Real structure of SrSi2O2N2

Oeckler, Oliver; Stadler, Florian; Rosenthal, Tobias; Schnick, Wolfgang

doi:10.1016/j.solidstatesciences.2006.11.009

Cited by 135 publications

(142 citation statements)

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“…Examples for such nitrido-or oxonitridosilicates are the framework silicates M 2 Si 5 N 8 (M ) Ca, Sr, Ba) or also the layer silicates MSi 2 N 2 O 2 (M ) Ca, Sr, Ba, Eu). [12][13][14][15][16] In this contribution we describe the synthesis, crystal structure, and magnetic properties of the mixed valence chain-type nitridosilicate Eu 2 SiN 3 comprising both Eu 2+ as well as Eu 3+ .…”

Section: Introductionmentioning

confidence: 99%

Mixed Valence Europium Nitridosilicate Eu₂SiN₃

et al. 2009

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Abstract:The mixed valence europium nitridosilicate Eu 2 SiN 3 has been synthesized at 900°C in welded tantalum ampules starting from europium and silicon diimide Si(NH) 2 in a lithium flux. The structure of the black material has been determined by single-crystal X-ray diffraction analysis (Cmca (no. 64), a ) 542.3(11) pm, b ) 1061.0(2) pm, c ) 1162.9(2) pm, Z ) 8, 767 independent reflections, 37 parameters, R1 ) 0.017, wR2 ) 0.032). Eu 2 SiN 3 is a chain-type silicate comprising one-dimensional infinite nonbranched zweier chains of corner-sharing SiN 4 tetrahedra running parallel [100] with a maximum stretching factor f s ) 1.0. The compound is isostructural with Ca 2 PN 3 and Rb 2 TiO 3 , and it represents the first example of a nonbranched chain silicate in the class of nitridosilicates. There are two crystallographically distinct europium sites (at two different Wyckoff positions 8f) being occupied with Eu 2+ and Eu 3+ , respectively. 151 Eu Mö ssbauer spectroscopy of Eu 2 SiN 3 differentiates unequivocally these two europium atoms and confirms their equiatomic multiplicity, showing static mixed valence with a constant ratio of the Eu 2+ and Eu 3+ signals over the whole temperature range. The Eu 2+ site shows magnetic hyperfine field splitting at 4.2 K. Magnetic susceptibility measurements exhibit Curie-Weiss behavior above 24 K with an effective magnetic moment of 7.5 µ B /f.u. and a small contribution of Eu 3+ , in accordance with Eu 2+ and Eu 3+ in equiatomic ratio. Ferromagnetic ordering at unusually high temperature is detected at T C ) 24 K. DFT calculations of Eu 2 SiN 3 reveal a band gap of ∼0.2 eV, which is in agreement with the black color of the compound. Both DFT calculations and lattice energetic calculations (MAPLE) corroborate the assignment of two crystallographically independent Eu sites to Eu 2+ and Eu 3+ .

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Section: Introductionmentioning

confidence: 99%

Mixed Valence Europium Nitridosilicate Eu₂SiN₃

et al. 2009

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“…Judging after the intensity of the −102 reflection, the amount of β phase is here distinctly smaller than in the sample studied in Ref. 15. Based on a simple comparison of peak intensities relationships with those of the data of two-phase sample of Ref.…”

Section: A Phase Analysis and Rietveld Refinementmentioning

confidence: 81%

“…The Rietveld refinement was performed using a similar approach as that in Ref. 15 the oxygen and nitrogen positions were not refined, and two very small angular ranges where the most intense spurious peaks appear were excluded. The lattice parameters of the α phase at temperature of 297(3) K are a = 7.1025(2) Å, b = 7.2535(2) Å, c = 7.2813(2) Å, α = 88.732(3)…”

Section: A Phase Analysis and Rietveld Refinementmentioning

confidence: 99%

“…According to a study employing a combined X-ray diffraction and electron diffraction, SrSi 2 O 2 N 2 adopts a triclinic structure (space group P1), hereafter referred to as the α phase. 15 In the cited paper, an approximate structure model has been proposed, being derived from the structure of EuSi 2 O 2 N 2 determined in Ref. 39.…”

Section: Introductionmentioning

confidence: 99%

“…Reported structural data for α and β SrSi 2 O 2 N 2 phases 15,18,33,39,[43][44][45] are quoted in Table II. Equation of state describes fundamental physicochemical properties of a substance.…”

Section: Introductionmentioning

confidence: 99%

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Equation of state for Eu-doped SrSi2O2N2

Ermakova

Paszkowicz

Kamińska

et al. 2014

The Journal of Chemical Physics

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α-SrSi2O2N2 is one of the recently studied oxonitridosilicates applicable in optoelectronics, in particular in white LEDs. Its elastic properties remain unknown. A survey of literature shows that, up to now, nine oxonitridosilicate materials have been identified. For most of these compounds, doped with rare earths and manganese, a luminescence has been reported at a wavelength characteristic for the given material; all together cover a broad spectral range. The present study focuses on the elastic properties of one of these oxonitridosilicates, the Eu-doped triclinic α-SrSi2O2N2. High-pressure powder diffraction experiments are used in order to experimentally determine, for the first time, the equation of state of this compound. The in situ experiment was performed for pressures ranging up to 9.65 GPa, for Eu-doped α-SrSi2O2N2 sample mounted in a diamond anvil cell ascertaining the hydrostatic compression conditions. The obtained experimental variation of volume of the triclinic unit cell of α-SrSi2O2N2:Eu with rising pressure served for determination of the Birch-Murnaghan equation of state. The determined above quoted bulk modulus is 103(5) GPa, its first derivative is 4.5(1.1). The above quoted bulk modulus value is found to be comparable to that of earlier reported oxynitrides of different composition.

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