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Neodymium europium oxynitridosilicates of β-K2SO4 type: Structural, magnetic and red luminescence properties.
- Source :
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Journal of Solid State Chemistry . Dec2022, Vol. 316, pN.PAG-N.PAG. 1p. - Publication Year :
- 2022
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Abstract
- Rare earth activated nitridosilicates have important applications as phosphor components in white light emitting diodes. (Oxy)nitridosilicates with β-K 2 SO 4 structure doped with Eu2+ are luminescent materials with emission wavelengths ranging from green to red under excitation with blue-UV light. Here we report the synthesis of isostructural NdEuSiO 3 N and the new oxynitridosilicate NdSrSiO 3 N by solid state reaction between Nd 2 O 3 , NdN, Eu 2 O 3 or SrO and Si 3 N 4 under N 2 /H 2 gas at temperatures of 1300 °C and 1500 °C respectively. These compounds are the limiting compositions of the solid solution NdSr 1-x Eu x O 3 N crystallizing in the space group Pmnb with cell parameters a = 5.62293(1), b = 7.02285(1) , c = 9.64784(2) Å for NdEuSiO 3 N, and a = 5.63074(9), b = 7.01658(10), c = 9.65765(15) Å for NdSrSiO 3 N. The Nd3+and Eu2+ cations in NdEuSiO 3 N or Nd3+ and Sr2+ in NdSrSiO 3 N show partial order in the two available crystallographic sites of coordination numbers 10 (M1) and 9 (M2), with strongly preferred occupancy of the larger divalent cations Eu2+ (77%) and Sr2+ (78%) for the M1 site, whereas the M2 site is preferred by Nd3+. Magnetic susceptibility measurements down to 2 K show that NdEuSiO 3 N is ferromagnetic with T c = 3 K, in contrast to NdSrSiO 3 N that shows antiferromagnetic interactions at low temperatures. The band gaps of NdEuSiO 3 N and NdSrSiO 3 N determined from diffuse reflection spectroscopy are 2.37 and 3.72 eV respectively. NdEuSiO 3 N and the members of the solid solution NdSr 0.98 Eu 0.02 SiO 3 N and NdSr 0.5 Eu 0.5 SiO 3 N are orange-red light emitting luminescent materials, showing a broad emission band centered between 605 and 639 nm under excitation at 405 nm. These compounds are new phosphor materials with emission wavelengths shifted to the red with respect to the isostructural oxysilicates, which is induced by the introduction of nitride. β-K 2 SO 4 type NdEuSiO 3 N and the new oxynitridosilicate host NdSrSiO 3 N activated with Eu2+ show orange-red luminescence under excitation at 405 nm. [Display omitted] • Synthesis of the new oxynitridosilicate NdSrSiO 3 N and the solid solution NdSr 1-x Eu x SiO 3 N (0 ≤ x ≤ 1) with β-K 2 SO 4 structure. • -Nd3+ ions preferentially occupy the 9th-coordinated sites whereas Sr2+ and/or Eu2+ prefer the 10th-coordinated sites. • NdEuSiO 3 N is ferromagnetic below 3 K whereas NdSrSiO 3 N shows antiferromagnetic correlations at low temperature. • NdEuSiO 3 N and NdSrSiO 3 N:Eu compounds are orange-red luminescent materials under excitation at 405 nm. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00224596
- Volume :
- 316
- Database :
- Academic Search Index
- Journal :
- Journal of Solid State Chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 159907765
- Full Text :
- https://doi.org/10.1016/j.jssc.2022.123571