Structural and optical properties of calcium neodymium hexaaluminates single crystals, potential laser materials

Cationic Distribution and Spectral Properties of Nd3+ in Hexa-aluminate Laser Crystals

“…The polarization absorption of the C 1 centers indicate clearly that the symmetry of the various centers from this family cannot be considered as D 3h , but one cannot speak of a given symmetry. This behavior is consistent with the considerably larger effects of crystal field perturbations on the energy levels of these centers and the deviation from ideal D 3h symmetry at Nd 3+ ions, for large x, that has been remarked in X-ray analysis [3].…”

“…In the early spectroscopic investigations of Nd 3+ in (Ln, Mg) strontium hexa -aluminate Sr 1-x Nd y La xy Mg x Al 12-x O 19 -ASL: Nd or ASN (for x=y) [2][3][4][5][6], a single center structural model for Nd 3+ ion, that replaces Sr 2+ in (2d) sites was used. This model has been based on X-ray, EPR and especially on the presence of a single line in the low temperature 4 I 9/2 → 2 P 1/2 absorption spectra.…”

“…The charge compensation can be accomplished by a partial substitution of Al 3+ with Mg 2+ [2][3]. The high O 2-coordination (12 near neighbors) of Nd 3+ (2d) site and its large size determines a high position of the 4 F 3/2 manifold as well as a moderate crystal field splitting of 4 I 9/2 manifold to avoid reabsorption.…”

“…The crystal growth studies of ASL: Nd 3+ show that congruent melting are connected with composition parameter x, for low x the melting is not congruent [4]. Thus, the range of x parameter (x≤1) is limited by the crystal growth conditions to x≥0.2, and the Nd 3+ content can be diluted within the limits imposed by the concentration self-quenching of Nd 3+ emission by the optically inert La 3+ ions [5] The Nd 3+ spectra in (Ln, Mg) strontium hexa-aluminates, ASN or ASL, have been initially interpreted in terms of a unique center model [2][3][4][5][6]. Recent high-resolution spectral investigations [7][8] on ASL: Nd samples with 0.2≤x≤0.4 and 0.05≤y≤0.15 have revealed the clear presence of the two structural centers, C 1 and C 2 .…”

CW blue laser emission by second harmonic generation of 900-nm oscillation of Nd-doped strontium and lanthanum aluminate (ASL)

“…It belongs to the uniaxial hexagonal magnetoplumbite structure. The neodymium ions lie in a 12 fold-coordinated axial site of D 3h point symmetry, with Sr(Nd) -O distances ranging from 2.69 to 2.79 Å [5]. Growth of large and optical quality crystals of Nd:ASL by Czochralski pulling technique has already been achieved [6][7].…”