Journalartikel

Jahr der Veröffentlichung: 1997

Seiten: 51-61

Zeitschrift: Journal of Alloys and Compounds

Bandnummer: 246

Heftnummer: 1-2

ISSN: 0925-8388

DOI Link: https://doi.org/10.1016/S0925-8388(96)02470-X

Verlag: Elsevier

Abstract: 

Attempts have been made to grow crystals of alkali metal hexagonal (HTB) and tetragonal (TTB) tungsten bronzes (M(x)WO(3)) by chemical transport in a temperature gradient. Different transport agents were used (HgCl2, HgBr2, HgI2, Cl-2, PtCl2). Needle-shaped crystals of up to 6 mm in length could be grown using only HgCl2 and HgBr2. It was observed that the size of HTB crystals and the transport rate drop with increasing content of alkali metal. TTB crystals larger than 0.1 mm in dimensions could not be prepared.

The electrical properties of different crystals have been investigated by reflection spectroscopy in the spectral range from 600 to 20 000 cm(-1). The spectral properties can be explained by using the Drude free carrier model. According to this there are plasma frequencies which are shifted systematically towards larger values for larger x, and anisotropic effective masses m*(E perpendicular to)approximate to 3m*(E parallel to c) with m*(E perpendicular to c) between 0.5 and 1.3 which also increase systematically with respect to x. An exclusion from Drude behaviour is observed for K-HTB for the E parallel to c polarization. For these cases the line profile can better be described using a Lorentz-oscillator model.

Harvard-Zitierstil: Hussain, A., Gruehn, R. and Ruscher, C. (1997) Crystal growth of alkali metal tungsten bronzes M(x)WO(3) (M=K, Rb, Cs), and their optical properties, Journal of Alloys and Compounds, 246(1-2), pp. 51-61. https://doi.org/10.1016/S0925-8388(96)02470-X

APA-Zitierstil: Hussain, A., Gruehn, R., & Ruscher, C. (1997). Crystal growth of alkali metal tungsten bronzes M(x)WO(3) (M=K, Rb, Cs), and their optical properties. Journal of Alloys and Compounds. 246(1-2), 51-61. https://doi.org/10.1016/S0925-8388(96)02470-X