Eu-151 Mossbauer study of calcium aluminate glass and glass ceramics containing a small amount of europium(III)

Eu-151 Mossbauer spectrum of IR-transmitting calcium aluminate glass, 60CaO .32Al(2)O(3).5Fe(2)O(3).3Eu(2)O(3), consists of a broad peak due to distort ed Eu(III) with delta and Delta values of 0.91 and -2.02 mm s(-1), respecti vely. Debye temperatures (theta (D)) of 360 and 320 K were obtained from th e temperature dependence of absorption area (A) and that of delta, respecti vely. These theta (D) values indicate that Eu(III) atoms occupy substitutio nal sites of distorted A(III)O-4 tetrahedra in calcium aluminate glass. The delta value of 0.62 mm/s obtained from the heat-treated sample (glass cera mic) indicates that Eu(III)-O bonds became less covalent. A smaller Delta v alue of -1.20 mm.s(-1) was obtained for Eu(III) in the glass ceramic, indic ating less distorted Eu(III)O-4 tetrahedra.