Local chemical environment of [Nd.sup.3+], [Eu.sup.3+], and [Er.sup.3+] luminescent centers in lead germanate glasses

The extended x-ray absorption fine structure at the Ln [L.sub.III] edges were used to study the local chemical environment of [Nd.sup.3+], [Eu.sup.3+], and Er.sup.3+] luminescent centers in various lead germanate glasses.The results showed that for all the [Ln.sup.3+] ions, first coordination sphere is more symmetrical in glasses with high lead concentration than in glasses with low Pb content.