be used to determine the gauze operating times, to calculate the average product yields for various types of operating conditions, and to select the optimal gauze rotation procedure.
Heterogeneous Enantioselective Hydrogenation of Ethyl Pyruvate Catalyzed by Cinchona-Modified Pt Catalysts: Effect of Modifier Structure
h. u. blaser, h. p. jalett, w. lottenbach and m. studer, J. Am. Chem. Soc ., 2000, 122, (51), 12675–12682
The effect of the structure of chiral modifiers derived from natural cinchona alkaloids on the enantioselectivity and rate of the Pt/Al2O3-catalysed hydrogenation of ethyl pyruvate is reported. The strongest effects on ee, but somewhat less on rate, were observed for changes in the O—C9—C8—N part of the cinchona alkaloid and for partial or total hydrogenation of the quinoline rings.
Pt/CeO2 Catalysts in Selective Hydrogenation of Crotonaldehyde: High Performance of Chlorine-Free Catalysts
m. abid and r. touroude, Catal. Lett ., 2000, 69, (3, 4), 139–144
The hydrogenation of crotonaldehyde was conducted in the gaseous phase at atmospheric pressure, on Pt/CeO2 catalysts (1) prepared from metal precursors, some containing Cl. (1), prepared from Pt(NH3)4(NO3)2, led to 5–20% crotyl alcohol selectivity when (1) was reduced at 473–673 K. When the reduction temperature was increased up to 973 K, the crotyl alcohol selectivity reached > 80%. When (1) contained Cl, crotyl alcohol selectivity was < 30%.
The Removal of Ammonia from Water by a Hydrophobic Catalyst
t.-l. huang, k. r. cliffe and j. m. maclnnes, Environ. Sci. Technol ., 2000, 34, (22), 4804–4809
A process for removing NH3 from H2O involves stripping NH3 from the aqueous phase followed by gas-phase oxidation of NH3 over a Pt/styrene divinyl benzene copolymer hydrophobic catalyst (1) at 90–125°C. The stripping and catalytic oxidation were carried out simultaneously in a continuous trickle-bed reactor, where the packing material was a mixture of (1) and γ-Al2O3 spheres. The NH3 concentration in the inlet gas was 500–1500 ppmv.
Formation of Platinum Suicide on a Platinum Nanoparticle Array Model Catalyst Deposited on Silica during Chemical Reaction
j. zhu and g. a. somorjai, Nano Lett ., 2001, 1, (1), 8–13
Pt nanoparticle model catalysts wim 28 ± 2 nm diameters and 100 ± 2 nm square periodicity have been fabricated with electron beam lithography on SiO2 substrates. The reactivity and selectivity of the Pt/SiO2 array favour dehydrogenation for a cyclo-hexene and H2 mixture, not hydrogenation, at 100°C. Experiments with Si deposited on Pt foil show that Pt suicide could form at the Pt/SiO2 interface.
The Mechanism of Palladium-Catalyzed Decomposition of Ethanol – A Comparison of Chemical Kinetic and Surface Science Studies
j. m. davidson, c. m. mcgregor and l. k. doraiswamy, Ind Eng. Chem. Res ., 2001, 40, (1), 108–113
The decompositions of EtOH and acetaldehyde over Pd/Al2O3 were studied in pulse reaction mode at 200°C in flowing He and with added H2, CO and H2O. Acetaldehyde decomposes to CH4 and CO with progressive coking that can be suppressed by H2. The response times, as monitored by MS peaks for CH4 and CO, were very similar. EtOH decomposed to CH4/CO/H2, the corresponding traces being either broad and unsymmetrical or resolved into two peaks. In H2/He, the slower set of responses is suppressed, and those from CH4 and CO appear sharp and similar in shape to those observed from acetaldehyde.
Environmentally Benign Oxidation Using a Palladium Catalyst System
m. hayashi, k. yamada, s. nakayama, h. hayashi and s. yamazaki, Green Chem ., 2000, 2, (6), 257–260
Benzylic and allylic alcohols were converted into the corresponding carbonyl compounds in the presence of 20–50 wt.% of 10% Pd/C, with 3 equiv. of vinyl acetate or under a C2H4 atmosphere in MeCN, at 50–80°C. The product distribution of the reaction of 2-cyclohexen-l-ol with 5 mol% of Pd(OAc)2 under a C2H4 atmosphere was 68% phenol, 28% cyclohexanone and 4% cyclohexanol. In the oxidation of D-glucal to 1,5-anhydrohex-l-en-3-ulose using Pd(OAc)2 and vinyl acetate, the Pd catalyst can be reused without a decrease of catalytic activity.
Ionic Liquids in Regioselective Platinum-Catalysed Hydroformylation
p. wasserscheid and h. waffenschmidt, J. Mol. Catal. A: Chem ., 2000, 164, (1–2), 61–67
Room temperature liquid chlorostannate ionic liquids (1) have been used as solvents for the catalyst (PPh3)2PtCl2 (2). (1) were prepared by the reaction of l-butyl-3-methylirnidazolium chloride or 1-butyl-4-methylpyridinium chloride with SnCl2. (2) dissolved in (1) has enhanced stability and selectivity in the hydroformylation of methyl-3-pentenoate compared to the identical reaction in conventional organic solvents. In the case of 1-octene hydroformylation, a biphasic reaction occurs when using (1) as the catalyst solvent for (2).
Salt-Free C-C Coupling Reactions of Arenes: Palladium-Catalyzed Telomerization of Phenols
a. krotz, f. vollmüller, g. stark and m. beller, Chem Commun ., 2001, (2), 195–196.
Electron-rich phenols were reacted with 2 molecules of 1,3-dienes (butadiene, isoprene) in the presence of Pd(OAc)2-PR3 catalysts (R = Cy, Ph, (OC6H3(C4H9)3)) to give C -allylated phenols. After reduction with H2 and Pd/C the corresponding alkylated products were obtained in high yields. This telomerisation of phenols with dienes constitutes a salt-free functionalisation of the aromatic nucleus and has remarkable catalyst turnover numbers.
A New Efficient Palladium Catalyst for Heck Reactions of Deactivated Aryl Chlorides
a. ehrentraut, a. zapf and m. beller, Synlett, 2000, (11), 1589–1592
A new Pd catalyst consisting of Pd(dba)2 and di-1-adamantyl-n -butylphosphine (1) has been developed for the Heck reaction of non-activated and deactivated aryl chlorides. (1) gives improved results for the Heck reactions of non-activated aryl chlorides than previously known catalyst systems.
Rhodium Catalyzed Hydroformylation of 1,1-Bis(p -fluorophenyl)allyl or Propargyl Alcohol: A Key Step in the Synthesis of Fluspirilen and Penfluridol
c. botteghi, m. marchetti, s. paganelli and f. persi-paoli, Tetrahedron, 2001, 57, (8), 1631–1637
A key intermediate, 4,4-bis(P -fluorophenyl)butyl-bromide, in the synthesis of the neuroleptic agents, Fluspirilen and Penfluridol, has been prepared starting from commercially available 4,4′-difluorobenzophenone (1). The preparation of (1) involved the Rh catalysed hydroformylation, in toluene or in the biphasic system toluene/H2O or cyclohexane/H2O, of 1,1-bis(p -fluorophenyl)-2-propenol (2) and/or 1,1-bis(P -fluorophenyl)-2-propynol. For (2), the H2O soluble catalytic systems [Rh(COD)Cl]2/TPPTS and Rh(CO)2acac/2,7-bis(SO3Na)2Xantphos were used.
Selectivity of the OsHCI(CO)(O2)(PCy3)2 Catalyzed Hydrogenation of Nitrile-Butadiene Rubber
j. s. parent, n. t. mcmanus and g. l. rempel, J. Appl. Polym. Sci ., 2001, 79, (9), 1618–1626
OsHCl(CO)(O2)(PCy3)2 (1) is an efficient catalyst precursor for the hydrogenation of olefin within acrylonitrile-butadiene copolymers. The nitrile unsaturation of the copolymer remains intact. However, (1) catalyses an undesirable crosslinking reaction, which is not produced by the commercial Rh-based systems. Further research of (1) may overcome this.
The Development of L2X2Ru=CHR Olefin Metathesis Catalysts: An Organometallic Success Story
t.m. trnka and r.h. grubbs, Acc. Chem . Res., 2001, 34, (1), 18–29
The evolution of Ru-based olefin metathesis catalysts from simple salts to highly tuned alkylidene complexes is described. Particular emphasis on (PCy3)2Cl2Ru=CHPh and its derivatives is given. Trends in catalyst activity are analysed and catalysts coordinated with N-heterocyclic carbene ligands are described. Ongoing work to improve the activity, stability and selectivity of this family of L2X2Ru=CHR complexes is overviewed. (85 Refs.)
Fuel Cells: Principles, Types, Fuels, and Applications
l. carrette, k. a. friedrich and u. stimming, ChemPbysChem, 2000, 1, (4), 162–193
In this review, the main reactions responsible for the conversion of chemical into electrical energy in fuel cells are given and the thermodynamic and kinetic fundamentals are stated. The theoretical and real efficiencies of fuel cells are also compared to those of the I.C.E. The different types of fuel cells and their main components are explained and related material issues are discussed. A section is devoted to fuel generation and storage. Attention is also given to the integration of fuel cells into complete systems. (191 Refs.)
Electroxidation of H2 on Pt/C Pt-Ru/C and Pt-Mo/C Anodes for Polymer Electrolyte Fuel Cell
a. pozio, l. giorgi, e. antolini and e. passalacqua, Electrvchim. Acta, 2000, 46, (4), 555–561
A semi-empirical equation that fits experimental electrode potential vs. current density data for gas diffusion anodes using Pt/C, Pt-Ru/C and Pt-Mo/C electrocatalysts is reported. A physico-chemical interpretation of all parameters used in the equation is given. The presence of a strong kinetic limitation on Pt-M/C (M = Ru, Mo) electrodes was demonstrated. A Heyrovsky-Volmer mechanism for the H2 oxidation reaction is proposed on Pt-M/C (M = Ru, Mo). Some Pt-Mo anodes showed performances comparable to the Pt-Ru (1:1) anode.
Effect of Structure of Carbon-Supported PtRu Electrocatalysts on the Electrochemical Oxidation of Methanol
y. takasu, t. fujiwara, y. murakami, k. sasaki, m. oguri, t. asaki and w. sugimoto, J. Electrochem. Soc ., 2000, 147, (12), 4421–427
Pt-Ru/C electrocatalysts (1) were prepared from EtOH solutions of Pt(NH3)2(NO2)2, Ru3(CO)12, RuNO(NO3)x and RuCl3, and C black. The Cl-free Ru3(CO)12 and RuNO(NO3)x gave highly dispersed and uniform PtRu nanoparricles. Ru3(CO)12 yielded high surface area catalysts. (1) from EtOH solutions of Pt(NH3)2(NO2)2-Ru3(CO)2 had high mass-specific activity toward MeOH oxidation.
Electrocatalysis in Direct Methanol Fuel Cells: In-Situ Probing of PtRu Anode Catalyst Surfaces
h.n. dinh, x. ren, f.h. garzon, p. zelenay and s. gottesfeld, J. Electroanal. Chem ., 2000, 491, (1–2), 222–233
Stripping voltammetry of CO adsorbed at unsupported, highly dispersed PtRu anode DMFC catalysts was used as an in situ probe of surface composition. CO stripping data for three dispersed, unsupported PtRu catalyst samples indicates that surface metal alloy domains of atomic ratio Ru:Pt near 1:1 are the key for higher DMFC anode activity. Catalyst free of blocking by oxide components gives highest activity.
ELECTRICAL AND ELECTRONIC ENGINEERING
Growth-Induced Perpendicular Magnetic Anisotropy and Clustering in Nix, Pt1-x, Alloys
d. vasumathi, a. l. shapiro, b. b. maranville and f. heellman, J. Magn. Magn. Mater ., 2001, 223, (3), 221–232
Polycrystalline and epitaxial (100), (110) and (111)-oriented Ni3Pt, NiPt and NiPt3 films were vapour deposited at 80–700°C. At moderate growth temperatures (200–400°C), the films exhibit growth-induced properties similar to those of Co-Pt alloys: enhanced and broadened Curie temperature, perpendicular magnetic anisotropy and large coercivity. Unlike Co-Pt, NiPt films exhibit a strong orientational dependence of anisotropy and enhanced Curie temperature.
Low Temperature Synthesis of Silver-Palladium Alloy Powders Internal Electrodes for Multilayer Ceramic Devices
r. ueyama, k. kamada, m. harada, t. ueyama, t. yamamoto, k. kuribayashi, k. koumoto and t. shiosaki. j Mater. Sci ., 2001, 36, (2), 371–379
Ag-Pd pastes were prepared from: (a) coprecipitated powder, (b) agglomerated alloy powder made by heat treatment, and (c) pulverised alloy powder produced by an improved pulverisation method. Paste from (c) showed a higher film packing density (6.3 g cm-3) than those from (a) and (b). The film consisting of (c) had a lower expansion at ˜ 500°C, a lower shrinkage at 700–1100°C and a lower electric resistivity.
Correlation between Magnetic and Transport Properties of Co/lr/Co Sandwiches and Surface Roughness
s. colis, g. schmerber and a. dinia, Thin Solid Films, 2000, 380, (1–2), 137–141
Co3nm/Irx/Co3nm sandwiches with 0.5, 1 and 1.5 run thickness of Ir were deposited on glass substrates covered by a Fe5nm/Co0.5nm/Cu3nm layer, using the ion beam sputtering technique. The maximum giant magnetoresistance and coupling strength were 2% and –0.55 erg cm -2, respectively. The average surface roughness was ∼ 0.3 nm, allowing antiferromagnetic exchange coupling to be seen in the sandwich stack.
Anisotropic Etching of RuO2 and Ru with High Aspect Ratio for Gigabit Dynamic Random Access Memory
t. yunogami and k. nojiri, J. Vac. Sci. Technol . B, 2000, 18, (4), 1911–1914
Anisotropic RuO2 and Ru etching technology for gigabit DRAM has been developed using high density O2 + 10% Cl2 plasma in an inductively coupled plasma etching system. The taper angle for RuO2/Ru increased with decreasing pressure, with increasing O2 + 10% Cl2 flow rate and with increasing overetch time. Under conditions of low pressure, high gas flow rate and 100% overetch time, a 0.3 μm thick RUO2/RU pattern having 0.2 μm critical dimension and a taper angle of 89° was obtained.
Carboplatin Decomposition in Aqueous Solution with Chloride Ions Monitored by X-Ray Absorption Spectroscopy
e. curis, k. provost, i. nicolis, d. bouvet, s. bÉnazeth, s. crauste-manciet, f. brion and d. brossard, New J. Chem ., 2000, 24, (12), 1003–1008
X-Ray absorption spectroscopy has been used to study carboplatin (1) in H2O, with Cl- at different concentrations. (1) is the major compound present in solution, even after 15 days, in neutral solutions with Cl- concentrations < 9%, exposed to light or not. With high Cl- concentrations (18%) or in acidic solutions (0.1 M HCl), (1) is chlorolysed and cisplatin formation as the decomposition product is observed.
Ruthenium(II) Complexes Containing Bidentate Schiff Bases and Their Antifungal Activity
n. dharmaraj, p. viswanathamurthi and k. natarajan, Transition Met. Chem ., 2001, 26, (1–2), 105–109
[RuHCl(CO)(PPh3)2(B)] complexes (B = PPh3, pyridine (py) or piperidine (pip)) were reacted with bidentate Schiff base ligands (from condensations of salicylaldehyde with aniline, o-, m- or p -toluidine) to give [RuCl(CO)(L)-(PPh3)(B)] (1) (L = Schiff base anion). In vitro activity against fungus Aspergillus flavus was: [RuCl(CO)(sal-p -toluidine)(PPh3)(py)] > [RuCl(CO)(sal-p -toluidine)-(PPh3)2] > [RuCl(CO)(sal-aniline)(PPh3)(py)] > [RuCl(CO)-(sal-aniline)(PPh3)2] > sal-p -toluidine > sal-aniline.