Synthesis, EPR and optical spectroscopy of the Cr-doped tetraborate glasses

EPR, optical absorption and luminescence studies of Cr3+-doped antimony phosphate glasses

“…In an octahedral crystal field, its ground state is an orbital singlet 4 A 2 (F). Under the field action of a low symmetric component and spin-orbit coupling, the fourfold spin degeneracy of 4 A 2 (F) is removed, splitting by zero-field splitting into two Kramers doublets M s = ±3/2 and M s = ±1/2 [11,20]. In glasses a large separation between the two doublets leads to a resonance at g = 2-6.…”

“…The effective g value in the low magnetic field portion of the spectrum (g = 5.11) is attributed to isolated Cr 3+ ions in distorted octahedral sites [14,15,22]. The effective g value in the high magnetic field (g = 1.97) is associated with the contribution of both exchange coupled pairs of Cr 3+ ions (antiferromagnetic Cr 3+ -Cr 3+ ) which are individually sixfold coordinated and isolated Cr 3+ ions at axiallydistorted octahedral sites [11,14,18,23].…”

“…1b), was attributed to isolated Cr 3+ ions at strongly-distorted octahedral sites. The more complex and broadened EPR signal at the high-magnetic-field region (SbPO6Cr) can also be associated with Cr 3+ -Cr 3+ exchange-coupled pairs or small clusters of several exchangecoupled Cr 3+ ions [11]. These characteristics observed in the EPR spectrum of the heavily doped glass sample suggest the existence of different Cr 3+ isolated centers, what explain the dependence of the EPR signals (g = 5.11 and g = 1.97) with chromium concentration.…”

“…Antimony phosphate glasses present enhanced non-linear optical properties [7], photosensitivity [8,9], and AC conductivity [4]. Furthermore, Cr 3+ -doped systems have technological applications such as high temperature sensors, tunable solid-state lasers, and others [10][11][12], the Cr 3+ ion being one of the most studied and efficient activators in a host matrix, which possesses luminescence spectrum in the visible and near infra-red region.…”

Optical spectroscopy of Li2B4O7, CaB4O7 and LiCaBO3 borate glasses doped with europium

“…Borate crystals and glasses, both undoped and doped with rare-earth and transition elements, are very promising materials for nonlinear optics and quantum electronics [1][2][3][4][5][6], scintillators, thermoluminescent dosimeters [7][8][9][10][11], gamma and neutron detectors [12][13][14], and many other applications. This especially applies to single crystals of lithium tetraborate (Li 2 B 4 O 7 ) characterized by extremely high radiation stability [15,16], good thermoluminescent properties [9][10][11] and high transparency in the wide interval beginning from vacuum ultraviolet (UV) to middle infrared (IR) ranges [17].…”