Phase Diagram for the System PrO_1.83-CaO-CuO

Abstract

We report the phase diagram for the pseudo-ternary system PrO_1.83-CaO-CuO at 970°C in air. This temperature was chosen because partial melting occurs at 1000°C but not at this temperature. Two ternary phases were identified.One is a solid solution fomulated as Pr_40-0.8xCa_xCu_60-0.2xOu (19<x<29). The XRD and electron diffraction patterns could be indexed by assuming orthorhombic structure of the NaCuO₂ type basically: Pr₂₀Ca₂₅Cu₅₅O (x=25) has a=10.693, b=2.825 and c=6.377 [Å] as an example.The structure is. however.modurated one-dimensionally and incommensurately the direction in the reciprocal space shifting from [010]toward [210] as x increases. The other phase, Pr₄Ca₁₀Cu₂₄O ?? . has orthorhombic structure of the Sr₁₄Cu₂₄O ??, type with a=11.279, b=12.464 and c=3.940[Å]. This structure is also one-dimensionally and incomnensurately modulated along the direction of [010].