pISSN 0374-4914 eISSN 2289-0041

## Research Paper

New Phys.: Sae Mulli 2020; 70: 563-570

Published online July 31, 2020 https://doi.org/10.3938/NPSM.70.563

Copyright © New Physics: Sae Mulli.

## EPR Investigation of Cu$^{2+}$ Ions with CuO Content in Na$_{2}$O-B$_{2}$O$_{3}$-CuO Glasses

Young Hoon KIM, Tae Ho NOH, Seung Kee SONG*

Department of Physics, Myongji University, Yongin 17058, Korea

Correspondence to:sksong902@naver.com

Received: March 27, 2020; Revised: June 4, 2020; Accepted: June 4, 2020

### Abstract

Glasses of the composition $x$Na$_{2}$O-B$_{2}$O$_{3}$-$y$CuO ($x$ = Na$_{2}$O mol% / B$_{2}$O$_{3}$ mol% and $y$ = CuO mol% / B$_{2}$O$_{3}$ mol%) with $x$ = 0.1, 0.3 and $y$ = 0.01 -- 0.07 were prepared using the conventional melt quenching method. EPR (electron paramagnetic resonance) spectral studies of Cu$^{2+}$ ions in the glasses were carried out. From the EPR spectra, the spin Hamiltonian parameters were obtained at room temperature, and the structural variation around Cu$^{2+}$ ions with CuO content were analyzed. EPR data indicate that the ground state of the Cu$^{2+}$ ions in the glass samples is $d_{x^2-y^2}$ orbital ($^{2}$B$_{1g}$ state) and that the Cu$^{2+}$ ions are located in the distorted octahedral site ($D_{4h}$) with tetragonally elongated symmetry along the $z$-axis. Values of $\Delta g$ and $\Delta g_{\parallel}/A_{\parallel}$ with increasing CuO content in the samples with $x$ = 0.1 and 0.3 slightly decreases, indicating that the tetragonal symmetry distortion of the ligand field around the Cu$^{2+}$ ions in the octahedral [CuO$_{6}$] complex decreases. With increasing in CuO content, the values of the optical basicity ($\Lambda_{th}$) slightly increase, which seems to be related with the creation of non-bridging oxygens (NBOs) around the Cu$^{2+}$ ions as Cu$^{2+}$ ions are introduced in to the glass network. With increasing Na$_{2}$O content, the values of the spin Hamiltonian parameters change and the $\Delta g$ and the $g_\parallel/A_\parallel$ values decreases which leads to a decrease the distortion of the ligand field around the Cu$^{2+}$ ions. The values of the optical basicity increase as the Na$_{2}$O content in the glasses is increased.

Keywords: EPR, Glass, Copper Glass