Monoclinic/orthorhombic phase transition in Ba sub(2)Cu(HCOO) sub(6): an optical and X-ray powder diffraction study

alpha -Ba sub(2)Cu(HCOO) sub(6) grown at room temperature crystallizes in space group P2 sub(1). On heating a reversible, hysteretic, equitranslational, first-order phase transition at about 60-90 degree C takes place. Here we discuss the influence of thermal treatments on the occurrence, coexistenc...

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Bibliographic Details
Published in:Phase transitions 2000-01, Vol.72 (1), p.15-24
Main Authors: Polla, G, Vega, D, Leyva, A G, de Perazzo, P K, Lanza, H, de Benyacar, M A R
Format: Article
Language:English
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Summary:alpha -Ba sub(2)Cu(HCOO) sub(6) grown at room temperature crystallizes in space group P2 sub(1). On heating a reversible, hysteretic, equitranslational, first-order phase transition at about 60-90 degree C takes place. Here we discuss the influence of thermal treatments on the occurrence, coexistence and stability ranges of the two observed phases, as studied by several techniques (optical microscopy, differential scanning calorimetry and X-ray diffraction). On cooling a single set of domain walls parallel to (001) have been observed. Taking into account experimental results and the crystal pseudosymmetry of the alpha phase we propose that the high-temperature beta phase crystallizes in space group Pbnm.
ISSN:0141-1594