TY - JOUR

T1 - Synthesis and characterization of niobium doped hexagonal tungsten bronze in the systems, CsxNbyW1-yO3

AU - Dey, Kalpana R.

AU - Debnath, Tapas

AU - Rüscher, Claus H.

AU - Sundberg, Margareta

AU - Hussain, Altaf

N1 - Funding Information: Acknowledgements This study is supported by DFG (RU 764/4-1) and KRD is thankful to DFG for financial support of her renewed stay at Leibniz University Hannover (LUH). AH thanks Alexander von Humboldt Stiftung for financial support through a collaborative research program (V-FOKOOP/DEU/1062067/Hussain). TD and KRD are grateful to ‘‘Land Niedersachsen, Germany’’ for funding Ph.D. research work within ‘‘Lichtenberg Stipendium’’.

PY - 2011/3

Y1 - 2011/3

N2 - Samples of nominal compositions, Cs0.25Nby W 1-yO3 and Cs0.3NbyW 1-yO3 with 0.0 ≤ y ≤ 0.25 and 0.0 ≤ y ≤ 0.3 were synthesized using appropriate amounts of Cs2WO 4,WO3 and WO2 in evacuated and closed silica glass tubes at 800 °C. The polycrystalline products contain hexagonal shaped crystals of up to 15 lmdiameter as long as y ≤ 0.15. X-ray powder patterns of the samples reveal the formation of hexagonal tungsten bronze (HTB-I) type phase with y <0.1. A mixture of HTB-I and an analogous less reduced hexagonal tungsten bronze (HTB-II) type phase is seen when y ≥ 0.1. HTB-II content increases with increasing y, revealing close similarity to bronzoid type phases when y = x. Results of SEM/EDX analysis also support a partial substitution of tungsten by niobiumin the HTB-I type phase. Infrared absorption and optical refiectivity data shows the effect of increasing amount of non-metallic phase for y >0.1 and the effect of counterdoping by Nb5+/W5+ substitution in the metallic HTB-I type phase for y ≤ 0.1, respectively. Reinvestigations in the system Rb0.3Nby W1-yO3 (0.0 ≤ y ≤ 0.175) show similar results with increasing content of HTB-II type phase related with y.

AB - Samples of nominal compositions, Cs0.25Nby W 1-yO3 and Cs0.3NbyW 1-yO3 with 0.0 ≤ y ≤ 0.25 and 0.0 ≤ y ≤ 0.3 were synthesized using appropriate amounts of Cs2WO 4,WO3 and WO2 in evacuated and closed silica glass tubes at 800 °C. The polycrystalline products contain hexagonal shaped crystals of up to 15 lmdiameter as long as y ≤ 0.15. X-ray powder patterns of the samples reveal the formation of hexagonal tungsten bronze (HTB-I) type phase with y <0.1. A mixture of HTB-I and an analogous less reduced hexagonal tungsten bronze (HTB-II) type phase is seen when y ≥ 0.1. HTB-II content increases with increasing y, revealing close similarity to bronzoid type phases when y = x. Results of SEM/EDX analysis also support a partial substitution of tungsten by niobiumin the HTB-I type phase. Infrared absorption and optical refiectivity data shows the effect of increasing amount of non-metallic phase for y >0.1 and the effect of counterdoping by Nb5+/W5+ substitution in the metallic HTB-I type phase for y ≤ 0.1, respectively. Reinvestigations in the system Rb0.3Nby W1-yO3 (0.0 ≤ y ≤ 0.175) show similar results with increasing content of HTB-II type phase related with y.

UR - http://www.scopus.com/inward/record.url?scp=79960894094&partnerID=8YFLogxK

U2 - 10.1007/s10853-010-4932-3

DO - 10.1007/s10853-010-4932-3

M3 - Article

AN - SCOPUS:79960894094

VL - 46

SP - 1388

EP - 1395

JO - Journal of materials science

JF - Journal of materials science

SN - 0022-2461

IS - 5

ER -