Microstructures and Theoretical Bulk Modulus of Layered Ternary Tantalum Aluminum Carbides

Lin, Zhijun; Zhuo, Mujin; Zhou, Yanchun; Li, Meishuan; Wang, Jiemin

doi:10.1111/j.1551-2916.2006.01303.x

Cited by 136 publications

(105 citation statements)

References 30 publications

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“…Related observations are the reports of Ta 6 AlC 5 and Ti 7 SnC 6 stacking sequences of a few unit cells in Ta 4 AlC 3 and Ti 2 SnC samples, suggesting the possible existence of "higher-order" MAX phases (i.e., M n+1 AX n phases with n > 3) [50,51]. Note, however, that these observations suggest but do not prove that higher-order MAX phases exist.…”

Section: Intergrown Structures -Hybrid "523" and "725" Max Phasesmentioning

confidence: 54%

The M+1AX phases: Materials science and thin-film processing

et al. 2010

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This article is a critical review of the M n+1 AX n phases ("MAX phases", where n =1, 2, or 3) from a materials science perspective. MAX phases are a class of hexagonal-structure ternary carbides and nitrides ("X") of a transition metal ("M") and an A-group element. The most well known are Ti 2 AlC, Ti 3 SiC 2 , and Ti 4 AlN 3 . There are ~60 MAX phases with at least 9 discovered in the last five years alone. What makes the MAX phases fascinating and potentially useful is their remarkable combination of chemical, physical, electrical, and mechanical properties, which in many ways combine the characteristics of metals and ceramics. For example, MAX phases are typically resistant to oxidation and corrosion, elastically stiff, but at the same time they exhibit high thermal and electrical conductivities and are machinable. These properties stem from an inherently nanolaminated crystal structure, with M n+1 X n slabs intercalated with pure A-element layers. The research on MAX phases has been accelerated by the introduction of thin-film processing methods.Magnetron sputtering and arc deposition have been employed to synthesize single-crystal material by epitaxial growth, which enables studies of fundamental materials properties. However, the surface-initiated decomposition of M n+1 AX n thin films into MX compounds at temperatures of 1000-1100 °C is much lower than the decomposition temperatures typically reported for the corresponding bulk material. We also review the prospects for low-temperature synthesis, which is essential for deposition of MAX phases onto technologically important substrates. While deposition of MAX phases from the archetypical Ti-Si-C and Ti-Al-N systems typically require synthesis temperatures of ~800 °C, recent results have demonstrated that V 2 GeC and Cr 2 AlC can be deposited at ~450 °C. Also, thermal spray of Ti 2 AlC powder has been used to produce thick coatings. We further treat progress in the use of first-principles calculations for predicting hypothetical MAX phases and their properties. Together with advances in processing and materials 3 analysis, this progress has led to recent discoveries of numerous new MAX phases such as Ti 4 SiC 3 , Ta 4 AlC 3 , and Ti 3 SnC 2 . Finally, important future research directions are discussed. These include charting the unknown regions in phase diagrams to discover new equilibrium and metastable phases, as well as research challenges in understanding their physical properties, such as the effects of anisotropy, impurities, and vacancies on the electrical properties, and unexplored properties such as superconductivity, magnetism, and optics. 4

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Section: Intergrown Structures -Hybrid "523" and "725" Max Phasesmentioning

confidence: 54%

The M+1AX phases: Materials science and thin-film processing

et al. 2010

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“…Oxidation may thus affect the predicted phase transformation. Third, experimental studies of the β-Ta 4 AlC 3 polymorph involve synthesis through hot pressing in addition to higher temperatures [8][9][10] and the synthesis pressure may also affect the relative phase stability. To test this hypothesis we hot-pressed a stoichiometric mixture of TaC, Al, and graphite powders in a graphiteheated vacuum hot-press at 1500 °C for 2 hrs under a pressure of 70 MPa.…”

Section: Discussionmentioning

confidence: 99%

“…While the 211 and 312 MAX phases have been extensively investigated and characterized, it was long believed that Ti 4 AlN 3 was the only 413 MAX phase [4]. Since 2004, however, several new 413 phases have been discovered; first with the synthesis of Ti 4 SiC 3 and Ti 4 GeC 3 thin films [5][6] and then bulk synthesis of Ta 4 AlC 3 in the form of polycrystals [7][8][9][10] and single crystals [11]. More recently, the 413 phases V 4 AlC 3 [12][13], Nb 4 AlC 3 [14], and Ti 4 GaC 3 [15] were also synthesized in bulk form.…”

Section: Introductionmentioning

confidence: 99%

High-temperature stability of α-Ta4AlC3

Lane¹,

Eklund²,

Lu³

et al. 2011

Materials Research Bulletin

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“…4) As a result, research on 413 phases is not as intensive as research on 211 and 312 phases. However, recently, important progresses on 413 phases were reported in Ta-Al-C system, in which Ta 4 AlC 3 bulk materials were synthesized either in the form of polycrystals [5][6][7][8][9] or single-crystals.…”

Section: Introductionmentioning

confidence: 99%

First-Principles Study of Carbon Vacancy in Ta<SUB>4</SUB>AlC<SUB>3</SUB>

Sun

Hashimoto

et al. 2008

Mater. Trans.

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We have investigated the carbon mono-vacancy in Ta 4 AlC 3 by first-principles calculations. We identify the 2a sites as the probable carbon vacancy sites in Ta 4 AlC 3 based on the energetics of vacancy formation. It was found that introducing carbon vacancies decreased the phase stability of Ta 4 AlC 3 . There are no significant changes in volume by introducing carbon vacancy. However, the bulk modulus decreased when introducing carbon vacancy. The differences in density of states of Ta 4 AlC 3 with and without carbon vacancies are analyzed. Some vacancy peaks near the Fermi level were observed. Additionally, the density of states at the Fermi level increases by introducing carbon vacancies, which may be of benefit to the electron transport in Ta 4 AlC 3 .

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Microstructures and Theoretical Bulk Modulus of Layered Ternary Tantalum Aluminum Carbides

Cited by 136 publications

References 30 publications

The M+1AX phases: Materials science and thin-film processing

The M+1AX phases: Materials science and thin-film processing

High-temperature stability of α-Ta4AlC3

First-Principles Study of Carbon Vacancy in Ta<SUB>4</SUB>AlC<SUB>3</SUB>

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