Whitlockite-Type Structure as a Matrix for Optical Materials: Synthesis and Characterization of Novel TM-SM Co-Doped Phosphate Ca9Gd(PO4)7, a Single-Phase White Light Phosphors

Ivan V Nikiforov,Dmitry A Spassky,Dina V Deyneko,Bogdan I Lazoryak,Sergey M Aksenov

doi:10.3390/min12010076

Ivan V Nikiforov, Dmitry A Spassky + Show 3 more

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https://doi.org/10.3390/min12010076

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Abstract

A series of novel phosphates with the general formulas Ca9Gd0.9−xTm0.1Smx(PO4)7 and Ca9Gd0.9−yTmySm0.1(PO4)7 were synthesized by solid-state method. As-obtained phosphates were characterized by powder X-ray diffraction and second harmonic generation analyses, dielectric measurements, luminescence spectroscopy. All samples were single phase and characterized by the whitlockite-type structure with space group R3c. An influence of admixture concentration of REE3+ ions in the initial host on dielectric properties was studied in details. Synthesized phosphates are characterized by intensive luminescence. The emission in the orange region of the visible spectrum is observed for Ca9Gd0.9Sm0.1(PO4)7 with a maximum intensity band at 602 nm. The line in blue region at 455 nm, which corresponds to 1D2 → 3F4 Tm3+ transition, is registered for Ca9Gd0.9Tm0.1(PO4)7. Emission in the white region of CIE coordinates was registered for Tm-Sm co-doped compounds.

Highlights

The precursors were controlled by the powder X-ray diffraction (PXRD) patterns, and no impurities were detected
The second harmonic generation (SHG) signal was measured with a Q-switched YAG: Nd laser at λω =1064 nm in the reflection mode (Karpov Institute, Moscow, Russia) [17]
(y = 0; 0.1; 0.2; 0.3) phosphates with β-Ca3 (PO4 )2 -type structure were synthesized by a solid0; 0.1; 0.2; 0.3) phosphates with β-Ca3(PO4)2-type structure were synthesized by a solidstate technique

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Inorganic oxysalts with the whitlockite-type structure [in particular, beta-tricalcium phosphate, β-Ca3 (PO4 )2 ] attract interest due to different physical properties [1]. In some compounds with β-Ca3 (PO4 )2 -type structure which contain cations of different oxidation states, the co-doping of admixture quantity ions is necessary to charge balance of the structure. Such doping may change physical properties and crystal structure [7]. A similar study for the phosphate analog has not been published so far, and the role of Tm3+ –Sm3+ co-doping admixture on the crystal structure and phase transitions of Ca9 Gd(PO4 ) remains unknown. Ca9 Gd0.9−x Tm0.1 Smx (PO4 ) and Ca9 Gd0.9−y Tmy Sm0.1 (PO4 ) based on the means X-ray powder diffraction, the second harmonic generation as well as dielectric and luminescence spectroscopy

Materials and Methods

Results

Conclusions