Crystal Growth and Spectroscopic Characterisation of BiB3O6:RE3+ (RE3+ = Pr3+, Nd3+, Gd3+, Er3+, Tm3+)

Ambient pressure synthesis of Eu3+ doped δ-BiB3O6 by seed-assisted high temperature solid state reactions

A high level of Eu³⁺ (7 atom%) was doped successfully, suggesting the possible single crystal growth of bi-functional RE³⁺-doped δ-BiB₃O₆.

First-principles calculation of vibrational frequencies for monoclinic tribismuth borate BiB3O6

Monoclinic BiB3O6 is an excellent nonlinear optical material with many advantages compared to other borate crystals. As one part of understanding the properties of BiB3O6, the harmonic frequencies of BiB3O6 are calculated by applying the numerical-difference technique based on first-principles gradient-corrected hybrid B3PW density functional theory electronic structure calculations within the Gaussian-orbital-based CO-LCAO scheme. The complete 13A and 14B vibrational modes are assigned, graphically visualized and classified according to the Bi—O and B—O motions. Comparisons with previous experimental reports are discussed in detail.

Crystallization of bismuth borate glasses

Bismuth borate glasses with Bi(2)O(3) concentration of 20-66 mol% were prepared by melt quenching and devitrified by heat treatment above their glass transition temperatures. All glasses show a strong tendency towards crystallization on annealing that increases with Bi(2)O(3) concentration. The crystalline phases formed on devitrification were characterized by FTIR absorption spectroscopy and DSC measurements. Our studies reveal that phases produced in glasses are strongly determined by initial glass composition and the two most stable crystalline phases are: Bi(3)B(5)O(12) and Bi(4)B(2)O(9). The metastable BiBO(3) phase can also be formed by devitrification of glass with 50 mol% of Bi(2)O(3). This phase is, however, unstable and decomposes into Bi(3)B(5)O(12) and Bi(4)B(2)O(9) on prolonged heat treatment.

First-Principles Electronic Structure Study of the Monoclinic Crystal Bismuth Triborate BiB3O6

Monoclinic BiB(3)O(6) is an excellent nonlinear optical material with many advantages compared to other borate crystals. The origins of the optical effects and the chemical stability of BiB(3)O(6) are studied with gradient-corrected hybrid B3PW density functional theory within the Gaussian-orbital-based CO-LCAO scheme. Including spin-orbit coupling, the B3PW hybrid functional provides an estimate of the indirect band gap of 4.29-4.99 eV closer to the experimental value of 4.3 eV than HF, LDA, or GGA. The crystal orbital overlap population to give a detailed first-principles analysis of chemical bonding and the density of optical absorptions by convoluting the occupied density of states and the virtual density of states have been calculated. Obvious Bi-O covalent bonds have been found with different energy ranges for 6s-2p and 6p-2p interactions. The reason that [BiO(4)](5-) units are mainly responsible for the optics of BiB(3)O(6) in the long-wavelength region is due to the electronic transfer from occupied O 2p to empty Bi 6p orbitals favored by the Bi-O covalent bonds. The relativistic and correlation effects lead to fundamental differences of the band structure, chemical bonds, and optical effects for BiB(3)O(6) compared with nonrelativistic and uncorrelated calculations.