Martin Dahlqvist

Martin Dahlqvist
Linköping University | LiU · Department of Physics, Chemistry and Biology (IFM)

PhD
Using stability predictions for identification of novel structures upon metal mixing (e.g. i-MAB, o-MAB, i-MAX, o-MAX)

About

80
Publications
19,159
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
2,867
Citations
Introduction
A materials scientist using density functional theory to investigate carbide and boride based materials. The research includes investigation of phase stability, relationship between chemical order and disorder upon alloying, and magnetism. All in close collaboration with experimentalists.
Additional affiliations
November 2016 - present
Linköping University
Position
  • Professor (Assistant)
January 2016 - October 2016
ETH Zurich
Position
  • PostDoc Position
October 2015 - December 2015
National University of Science and Technology MISIS
Position
  • PostDoc Position
Education
August 2003 - June 2007
Lund University
Field of study
  • Physical Chemistry

Publications

Publications (80)
Article
Full-text available
MAX phases (M = metal, A = A-group element, X = C and/or N) are layered materials, combining metallic and ceramic attributes. They are also parent materials for the two-dimensional (2D) derivative, MXene, realized from selective etching of the A-element. In this work, we present a historical survey of MAX phase alloying to date along with an extens...
Article
Planar defect structures appearing in transition metal diboride (TMB2) thin films, grown by different magnetron sputtering-deposition approaches over a wide compositional and elemental range, were systematically investigated. Atomically resolved scanning transmission electron microscopy (STEM) imaging, electron energy loss spectroscopy (EELS) eleme...
Preprint
A desired prerequisite when performing a quantum mechanical calculation is to have an initial idea of the atomic positions within an approximate crystal structure. The atomic positions combined should result in a system located in, or close to, an energy minimum. However, designing low-energy structures may be challenging when prior knowledge is sc...
Article
In the quest for finding novel thermodynamically stable, layered, MAB phases promising for synthesis, we herein explore the phase stability of ternary MAB phases by considering both orthorhombic and hexagonal crystal symmetries for various compositions (MAB, M2AB2, M3AB4, M4AB4, and M4AB6 where M = Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, a...
Article
The laminated ternary boride Mo5SiB2of a T2 structure have two symmetrically inequivalent metallic sites, 16l and 4c, being occupied in a 4:1 ratio. The phase was recently shown to be stable for 80% substitution of Mo for Ti, at the majority site, forming an out-of-plane chemically ordered quaternary boride: Ti4MoSiB2. Considering that the hypothet...
Preprint
Full-text available
We perform a theoretical study of the electronic structure and magnetic properties of the prototypical magnetic MAX-phase Mn$_2$GaC with the main focus given to the origin of magnetic interactions in this system. Using the density functional theory+dynamical mean-field theory (DFT+DMFT) method we explore the effects of electron-electron interaction...
Article
Full-text available
We perform a theoretical study of the electronic structure and magnetic properties of the prototypical magnetic MAX-phase Mn2GaC with the main focus given to the origin of magnetic interactions in this system. Using the density functional theory+dynamical mean-field theory (DFT+DMFT) method, we explore the effects of electron-electron interactions...
Article
Full-text available
Inspired by the recent discovery of Ti 4 MoSiB 2 , a quaternary phase with out-of-plane chemical order that we denote o -MAB, we perform an extensive first-principles study to explore attained chemical order and...
Article
Full-text available
MAB phases are layered materials combining metallic and ceramic attributes. Their ternary compositions, however, have been limited to a few elemental combinations which makes controlled and tailored properties challenging. Inspired by the recent discovery of Mo4/3Y2/3AlB2 and Mo4/3Sc2/3AlB2i-MAB phases, i.e., quaternary layered MAB phases with in-p...
Article
Full-text available
Exploratory theoretical predictions in uncharted structural and compositional space are integral to materials discoveries. Inspired by M5SiB2 (T2) phases, the finding of a family of laminated quaternary metal borides, M′4M″SiB2, with out-of-plane chemical order is reported here. 11 chemically ordered phases as well as 40 solid solutions, introducin...
Article
Extensive research has been invested in two-dimensional (2D) materials, typically synthesized by exfoliation of van der Waals solids. One exception is MXenes, derived from the etching of constituent layers in transition metal carbides and nitrides. We report the experimental realization of boridene in the form of single-layer 2D molybdenum boride s...
Article
We have by means of first principles density functional theory calculations studied the mechanical and electronic properties of the so called i-MAB phases, M'4/3M''2/3AlB2, where M'= Cr, Mo, W and M'' = Sc, Y. These phases, experimentally verified for Mo4/3Sc2/3AlB2and Mo4/3Y2/3AlB2, display an atomically laminated structure with in-plane chemical...
Article
Full-text available
The MAB phases are a family of layered ternary transition metal borides, with atomically laminated crystal structures comprised of transition metal boride (M-B) layers interleaved by single, or double, Al (A) layers. Herein, density functional theory is implemented to evaluate the thermodynamic stability of disordered (Mn1-xCrx)2AlB2, and disordere...
Article
Full-text available
The atomic structure and local composition of high quality epitaxial substoichiometric titanium diboride (TiB1.9) thin film, deposited by unbalanced magnetron sputtering, were studied using analytical high-resolution scanning transmission electron microscopy, density functional theory, and image simulations. The unpaired Ti is pinpointed to inclusi...
Article
Full-text available
Using density functional theory, the phase stability and physical properties, including structural, electronic, mechanical, thermal and vibrational with defect processes, of a newly synthesized 211 MAX phase V 2 SnC are investigated for the first time. The obtained results are compared with those found in the literature for other existing M 2 SnC (...
Article
Full-text available
Nanolaminated materials including magnetic elements are of special interest for commonly observed nontrivial magnetic characteristics and as potential precursors for 2D materials. Here, we explore the previously unknown layered phase M2Al2C3, where M = Sc and Er. Sc2Al2C3 was synthesized as single crystals of ∼mm² size, and its structure was determ...
Article
Full-text available
All atomically laminated MAB phases (M = transition metal, A = A-group element, and B = boron) exhibit orthorhombic or tetragonal symmetry, with the only exception being hexagonal Ti2InB2. Inspired by the recent discovery of chemically ordered hexagonal carbides, i-MAX phases, we perform an extensive first-principles study to explore chemical order...
Preprint
Full-text available
Using density functional theory the phase stability and physical properties including structural, electronic, mechanical, thermal, and vibrational with defect processes of a newly synthesized 211 MAX phase V 2 SnC are investigated for the first time. The obtained results are compared with those found in literatures for other existing M 2 SnC (M = T...
Article
Full-text available
The atomically laminated Mn2GaC has previously been synthesized as a heteroepitaxial thin film and found to be magnetic with structural changes linked to the magnetic anisotropy. Related theoretical studies only considered bulk conditions and thus neglected the influence from possible strain linked to the choice of substrate. Here we employ first p...
Preprint
div>The atomic structure and local composition of high quality epitaxial substoichiometric titanium diboride (TiB<sub>1.9</sub>) thin film, deposited by unbalanced magnetron sputtering, were studied using analytical high-resolution scanning transmission electron microscopy, density functional theory and image simulations. The unmatched Ti is pin...
Preprint
This work investigates the compatibility of $Zr_{2}AlC$ MAX phase-based ceramics with liquid LBE, and proposes a mechanism to explain the observed local $Zr_{2}AlC$/LBE interaction. The ceramics were exposed to oxygen-poor ($C_{O}\le2.2 \cdot10^{-10}$ mass%), static liquid LBE at 500{\deg}C for 1000 h. A new $Zr_{2}(Al,Bi,Pb)C$ MAX phase solid solu...
Article
In this work, we present high-pressure diffraction results of the Mo-based Mn + 1AXn phase, Mo2GaC. A diamond anvil cell was used to compress the material up to 30 GPa, and x-ray diffraction was used to determine the structure and unit cell parameters as a function of pressure. Somewhat surprisingly, we find that, at 295 ± 25 GPa, the bulk modulus...
Article
This work investigates the compatibility of Zr2AlC MAX phase-based ceramics with liquid LBE, and proposes a mechanism to explain the observed local Zr2AlC/LBE interaction. The ceramics were exposed to oxygen-poor (CO ≤ 2.2 × 10⁻¹⁰ mass%), static liquid LBE at 500 °C for 1000 h. A new Zr2(Al,Bi,Pb)C MAX phase solid solution formed in-situ in the LBE...
Article
Full-text available
In this work we systematically explore a class of atomically laminated materials, Mn+1AXn (MAX) phases upon alloying between two transition metals, M´ and M´´, from Group III to VI (Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W). The materials investigated focus on so called o-MAX phases with out-of-plane chemical ordering of M´ and M´´, and their disord...
Article
We combine predictive ab-initio calculations with experimental verification of bulk materials synthesis for exploration of new and potentially magnetic atomically laminated i-MAX phases. Two such phases are discovered: (Cr2/3Sc1/3)2GaC and (Mn2/3Sc1/3)2GaC, where the latter compound displays a two-fold increase in Mn content compared to previously...
Article
New bulk MAX phase-based ceramics were synthesized in the Ta–Hf–Al–C and Ta–Nb–Al–C systems. Specifically, (Ta1-x,Hfx)4AlC3 and (Ta1-x,Nbx)4AlC3 stoichiometries with x = 0.05, 0.1, 0.15, 0.2, 0.25 were targeted by reactive hot pressing of Ta2H, HfH2, NbH0.89, Al and C powder mixtures at 1550 °C in vacuum. The produced ceramics were characterized in...
Article
Full-text available
Research on low-dimensional materials has increased drastically in the last decade, with the discovery of two-dimensional transition metal carbides and nitrides (MXenes) produced by atom-selective chemical etching of laminated parent Mn+1AXn (MAX) phases. Here, we apply density functional theory and subsequent materials synthesis and analysis to ex...
Article
Full-text available
Interfaces containing misfit dislocations deteriorate electronic properties of heteroepitaxial wide bandgap III-nitride semiconductors grown on foreign substrates, as a result of lattice and thermal expansion mismatches and incompatible chemical bonding. We report grain-boundary-free AlN nucleation layers (NLs) grown by metalorganic chemical vapor...
Chapter
The family of MXenes has expanded since the discovery of chemical order in parent quaternary MAX phases, displaying either out-of-plane (o-MAX) or in-plane (i-MAX) order upon alloying. Through selective chemical etching of these materials, corresponding MXenes can be derived, with out-of-plane and in-plane ordering of elements, as well as with orde...
Article
Synthesis of delaminated 2D W1.33C (MXene) has been performed by selectively etching Al as well as Sc/Y from the recently discovered nanolaminated i-MAX phases (W2/3Sc1/3)2AlC and (W2/3Y1/3)2AlC. Both quaternary phases produce MXenes with similar flake morphology, and with a skeletal structure due to formation of ordered vacancies. The measured O,...
Article
Full-text available
In 2017, we discovered quaternary i-MAX phases - atomically layered solids, where M is an early transition metal, A is an A group element, and X is C - with a (M12/3M21/3)2AC chemistry, where the M1 and M2 atoms are in-plane ordered. Herein we report on the discovery of a new class of magnetic i-MAX phases in which bi-layers of a quasi-2D magnetic...
Article
Nanolamellar transition metal carbides are gaining increasing interests because of the recent developments of their two-dimensional (2D) derivatives and promising performance for a variety of applications from energy storage, catalysis to transparent conductive coatings, and medicine. To develop more novel 2D materials, new nanolaminated structures...
Article
Full-text available
With increased chemical diversity and structural complexity comes the opportunities for innovative materials possessing advantageous properties. Herein, we combine predictive first-principles calculations with experimental synthesis, to explore the origin of formation of the atomically laminated i-MAX phases. By probing (Mo2/3 M21/3)2 AC (where M2...
Article
Full-text available
With the recent discovery of in-plane chemically ordered MAX phases ( i -MAX) of the general formula ( M <sup>1</sup><sub>2/3</sub> M <sup>2</sup><sub>1/3</sub>)<sub>2</sub>AC comes addition of non-traditional MAX phase elements. In the present study, we use density functional theory calculations to investigate the electronic structure, bonding nat...
Article
Guided by predictive theory, a new compound with chemical composition (Cr2/3Zr1/3)2AlC was synthesized by hot pressing of Cr, ZrH2, Al, and C mixtures at 1300 °C. The crystal structure is monoclinic of space group C2/ c and displays in-plane chemical order in the metal layers, a so-called i-MAX phase. Quantitative chemical composition analyses conf...
Article
Structural design on the atomic level can provide novel chemistries of hybrid MAX phases and their MXenes. Herein, density functional theory is used to predict phase stability of quaternary i‐MAX phases with in‐plane chemical order and a general chemistry (W2/3M²1/3)2AC, where M² = Sc, Y (W), and A = Al, Si, Ga, Ge, In, and Sn. Of over 18 compositi...
Article
Full-text available
Incorporation of layers of noble metals in non-van der Waals layered materials may be used to form novel layered compounds. Recently, we demonstrated a high-temperature-induced exchange process of Au with Si in the layered phase Ti3SiC2, resulting in the formation of Ti3AuC2 and Ti3Au2C2. Here, we generalize this technique showing that Au/Ti2AlC an...
Article
Full-text available
The enigma of MAX phases and their hybrids prevails. We probe transition metal (M) alloying in MAX phases for metal size, electronegativity, and electron configuration, and discover ordering in these MAX hybrids, namely, (V 2/3 Zr 1/3) 2 AlC and (Mo 2/3 Y 1/3) 2 AlC. Predictive theory and verifying materials synthesis, including a judicious choice...
Article
Full-text available
The large class of layered ceramics encompasses both van der Waals (vdW) and non-vdW solids. While intercalation of noble metals in vdW solids is known, formation of compounds by incorporation of noble-metal layers in non-vdW layered solids is largely unexplored. Here, we show formation of Ti3AuC2 and Ti3Au2C2 phases with up to 31% lattice swelling...
Article
Full-text available
The exploration of two-dimensional solids is an active area of materials discovery. Research in this area has given us structures spanning graphene to dichalcogenides, and more recently 2D transition metal carbides (MXenes). One of the challenges now is to master ordering within the atomic sheets. Herein, we present a top-down, high-yield, facile r...
Data
Supplementary Figures, Supplementary Tables and Supplementary References
Article
We present theoretical prediction and experimental evidence of a new MAX phase alloy, Mo2ScAlC2, with out-of-plane chemical order. Evaluation of phase stability was performed by ab initio calculations based on Density Functional Theory, suggesting that chemical order in the alloy promotes a stable phase, with a formation enthalpy of −24 meV/atom, a...
Article
Full-text available
The data presented in this article are related to the research article entitled “Theoretical stability and materials synthesis of a chemically ordered MAX phase, Mo2ScAlC2, and its two-dimensional derivate Mo2ScC” (R. Meshkian, Q. Tao, M. Dahlqvist, J. Lu, L. Hultman, J. Rosen, 2016) [1]. This article describes theoretical phase stability calculati...
Article
Full-text available
This review presents MAX phases (M is a transition metal, A an A-group element, X is C or N), known for their unique combination of ceramic/metallic properties, as a recently uncovered family of novel magnetic nanolaminates. The first created magnetic MAX phases were predicted through evaluation of phase stability using density functional theory, a...
Article
Full-text available
The nature of the magnetic structure in magnetic so-called MAX phases is a topic of some controversy. Here we present unpolarized neutron-diffraction data between 3.4 and 290.0 K and momentum transfer between Q = 0.0 and 1.1 ˚ A −1 , as well as complementary x-ray-diffraction data on epitaxial thin films of the MAX phase material Mn 2 GaC. This inh...
Article
Full-text available
We here use first-principles calculations to investigate the phase stability of the hypothetical laminated material V2Ga2C and the related alloy (Mo1-xVx)2Ga2C, the latter for a potential parent material for synthesis of (Mo1-xVx)2C, a new two-dimensional material in the family of so called MXenes. We predict that V2Ga2C is thermodynamically stable...
Article
Full-text available
Atomic laminates such as MAX phases benefit from the addition of oxygen in many ways, from the formation of a protective oxide surface layer with self-healing capabilities when cracks form to the tuning of anisotropic conductivity. In this paper oxygen incorporation and vacancy formation in M 2AlC (M = Ti, V, Cr) MAX phases have been studied using...
Article
Full-text available
In this work, we employ and critically evaluate a first-principles approach based on supercell calculations for predicting the magnetic critical order-disorder temperature Tc. As a model material we use the recently discovered nanolaminate Mn2GaC. First, we derive the exchange interaction parameters Jij between pairs of Mn atoms on sites i and j of...
Article
Full-text available
Inherently layered magnetic materials, such as magnetic Mn+1AXn (MAX) phases, offer an intriguing perspective for use in spintronics applications and as ideal model systems for fundamental studies of complex magnetic phenomena. The MAX phase composition Mn+1AXn consists of Mn+1Xn blocks separated by atomically thin A-layers where M is a transition...
Article
Full-text available
We report on the phase stability of chemically ordered and disordered quaternary MAX phases – TiMAlC, TiM2AlC2, MTi2AlC2, and Ti2M2AlC3 where M=Zr,Hf (group IV), M=V,Nb,Ta (group V), and M=Cr,Mo,W (group VI). At 0 K, layered chemically ordered structures are predicted to be stable for M from group V and VI. By taking into account the configurationa...
Article
Full-text available
Transition metal diborides in hexagonal AlB2 type structure typically form stable MB 2 phases for group IV elements (M = Ti, Zr, Hf). For group V (M = V, Nb, Ta) and group VI (M = Cr, Mo, W) the stability is reduced and an alternative hexagonal rhombohedral MB 2 structure becomes more stable. In this work we investigate the effect of vacancies on t...
Article
Full-text available
Herein, we report on the phase stabilities and crystal structures of two newly discovered ordered, quaternary MAX phases—Mo 2 TiAlC 2 and Mo 2 Ti 2 AlC 3 —synthesized by mixing and heating different elemental powder mixtures of mMo:(3-m)Ti:1.1Al:2C with 1.5 m 2.2 and 2Mo: 2Ti:1.1Al:2.7C to 1600 C for 4 h under Ar flow. In general, for m ! 2 an orde...
Article
Following our recent discovery of a new nanolaminated carbide, Mo 2 Ga 2 C, we herein present a detailed structural and chemical analysis of this phase based on ab initio calculations, X-ray photoelectron spec-troscopy, high resolution scanning transmission electron microscopy, and neutron powder diffraction. Calculations suggest an energetically a...
Article
Full-text available
In this work we critically evaluate methods for treating electron correlation effects in multicomponent carbides using a GGA + U framework, addressing doubts from previous works on the usability of density functional theory in the design of magnetic MAX phases. We have studied the influence of the Hubbard U-parameter, applied to Cr 3d orbitals, on...
Article
The phase stability of Mon +1GaCn has been investigated using ab-initio calculations. The results indicate stability for the Mo2GaC phase only, with a formation enthalpy of –0.4 meV per atom. Subsequent thin film synthesis of Mo2GaC was performed through magnetron sputtering from elemental targets onto Al2O3 [0001], 6H-SiC [0001] and MgO [111] subs...