The Magnetic, Electrical and Optical Properties of Rare Earth Er 3+ Doped Lead Borate Glass MOHAMMAD AHMAD-FOUAD BASHA , 1,4 REHAM MORSI MOHAMED MORSI, 2 MORSI MOHAMED MORSI, 3 and AHMAD FOUAD BASHA 1 1.—Physics Department, Faculty of Science, Cairo University, P.O. Box 12613, Giza, Egypt. 2.—Physical Chemistry Department, National Research Centre, 33 El Bohoth Street (Former El Tahrir Street), Dokki, P.O. Box 12622, Giza, Egypt. 3.—Glass Research Department, National Research Centre, 33 El Bohoth Street (Former El Tahrir Street), Dokki, P.O. Box 12622, Giza, Egypt. 4.—e-mail: mafbasha@sci.cu.edu.eg Owing to the unique electronic structure of rare earth elements, we address in this paper the magnetic, electrical and optical properties of a prepared lead borate glass of composition (mol.%) 70PbOÆ30B 2 O 3 . The glass is doped with different ErCl 3 contents. A vibrating-sample magnetometer was used to characterize the magnetic properties. Increasing the additive concentration led to an increase in the saturation magnetization without significant effects on the coercivity. Optical reflectance spectra of the doped glasses revealed the development of absorption bands as a result of Er 3+ intra-configurational (f–f) transitions. The calculated allowed direct energy gap was found to increase monotonically with increasing dopant concentration. The results of the ac conductivity showed a decrease in the activation energy values with increas- ing frequency and an increase in the ac conductivity values with increasing temperature, which mimics the semiconducting behavior. The incorporation of the rare earth ion (Er 3+ ) facilitated the electronic conduction due to the in- crease of the non-bridging oxygen units. Increasing the dopant concentration led also to the participation of the ionic conductions. However, further in- crease of ErCl 3 (above 1 mol.%) caused a decrease in the conductivity. Samples with dopant content up to 1 mol.% ErCl 3 are accompanied by a high dielectric constant value of about 40. It can be concluded that samples doped with 1 mol.% ErCl 3 or less can be used as energy storage material in electronic devices, whereas glass samples with higher dopant content can be used for magnetic applications. Key words: Lead borate glasses, rare earth elements, magnetic properties, optical properties, electrical properties, A.C. conductivity INTRODUCTION Nowadays, use of glass materials has evolved from the simple conventional passive functions to more sophisticated active functions in many optical, electronic, structural, chemical and biochemical interdisciplinary applications. 1 The importance of developing new types of glass with more active functions has recently received great attention and extensive work has been carried out on the design of new glass compositions with particular emphasis on rare-earth-doped transparent glass systems that are characterized by various unique properties. 2–4 Heavy metal borate glass systems, which are based on heavy metal ions during their preparation, are characterized by high refractive indices and higher transmission in the infrared region. 5,6 They have received great attention for their expected use (Received January 19, 2019; accepted July 25, 2019) Journal of ELECTRONIC MATERIALS https://doi.org/10.1007/s11664-019-07487-x Ó 2019 The Minerals, Metals & Materials Society