Structural and Optical Characterization of Ytterbium Doped Lutetium Double Phosphates

Abstract

Abstract. Powder samples of the ternary phosphates A 3 Lu(PO 4 ) 2 :Yb 3ϩ (A ϭ Na, Rb) have been synthesised by solid state reactions. The spectroscopic properties of Yb 3ϩ in double phosphate host lattices were investigated using absorption, emission and excitation spectra at 4, 10 and 293 K in the VUV to IR range. The results obtained for both types of phosphates are compared. Together with the fundamental 2 F 5/2 Ǟ 2 F 7/2 emission in the IR range, a broad band emission with two peaks in the UV region Compounds containing Yb 3ϩ ions have potential applications as laser devices because of their simple electronic structure. There is no concentration quenching and no excited state absorption reducing the effective laser crossrelaxation process. The Yb 3ϩ ion exhibits intense and broad absorption bands in the IR region which is suitable for a diode-pumped laser. It was reported that ytterbium-doped lasers have longer emission lifetimes than the Nd 3ϩ -doped materials. All these properties of Yb 3ϩ indicate that the ytterbium-doped materials seem to be more promising than the neodymium-doped systems, already employed in laser materials. The fundamental luminescence of the Yb 3ϩ ion originating from the 2 F 5/2 Ǟ 2 F 7/2 transitions between the manifold of Stark-splitted levels occur in the IR range around 1000 nm.While searching for interesting laser host materials for solid state lasers, alkali rare-earth double phosphates of the M 3 RE(PO 4 ) 2 type were studied by several authors [1Ϫ10]. These compounds have their host absorption edge at a rather short wavelength which makes them suitable as host lattices for various luminescent materials.In addition to the intraconfigurational 4f-4f transitions, a broad emission band (called charge transfer band, CT) were observed in Yb 3ϩ -activated Na 3 Lu(PO 4 ) 2 . The second emission is due to a chargeϪtransfer transition type. The influence of the alkali metal cation site of the host lattice on the luminescence properties was investigated. The tentative energy level scheme of the ground and excited 2 F J (Jϭ7/2, 5/2) levels is described.

Charge transfer and f–f emission of trivalent ytterbium observed in double phosphates MIMIII(PO4)2 (MI=Na, Rb; MIII=Lu, Y)

“…Knowledge about the crystal structure and spectroscopy of lutetium double phosphates with sodium and rubidium of the M 3 Lu(PO 4 However, these structural investigations are very important, since substitution of the Y 3+ ion by Lu 3+ in the materials codoped with the Yb 3+ ions reduces the solarisation effects and improves the lasing performance, as was reported by several authors [7]. In the current article, we continue our studies initiated in the last year and devoted to the new ytterbium-doped lutetium double phosphates of the sodium and rubidium salts [9][10][11]. A comparison of the luminescence characteristics of all the Yb-containing double phosphates will be made.…”

“…3). Since the results of the absorption measurements of ytterbium-doped M 3 Y(PO 4 ) 2 and M 3 Lu(PO 4 ) 2 at room temperature have been already studied in detail [9][10][11], we now present some additional results for these compounds. An important fact worth noting is that the absorption spectra for both rubidium and sodium yttrium double phosphates are more complex than those observed at 293 K. However, when one compares the yttrium and lutetium compounds, it becomes clear that the shape of the spectrum of M 3 Lu(PO 4 ) 2 :Yb 3+ is different than that of M 3 Y(PO 4 ) 2 :Yb 3+ .…”

“…On the basis of relationships between the total CF splitting of the 2 F 7/2 and 2 F 5/2 levels we propose the energy level schemes for all kinds of the investigated samples (Fig. 4) [10,11].…”

“…Ytterbium doped compounds are constantly the object of extensive structural and spectroscopic investigations, which are motivated by their important physical and optical properties [1][2][3][4][5][6][7][8][9][10][11]. The Yb 3+ ion could be used as the laser-emitting center because of its luminescence occurring at about 1 m. Moreover, among the lanthanide (III) ions, Yb 3+ is the only one that exhibits the charge transfer emission.…”

Spectroscopy and structural characteristic of Yb3+ and Nd3+ ions doped nanostructured Lu2O3 and sol–gel derived silica host materials

“…Because of the large energy difference between its charge transfer state and the highest 4f excited state charge transfer luminescence is in some cases possible. Such a luminescence was reported by Nakazawa [2,3] and later by Van Pieterson et al in different hosts [4], and also by us [5,6], but not in nanostructured Lu 2 O 3 obtained by the solution combustion method. Lu 2 O 3 is a valuable host material for various activators [1,[7][8][9], because of good thermomechanical properties, low phonon energy, structural similarity (cubic structure) to others lanthanide sesquioxides.…”