The relationships between sputter deposition conditions, grain size, and phase transformation temperatures in NiTi thin films

AbstractThe kinetics of the TiSi2 C49 to C54 phase transformation in thin films on patterned deepsub- micron lines, were studied to obtain the full time, temperature and linewidth dependence of the fraction transformed during rapid thermal annealing. A Johnson-Mehl-Avrami kinetic analysis was performed, obtaining Avrami exponents of 0.8±0.2 for all sub-micron lines and 1. 9±0.2 for a 40 μm side square structure, indicating heterogeneous nucleation followed by one dimensional growth for the narrow lines, and two dimensional growth for the square structure. The activation energy, of 3.9 eV, was independent of linewidth in the sub-micron range. Transformation times increased dramatically for decreasing linewidth, as the linewidth approached the grain size of the starting C49 phase. A kinetic model based on the density of nucleation sites as a function of linewidth and C49 grain size is proposed and shown to fit the data, for samples with two different C49 grain sizes.

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Effects of Stress Induced by the Underlying Layers on the Micro-Structures and Characteristic Phase Transformation Temperatures of Sputtered TiNi Thin Films

10.1115/imece2001/mems-23855 ◽

2001 ◽

Author(s):

Rong Xin Wang ◽

Yitshak Zohar ◽

Man Wong

Keyword(s):

Thin Films ◽

Phase Transformation ◽

Shape Memory Alloy ◽

Shape Memory ◽

Free Standing ◽

Transformation Temperatures ◽

Lattice Constants ◽

Induced Stress ◽

Titanium Nickel ◽

Micro Structures

Abstract The micro-structures and the phase transformation temperatures of sputtered titanium-nickel (TiNi) thin films, both free-standing and attached on different underlying multi-layer substrates have been studied. Differences in the micro-structures, such as the lattice constants and the relative concentrations of TiNi, Ti2Ni and TiNi3 phases, were observed (1) among the free-standing and the attached films, (2) among the films attached on different underlying multi-layers and (3) among films with different relative orders of aging and release. Not surprisingly, the corresponding phase transformation temperatures are also different. It is proposed that both substrate- and process-induced stress significantly affect the micro-structures, hence the phase transformation characteristics, of the resulting shape-memory alloy thin films.

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Effects of Grain Size and Co Addition on the Transformation Temperatures of Ti–Ni–Zr Thin Films

Shape Memory and Superelasticity ◽

10.1007/s40830-015-0042-z ◽

2015 ◽

Vol 1 (4) ◽

pp. 408-417 ◽

Cited By ~ 6

Author(s):

Akira Ishida

Keyword(s):

Thin Films ◽

Grain Size ◽

Transformation Temperatures ◽

Co Addition

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Physical properties of spinel iron oxide thin films

Journal of Materials Research ◽

10.1557/jmr.1988.0344 ◽

1988 ◽

Vol 3 (2) ◽

pp. 344-350 ◽

Cited By ~ 24

Author(s):

C. Ortiz ◽

G. Lim ◽

M. M. Chen ◽

G. Castillo

Keyword(s):

Thin Film ◽

Thin Films ◽

Grain Size ◽

Physical Properties ◽

Room Temperature ◽

Lattice Parameter ◽

Infrared Transmission ◽

Transmission Properties ◽

Annealing Conditions ◽

Deposition Conditions

This paper describes the complexity of the spinel iron oxides in thin-film configuration. First, the experimental deposition conditions are determined for the parameters of substrate temperature and oxygen flow such that only the “Fe3O4” phase is formed. Then a study is made of how the structural (grain size, lattice parameter, texture), magnetic (M), and optical (visible and infrared transmission) properties of the films depend on the deposition and postdeposition (air annealing) conditions. The experimental deposition region is defined where the films have the most similar physical properties to bulk Fe3O4 and subsequently, after annealing, to bulk gamma Fe2O3. Finally, a discussion is presented of a model that accounts for the anomalous, low values of the magnetic moment for the samples deposited at room temperature. The model proposes an overpopulation of the iron tetrahedral A sites.

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