EPR study of coordination of Ag and Pb cations in BaB2O4 crystals and barium borate glasses

Raman scattering study of crystalline and melting states of BaO·2B2O3

“…7) shows that spectra of these two phases differ considerably (Table 1). We think that the shift of the low-frequency peaks and wide bands in the region 300-500 cm À 1 and their further splitting into b-BaB 4 O 7 (D¼ 94.7 À68.2 ¼26.5 cm À 1 ) compared to a-BaB 4 O 7 (D¼61.5 À49.8 ¼11.7 cm À 1 ) suggests changes in the structure and symmetry of the coordination polyhedra (associative complexes [9]). This agrees well with the results of the structural analysis [8].…”

Growth and optical properties of Nd 3+ -doped Ba 2 Na 3 [B 3 O 6 ] 2 F crystals

“…At lower sodium content the TSL peaks at 80-90ºɋ had demonstrate emission near 360 nm [17,18]. This evidences that PLE bands for 300-450 nm emission, located in the 200-215, 220-250, and 250-295 nm ranges belong to different luminescence centers [18][19][20][21][22][23]. Here, one can observe different energy states for sodium ions depending on their position in the structure: in the case of cation antisite defect (Na + → Ba 2+ ) or Na + in channel positions, with formation of Ba and Ɉ vacancies [11][12][13]16].…”

“…This evidences that PLE bands for 300-450 nm emission, located in the 200-215, 220-250, and 250-295 nm ranges belong to different luminescence centers [18][19][20][21][22][23]. Here, one can observe different energy states for sodium ions depending on their position in the structure: in the case of cation antisite defect (Na + → Ba 2+ ) or Na + in channel positions, with formation of Ba and Ɉ vacancies [11][12][13]16]. We suppose that upon introduction of Re 3+ (Nd 3+ ) ions into ȼȼɈ and Ba 2 Na 3 [B 3 O 6 ] 2 F structure, the charge compensation for RE ions can be realized both by formation of barium vacancies (2 Re 3+ →2 Ba 2+ + V Ba ) and Ba 2+ replacing with Na + (Re 3+ → Ba 2+ , Na + → Ba 2+ ).…”

“…Intense broad band near 330 nm in RL spectrum (Fig.5) is likely related to native defects in the Ba 2 Na 3 [B 3 O 6 ] 2 F crystal lattice. These can be vacancies of barium or oxygen which produce deep levels in the forbidden zone [11][12][13]16].…”

“…4). These short-wave bands are likely due to native defects in the lattice [11][12][13]. Taking into account that vibration spectrum of Ba 2 Na 3 [B 3 O 6 ] 2 F covers the 0 to 800 cm -1 range we suppose that absorption at Ȝ>3 ȝm in the mid-IR is due to three-phonon absorption.…”