Synthesis and characterisation of alkali metal tungsten bronzes, Li_1tnxWO_1tn3 and M_1tnxM'_1tnyW_1tn1_1tn-_1tnyO_1tn3 (M'=Li, Na, Cs and M'=Nb, Mo) systems [Elektronische Ressource] / von Kalpana Rani Dey

SYNTHESIS AND CHARACTERISATION OF ALKALI METAL TUNGSTEN BRONZES, Li WO AND M M ′ W O (M = Li, Na, Cs and x 3 x y 1-y 3M ′= Nb, Mo) SYSTEMS Vom Fachbereich Geowissenschaften und Geographie der Universität Hannover zur Erlangung des Grades Doktor der Naturwissenschaften Dr. rer. nat genehmigte Dissertation von: Kalpana Rani Dey Geboren am 17. Januar 1971 in Dhaka, Bangladesh Dezember, 2004 Referent: PD Dr. C. H. Rüscher Korreferent: Prof. Dr. J. –Ch. Buhl Prof. Margareta Sundberg Tag der Promotion: 26.11.2004 Datum der Veröffentlichung: Dezember, 2004 ABSTRACT i ABSTRACT Keywords: Tungsten bronze systems: Li-Nb-PTB/Cs-Nb-HTB, optical properties, Phase stability range Synthesis and characterisation of Li WO (x = 0.03 – 0.7), Li Nb W O (x = 0.1, 0.4; y = x 3 x y 1-y 3 0.00 – 0.4), Li Mo W O (x = 0.1, 0.4; y = 0.00 – 0.3), Na Mo W O (y = 0.00 – 0.25) x y 1-y 3 0.6 y 1-y 3 and Cs Nb W O (x =0.25, 0.3; y = 0.00 – 0.2) systems have been studied. Powder samples x y 1-y 3 were prepared by solid state method at 700°C for 7 days. Single crystals of Li WO (x = 0.1 – x 30.45) system were grown by chemical vapour transport method using HgCl transporting agent 2 in a temperature gradient T / T = 700°C / 800°C.