Growth, structure, thermal properties and spectroscopic characteristics of Nd3+-doped KGdP4O12 crystal.

Tongqing Sun,Shaolin Chen,Pai Shan,Yongfa Kong,Zichang Zhang,Jingjun Xu,Yu Zhang,Andreas Hofmann

doi:10.1371/journal.pone.0100922

Abstract

A single crystal of Nd3+-doped KGdP4O12 was successfully grown with the top-seeded solution growth and slow cooling (TSSG−SC) technique. It crystallizes in space group C2/c with cell parameters a = 7.812(2) Å, b = 12.307(3) Å, c = 10.474(2) Å, β = 110.84(3)° and Z = 4. The IR and Raman spectra also indicated that the phosphoric polyhedra of Nd:KGdP4O12 has a cyclic symmetry. The chemical composition of the crystal was analyzed and the distribution coefficient of Nd3+ was calculated. The crystal morphology of KGdP4O12 was identified using X-ray diffraction. The compound has good thermal stability to 920°C. Its specific heat and thermal conductivity were determined for potential applications. The spectral properties of Nd:KGdP4O12 indicates that it exhibits broad absorption and emission bands, which are attributed to low symmetry of the crystal. The broad absorption band around 798 nm has a full-width at half-maximum (FWHM) of 14.8 nm and is suitable for AlGaAs laser diode pumping. Moreover, 5 at% Nd3+-doped KGdP4O12 crystal has a long luminescence lifetime of 300 μs and a high quantum efficiency of 96%.

Highlights

With the development of the diode-pumped solid-state (DPSS) lasers based on neodymium-doped crystals, research on new laser host materials has gained much interest [1]
The diffraction peak is intense and with good symmetry without splitting, and its full-width at halfmaximum (FWHM) value is 0.006u. These results demonstrate that the asgrown Nd:KGdP4O12 crystal has a nearly perfect lattice structure
The Nd:KGdP4O12 crystallizes in space group C2/c, and the phosphoric anions have a cyclic geometry of [P4O12]42

Summary

Introduction

With the development of the diode-pumped solid-state (DPSS) lasers based on neodymium-doped crystals, research on new laser host materials has gained much interest [1]. Some Nd3+-doped laser crystals with broad absorption bands have been reported They include host crystals with disordered structures such as NaLn(WO4) (Ln = Y or Gd, I41/a) [2,3], SrLaGa3O7 (P421m) [4], Ca3La2(BO3) (Pnma) [5], Li3Ba2Ln3(MO4) (Ln = Y, La or Gd, M = W or Mo, C2/c) [62 11], KBaGd(MO4) (M = W or Mo, C2/c) [12,13] and CaNb2O6 (Pbcn) [14]. Compared to other double phosphates of alkali and lanthanide ions with the general formula MILnIII(PO3), KGdP4O12 has the following characteristics as a new laser host material. While maintaining the oscillating crucible rotation, the melt temperature was reduced at 0.4uC?d21 until it reached 794uC During this process, the solute first crystallized on the platinum wire, which served as the seed for larger crystals. The step time and step size were 0.1 s and 0.001u, respectively

IR and Raman spectroscopy

Thermal analysis

Results and Discussion

Crystal structure

Absorption spectrum Figure 5 shows the unpolarized absorption spectrum of the

Conclusions