Bipolaron absorption in Ba_{1 - x}K_xBiO₃ and Ba_0.6K_{0.4 - x}Cs_xBiO₃

verfasst von

C. H. Rüscher, A. Heinrich, W. Urland

Abstract

We present new results on the optical absorption of the family of compounds K_xBa_{1 - x}BiO₃ (KBB) and Cs_xK_{0.4 - x}Ba_0.6BiO₃ (CKBB) (0 < x < 0.4) using powder methods. All cubic compounds of the KBB system (x ≥ 0.3, T_c ≈ 30 K) possess a broad near- infrared (NIR) absorption band, which appears to evolve on increasing the K dopant content with respect to the noncubic compounds (x < 0.3), which show no T_c. For the series of solid solution with Cs substitution for K (i.e. no change in the nominal charge carrier concentration), we observe a strong increase of the absorption in the visible range with increasing Cs content, simultaneous to the gradual decrease of T_c. The NIR absorption is analysed using the theory for small polaron absorption in disordered media. The results indicate the formation of intersite bipolarons. Characteristic differences in the absorption behaviour with the high-T_c family Bi₂Sr₂Ca_{1 - x}Y_xCu₂O_{8 + δ} (BSCC) are outlined.

Organisationseinheit(en)

Institut für Mineralogie
Institut für Anorganische Chemie

Externe Organisation(en)

Reichsuniversität Groningen

Typ

Artikel

Journal

Physica C: Superconductivity and its Applications

Band

219

Seiten

471-482

Anzahl der Seiten

12

ISSN

0921-4534

Publikationsdatum

15.01.1994

Publikationsstatus

Veröffentlicht

Peer-reviewed

Ja

ASJC Scopus Sachgebiete

Elektronische, optische und magnetische Materialien, Physik der kondensierten Materie, Energieanlagenbau und Kraftwerkstechnik, Elektrotechnik und Elektronik

Elektronische Version(en)

https://doi.org/10.1016/0921-4534(94)90402-2 (Zugang: Geschlossen)