Computer modelling of the optical behaviour of rare earth dopants in BaY ₂ F ₈

Abstract

BaY 2 F 8 , when doped with rare earth elements is a material of interest in the development of solid-state laser systems, especially for use in the infrared region. This paper presents the application of a new computational technique, which combines atomistic modelling and crystal field calculations in a study of rare earth doping of the material. Atomistic modelling is used to calculate the symmetry and detailed geometry of the dopant ion-host lattice system, and this information is then used to calculate the crystal field parameters, which are an important indicator in assessing the optical behaviour of the dopant-crystal system. Comparisons with the results of recent experimental work on this material are made.

A computational study of intrinsic and extrinsic defects in LiNbO3

“…The application of computer modelling techniques to the study of the defect chemistry of solid state materials is widely established; recent applications to technologically important materials have included topaz, used in dosimeter devices [13], and LiCaAlF 6 /LiSrAlF 6 [14] and BaY 2 F 8 [15], used as solid state laser materials. Use is made of the Mott-Littleton method [16] in which point defects are considered to be at the centre of a region in which all interactions are treated explicitly, while approximate methods are employed for regions of the lattice more distant from the defect.…”

Computer modelling of intrinsic and substitutional defects in LiNbO3

“…The application of computer modelling techniques to study the defect chemistry of solid state materials is widely established; recent applications to technologically important materials reported in the EURODIM/ICDIM series of conferences have included LiCaAlF 6 /LiSrAlF 6 [4] and BaY 2 F 8 [5] used as solid state laser materials. The techniques specify interactions between ions by the use of effective potentials, and use the Mott-Littleton approximation [6] to model point defects and defect clusters in materials.…”

“…The techniques specify interactions between ions by the use of effective potentials, and use the Mott-Littleton approximation [6] to model point defects and defect clusters in materials. Full details of the potential employed can be found in [3], and details of the procedure adopted can be found in [4,5].…”

Crescimento e caracterização de monocristais de BaY2F8:TR onde TR = Nd3+, Pr3+, Er3+, Tb3+, Dy3+

“…Portanto o primeiro estado excitado é essencialmente depopulado de elétrons, exceto em temperaturas muito altas[41].Em função das características estruturais dos cristais do tipo fluoreto, os íons terras-raras sob a forma trivalente podem ser introduzidos em diversas concentrações nestas matrizes. A incorporação da terra-rara no BaYF é dada pela substituição do íon Y 3+[42]. Na tabela 2.2 é indicado o raio iônico e a energia de substituição do íon Y 3+ por TR 3+ no cristal BaYF, calculada por métodos computacionais.Estudos a respeito das propriedades ópticas destes compostos têm confirmado sua potencial aplicação como meio ativo, tanto em materiais simplesmente dopados como em casos de combinação de diferentes tipos de íons terras-raras.A conversão ascendente (up-conversion) refere-se a processos de transferência de energia que produzem populações de estados excitados cujas energias são maiores que a energia do fóton absorvido.…”