Defect structure and chemistry of (Ca x Sr 1-x ) n+1 Ti n 0 3n+1 layer perovskites

1991 ◽  
Vol 336 (1644) ◽  
pp. 541-569 ◽  
Keyword(s):  
Neutron Diffraction ◽  
Alkaline Earth ◽  
Structural Information ◽  
High Resolution Electron Microscopy ◽  
Oxide Superconductors ◽  
Orthorhombic Symmetry ◽  
X Ray ◽  
Resolution Electron ◽  
The Stability

The Ruddlesden-Popper structural family is constructed from ordered intergrowths of rocksalt type (AX) layers with perovskite (ABX 3 ) blocks of varying widths, yielding phases with the general formula n ABX 3 AX where 1 < n < ∞ In this article, the characterization of (Ca x Sr 1-x ) n+1 Ti n O 3n+1 layer perovskites by powder X-ray and neutron diffraction and high resolution electron microscopy is described. These phases undergo a phase transition from tetragonal to orthorhombic symmetry at x = 0.65. Structure solutions of neutron diffraction data are presented for the end-member phases Sr 3 Ti 2 O 7 (I4/mmm), Ca 3 Ti 2 O 7 (Ccm2 1 ) and Ca 4 Ti 3 O 10 (Pcab). Refinement of the mixed alkaline earth preparation (Ca 0.85 Sr 0.15 ) 4 Ti 3 O 10 showed that Sr partitioned preferentially to the perovskite blocks rather than the rocksalt layers. Ordered and disordered intergrowths of rocksalt layers were found on the{101} orth = {100} tet perovskite planes with extensive disorder most prevalent in samples annealed for short periods (less than 24 hours). Evidence is presented for the existence of V"A and V"," point defects in the intermediate structures that precede the formation of ordered layer sequences. These data are discussed in terms of existing thermodynamic and structural information. For generalized Ruddlesden Popper phases the relation between chemistry and symmetry is reviewed and factors contributing to the stability of different n -members enunciated. For completeness, the (Ca x Sr 1-x ) n+1 Ti n O 3n+1 perovskites are considered as the structural prototypes of the oxide superconductors being a subset of an extended n ABX 3 mAX Ruddlesden-Popper family.

scholarly journals Structure of Carbon Materials Explored by Local Transmission Electron Microscopy and Global Powder Diffraction Probes

2018 ◽  
Vol 4 (4) ◽  
pp. 68 ◽  
Author(s):  
Karolina Jurkiewicz ◽  
Mirosława Pawlyta ◽  
Andrzej Burian
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Neutron Diffraction ◽  
Carbon Materials ◽  
Structural Information ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Local Transmission

Transmission electron microscopy and neutron or X-ray diffraction are powerful techniques available today for characterization of the structure of various carbon materials at nano and atomic levels. They provide complementary information but each one has advantages and limitations. Powder X-ray or neutron diffraction measurements provide structural information representative for the whole volume of a material under probe but features of singular nano-objects cannot be identified. Transmission electron microscopy, in turn, is able to probe single nanoscale objects. In this review, it is demonstrated how transmission electron microscopy and powder X-ray and neutron diffraction methods complement each other by providing consistent structural models for different types of carbons such as carbon blacks, glass-like carbons, graphene, nanotubes, nanodiamonds, and nanoonions.

Characterization of Inconel/Carbon Multilayer Structures

1991 ◽  
Vol 238 ◽  
Author(s):  
J. Liu ◽  
Y. Cheng ◽  
M. W. Lund ◽  
Q. Wang ◽  
A. Higgs
Keyword(s):  
High Resolution Electron Microscopy ◽  
Optical Systems ◽  
Multilayer Structures ◽  
High Angle ◽  
Dc Magnetron Sputtering ◽  
X Ray ◽  
X Ray Scattering ◽  
Resolution Electron ◽  
Microscopy Techniques

ABSTRACTDC magnetron sputtering technique is used to fabricate inconel/carbon multilayers (ML) for applications in soft x-ray optical systems. The ML films were characterized by small angle x-ray scattering (SAXS), high resolution electron microscopy (HREM) and high-angle annular darkfield (HAADF) microscopy techniques. The HREM showed that the ML films are composed of smooth layers of amorphous components. The HAADF showed strong interdiffusion between inconel and carbon. There is no indication of any pure inconel or carbon regions in the ML films.

Quantitative characterization of epitaxial superlattices by x‐ray diffraction and high resolution electron microscopy

1993 ◽  
Vol 63 (4) ◽  
pp. 482-484 ◽  
Author(s):  
Eric E. Fullerton ◽  
Wei Cao ◽  
Gareth Thomas ◽  
Ivan K. Schuller ◽  
Matthew J. Carey ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
X Ray Diffraction ◽  
Quantitative Characterization ◽  
X Ray ◽  
Resolution Electron

Characterization of Cadmium Zinc Tellurium Obtained by Modified - Bridgman Technique

1993 ◽  
Vol 324 ◽  
Author(s):  
D.R. Acosta ◽  
F. Rabago
Keyword(s):  
Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Bridgman Technique ◽  
Selected Area Electron Diffraction ◽  
Resolution Electron ◽  
Structural Details ◽  
Semiconductor Compounds ◽  
Ternary Semiconductor ◽  
The Stability

AbstractThe growth of ternary semiconductor compounds Cd1-ZZnx. Te leads to possible uses of this material like optoelectronic devices. In the present work we report the structural characterization of Cd0.96Zn0.04Te obtained by modified - Bridgman technique. Structural studies were carried out using Scanning Electron Microscopy (SEM) and Conventional and High Resolution Electron Microscopy (TEM and HREM, respectively). Selected Area Electron Diffraction (SAED) was used to determine local variations in composition. Characteristics of the growth of the bulk samples were observed and structural details that might be related with the stability of ternary phase were derived.

Electron microscopy of rabbit FC crystals

1983 ◽  
Vol 41 ◽  
pp. 730-731
Author(s):  
Robert A. Grant ◽  
Laura L. Degn ◽  
Wah Chiu ◽  
John Robinson
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Molecular Replacement ◽  
X Ray ◽  
X Ray Crystallography ◽  
Resolution Electron ◽  
Replacement Technique ◽  
Hydrated Crystal ◽  
Molecular Structure Analysis

Proteolytic digestion of the immunoglobulin IgG with papain cleaves the molecule into an antigen binding fragment, Fab, and a compliment binding fragment, Fc. Structures of intact immunoglobulin, Fab and Fc from various sources have been solved by X-ray crystallography. Rabbit Fc can be crystallized as thin platelets suitable for high resolution electron microscopy. The structure of rabbit Fc can be expected to be similar to the known structure of human Fc, making it an ideal specimen for comparing the X-ray and electron crystallographic techniques and for the application of the molecular replacement technique to electron crystallography. Thin protein crystals embedded in ice diffract to high resolution. A low resolution image of a frozen, hydrated crystal can be expected to have a better contrast than a glucose embedded crystal due to the larger density difference between protein and ice compared to protein and glucose. For these reasons we are using an ice embedding technique to prepare the rabbit Fc crystals for molecular structure analysis by electron microscopy.

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