T. Mahalingam

Plastic flow and tensile ductility of a bulk amorphous Zr55Al10Cu30Ni5 alloy at 700 K

Abstract Tensile deformation behavior of a Zr 55 Al 10 Cu 30 Ni 5 bulk metallic glass at 700 K (in the supercooled liquid region) was investigated at strain rates ranging from 3xa0×xa010 −3 to 3xa0×xa010 −2 s −1 . The material exhibited excellent mechanical formability with a maximum elongation of ∼800%. Structures of the material, both before and after deformation, were examined.

Thermal stability of sputtered copper films containing dilute insoluble tungsten: Thermal annealing study

This paper describes studies on the thermal annealing behavior of Cu films with 2.3 at.% W deposited on Si substrates. The magnetron cosputtered Cu films with insoluble W were vacuum annealed at temperatures ranging from 200 to 800 °C. Twins were observed in focused ion beam and transmission electron microscopy images of as-deposited and 400 °C annealed pure Cu film, and these twins were attributed to the intrinsic low stacking fault energy. Twins in pure Cu film may provide an additional diffusion path during annealing for copper silicide formation. The beneficial effect of W on the thermal stability of Cu film was supported by the following observations: (i) x-ray diffraction studies show that Cu 4 Si was formed at 530 °C in Cu-W film, whereas pure Cu film exhibited Cu 4 Si growth at 400 °C; (ii) shallow diffusion profiles for Cu into Si in Cu-W film through secondary ion mass spectroscopy analyses, and the high activation energy needed for the copper silicide formation from the differential scanning calorimetry study; (iii) addition of W in Cu film increases the stacking fault energy and results in a low twin density.

Dielectric properties and microstructure of nano-MgO dispersed Ba0.3Sr0.7TiO3 thin films prepared by sputter deposition

In this study, thin films prepared from the targets of Ba0.3Sr0.7TiO3 (BST), BST∕5mol%MgO,BST∕10mol%MgO, and BST∕20mol%MgO composites, using radio frequency magnetron sputtering, have been reported. As-deposited films were found to be amorphous and began to crystallize after annealing at temperatures of 650u2009°C and above. The addition of MgO in the BST films resulted in the hindrance of crystallization and inhibition of grain growth. MgO was substituted into the BST lattices to a certain degree. High-resolution transmission electron microscopy results revealed some MgO dispersed in the BST matrix. The MgO dispersed in the dense BST matrix was found to be around 25 nm in size. The dielectric constant was estimated to be 90 for the pure BST film annealed at 700u2009°C, and observed to be slightly reduced with the MgO addition. The dielectric losses of the Ba0.3Sr0.7TiO3 (0.006) and BST∕MgO films (0.002–0.004) were much less than those of the Ba0.6Sr0.4TiO3(0.013) and Ba0.7Sr0.3TiO3 films (0.11–0.13). The leakage...

Mixed phase solid polymer electrolytes based on poly(methylmethacrylate) systems

Abstract A composite polymer electrolyte PMMA–Li2SO4–DBP–ZrO2 was prepared by a solution casting technique; poly(methymethacrylate) (PMMA), dibuthylphalate (DBP). A conductivity of 0.13×10−6xa0Sxa0cm−1 can be achieved at room temperature for the composition PMMA–Li2SO4–DBP (25–5–70xa0mol%), whereas it improves an order of magnitude (7.5×10−6xa0Sxa0cm−1) upon dispersing fine particles of ZrO2 (particle size = 21.5xa0μm) as inert fillers into the above plasticized polymer electrolyte matrix. The role of the ceramic phase is to reduce the melting temperature and to retard the kinetics of crystallization of PMMA. This results in a conductivity relaxation below the melting temperature of PMMA, which appears to be a characteristic of these composite electrolytes.

Erratum: “Thermal Stability Enhancement in Nanostructured Cu Films Containing Insoluble Tungsten Carbides for Metallization” [J. Mater. Res. 20, 1379 (2005)]

An error occurred while printing this article in the June issue of the Journal of Materials Research. The end of the abstract was cut off, leaving it incomplete. The complete abstract is shown below:

Thermal Stability Enhancement in Nanostructured Cu Films Containing Insoluble Tungsten Carbides for Metallization

We report enhanced thermal stabilities of nanostructured Cu films containing insoluble tungsten carbides prepared by sputter deposition. Tungsten carbides in the form of W 2 C are present in the supersaturated solid solution of Cu, as confirmed by x-ray photoelectron spectroscopy, scanning electron microscopy, and x-ray diffraction analyses. Focused ion beam analysis revealed that the films are thermally stable during annealing when they are in contact with Si without a diffusion barrier, and the copper silicide was not formed up to an annealing temperature of 400 °C. Leakage current characteristic evaluation on SiO 2 /Si metal oxide semiconductor (MOS) structure also revealed the superior reliability of Cu with a dilute amount of tungsten carbides, indicating their usefulness in advanced barrierless metallization applications. The films with higher amount of tungsten carbides exhibited good thermal stability at high temperatures and could be rationalized as a consequence of a refined grain structure together with the strengthening effect of W 2 C.

Microstructure and magnetic properties of sputtered Fe?Pt thin films

The characterization of rf magnetron-sputtered Fe–Pt thin films at various compositions (Pt = 15, 24, 46 and 78 at%) is reported. X-ray diffraction studies on annealed Fe–46%Pt thin films at 600 °C revealed an ordered L10 γ2-FePt phase with fct structure whereas annealed Fe–24%Pt and Fe–78%Pt films exhibited ordered γ1-Fe3 Pt and γ3-FePt3 phases, respectively. The effects of argon quenching and rapid thermal annealing (RTA) on the structural and magnetic properties are investigated. When the films are annealed at 600 °C for 1 h and then quenched to room temperature in argon gas, ordered γ2-FePt with L10 phase is obtained. Argon-quenched and rapid thermal annealed films exhibit microtwins in scanning electron microscopy analysis. The appearance of microtwins may be attributed to the planar defects developed in the FePt films due to the release of elastic strain during annealing. The saturation magnetization is found to increase with ferrous content in the films. Argon-quenched Fe–46%Pt films exhibited larger saturation magnetization than RTA-processed films. The large value of saturation magnetization obtained from M– H hysteresis indicates the predominant existence of the hard fct γ2-FePt phase. The combined effects of twins, long-range order and the hard γ2-FePt phase on the magnetic properties are discussed.

Synthesis and characterization of Fe100-xPtx alloy thin films

Abstract Polycrystalline alloy thin films of Fe 100 − x Pt x with various platinum compositions ( x =15, 24, 46 and 78xa0at.%) were synthesized by magnetron sputtering. The variation of platinum content and deposition rate with the platinum area target fraction in the sputtering was studied. It is observed that the X-ray diffraction patterns of as-deposited FePt films with all compositions exhibited a disordered phase with fcc structure. The effects of annealing on the crystal structure and morphology are studied. Annealing of Fe 54 Pt 46 films at high temperatures yielded an ordered L1 0 γ 2 phase with face centered tetragonal (fct) structure. Differential scanning calorimetric (DSC) studies reveal exothermic peaks for phase transformation in different alloy compositions. The activation energies of phase transformations are estimated and the results are discussed.

Structural and ionic conductivity studies of solid polymer electrolytes based on poly (vinylchloride) and poly (methylmethacrylate) blends

Thin film of poly (vinylchloride) and poly (methylmethacrylate) blend polymer electrolytes plasticized with a combination of DBP and Li2SO4 salts have been prepared by solution casting technique. The prepared films were subjected to a.c. impedance measurements as a function of temperature ranging from 304–373 K. The maximum conductivity at 304 K was found to be 1.24 × 10−8 S·cm−1 for PVC-PMMA-Li2SO4-DBP (7.5-17.5-5-70 mole-%). Temperature dependence studies on the ionic conductivity in the PVC-PMMA-Li2SO4-DBP system suggest that the ion conduction follows the Williams-Landel-Ferry (WLF) mechanism, which is further confirmed by Vogel-Tamman-Fulcher (VTF) plots. XRD, FTIR, SEM and thermal studies revealed complex formation in.