Structure of long-period tetragonal lattice formed by solid-state alloying in Bi-Mn double-layer thin films

1990 ◽  
Vol 48 (4) ◽  
pp. 160-161
Author(s):  
Kentaroh Yoshida ◽  
Takashi Yamada
Keyword(s):  
Thin Films ◽  
Solid State ◽  
Double Layer ◽  
Metastable Phase ◽  
High Resolution Electron Microscopy ◽  
Ferromagnetic Phase ◽  
Amorphous Films ◽  
Long Period ◽  
Tetragonal Lattice ◽  
Resolution Electron

It has been a well known fact that BI and Mn are, by melting, immiscible with each other and only a ferromagnetic phase, MnBi, forms by a peritectic reaction at 446°C between solid Mn and the melt. However, the authors succeeded in mixing these two atomic elements by simultaneous vacuum deposition and found that a new metastable phase, Mn3Bi, appears as a crystallization product of the as-deposited amorphous films at 180°C, when their composition is in a range 85 to 65 at% Mn. They derived its atomic arrangement only by means of high resolution electron microscopy. In the present investigation, double layer thin films, consisting of Bi layer (300 Å) and of Mn layer (200°Å), were prepared by successive deposition and were heated at 265°C, just below the melting point of Bi (271°C), for 150 to 200 hr. By this heat treatment, solid-state alloying reaction takes place at the interface between the two layers and as many as four kinds of new alloy phases were found to appear.

Mg–Ti–spinel formation at the TiN/MgO interface by solid state reaction: Confirmation by high-resolution electron microscopy

1991 ◽  
Vol 6 (8) ◽  
pp. 1744-1749 ◽  
Author(s):  
L. Hultman ◽  
D. Hesse ◽  
W-A. Chiou
Keyword(s):  
Electron Microscopy ◽  
Solid State ◽  
High Resolution ◽  
Solid State Reaction ◽  
Spinel Phase ◽  
High Resolution Electron Microscopy ◽  
Cation Sublattice ◽  
Spinel Formation ◽  
Spinel Lattice ◽  
Resolution Electron

Mg–Ti–spinel formation along the interface of epitaxial TiN(100) films to MgO(100) substrates has recently been investigated by transmission electron microscopy (TEM) in the diffraction-contrast mode in samples grown at substrate temperatures higher than 800 °C and in such post-annealed at 850 °C. This phenomenon has now been investigated by high resolution electron microscopy of cross-sectional samples, at an acceleration voltage of 300 kV. Emphasis is given to the TiN/spinel and the spinel/MgO interfaces with respect to their structure and morphology. The results obtained confirm the previously drawn conclusions on the atomic mechanism of the solid state reaction during the spinel-forming process: The spinel, which most likely is of the composition Mg2TiO4, forms by counterdiffusion of the cations Ti4+ and Mg2+ in the rigid oxygen frame provided by the fcc oxygen sublattice of MgO. The latter is completely taken over by the spinel lattice. This “host” character of the MgO substrate lattice for the topotaxial growth of the spinel lattice and the coherency of the solid state reaction with respect to the lattices of all the phases involved are demonstrated. Misfit dislocations at the TiN/MgO, TiN/spinel, and the spinel/MgO interfaces, as well as antiphase boundaries of the cation sublattice of the spinel phase, have also been observed.

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