NQR study of chalcogenide glasses Ge‐As‐Se

Abstract

A three-component Ge-As-Se system is studied by the nuclear quadrupole resonance (NQR) method on (75)As nuclei and by the nutation NQR spectroscopy. The NQR (75)As spectra of the glasses Ge(0.021) As(0.375) Se(0.604), Ge(0.043) As(0.348) Se(0.609) and Ge(0.068) As(0.318) Se(0.614) reveal broad lines with two peaks assigned to the main structural unit of As(2)Se(3). With increasing average coordination number ( ̅r), the spectrum signals are shifted towards higher frequencies. At ̅r > 2.54, the spectrum becomes complex, which is a consequence of formation of more complex molecular structures in the glasses of high content of germanium. At fixed frequencies the asymmetry parameter η of the samples studied is determined.

Experimental study of the structure of chalcogenide glassy semiconductors in three-component systems of Ge-As-Se and As-Sb-Se by means of NQR and EPR spectroscopy

“…leading to effects of the formation of clusters. The 75 As NQR spectra and their frequencies and linewidths for chalcogenide semiconductors of Ge-AsSe different compositions are presented in our previous work [9]. The results of our study of the NQR spectra for the samples of this system show that changing their chemical composition leads to significant differences in the NQR spectra.…”

“…It has been found that function η (¯ ), exhibits a maximum at r = 2.425 which probably indicates a change in the glass structure. Table 2 shows the frequency and width of NQR 75 As in Ge-As-Se glasses (T = 77 K) from the works [6,9]. Fig.…”

“…Publications [9,10] include the NQR spectra and spectral parameters of 75 As, 121 Sb and 123 Sb (T = 77 K) glassy systems of Ge-AsSe and As-Sb-Se in the frequency range of 48-70 MHz. For the As-Sb-Se system, the NQR spectra indicate that besides the lines from the two nonequivalent positions of arsenic 75 As nuclei, there are also the lines observed from the nuclei 121 Sb and 123 Sb, which complicates the NQR spectrum itself and its interpretation.…”

Study of the EFG tensor at 75As nuclei in Ge‐As‐Se chalcogenide glasses

“…The application of NQR to study disordered systems, in particular glassy semiconductors, is based on the relation between their structure and the distribution of magnitudes of the electric field gradient (EFG) at the quadrupolar nuclei. Applying new research methods in the NQR spectroscopy [on the basis of the spin echo signal theory for very wide NQR lines and on examining the geometrical phase (Berry phases) of NQR signals] to determine the asymmetry parameter of the EFG in the examined semiconductors allowed much information to be obtained in relation to the local structure of these compounds …”

Study of As-Sb-Se chalcogenide glasses by NQR and EPR spectroscopy methods

“…Recently nuclear quadrupole resonance (NQR) spectroscopy has been employed to study the structure of disordered solids [1][2][3][4][5][6]. A second spectroscopic method that has been used for the same goal is the electron paramagnetic resonance * E-mail: glotova@amu.edu.pl (EPR) spectroscopy [7].…”