Understanding surface structure and chemistry of single crystal lanthanum aluminate.

Title Understanding surface structure and chemistry of single crystal lanthanum aluminate.
Authors S.S. Pramana; A. Cavallaro; J. Qi; C.L. Nicklin; M.P. Ryan; S.J. Skinner
Journal Sci Rep
DOI 10.1038/srep43721
Abstract

The surface crystallography and chemistry of a LaAlO3 single crystal, a material mainly used as a substrate to deposit technologically important thin films (e.g. for superconducting and magnetic devices), was analysed using surface X-ray diffraction and low energy ion scattering spectroscopy. The surface was determined to be terminated by Al-O species, and was significantly different from the idealised bulk structure. Termination reversal was not observed at higher temperature (600?°C) and chamber pressure of 10(-10)?Torr, but rather an increased Al-O occupancy occurred, which was accompanied by a larger outwards relaxation of Al from the bulk positions. Changing the oxygen pressure to 10(-6)?Torr enriched the Al site occupancy fraction at the outermost surface from 0.245(10) to 0.325(9). In contrast the LaO, which is located at the next sub-surface atomic layer, showed no chemical enrichment and the structural relaxation was lower than for the top AlO2 layer. Knowledge of the surface structure will aid the understanding of how and which type of interface will be formed when LaAlO3 is used as a substrate as a function of temperature and pressure, and so lead to improved design of device structures.

Citation S.S. Pramana; A. Cavallaro; J. Qi; C.L. Nicklin; M.P. Ryan; S.J. Skinner.Understanding surface structure and chemistry of single crystal lanthanum aluminate.. Sci Rep. 2017;7:43721. doi:10.1038/srep43721

Related Elements

Aluminum

See more Aluminum products. Aluminum (or Aluminium) (atomic symbol: Al, atomic number: 13) is a Block P, Group 13, Period 3 element with an atomic weight of 26.9815386. It is the third most abundant element in the earth's crust and the most abundant metallic element. Aluminum Bohr Model Aluminum's name is derived from alumina, the mineral from which Sir Humphrey Davy attempted to refine it from in 1812. Aluminum was first predicted by Antoine Lavoisier 1787 and first isolated by Hans Christian Øersted in 1825. Aluminum is a silvery gray metal that possesses many desirable characteristics. It is light, nonmagnetic and non-sparking. It stands second among metals in the scale of malleability, and sixth in ductility. It is extensively used in many industrial applications where a strong, light, easily constructed material is needed. Elemental AluminumAlthough it has only 60% of the electrical conductivity of copper, it is used in electrical transmission lines because of its light weight. Pure aluminum is soft and lacks strength, but alloyed with small amounts of copper, magnesium, silicon, manganese, or other elements, it imparts a variety of useful properties.

Lanthanum

See more Lanthanum products. Lanthanum (atomic symbol: La, atomic number: 57) is a Block F, Group 3, Period 6 element with an atomic weight of 138.90547. Lanthanum Bohr ModelThe number of electrons in each of lanthanum's shells is [2, 8, 18, 18, 9, 2] and its electron configuration is [Xe] 5d1 6s2. The lanthanum atom has a radius of 187 pm and a Van der Waals radius of 240 pm. Lanthanum was first discovered by Carl Mosander in 1838. In its elemental form, lanthanum has a silvery white appearance.Elemental Lanthanum It is a soft, malleable, and ductile metal that oxidizes easily in air. Lanthanum is the first element in the rare earth or lanthanide series. It is the model for all the other trivalent rare earths and it is the second most abundant of the rare earths after cerium. Lanthanum is found in minerals such as monazite and bastnasite. The name lanthanum originates from the Greek word Lanthaneia, which means 'to lie hidden'.

Related Forms & Applications