On the Perpendicular Magnetic Anisotropy of Pt/Co Multilayers: Structure-Property Relationships

1994 ◽  
Vol 343 ◽  
Author(s):  
G. A. Bertero ◽  
R. Sinclair
Keyword(s):  
Structural Changes ◽  
Perpendicular Magnetic Anisotropy ◽  
Analytical Techniques ◽  
Boundary Structure ◽  
Structure Property ◽  
Secondary Importance ◽  
Structure Property Relationships ◽  
Grain Boundary Structure ◽  
Transmission Electron ◽  
Sputter Deposited

ABSTRACTA series of Pt/Co multilayers were sputter-deposited under various deposition conditions to promote structural changes resulting in marked differences in both the perpendicular anisotropy and magnetic coercivity. High resolution transmission electron microscopy was used in combination with other analytical techniques to study the structure of these films. It was found that the most important feature controlling the magnitude of the anisotropy is the interface sharpness. Conversely properties such as the quality of the (111) texture, grain shape or the defect structure, were found to be of secondary importance. The magnetic coercivity ranged from 0.6 to 7 kOe depending on the sputtering conditions and was found to depend strongly on the grain boundary structure rather than on the grain size.

Fracture of Thin Tantalum Nitride Films on Ain Substrates

1996 ◽  
Vol 436 ◽  
Author(s):  
N. R. Moody ◽  
D. Medlin ◽  
D. P. Norwood
Keyword(s):  
Tantalum Nitride ◽  
High Porosity ◽  
Structure Property ◽  
Structure Property Relationships ◽  
Production Run ◽  
Transmission Electron ◽  
Nominal Thickness ◽  
Columnar Grains ◽  
Sputter Deposited ◽  
Film Substrate

AbstractNanoindentation, continuous nanoscratch testing, and transmission electron microscopy were used in this study to determine the structure-property relationships of thin tantalum nitride resistor films on aluminum nitride substrates. The films were sputter-deposited to a nominal thickness of 200 nm during one production run and then tested at room temperature. Most films were uniform in structure and thickness, consisting of fine equiaxed crystallites along the film-substrate interfaces and long columnar grains further away from the interface. However, one film varied greatly in thickness across the substrate. It had large crystallites along the film-substrate interface and clusters of columnar grains. Most importantly, it contained a far greater amount of porosity than the other films. The high porosity content led to significantly lower elastic moduli and hardness values than the low porosity films and a much greater susceptibility to fracture.

Disruption of Dislocation Cores at Grain Boundary in Nb-Doped SrTiO3 Bicrystals

2007 ◽  
Vol 558-559 ◽  
pp. 869-872
Author(s):  
S.Y. Choi ◽  
J.P. Buban ◽  
Naoya Shibata ◽  
Takahisa Yamamoto ◽  
Yuichi Ikuhara
Keyword(s):  
Grain Boundary ◽  
Tilt Angle ◽  
Structural Changes ◽  
Boundary Region ◽  
Boundary Structure ◽  
Regular Array ◽  
Density Of Dislocations ◽  
Discrete Dislocation ◽  
Grain Boundary Structure ◽  
Oriented Region

Bicrystals of Nb-doped SrTiO3, having tilt angles of 4o~18 o with respect to [001], were prepared by joining two single crystals at 1873 K and then investigated to identify the effect of tilt angle on the grain boundary structure. The boundaries consisted of a regular array of dislocations but the positioning of cores along the boundary was found to be changed from a line to a zigzag as a tilt angle was increased up to 10o. The 14° - tilted boundary exhibited two kinds of boundary region exist at the same grain boundary; (1) the discrete cores region as observed in 4° ~ 10° - tilted boundaries and (2) the randomly oriented region as found in the 18° boundary. Thus it was observed that the structure of low-angle tilt boundary changed from the discrete dislocation structure to the randomly oriented structure as a tilt angle increases. These structural changes at the grain boundaries are considered to be related to a minimization of strain due to the high density of dislocations.

Electron Microscopy Study of Stoichiometric and Non-Stoichiometric Titania

1997 ◽  
Vol 3 (S2) ◽  
pp. 669-670
Author(s):  
Solórzano I.G. ◽  
Kotani T. ◽  
Tuller H.L. ◽  
Van der Sande J.B.
Keyword(s):  
Electron Microscopy ◽  
Electric Activity ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Boundary Structure ◽  
High Tc Superconductors ◽  
High Tc ◽  
Grain Boundary Structure ◽  
Transmission Electron ◽  
Crystallographic Shear

It is currently well recognized that oxides are able to accommodate deviations from stoichiometry (1) and great advances in this understanding have been achieved by using transmission electron microscopy (TEM), particularly through lattice imaging and electron diffraction techniques (2). The physical properties of non-stoichiometric oxides are strongly influenced by their exact composition and for this reason they represent a class of materials with increasing and novel properties that are put to use in, for example, oxygen sensors and high-Tc superconductors. On the other hand, in electroceramic materials, such as TiO2, grain boundary structure and chemistry are important to be characterized in detail since these variables are responsible for the electric activity.Rutile (TiO2) can accommodate relatively large deviations from stoichiometry (TiOx with 2.0≥x≤ 1.75) by the crystallographic shear (CS) mechanism (1). The formation of CS planes is effectively a two-step process which involves the ordering of oxygen vacancies on a crystallographic plane and on their elimination by a shear of the lattice.

Preparation of a-axis YBa2Cu3Ox epitaxial films using direct current-95 MHz hybrid plasma sputtering

1995 ◽  
Vol 10 (9) ◽  
pp. 2216-2234 ◽  
Author(s):  
Wataru Ito
Keyword(s):  
Substrate Surface ◽  
Tilt Boundary ◽  
Boundary Structure ◽  
Ion Density ◽  
Ybco Films ◽  
Plasma Sputtering ◽  
Grain Boundary Structure ◽  
Transmission Electron ◽  
Hybrid Plasma ◽  
Symmetrical Tilt

The dc-95 MHz hybrid plasma magnetron sputtering has been newly developed for obtaining a-axis oriented YBa2Cu3Ox (YBCO) films with an excellent crystallinity. The crystallinity was found to be the best among the films reported so far: the full width at half maximum value of 0.027°in the rocking curve measurement through the film (200) diffraction peak and Xmin of 2% estimated from the barium signal behind the surface peak in Rutherford backscattering (RBS) measurement using a 1 MeV He+ ion. The success in the excellent crystallinity was explained from the ion acceleration model at the ion sheath formed near the substrate surface considering the high ion density, which was revealed to be a characteristic of hybrid plasma. Almost perfect epitaxial growth was also confirmed by transmission electron microscopy. A characteristic grain boundary structure depending on the substrate was observed for the films on NdGaO3 and SrTiO3 substrates. Twist boundary is dominant for the film on NdGaO3, while symmetrical tilt boundary and basal-plane-faced tilt boundary exclusively exist for the film on SrTiO3. The microstructure of the film on SrTiO3 is very resistive against film relaxation. Strain relief was observed by RBS channeling spectra for the relatively high superconducting films. The results of Raman spectroscopy and RBS oxygen resonant measurements indicated that the oxygen content is not a critical parameter for determining the superconductivity of the a-axis oriented YBCO films, but oxygen ordering in the plane of the Cu-O chain and relief of the film strain are important for the improvement of Tc.

Observations and implications of grain boundary dislocation networks in high-angle YBa2Cu3O7−δ grain boundaries

1990 ◽  
Vol 5 (5) ◽  
pp. 919-928 ◽  
Author(s):  
S. E. Babcock ◽  
D. C. Larbalestier
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Weak Link ◽  
Coincidence Site Lattice ◽  
Boundary Structure ◽  
High Angle ◽  
Grain Boundary Structure ◽  
Transmission Electron ◽  
Means Of Transmission ◽  
Regular Networks

Regular networks of localized grain boundary dislocations (GBDs) have been imaged by means of transmission electron microscopy in three different types of high-angle grain boundaries in YBa2Cu3O7-δ, implying that these boundaries possess ordered structures upon which a significant periodic strain field is superimposed. The occurrence of these GBD networks is shown to be consistent with the GBD/Structural Unit and Coincidence Site Lattice (CSL)/Near CSL descriptions for grain boundary structure. Thus, these dislocations appear to be intrinsic features of the boundary structure. The spacing of the observed GBDs ranged from ∼10 nm to ∼100 nm. These GBDs make the grain boundaries heterogeneous on a scale that approaches the coherence length and may contribute to their weak-link character by producing the “superconducting micro-bridge” microstructure which has been suggested on the basis of detailed electromagnetic measurements on similar samples.

Investigation of Grain Boundary Structure and Composition of Bismuth Embrittled Copper Bicrystals with Aberration-Corrected Scanning Transmission Electron Microscopy

2012 ◽  
Vol 18 (S2) ◽  
pp. 346-347
Author(s):  
C. Wade ◽  
M. McLean ◽  
R. Vinci ◽  
M. Watanabe ◽  
L. Giannuzzi
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Boundary ◽  
Scanning Transmission Electron Microscopy ◽  
Boundary Structure ◽  
Scanning Transmission Electron ◽  
Grain Boundary Structure ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Aberration Corrected

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

Brittle Grain Boundary Fracture in Iridium

1977 ◽  
Vol 35 ◽  
pp. 294-295
Author(s):  
D. L. Rohr ◽  
S. S. Hecker ◽  
L. E. Murr
Keyword(s):  
Grain Boundary ◽  
Nuclear Power ◽  
Boundary Structure ◽  
Grain Boundary Structure ◽  
Thin Foils ◽  
Transmission Electron ◽  
Grain Boundary Fracture ◽  
Space Nuclear Power ◽  
Boundary Fracture ◽  
Brittle Intergranular Fracture

Iridium is a most interesting fee metal with a high melting point (2443°C) and extremely high elastic moduli (Young's modulus of 76 million psi). Single crystals of Ir fail by brittle cleavage and polycrystalline Ir fails by brittle intergranular fracture at temperatures below 1000°C. We have previously shown that both modes of fracture are intrinsic and not impurity related. (1)The present study was undertaken to study the grain boundary structure of Ir by transmission electron microscopy. Sheet specimens of Ir-0.3%W (used in space nuclear power applications) were recrystallized at temperatures above 1300°C. Thin foils were prepared by spark planing and electropolishing with an acidified CaCl2 solution in a jet polisher and were examined in a JEOL 200 B electron microscope operated at 200 kv.We examined a large number of foils and found the most interesting grain boundary features to be ledges (2) (Fig. la).

scholarly journals Inferring grain boundary structure–property relations from effective property measurements

2015 ◽  
Vol 50 (21) ◽  
pp. 6907-6919 ◽  
Author(s):  
Oliver K. Johnson ◽  
Lin Li ◽  
Michael J. Demkowicz ◽  
Christopher A. Schuh
Keyword(s):  
Grain Boundary ◽  
Effective Property ◽  
Boundary Structure ◽  
Structure Property ◽  
Property Relations ◽  
Grain Boundary Structure

Magnetic and Magneto-Optical Properties of Sputter-Deposited and Annealed Co-Pt Alloys

1994 ◽  
Vol 343 ◽  
Author(s):  
Sung-Eon Park ◽  
Pu-Young Jung ◽  
Ki-Bum Kim ◽  
Seh-Kwang Lee ◽  
Soon-Gwang Kim
Keyword(s):  
Magnetic Properties ◽  
Perpendicular Magnetic Anisotropy ◽  
Xrd Analysis ◽  
Atomic Scale ◽  
Alloy Films ◽  
X Ray ◽  
Transmission Electron ◽  
Ordered Phases ◽  
Pt Alloy ◽  
Sputter Deposited

ABSTRACTWe have produced Co1-xPtX (X = 0.53 and 0.75) alloy films using DC magnetron sputtering and investigated their magnetic properties using vibrating sample magnetometry(VSM) and Kerr hysteresis loop tracer. The as-deposited Co-Pt alloy films show a strong in-plane magnetization. By annealing the alloy samples, we have identified that the magnetic properties are drastically changed. While the magnetic properties of the Co0 25Pt0 75 alloy films show no noticeable changes, the coercivity and the squareness of the Co0.47Pt0.53 alloy films are drastically increased after annealing. Transmission electron microscopy(TEM) and x-ray diffractometry(XRD) analysis showed that CoPt(L10) and Co-Pt3 (L12) ordered phases, respectively, are formed in each case with a strong (11) texture. We suggest that the perpendicular magnetic anisotropy in the Co-Pt system does not depend on the mere textureness of the layer but strongly depends on the arrangement of Co and Pt at an atomic scale.

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