Electronic Bonding of Cu2+ in Amorphous and Crystalline TeO2: EPR and Optical Spectra

Abstract

Electron paramagnetic resonance and optical spectra of Cu H ions doped into polymorphic Te02 have been investigated. Spectra were obtained for the non-Zachariasen, octahedrally coordinated amorphous form and for the tetragonal crystalline form. The spectra were interpreted in terms of a molecularorbital model of a Cu H ion in square-planar coordination to the oxygen ligands and compared to results obtained previously for amorphous and tetragonal Ge02. The properties of the dopant Cu H ions in the non-Zachariasen Te02 glass were found to be similar to those of Cu H ions in the Zachariasen Ge02 glass. The Cu H ions were more covalently bonded in the Te02 glass than in the Te02 crystal and less covalently bonded in both forms of Te02 than in the corresponding Ge02 polymorphs.

Crystal Field Splitting of S‐State Ions in Crystalline TeO2 and Amorphous TeO2‐V2O5

“…The results af [18] imply, that the Cu++ ions in the amorphous compound TeO, are more covalently bound than in crystalline TeO,. These Cuff spectra were also interpreted in terms of a model of a Cu++ ion in a square planar coordination to the oxygen ligands.…”

Theoretical investigations of the spin Hamiltonian parameters and local tetragonal distortions for Cu2+in crystalline and amorphous TeO2and GeO2

“…As for the theoretical interpretation for the above experimental results, the previous analysis was generally unsatisfactory [14,15]. First, the simple second-order g formulas were adopted with various adjusted molecular orbital coefficients [14,15].…”

“…First, the simple second-order g formulas were adopted with various adjusted molecular orbital coefficients [14,15]. Moreover, local structures were not involved in the calculations.…”

“…Meanwhile, Cu 2 + impurities doped into crystals may be regarded as model systems due to the relatively simpler energy levels (only one ground state and one single excited state under ideal octahedral crystal-fields [11]) and have been an important topic of electron paramagnetic resonance (EPR) spectroscopic measurements [12,13]. EPR experiments were carried out for low concentration (0.1% mol) Cu 2 + doped crystalline and amorphous TeO 2 and GeO 2 , and the spin Hamiltonian parameters (i.e., anisotropic g factors g and g ⊥ and hyperfine structure constants A and A ⊥ ) were also measured at 77 K [14,15]. As for the theoretical interpretation for the above experimental results, the previous analysis was generally unsatisfactory [14,15].…”

“…EPR experiments were carried out for low concentration (0.1% mol) Cu 2 + doped crystalline and amorphous TeO 2 and GeO 2 , and the spin Hamiltonian parameters (i.e., anisotropic g factors g and g ⊥ and hyperfine structure constants A and A ⊥ ) were also measured at 77 K [14,15].…”