Flat interface in the growth of LiNbO3, Bi12SiO20 and Bi12GeO20 crystals from the melt

Cathodoluminescence and photoluminescence in the core region of Bi12GeO20 and Bi12SiO20 crystals

“…1͑b͔͒. The CL emission for Bi 12 SiO 20 ͑BSO͒ samples is very weak out of the core showing a band peaked at about 600 nm. In the core the total CL emission increases considerably due to an intense band peaked at about 625 nm.…”

“…CL spectra for Bi 12 GeO 20 ͑BGO͒ samples are of comparable total intensity in both regions but with different spectral distribution. The yellow region is characterized by two wide bands peaked at about 500 and 620 nm, respectively ͓Fig.…”

“…The details of the equipment and growth experiments have been previously described. 12,14 The starting materials were pure Bi 2 O 3 and GeO 2 or SiO 2 ͑J. Matthey, Grade A1͒.…”

“…1 For technological applications, the best known is Bi 4 Ge 3 O 12 , which is a scintillator material. The sillenite family formed by Bi 12 SiO 20 ͑BSO͒, Bi 12 GeO 20 ͑BGO͒, and Bi 12 TiO 20 ͑BTO͒ is widely employed in different advanced technological applications. 2 All of these compounds can be considered as a stabilized form of ␥-Bi 2 O 3 .…”

“…͑i͒ the composition or ratio of Bi to M in the core, is equal to that in the regions outside the core; 9,10 ͑ii͒ the origin of the core is a consequence of a nonplanar solid-liquid interface during growth, with the appearance of facets; 11,12 and ͑iii͒ the concentration of intentional or unintentional impurities in the core is higher compared to the regions outside the core. 13 In this paper, we have studied the core regions in BGO and BSO crystals by means of the cathodoluminescence ͑CL͒ and photoluminescence ͑PL͒ techniques.…”