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Abstract

It is known that the conductance of a bismuth iron molybdate pellet is greatly affected by the stoichiometry (number of oxygen vacancies) of the compound. The number of these vacancies is determined by the amount of reducing vapor (such as ethanol), which tends to increase their number and the amount of oxygen, which tends to decrease it, in the atmosphere. For this reason the compound can be used as a chemical sensor. Earlier measurements of the conductance in a highly reducing methanol vapor atmosphere, determined by measuring the current passing between two gold wires embedded in a pressed pellet, have shown three well-defined stages in the conductance, which are related to solid-state phase transitions occurring on the surface of the pellet granules. In this paper we further examine the nature of these transitions using infrared, Raman, and photoluminescence spectroscopy to follow the structural changes that occur as greater amounts of oxygen are removed. These changes are seen as shifts in relative scattering intensity as well as frequency.

Keywords

Chemical sensor Catalysis Vacancy donor Bismuth iron molybdate Phase transitions

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References

Hykaway

Sears

W. M.

Frindt

R. F.

and Roy Morrison

, Sensors and Actuators 15, 105 (1988).

Sears

W. M.

, Sensors and Actuators 19, 351 (1989).

Batist

PH. A.

Kapteijns

C. J.

Lippens

B. C.

and Schuit

G. C. A

, J. Catal. 7, 33 (1967).

Sancier

K. M.

Aoshima

and Wise

, J. Catal. 34, 257 (1974).

Sancier

K. M.

Dozono

and Wise

, J. Catal. 23, 270 (1971).

Peacock

J. M.

Parker

A. J.

Ashmore

P. G.

and Hockey

J. A

, J. Catal. 15, 387 (1969).

Van Oeffelen

D. A. G.

Van Hooff

J. H. C.

and Schuit

G. C. A

, J. Catal. 95, 84 (1985).

Keulks

G. W.

, J. Catal. 19, 232 (1970).

Wragg

R. D.

Ashmore

P. G.

and Hockey

J. A

, J. Catal. 22, 49 (1971).

10.

Batist

PH. A.

Der Rinderen

A. H. W. M.

Leeuwenburgh

Metz

F. A. M. G.

and Schuit

G. C. A

, J. Catal. 12, 45 (1968).

11.

Krenzke

L. D.

and Keulks

G. W

, J. Catal. 61, 316 (1980).

12.

Kimoto

and Roy Morrison

, Z. Phys. Chem. (NF) 108, 11 (1977).

13.

Matsuura

and Schuit

G. C. A

, J. Catal. 20, 19 (1971).

14.

Hoefs

E. V.

Monnier

J. R.

and Keulks

G. W

, J. Catal. 57, 331 (1979).

15.

Sears

W. M.

, paper submitted to Sensors and Actuators, Sept 11, 1991.

16.

Sears

W. M.

, paper submitted to J. Appl. Phys. Sept 30, 1991.

17.

Jeitschko

Sleight

A. W.

McClellan

W. R.

and Weiher

J. F

, Acta Cryst. B32, 1163 (1976).

18.

Hardcastle

F. D.

and Wachs

I. E

, J. Raman Spectrosc. 21, 683 (1990).

19.

Matsuura

Schut

and Hirakawa

, J. Catal. 63, 152 (1980).

20.

Kovats

W. D.

Hill

C. G.

Jr. , Appl. Spectrosc. 40, 1215 (1986).

21.

Grzybowska

Payen

Gengembre

and Bonnelle

J. P

, Bull. Pol. Acad. Sci. 31, 245 (1983).

22.

Brazdil

J. F.

Mehicic

Glaeser

L. C.

Hazle

M. A. S.

and Grasselli

R. K

, in Catalyst Characterization Science, Surface and Solid State Chemistry, ACS Symposium Series 288 (American Chemical Society, Washington, D.C., 1985), p. 26.

23.

Skliarov

Maximov

Yu.

Margolis

L. Ya.

and Krylov

O. V

, J. Catal. 39, 286 (1975).

24.

Matsuura

Hashiba

and Kanesaka

, Chem. Lett. 533 (1986).

25.

Sleight

A. W.

and Jeitschko

, Mat. Res. Bull. 9, 951 (1974).

26.

Kubelka

and Munk

, Z. Tech. Phys. 12, 593 (1931).

27.

Kubelka

, J. Opt. Soc. Am. 38, 448 (1948).

28.

International Centre for Diffraction Data, 1601 Park Lane, Swarthmore, Pennsylvania (1990).

29.

Roy Morrison

, Sensors and Actuators 2, 329 (1982).

30.

Roy Morrison

, Sensors and Actuators 11, 283 (1987).

Optical Measurements on Heavily Reduced Bismuth Iron Molybdate: Evidence for Vacancy-Induced Phase Transitions

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