Sputter-deposited Pt-Au thin films have been reported to develop a hard, stable, nanocrystalline structure, yet little is known about how these characteristics vary with PtxAu1-x composition and process conditions. Toward this end, this document describes an extensive, combinatorial Pt-Au thin film library including characterized film compositions, structure, and properties. Complemented by kinematic Monte Carlo simulations of codeposition, a broad range of PtxAu1-x compositions (from x ~ 0.02 to 0.93) was first established by sputtering with varied magnetron powers and gun tilt angles. Further, the produced films were subsequently interrogated using automated nanoindentation, x-ray reflectivity, x-ray diffraction, atomic force microscopy, surface profilometry, four-point probe sheet resistance techniques, and wavelength dispersive spectroscopy in order to determine how hardness, modulus, density, surface roughness, structure, and resistivity vary with film stoichiometry and process parameters. Combinatorial films displayed an assortment of properties with the hardness of some films exceeding values reported previously for this material system. High hardness, high modulus, and low resistivity were generally attained when using increased deposition energy and reduced angle-of-incidence processes. Overall, the research identified promising, new PtxAu1-x compositions for future study and pinpointed strategies for improved deposition.
Here, phase formation and stability of five component compositionally complex rare earth zirconates (5RE2Zr2O7) were investigated by X-ray diffraction and electron microprobe analysis. Zirconates with different rare earth compositions (LaNdSmEuDy, LaNdSmEuYb, LaNdEuErYb, LaNdDyErYb, SmEuDyYHo, LaYHoErYb, and DyYHoErYb) were synthesized at 1700°C and 2000°C by the solid-state method to investigate the effect of A-site site disorder (δA) on phase stability. Increased site disorder results from mixed cation occupancy with localized crystallographic strain and bond disorder. Compositions LaNdSmEuDy (δA = 4.6) and LaNdSmEuYb (δA = 6.0) produced a single pyrochlore phase and compositions SmDyYHoErYb (δA = 2.8), LaYHoErYb (δA = 6.2), and DyYHoErYb (δA = 1.7) produced a single fluorite phase. High δA compositions LaNdEuErYb (δA = 6.9) and LaNdDyErYb (δA = 7.2) produced a pyrochlore and fluorite phase mixture at 1700°C. Single phase was obtained for the latter composition at 2000°C. Of the single phase compositions calcined at 1700°C, LaNdSmEuYb and LaYHoErYb (both with largest δA) showed decomposition to mixed fluorite and pyrochlore phases during lower temperature anneals, indicating entropic stabilization. Comparison with prior work shows a temperature dependence of the critical δA for phase stability, and compositions near it are expected to be entropy stabilized.
In this report we detail demonstration of temperature dependent effects on grayscale intensity imaged in Focused Ion Beam (FIB) microscope, as well as secondary electron (SE) dependence on temperature in the Auger Electron Spectroscopy (AES) and a Scanning Electron Microscope (SEM). In each instrument an intrinsic silicon sample is imaged at multiple temperatures over the course of each experiment. The grayscale intensity is shown to scale with sample temperature. Sample preparation procedures are discussed, along with hypothesized explanations for unsuccessful trials. Anticipated outcomes and future directions for these measurements are also detailed.
The composition and phase fraction of the intergranular phase of 94ND10 ceramic is determined and fabricated ex situ. The fraction of each phase is 85.96 vol% Al2O3 bulk phase, 9.46 vol% Mg-rich intergranular phase, 4.36 vol% Ca/Si-rich intergranular phase, and 0.22 vol% voids. The Ca/Si-rich phase consists of 0.628 at% Mg, 12.59 at% Si, 10.24 at% Ca, 17.23 at% Al, and balance O. The Mgrich phase consists of 14.17 at% Mg, 0.066 at% Si, 0.047 at% Ca, 28.69 at% Al, and balance O. XRD of the ex situ intergranular material made by mixed oxides consisting of the above phase and element fractions yielded 92 vol% MgAl2O4 phase and 8 vol% CaAl2Si2O8 phase. The formation of MgAl2O4 phase is consistent with prior XRD of 94ND10, while the CaAl2Si2O8 phase may exist in 94ND10 but at a concentration not readily detected with XRD. The MgAl2O4 and CaAl2Si2O8 phases determined from XRD are expected to have the elemental compositions for the Mg-rich and Ca/Si-rich phases above by cation substitutions (e.g., some Mg substituted for by Ca in the Mg-rich phase) and impurity phases not detectable with XRD.
