Investigation of the structure of β-tantalum

Jiang, Aiqin; Yohannan, Anto; Nnolim, Neme O.; Tyson, Trevor; Axe, Lisa; Lee, Sabrina L.; Côté, Paul J.

doi:10.1016/s0040-6090(03)00702-8

Cited by 48 publications

(27 citation statements)

References 20 publications

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“…Various crystal structures have been reported for h-Ta [8][9][10][11][12][13][14][15] since its discovery. The work by Mosley et al [12] interpreted the X-ray powder diffraction data in terms of a tetragonal unit cell, which is isomorphous with h-uranium, with lattice constants a=1.0194/c=0.5313 nm and space group P4 2 /mnm.…”

Section: Introductionmentioning

confidence: 99%

The structure and stability of β-Ta thin films

et al. 2005

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Ta films with tetragonal crystalline structure (h-phase), deposited by magnetron sputtering on different substrates (steel, silicon, and silicon dioxide), have been studied. In all cases, very highly preferred (001) orientation was observed in X-ray diffraction measurements. All diffraction data revealed two weak reflections corresponding to d-spacing of 0.5272 and 0.1777 nm. The presence of the two peaks, attributed to (001) and (003) reflections, indicates that h-Ta films exhibit a high preference for the space group of P-42 1 m over P4 2 /mnm, previously proposed for h-Ta. Differences in relative intensities of (00l) reflections, calculated for single crystal h-Ta j-type Frank-Kasper structure and those measured in the films, are attributed to defects in the films. Molecular dynamics simulations performed on tantalum clusters with six different initial configurations using the embedded-atom-method potential revealed the stability of h-Ta, which might explain its growth on many substrates under various deposition conditions. D

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Section: Introductionmentioning

confidence: 99%

The structure and stability of β-Ta thin films

et al. 2005

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“…The maximum impurity content by chemical analysis was given as 39.4 ppm with O, N, C, W, and Nb (16,8,5,3.3 and 5.5 ppm respectively) being the main impurities. Conventional tensile specimens approximately 50 mm 9 3 mm 9 1.5 mm (5 mm wide at the ends for gripping) were prepared from bulk disks and cut to shape using J Mater Sci (2015) 50:3706-3715 3707 electro-discharge machining (EDM) following the procedures used previously for Ta metal obtained from a different source.…”

Section: Methodsmentioning

confidence: 99%

“…A second phase of Ta, known as the b phase [5], is metastable and has the tetragonal crystal symmetry (space group P4 2 /mnm; a = 1.0194 nm, c = 0.5313 nm) [6]. The b phase has been produced in thin-film form by sputtering [7][8][9][10][11], chemical vapor deposition [12,13], and electrochemical deposition from a molten-salt solution [14]. The bcc form of Ta can also be produced by sputtering using a suitable buffer layer [11].…”

Section: Introductionmentioning

confidence: 99%

Observations of fcc and hcp tantalum

et al. 2015

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The metal tantalum has many varied uses including in microelectronics (especially in capacitors) as thin films, in medical applications as an implant material or for surgical instruments, in X-ray lithography for masks, and in high-temperature structural applications. Ta is particularly useful because it is relatively ductile, refractory in nature, and does not readily react with corrosive materials. The body-centered cubic (bcc) crystal structure of pure Ta, also known as the a-phase, is the most commonly observed, but Ta is also known to exist in two other allotropes, one tetragonal and the other (much less-wellknown) face-centered cubic (fcc). The tetragonal form (bTa) has been produced by various deposition techniques and often occurs mixed with the a-phase; the fcc phase has only previously been reported in thin films deposited by thermal evaporation. There have been other reports of 'bcc metals' such as V and Fe existing with an fcc crystal structure when the metal is deposited as a thin film. In the present study, fcc Ta with a = 0.43 nm has been observed using transmission electron microscopy in bulk samples of Ta that have been subjected to quasi-static tensile deformation that was so large as to cause fracture of the material. The fcc phase has a relatively small grain size but appears to be stable at room temperature. It is also shown that relatively large grains (10-20 nm in diameter) of Ta can also exist with an hcp structure with a = 0.304 nm and c = 0.494 nm.

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“…Despite these and other studies devoted to h-Ta [4][5][6][7][8], the growth mechanism of oriented h-Ta is not clear. There is sufficient lack of information on the related properties of oriented h-Ta/silicon dioxide (SiO 2 ) and the h-Ta/Si interface.…”

Section: Introductionmentioning

confidence: 95%

X-ray characterization of oriented β-tantalum films

et al. 2004

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Tantalum (Ta) metal films (10-70 nm) were deposited on a Si(100) substrate with a 500 nm silicon dioxide (SiO 2 ) interlayer by ion-beamassisted sputtering. The as-deposited films have been characterized by X-ray diffraction (XRD) and X-ray reflectivity (XRR) techniques. XRD measurements showed the presence of films of the tetragonal phase of tantalum (h-Ta) oriented along the (00l) plane. XRR measurements indicated the presence of graded Ta films, with a thin interface layer between the 500 nm SiO 2 layer and the Ta films. The thickness and density of this interface layer was estimated to be 1.9F0.2 nm and 10.5F0.5 g/cm 3 , respectively. X-ray photoelectron spectroscopy (XPS) was used to probe the chemical composition of this interface layer. XPS investigative studies indicated that the interface was likely composed of tantalum silicide (TaSi 2 ) and tantalum silicate (TaSiO x ). However, the TaSiO x layer was reduced during Ar ion sputter depth profile analysis. D

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Investigation of the structure of β-tantalum

Cited by 48 publications

References 20 publications

The structure and stability of β-Ta thin films

The structure and stability of β-Ta thin films

Observations of fcc and hcp tantalum

X-ray characterization of oriented β-tantalum films

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