A.T. Chang

Bio: A.T. Chang is an academic researcher from Argonne National Laboratory. The author has contributed to research in topics: Hexagonal phase & Orthorhombic crystal system. The author has an hindex of 1, co-authored 1 publications receiving 61 citations.

Structural Properties of Lanthanide and Actinide Compounds within the Plane Wave Pseudopotential Approach

Abstract: We show that plane wave ultrasoft pseudopotential methods readily extend to the calculation of the structural properties of lanthanide and actinide containing compounds. This is demonstrated through a series of calculations performed on UO, UO2 ,U O 3 ,U 3O8 ,U C 2, a-CeC2, CeB6, CeSe, CeO2, NdB6, TmOI, LaBi, LaTiO3, YbO, and elemental Lu. PACS numbers: 61.50.Ah, 61.66.Fn The plane wave pseudopotential approach has developed steadily in applicability. Initially, empirical pseudopotentials were constructed for the so-called “easy” elements such as silicon and aluminum. These potentials were used mainly in the prediction and understanding of electronic band structures and were found to be particularly accurate for semiconductors. With the subsequent development of ab initio pseudopotentials and expressions for the accurate calculation of forces and stresses, the plane wave pseudopotential approach has come into its own as the method of choice for the first principles prediction of structural parameters. A combination of improved computing resources, algorithms, and pseudopotential formalisms has allowed the plane wave pseudopotential technique to be applied to ever “harder” elements, such as, initially, the first row elements (including carbon and oxygen), and later the transition metal elements. In this paper we will show

Adaptation of an electrochemical system for measurement and regulation of oxygen partial pressure to a symmetrical thermogravimetric analysis system developed using a Cahn 1000 electrobalance

Abstract: We report equipment consisting of the coupling of an electrochemical system for measurement and regulation of oxygen partial pressure (PO2) to a symmetrical thermogravimetric analysis system built on the basis of a Cahn 1000 electrobalance. The electrochemical system allows the measurement and regulation of PO2 within a few percent, and has the additional advantage that it can be checked against systematic errors in an absolute way by means of the ’’Faraday’s law test.’’ The performance of the whole experimental setup is demonstrated by the resolution of a narrow hysteresis loop shown by PO2 as a function of composition in the U3O8 phase of the uranium–oxygen system.