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

authored by

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.

Organisation(s)

Institute of Mineralogy
Institute of Inorganic Chemistry

External Organisation(s)

University of Groningen

Type

Article

Journal

Physica C: Superconductivity and its Applications

Volume

219

Pages

471-482

No. of pages

12

ISSN

0921-4534

Publication date

15.01.1994

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials, Condensed Matter Physics, Energy Engineering and Power Technology, Electrical and Electronic Engineering

Electronic version(s)

https://doi.org/10.1016/0921-4534(94)90402-2 (Access: Closed)