Lasing and spectroscopic properties of calcium-niobium-gallium garnet crystals doped with Tm³⁺ions

Abstract

The recently discovered weak neutral current interaction may give rise to observable parity non-conserving effects in atoms. We have calculated the expected magnitude of the optical rotation in bismuth and find values q5pPNC = 3.0 x IO-' and 4 0 x rad for the I. = 876 and 648 nm allowed MI transitions from the ground state.

Boron Influence on Defect Structure and Properties of Lithium Niobate Crystals

“…Due to the predominance of the covalent bond type, the niobium cation tends to form in the melt anionic motifs consisting of NbO 4 tetrahedra. That is, when LN melts, anionic structure rearranges significantly: the coordination of niobium atoms changes from octahedral to tetrahedral, which is confirmed by Raman spectroscopy data [79][80][81]. Strong covalent bond implies the ability to preserve the structure of oxyanions in the molten state.…”

“…The existence in the melt of strongly bound groups of atoms or ions (clusters) of a certain structure was considered as the main concept in the literature [78]. In [79][80][81], high-temperature Raman spectroscopy was effectively used to study the crystallization from a melt. In the pre-crystallization temperature of a LN melt, the Raman spectra revealed a noticeable change in the structure of the melt and a mismatch between the structure of anionic motifs in the melt and crystal.…”

“…In the pre-crystallization temperature of a LN melt, the Raman spectra revealed a noticeable change in the structure of the melt and a mismatch between the structure of anionic motifs in the melt and crystal. The mismatch effect near the melting point creates serious obstacles to the nucleation of equilibrium structures [79][80][81]. Metastable phases have an advantage in crystallization under these conditions.…”

“…The phases crystal lattice is very far from the structure of the short-range order of the melt. The mismatch in the anionic structure of the melt and crystal can also affect the growth of crystal faces or the formation of structural defects [79,80].…”

“…Strong covalent bond implies the ability to preserve the structure of oxyanions in the molten state. Thus, the melt can contain not only isolated tetrahedral groups, but also complexes with a stable structure [79]. Raman studies of Li 2 O-Nb 2 O 5 system melts have revealed not only bands corresponding to vibrations of terminal NbO 3− and middle NbO 2− groups (815-870 cm −1 ) but also bands corresponding to symmetric stretching bridge vibrations of Nb-O-Nb bonds (670-690 cm −1 ).…”