Electron Spin Resonance of Boron in Single—Crystal BeO

Abstract

Single crystals of synthetic BeO which have been irradiated with 6-MeV electrons show an ESR spectrum at room temperature identified as being due to boron ions substituting for beryllium at normal lattice sites. The hyperfine tensor A is cylindrically symmetric with its principal axis pointing towards one of the near oxygen bonds. Six equivalent directions are observed corresponding to the positions of the nonaxial nearest-neighbor oxygen atoms. The constants of the spin Hamiltonian are: g∥ = 2.0035±0.0005, g⊥ = 2.0044±0.0005, A∥ = 122 Oe, A⊥ = 76.5 Oe. The spectrum is analyzed in terms of the paramagnetic electron occupying an antibonding orbital located along the direction of a B–O bond. Comparison of the observed hyperfine interaction with those expected for the free atom suggests deviations of the orbital from tetrahedral sp3 configuration to one in which the ratio of the p to s contribution increases from √3 to 2.64, implying that the B–O bond is lengthened along the direction in which the paramagnetic electron is stabilized, the bond angle decreasing from 109 to 105 deg.

Defect states in hexagonal boron nitride: Assignments of observed properties and prediction of properties relevant to quantum computation

“…Oxidation of mono-vacancies in h-BN has previously been studied with the aim of investigating the potential degradation of h-BN in the atmosphere and its impact on electronic and magnetic properties [18]. It has been suggested that oxidized species provides the paramagnetic centre producing observed OBC 4-line EPR spectra [21,53]. To understand this effect, we consider a possible V N O 2B structure in which two oxygen atoms substitute boron at the defect site, making the simplest-possible oxidized OBC.…”

“…It has been suggested that oxidized species provides the paramagnetic centre producing observed OBC 4-line EPR spectra [21,53]. To understand this effect, we consider a possible V N O 2B structure in which two oxygen atoms substitute boron at the defect site, making the simplest-possible oxidized OBC.…”

Résonance paramagnétique électronique d'un nouveau centre bore dans BeO irradié aux neutrons

“…La présence de l'ion Bore en substitution dans le réseau cationique a été confirmée en analysant le spectre de résonance du cristal soumis à une irradiation gamma (dose intégrée : 1 Mrad), à température ambiante. Sur ce spectre on distingue les raies correspondant au centre bore étudié par Reinberg [2] et Schirmer [3]. Dans le modèle proposé par ces auteurs, un ion B3+ en substitution dans le réseau cationique capture un électron libéré par l'irradiation et se met sous la forme paramagnétique B2 +.…”

“…-A.MODÈLE. -La façon dont il est créé et ses caractéristiques de résonance électronique nous permettent d'affirmer que ce centre est différent du centre bore précédemment étudié par Reinberg [2] et Schirmer [3].…”

TL, OSL and ESR studies on beryllium oxide

“…Defects identified using ESR and OA and PL studies a. Impurities that might be expected [5,6] to exist in undoped BeO are Mg, Ca, B, Al and Si. Of these, only B 3 + and Al 3 + have been studied by ESR techniques [7,8]. ESR spectra following exposure to ionizing radiation reveal that both of these impurities trap an electron during irradiation to become B 2 + and Al 2 + , respectively, with the electron being trapped in one of the basal antibonding orbitals.…”