Structural study of monoclinic KGd(WO₄)₂and effects of lanthanide substitution

Abstract

The crystal structure of monoclinic KGd(WO4)2 (KGW) has been refined at room temperature by using single‐crystal X‐ray diffraction data. The unit‐cell parameters are a = 10.652 (4), b = 10.374 (6), c = 7.582 (2) Å, β = 130.80 (2)°, with Z = 4, in space group C2/c. The linear thermal expansion tensor has been determined and the principal axes are [302], [010] and [106]. The principal axis with maximum thermal expansion ( = 23.44 × 10−6 K−1), , was located 12° from the c axis. Undoped crystals of KGW and crystals that were partially doped by Pr, Nd, Ho, Er, Tm and Yb were grown by the top‐seeding‐solution growth slow‐cooling method. The effect of doping on the KGW structure was observed in the cell parameters and in morphological changes. The changes in parameters follow the changes in lanthanide ionic radii. The doped crystals show {021} and {21} faces in addition to the {110}, {11}, {010}, {130} and {310} faces which basically follow the habit of the undoped KGW crystals. The development of the faces is related to the number of the most important periodic bond chains parallel to them.

Thulium doped monoclinic KLu(WO4)2 single crystals: growth and spectroscopy

“…Tm:KLuW crystals were grown by the TSSG-SC method using K 2 W 2 O 7 as the solvent and the growth methodology described elsewhere [12,13]. The chemical composition of the single crystals was measured by electron probe TS a Unit should be mm 3 .…”

Sensitization ofEr3+emission at1.5μmbyMateos1, Pujol2, Güell3 et al. 2002Phys. Rev. BSelf Cite

“…The temperature gradient in the solution was 0.13 K/mm and the saturation temperature was between 1173 and 1178 K. Other crystal growth data are given in Table I. Previous studies 18 show that the dopant ions are located in the rare-earth crystallographic position of the host (KREW, in our case REϭYb). A distribution coefficient close to 1 means that the solute composition is conserved in the crystal.…”

“…From these two observations we conclude that the crystal field of KYbW is stronger than in KGW, which agrees well with smaller interatomic distances 22 Yb-Yb presented in KYbW than 11 the distances Gd-Gd, presented in KGW. 18 Also, the Judd-Ofelt parameters of erbium in KYbW ͑calcu-lated later͒ and those of KGW, 21 showed the influence of this crystal field, in which the Judd-Ofelt parameters of KYbW were larger than those of KGW.…”

Thermal lens study in diode pumped Ng- and Np-cut Nd:KGd(WO_4)_2 laser crystals

“…The modified Czochralski technique was used under conditions of low thermal gradient [20]. The N p -cut Nd:KGW laser gain medium was grown along the crystallographic axis b which is parallel to the principle refractive axis N p , whereas, the N g -cut Nd:KGW material was grown along the crystallographic axis c (the angle between the c-and N g -axis is 21.5° [21]). Other properties of the N p -and N g -cut Nd:KGW crystals were identical.…”