Synthesis, Crystal Structure, and Optical Properties of LiGd5P2O13, a Layered Lithium Gadolinium Phosphate Containing One-Dimensional Li Chains

Temperature dependent structural, vibrational and magnetic properties of K3Gd5(PO4)6

Herein we report the evolution of the crystal structure of K₃Gd₅(PO₄)₆ in the temperature range from 20 K to 1073 K, as observed from variable temperature X-ray diffraction and Raman spectroscopic studies. K₃Gd₅(PO₄)₆ has an open tunnel containing a three dimensional structure built by [Gd₅(PO₄)₆]^3- ions which in turn are formed of PO₄ tetrahedra and GdO_n (n = 8 and 9) polyhedra. The empty tunnels in the structure are occupied by K⁺ ions and maintain charge neutrality in the lattice. Evolution of unit cell parameters with temperature shows a systematic increase with temperature. The average axial thermal expansion coefficients between 20 K and 1073 K are: α_a = 10.6 × 10^-6 K^-1, α_b = 5.5 × 10^-6 K^-1 and α_c = 16.4 × 10^-6 K^-1. The evolution of distortion indices of the various coordination polyhedra with temperature indicates a gradual decrease with increasing temperature, while those of Gd2O₉ and K2O₈ polyhedra show opposite trends. The overall anisotropy of the lattice thermal expansion is found to be controlled largely by the effect of temperature on GdO_n polyhedra and their linkages. Temperature dependent Raman spectroscopic studies indicated that the intensities and wavenumbers of most of the Raman modes decrease continuously with increasing temperature. Anharmonic analyses of Raman modes indicated that the lattice, rigid translation and librational modes have larger contributions towards thermal expansion of K₃Gd₅(PO₄)₆ compared to high frequency internal modes. The temperature and field dependent magnetic measurements indicated no long range ordering down to 2 K and the observed effective magnetic moment per Gd³⁺ ion and the Weiss constant are 7.91 μ_B and 0.38 K, respectively.

Synthesis, photoluminescence and Judd–Ofelt analysis of red LiGd5P2O13 : Eu3+ phosphors for white LEDs

LiGd₅P₂O₁₃ : Eu³⁺ red phosphors were prepared by solid-state reaction method. Phosphors could be efficiently excited by NUV/blue light and emit pure-red light. LiGd₅P₂O₁₃ : Eu³⁺ shows good thermal stability with quantum yield of 46.5%.

Cs6RE2(PO4)4 (RE = Y and Gd): two new members of the alkali rare-earth double phosphates

Two double phosphates with new structural types were prepared and demonstrated to be suitable hosts for luminescence materials.

Spectroscopic properties of Eu3+ doped RbLaP4O12 powders

Monophasic RbLaP4O12 possessing monoclinic symmetry with varied Eu(3+) concentrations was synthesized by flux method. The obtained cyclotetraphosphate exhibits very small crystals and the dopant Eu(3+) ions were successfully incorporated into the sites of La(3+) ions of the host lattice. These compounds were characterized by infrared and Raman spectroscopy, X-ray diffraction (XRD) and luminescence spectroscopy. The spectroscopy properties confirm the potentiality of present RbLaP4O12 doped with Eu(3+) ions as luminophore host materials to produce an intense red luminescence at 616 nm corresponding to (5)D0→(7)F2 emission level and have significant importance in the development of emission optical systems.