Anisotropic Ordering in 1T' Molybdenum and Tungsten Ditelluride Layers Alloyed with Sulfur and Selenium.

Title Anisotropic Ordering in 1T' Molybdenum and Tungsten Ditelluride Layers Alloyed with Sulfur and Selenium.
Authors J. Lin; J. Zhou; S. Zuluaga; P. Yu; M. Gu; Z. Liu; S.T. Pantelides; K. Suenaga
Journal ACS Nano
DOI 10.1021/acsnano.7b08782
Abstract

Alloying is an effective way to engineer the band-gap structure of two-dimensional transition-metal dichalcogenide materials. Molybdenum and tungsten ditelluride alloyed with sulfur or selenium layers (MX2xTe2(1-x), M = Mo, W and X = S, Se) have a large band-gap tunability from metallic to semiconducting due to the 2H-to-1T' phase transition as controlled by the alloy concentrations, whereas the alloy atom distribution in these two phases remains elusive. Here, combining atomic resolution Z-contrast scanning transmission electron microscopy imaging and density functional theory (DFT), we discovered that anisotropic ordering occurs in the 1T' phase, in sharp contrast to the isotropic alloy behavior in the 2H phase under similar alloy concentration. The anisotropic ordering is presumably due to the anisotropic bonding in the 1T' phase, as further elaborated by DFT calculations. Our results reveal the atomic anisotropic alloyed behavior in 1T' phase layered alloys regardless of their alloy concentration, shining light on fine-tuning their physical properties via engineering the alloyed atomic structure.

Citation J. Lin; J. Zhou; S. Zuluaga; P. Yu; M. Gu; Z. Liu; S.T. Pantelides; K. Suenaga.Anisotropic Ordering in 1T' Molybdenum and Tungsten Ditelluride Layers Alloyed with Sulfur and Selenium.. ACS Nano. 2018. doi:10.1021/acsnano.7b08782

Related Elements

Molybdenum

See more Molybdenum products. Molybdenum (atomic symbol: Mo, atomic number: 42) is a Block D, Group 6, Period 5 element with an atomic weight of 95.96. Molybdenum Bohr ModelThe number of electrons in each of molybdenum's shells is [2, 8, 18, 13, 1] and its electron configuration is [Kr] 4d5 5s1. The molybdenum atom has a radius of 139 pm and a Van der Waals radius of 209 pm. In its elemental form, molybdenum has a gray metallic appearance. Molybdenum was discovered by Carl Wilhelm in 1778 and first isolated by Peter Jacob Hjelm in 1781. Molybdenum is the 54th most abundant element in the earth's crust. Elemental MolybdenumIt has the third highest melting point of any element, exceeded only by tungsten and tantalum. Molybdenum does not occur naturally as a free metal, it is found in various oxidation states in minerals. The primary commercial source of molybdenum is molybdenite, although it is also recovered as a byproduct of copper and tungsten mining. The origin of the name Molybdenum comes from the Greek word molubdos meaning lead.

Selenium

Selenium Bohr ModelSee more Selenium products. Selenium (atomic symbol: Se, atomic number: 34) is a Block P, Group 16, Period 4 element with an atomic radius of 78.96. The number of electrons in each of Selenium's shells is 2, 8, 18, 6 and its electron configuration is [Ar] 3d10 4s2 4p4. The selenium atom has a radius of 120 pm and a Van der Waals radius of 190 pm. Selenium is a non-metal with several allotropes: a black, vitreous form with an irregular crystal structure three red-colored forms with monoclinic crystal structures and a gray form with a hexagonal crystal structure, the most stable and dense form of the element. Elemental SeleniumOne of the most common uses for selenium is in glass production the red tint that it lends to glass neutralizes green or yellow tints from impurities in the glass materials. Selenium was discovered and first isolated by Jöns Jakob Berzelius and Johann Gottlieb Gahn in 1817. The origin of the name Selenium comes from the Greek word "Selênê," meaning moon.

Sulfur

See more Sulfur products. Sulfur (or Sulphur) (atomic symbol: S, atomic number: 16) is a Block P, Group 16, Period 3 element with an atomic radius of 32.066. Sulfur Bohr ModelThe number of electrons in each of Sulfur's shells is 2, 8, 6 and its electron configuration is [Ne] 3s2 3p4. In its elemental form, sulfur has a light yellow appearance. The sulfur atom has a covalent radius of 105 pm and a Van der Waals radius of 180 pm. In nature, sulfur can be found in hot springs, meteorites, volcanoes, and as galena, gypsum, and epsom salts. Sulfur has been known since ancient times but was not accepted as an element until 1777, when Antoine Lavoisier helped to convince the scientific community that it was an element and not a compound.

Tellurium

See more Tellurium products. Tellurium (atomic symbol: Te, atomic number: 52) is a Block P, Group 16, Period 5 element with an atomic radius of 127.60. Tellurium Bohr ModelThe number of electrons in each of tellurium's shells is 2, 8, 18, 18, 6 and its electron configuration is [Kr] 4d10 5s2 5p4. Tellurium was discovered by Franz Muller von Reichenstein in 1782 and first isolated by Martin Heinrich Klaproth in 1798. In its elemental form, tellurium has a silvery lustrous gray appearance. The tellurium atom has a radius of 140 pm and a Van der Waals radius of 206 pm. Elemental TelluriumTellurium is most commonly sourced from the anode sludges produced as a byproduct of copper refining. The name Tellurium originates from the Greek word Tellus, meaning Earth.

Tungsten

See more Tungsten products. Tungsten (atomic symbol: W, atomic number: 74) is a Block D, Group 6, Period 6 element with an atomic weight of 183.84. The number of electrons in each of tungsten's shells is [2, 8, 18, 32, 12, 2] and its electron configuration is [Xe] 4f14 5d4 6s2. Tungsten Bohr ModelThe tungsten atom has a radius of 139 pm and a Van der Waals radius of 210 pm. Tungsten was discovered by Torbern Bergman in 1781 and first isolated by Juan José Elhuyar and Fausto Elhuyar in 1783. In its elemental form, tungsten has a grayish white, lustrous appearance. Elemental TungstenTungsten has the highest melting point of all the metallic elements and a density comparable to that or uranium or gold and about 1.7 times that of lead. Tungsten alloys are often used to make filaments and targets of x-ray tubes. It is found in the minerals scheelite (CaWO4) and wolframite [(Fe,Mn)WO4]. In reference to its density, Tungsten gets its name from the Swedish words tung and sten, meaning heavy stone.

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