Enhanced electrical properties and strong red light‐emitting in Eu³⁺‐doped Sr_1.90Ca_0.15Na_0.9Nb₅O₁₅ ceramics

Abstract

The luminescent‐ferroelectic materials based on Sr1.90Ca0.15Na0.9Nb5O15 (SCNN) matrix doping with Eu3+ were synthesized by the conventional solid‐state reaction method. The crystal structure, photoluminescence, thermal stability, dielectric, ferroelectric, and piezoelectric behaviors were systematically investigated. XRD results revealed that Eu3+ introduction could induce the tungsten bronze phase transition from orthorhombic to tetragonal structures. The dielectric spectra of all specimens showed two broad dielectric anomalies: a high‐temperature ferroelectric phase transition (Tc) and a low‐temperature ferroelastic phase transition (Ts), both of which were suppressed at higher Eu3+ concentrations. The enhanced electrical properties were obtained in a proper Eu3+ concentration range of 0.03‐0.05. For all SCNN:xEu3+ samples, the strong red emission peak at 617 nm originating from the electric dipole transition of 5D0 →7F2 was excited by different light excitations of 395 or 463 nm. Our results demonstrated that Eu3+‐doped SCNN materials might have promising potential in advanced multifunctional optoelectronic applications.

Enhancing emission intensity and thermal stability by charge compensation in Sr2Mg3P4O15:Eu3+

“…Meanwhile, when x mol Eu 3+ occupied the Sr 2+ sites, it would yield x /2 mol Sr 2+ ion vacancy which generated x mol positively charged defects. Thus, the positively charged defects and the negatively charged defects would neutralize which realized the charge compensation and improved the emission intensity of phosphors . In this case, the substitution of Si 4+ ions for P 5+ would possibly make less changing of the lattice structure, even smaller than the Na + caused, so, the emission intensity of Si 4+ substituting P 5+ sample was higher than that of the sample of Na + co‐doping.…”

“…In order to better understand the relationship between the temperature and luminescence intensity, the activation energy ( ∆E ) was another important parameter which could better explain the thermal quenching phenomenon. The activation energy could be estimated using the Arrhenius equation:…”

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“…Substitution of Sb 5+ for Nb 5+ produced a change from orthorhombic Ccm2 to tetragonal P4bm Space Group, and shifted T C to lower temperatures [28]. An evolution from orthorhombic to tetragonal crystal system was also induced by Eu 3+ , and there was some indication from ε r -T. The same research group also examined Sm 3+ substitution in relation to thermal luminescent properties [29,30].…”

Investigation of the crystal-oriented behavior of rare earth substituted Sr2NaNb5O15 lead-free piezoelectric materials under a high magnetic field

“…Therefore, it is necessary to design the piezoelectric properties of Eu-substituted SNN by the co-substitution of alkali-Earth elements such as Ca and Ba. [29][30][31][40][41][42][43] When Sr in SNN is replaced with Ca, which has a small ionic radius, and Ba, which has a large ionic radius, the occupancies of the A1 and A2 sites in the crystal structure are changed, causing an increase in the Curie temperature and a change to relaxor ferroelectrics with an increase in the piezoelectric characteristics.…”