151Eu Mössbauer Study of Calcium Aluminate ... - Springer Link

Journal of Radioanalytical and Nuclear Chemistry, Vol. 246, No. 1 (2000) 57–60

151Eu

Mössbauer study of calcium aluminate glass and glass ceramics containing a small amount of europium(III) T. Nishida,1* Z. Klencsár,2 E. Kuzmann,2 A. Vértes,2 T. Tamaki3 1 Department of Biological and Environmental Chemistry, Kyushu School of Engineering, Kinki University, Kayanomori, Iizuka 820-8555, Japan

2Department of Nuclear Chemistry, Eötvös Lóránd University, H–1518, Budapest, P.O. Box 32, Hungary

3 Department of Physics, Faculty of Science, Ochanomizu University, Otsuka, Bunkyoku, Tokyo 112–8610, Japan (Received May 8, 2000)

151Eu Mössbauer spectrum of IR-transmitting calcium aluminate glass, 60CaO.32Al O .5Fe O .3Eu O , consists of a broad peak due to distorted 2 3 2 3 2 3 . –1 Eu(III) with δ and ∆ values of 0.91 and –2.02 mm s , respectively. Debye temperatures (θD) of 360 and 320 K were obtained from the

δ, respectively. These θD values indicate that Eu(III) atoms occupy substitutional sites δ value of 0.62 mm/s obtained from the heat-treated sample (glass ceramic) . –1 indicates that Eu(III)-O bonds became less covalent. A smaller ∆ value of –1.20 mm s was obtained for Eu(III) in the glass ceramic, indicating

temperature dependence of absorption area (A) and that of

of distorted Al(III)O4 tetrahedra in calcium aluminate glass. The



less distorted Eu(III)O4 tetrahedra.

Introduction

Heat treatment conducted at around the

T c

of 863 °C

resulted in the formation of mayenite.8 Heat treatment at Mössbauer

spectroscopy

has

been

successfully

utilized for the local structural study of sophisticated oxide glasses.1–3 Fe(III) and Sn(IV) occupy the sites of network former (NWF) in several oxide glasses. Very few

151

Eu Mössbauer studies have been reported so far

on the structural study of oxide glass. Crystallization

890 °C (>Tc) resulted in the formation of brownmillerite, 4CaO.Al2O3.Fe2O3, in addition to mayenite.8 Brownmillerite

is

a

family

of

the

solid

solution,

Ca2Fe2–xAlxO5, in which Fe(III) and Al(III) substitute each other in a wide range (0