10.1021/acscombsci.7b00135.s001
Peter M. Kadletz
Peter M.
Kadletz
Yahya Motemani
Yahya
Motemani
Joy Iannotta
Joy
Iannotta
Steffen Salomon
Steffen
Salomon
Chinmay Khare
Chinmay
Khare
Lukas Grossmann
Lukas
Grossmann
Hans Jürgen Maier
Hans Jürgen
Maier
Alfred Ludwig
Alfred
Ludwig
Wolfgang W. Schmahl
Wolfgang W.
Schmahl
Crystallographic Structure Analysis of a Ti–Ta
Thin Film Materials Library Fabricated by Combinatorial Magnetron
Sputtering
American Chemical Society
2018
chemical composition
transformation temperatures
parent phase
film materials library
martensitic nature
coarser columns
Crystallographic Structure Analysis
lattice strain
actuation response
lattice correspondences
martensitic transformation temperatures fall
Rietveld refinement
Film Materials Library Fabricated
matrix form
films exhibit properties
incidence X-ray diffraction
Ti 87 Ta 13
Martensitic properties
crystal structure
ω phase
Ta-rich region
Subsequent high-throughput characterization methods
Ta-rich phase
combinatorial approach
Landau theory
Ti 14 Ta 86
β phase
columnar morphology
SEM investigation
room temperature
2018-01-22 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Crystallographic_Structure_Analysis_of_a_Ti_Ta_Thin_Film_Materials_Library_Fabricated_by_Combinatorial_Magnetron_Sputtering/5895604
Ti–Ta
thin films exhibit properties that are of interest
for applications as microactuators and as biomedical implants. A Ti–Ta
thin film materials library was deposited at <i>T</i> =
25 °C by magnetron sputtering employing the combinatorial approach,
which led to a compositional range of Ti<sub>87</sub>Ta<sub>13</sub> to Ti<sub>14</sub>Ta<sub>86</sub>. Subsequent high-throughput characterization
methods permitted a quick and comprehensive study of the crystallographic,
microstructural, and morphological properties, which strongly depend
on the chemical composition. SEM investigation revealed a columnar
morphology having pyramidal, sharp tips with coarser columns in the
Ti-rich and finer columns in the Ta-rich region. By grazing incidence
X-ray diffraction four phases were identified, from Ta-lean to Ta-rich:
ω phase, α″ martensite, β phase, and a tetragonal
Ta-rich phase (Ta<sub>(tetr)</sub>). The crystal structure and microstructure
were analyzed by Rietveld refinement and clear trends could be determined
as a function of Ta-content. The lattice correspondences between β
as the parent phase and α″ and ω as derivative
phases were expressed in matrix form. The β ⇌ α″
phase transition shows a discontinuity at the composition where the
martensitic transformation temperatures fall below room temperature
(between 34 and 38 at. % Ta) rendering it first order and confirming
its martensitic nature. A short study of the α″ martensite
employing the Landau theory is included for a mathematical quantification
of the spontaneous lattice strain at room temperature (ϵ̂<sub>max</sub> = 22.4(6) % for pure Ti). Martensitic properties of Ti–Ta
are beneficial for the development of high-temperature actuators with
actuation response at transformation temperatures higher than 100
°C.