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Repozytorium publikacji
Politechniki Gdańskiej

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Superconductivity and appearance of negative magnetocaloric effect in Ba1–xKxBiO3 perovskites, doped by Y, La and Pr

Recently, substantial attention is given to the bismuth-based perovskites for variety of electronic applications. The perovskites are used for quantum dots displays (QLED), photovoltaic systems and superconducting (HTS) devices. In this paper comprehensive studies of Ba1–xKxBi1–yREyO3 bismuth perovskites (REBKBO, RE = Y , La or Pr) are reported. Apart from structural anomalous behavior at low temperatures, the electronic properties of the REBKBO can be easily tailored by doping. For instance, critical current den- sities differ by 3 orders of magnitude from 0.07 kA/cm2 (LaBKBO) to 65 kA/cm2 (BKBO). To explain the above behavior, microstructural, magnetic, calorimetric, spectroscopic (FT-IR) studies and ab-initio electronic structure calculations were carried out. The FT-IR shows that the biggest difference in the spectrum compared to the undoped sample was recorded for PrBKBO, due to magnetic contribution of the Pr3+ multiplet. Electronic structure calculations revealed that the BKBO compound shows the highest DOS(EF) compared to the other samples, however, the electronic structure of PrBKBO is very different. The negative magnetocaloric effect observed below 30 K is a highlight of the peculiar properties of that sample. These findings extend possible usage of bismuth-based perovskites towards new applications.

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