Journal of Materials Research

Articles

Modification of the phase transition temperatures in titania doped with various cations

R. Rodríguez-Talaveraa1 c1, S. Vargasa2, R. Arroyo-Murilloa2, R. Montiel-Camposa3 and E. Haro-Poniatowskia3

a1 Departmento de Física, Universidad Autónoma Metropolitana-Iztapalapa Apdo. Postal 55–534, México, D.F. 09340

a2 Departmento de Química, Universidad Autónoma Metropolitana-Iztapalapa Apdo. Postal 55–534, México, D.F. 09340

a3 Departmento de Física, Universidad Autónoma Metropolitana-Iztapalapa Apdo. Postal 55–534, México, D.F. 09340

Abstract

Titania matrices prepared by a sol-gel technique were doped with several cations (La, Zn, Al, K, Na, Ca, Ba, and Co). The effect of the dopants on the thermal and structural properties of the materials is analyzed. The dopant concentration was 2% mol with respect to titanium, and in all cases the same anion (nitrate) was used. The transition temperatures from amorphous to anatase and from anatase to rutile were measured using x-ray diffraction. The amorphous-anatase transition is independent, for almost all samples, of the type of dopant used; however, the anatase-to-rutile phase transition depends strongly on the kind of cation. This means that the temperature range where the anatase phase exists can be controlled by choosing the appropriate dopant. We have found a correlation between the anatase-rutile phase transition temperature and the radius of the cations and their electric charge.

(Received July 21 1995)

(Accepted July 12 1996)

Correspondence:

c1 Author to whom correspondence should be addressed.

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