Characterization of photorefractive undoped and doped sillenite crystals using holographic and photoconductivity techniques

Optical recording mechanisms in undoped titanosillenite crystals

“…Holography ͑and related techniques like two-beam coupling, four-wave mixing, phase conjugation, etc.͒ has been and is still largely employed for studying photosensitive films and volume recording media 5,7,8 and is, particularly, useful for the research on volume, real-time, and reversible materials like photorefractive crystals. [9][10][11][12][13][14][15][16][17] The recording of parasitic holograms has also been reported 18 for the characterization of highly diffractive materials like LiNbO 3 . Holographic erasure after recording 19,20 is, particularly, useful because it is not affected by environmental perturbations and provides a direct measure of the space-charge relaxation response time sc that is inversely proportional to the conductivity…”

First-principles study of the BiMO4antisite defect in the Bi12MO20(M=Si, Ge, Ti) sillenite compounds

“…The nominally pure sillenites possess a complex structure of intrinsic defects [11][12][13][14][15], a fact proven by observation of the PR effect in undoped materials [16][17][18]. Summarizing [11][12][13][14][15], the majority of them involve wrong population of the M site (with nominal valence 4+) which can be partially (I) occupied by the Bi 3+ ion tetrahedrally coordinated by the O ions (Bi M O 4 ), (II) occupied by the Bi 3+ ion coordinated with three O ions (Bi M O 3 ) and with the Bi 6s 2 lone pair pointing in the direction of the fourth absent O, or (III) vacant (VO 4 ).…”

Crystal growth and optical characterization of terbium and niobium doped BTO single crystals

“…In sillenite family, Bi12TiO20 (BTO) crystals present some practical advantages for photorefractive applications, such as lower optical activity, higher electro-optic coefficient, higher photoconductivity and increased sensitivity to red light [1], and the influence of impurities on the properties affecting the photorefractive response of BTO has been subject of extensive research [3][4][5][6][7]. However, the search for new compositions resulting in crystals with improved photorefractive response remains as a present challenge.…”