Vacancy Ordering Effects in AlB2-type ErGe2-x(0.4 < x < or = 0.5)

• In the Er-Ge system, the compostion range ErGe2 to Er2Ge3 has been investigated. Eight samples were produced by arc melting of the elements, and analyzed using X-ray powder diffraction. Nine crystal structures were found to be present in the samples. The structures are described as a homologous series and presented within the superspace formalism using the superspace group X2/m(0)0s, X representing the centring vector (½, ½, 0, ½). In this description the modulation vector q = (a* + c*) is shown to be a direct measure of the Ge content as ErGe2 -  ( falls in the range to ½). The large composition range is achieved by extended vacancy ordering in the planar 63 net of Ge with subsequent relaxation.

Ämnesord

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Nyckelord

modulation

rare-earth germanides

vacancy ordering.

Chemistry

Kemi

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