Crystal structure determination of nanolaminated Ti5Al2C3 by combined techniques of XRPD, TEM and ab initio calculations

Zhang, Hui; Wang, Xiaohui; Ma, Yonghui; Sun, Luchao; Zheng, Lai; Zhou, Yanchun

doi:10.1007/s40145-012-0034-9

Cited by 23 publications

(21 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[20] was submitted, reviewed, and accepted in exactly one week and published soon thereafter. It was only after our paper was published that the same group, working with a composition that was only 19.7 wt% Ti 5 Al 2 C 3 , made the case that the space group was R3m [23].…”

Section: Introductionmentioning

confidence: 99%

High-temperature neutron diffraction and first-principles study of temperature-dependent crystal structures and atomic vibrations in Ti3AlC2, Ti2AlC, and Ti5Al2C3

Lane

Vogel

Caspi

et al. 2013

Journal of Applied Physics

View full text Add to dashboard Cite

Herein we report on the thermal expansions and temperature-dependent crystal structures of select ternary carbide MAX phases in the Ti-Al-C phase diagram in the 100-1000• C temperature range. A bulk sample containing 38(±1) wt.% Ti5Al2C3 ("523"), 32(±1) wt.% Ti2AlC ("211"), 18(±1) wt.% Ti3AlC2 ("312"), and 12(±1) wt.% (Ti0.5Al0.5)Al is studied by Rietveld analysis of high-temperature neutron diffraction data. We also report on the same for a single-phase sample of Ti3AlC2 for comparison. The thermal expansions of all the MAX phases studied are higher in the c direction than in the a direction. The bulk expansion coefficients -9.3(±0

show abstract

Section: Introductionmentioning

confidence: 99%

High-temperature neutron diffraction and first-principles study of temperature-dependent crystal structures and atomic vibrations in Ti3AlC2, Ti2AlC, and Ti5Al2C3

Lane

Vogel

Caspi

et al. 2013

Journal of Applied Physics

View full text Add to dashboard Cite

show abstract

“…These can be seen as combinations of alternating half-unit cell stackings of 211 and 312 for 523, and of 312 and 413 for 725. Later the same phases were revealed also for the Ti-Ge-C [67] and Ti-Al-C [68][69][70][71] systems. In the latter system there has been a controversy weather the 523 consist of 20 atoms/uc, space group P6 3 /mmc (194) [70], or 30 atoms/uc, space group P3m1 (156) [68,69] or 3 (166) [71].…”

Section: Related Laminated Materialsmentioning

confidence: 79%

“…Later the same phases were revealed also for the Ti-Ge-C [67] and Ti-Al-C [68][69][70][71] systems. In the latter system there has been a controversy weather the 523 consist of 20 atoms/uc, space group P6 3 /mmc (194) [70], or 30 atoms/uc, space group P3m1 (156) [68,69] or 3 (166) [71]. Lane et al presented evidence from both experimental and simulated X-ray diffraction (XRD) as well as selected area electron diffraction patterns proving that the double stacking sequence of atoms is wrong; it needs to be repeated three times [68].…”

Section: Related Laminated Materialsmentioning

confidence: 79%

See 1 more Smart Citation

Materials Design from First Principles : stability and magnetism of nanolaminates

Dahlqvist¹

2014

View full text Add to dashboard Cite

The front cover image is a close up of M (red and blue spheres) and X (grey sphere) in M 2 AX. In the background its nanolaminated structure consisting of ordered, clustered, and disordered atoms or magnetic moments is illustrated.The spine image shows charge redistribution for an interstitial oxygen atom in Cr 2 AlC where blue indicate gain of electrons and red loss of electrons.The back cover image shows charge redistribution when oxygen substitutes for carbon in Ti 2 AlC where blue indicate gain of electrons and red loss of electrons. My daughter described it as "a planet, with water, and trees, and blue leaves". © Martin Dahlqvist, unless otherwise stated. Printed by LiU-Tryck, Linköping, Sweden, 2014 To my JETs ♥ v ABSTRACT In this thesis, first-principles calculations within density functional theory are presented, with a principal goal to investigate the phase stability of so called M n+1 AX n (MAX) phases. MAX phases are a group of nanolaminated materials comprised of a transition metal (M), a group 12-16 element (A), and carbon or nitrogen (X). They combine ceramic and metallic characteristics, and phase stability studies are motivated by a search for new phases with novel properties, such as magnetism, and for the results to be used as guidance in attempted materials synthesis in the lab.To investigate phase stability of a hypothetical material, a theoretical approach has been developed, where the essential part is to identify the set of most competing phases relative to the material of interest. This approach advance beyond more traditional evaluation of stability, where the energy of formation of the material is generally calculated relative to its single elements, or to a set of ad hoc chosen competing phases. For phase stability predictions to be reliable, validation of previous experimental work is a requirement prior to investigations of new, still hypothetical, materials. It is found that the predictions from the developed theoretical approach are consistent with experimental observations for a large set of MAX phases. The predictive power is thereafter demonstrated for the new phases Nb 2 GeC and Mn 2 GaC, which subsequently have been synthesized as thin films. It should be noted that Mn is used for the first time as sole M-element in a MAX phase. Hence, the theory is successfully used to find new candidates, and to guide experimentalists in their work on novel promising materials. Phase stability is also evaluated for MAX phase alloys. Incorporation of oxygen in different M 2 AlC phases are studied, and the results show that oxygen prefer different sites depending on M-element, through the number of available non-bonding M delectrons. The theory also predicts that oxygen substituting for carbon in Ti 2 AlC stabilizes the material, which explains the experimentally observed 12.5 at% oxygen (x = 0.5) inMagnetism is a recently attained property of MAX phase materials, and a direct result of this Thesis work. We have demonstrated the importance of choice of magnetic spin configuration and elec...

show abstract

“…Machinable ternary carbides (MTCs, having a general chemical formula M m A n C m – n , where M is an early transition metal element; A is an A group element; m and n are integers, m ≥ 2 n )678910 are the most investigated carbides in the last two decades. Crystallizing in the P 6 3 / mmc (for n = 1)6 or R 3– m (for n = 2)1011 space group, their crystal structures are closely related, which can be regarded as the periodically stacking of strongly bonded “M m C m – n ” sheets and “A” atomic layers along [0001].…”

mentioning

confidence: 99%

Discovery of carbon-vacancy ordering in Nb4AlC3–x under the guidance of first-principles calculations

Zhang

Wang

et al. 2015

Sci Rep

Self Cite

View full text Add to dashboard Cite

The conventional wisdom to tailor the properties of binary transition metal carbides by order-disorder phase transformation has been inapplicable for the machinable ternary carbides (MTCs) due to the absence of ordered phase in bulk sample. Here, the presence of an ordered phase with structural carbon vacancies in Nb4AlC3–x (x ≈ 0.3) ternary carbide is predicted by first-principles calculations, and experimentally identified for the first time by transmission electron microscopy and micro-Raman spectroscopy. Consistent with the first-principles prediction, the ordered phase, o-Nb4AlC3, crystalizes in P63/mcm with a = 5.423 Å, c = 24.146 Å. Coexistence of ordered (o-Nb4AlC3) and disordered (Nb4AlC3–x) phase brings about abundant domains with irregular shape in the bulk sample. Both heating and electron irradiation can induce the transformation from o-Nb4AlC3 to Nb4AlC3–x. Our findings may offer substantial insights into the roles of carbon vacancies in the structure stability and order-disorder phase transformation in MTCs.

show abstract

Crystal structure determination of nanolaminated Ti5Al2C3 by combined techniques of XRPD, TEM and ab initio calculations

Cited by 23 publications

References 22 publications

High-temperature neutron diffraction and first-principles study of temperature-dependent crystal structures and atomic vibrations in Ti3AlC2, Ti2AlC, and Ti5Al2C3

High-temperature neutron diffraction and first-principles study of temperature-dependent crystal structures and atomic vibrations in Ti3AlC2, Ti2AlC, and Ti5Al2C3

Materials Design from First Principles : stability and magnetism of nanolaminates

Discovery of carbon-vacancy ordering in Nb4AlC3–x under the guidance of first-principles calculations

Contact Info

Product

Resources

About