M2(Si,Al)4(N,C)7 (M=La,Y,Ca) carbonitrides

Liddell, K.; Thompson, D. P.; Bräuniger, Thomas; Harris, Robin K.

doi:10.1016/j.jeurceramsoc.2004.03.009

Cited by 25 publications

(31 citation statements)

References 15 publications

(15 reference statements)

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“…[19] Several studies have proposed that higher covalence is expected in the Y 2 Si 4 N 6 C network owing to the introduction of carbon, so that the thermal stability of photoluminescence in carbidonitridosilicates is expected to be better than that of corresponding SrYSi 4 N 7 type nitrides. [17,20,21] However, no studies of the evolution of phosphor properties within is surprising, as the progressive replacement of Sr 2+ and N 3− by Y 3+ and C 4− was expected to introduce more covalency into the materials and hence raise lattice rigidity and the quenching barrier height. [21,22] We propose that this reveals a dominant neighboring-cation influence as follows.…”

Section: Main Textmentioning

confidence: 99%

“…[17,20,21] However, no studies of the evolution of phosphor properties within is surprising, as the progressive replacement of Sr 2+ and N 3− by Y 3+ and C 4− was expected to introduce more covalency into the materials and hence raise lattice rigidity and the quenching barrier height. [21,22] We propose that this reveals a dominant neighboring-cation influence as follows. .…”

Section: Main Textmentioning

confidence: 99%

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Nanosegregation and Neighbor‐Cation Control of Photoluminescence in Carbidonitridosilicate Phosphors

et al. 2013

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Blue, green, and yellow phosphors are obtained in the Sr1−xY0.98+xCe0.02Si4N7−xCx system (x=0→1). Decreases in thermal quenching barrier height with x result from a dominant neighboring‐cation effect, through which the replacement of Sr2+ by Y3+ reduces the covalency of CeN bonding. Green emission is observed from a cation‐segregated nanostructure of SrYSi4N7 and Y2Si4N6C domains in x=0.2–0.6 samples.

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Section: Main Textmentioning

confidence: 99%

Section: Main Textmentioning

confidence: 99%

Nanosegregation and Neighbor‐Cation Control of Photoluminescence in Carbidonitridosilicate Phosphors

et al. 2013

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“…11 Recently, Liddell et al 5 proposed the composition was represented as Y 2 Si 4 N 6 C and the structure belonged to the orthorhombic system ͑Pmnb, a = 5.988, b = 10.265, c = 9.894 Å͒ as well as that of La 2 Si 4 N 6 C. However, the crystal structure refinement using the coordinates of La 2 Si 4 N 6 C as a starting model failed. Likewise, the monoclinic structural analogue of Ho 2 Si 4 N 6 C was considered as another starting model, but they were unsuccessful.…”

Section: Resultsmentioning

confidence: 99%

“…The different sets of atomic coordinates for SrYSi 4 N 7 , 12 La 2 Si 4 N 6 C, 5 and Ho 2 Si 4 N 6 C 9 were used as the starting models for refinement. For the structure model of Ho 2 Si 4 N 6 C, the Rietveld R-factors, R p and R wp , were converged to 5.16 and 8.82%, respectively.…”

Section: Resultsmentioning

confidence: 99%

Preparation, Structure, and Luminescence Properties of Y[sub 2]Si[sub 4]N[sub 6]C:Ce[sup 3+] and Y[sub 2]Si[sub 4]N[sub 6]C:Tb[sup 3+]

Zhang¹,

Horikawa²,

Machida³

2006

J. Electrochem. Soc.

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Rare-earth silicon carbonitrides, Y 2 Si 4 N 6 C and Y 2 Si 4 N 6 C:M 3+ ͑M = Ce,Tb͒, were prepared by a carbothermal reduction and nitridation method. The crystal structure of Y 2 Si 4 N 6 C was determined by Rietveld refinement using the atomic coordinates of Ho 2 Si 4 N 6 C as a starting model. The host lattice was isostructural with Ho 2 Si 4 N 6 C of monoclinic system ͓P2 1 /c, a = 5.9295͑1͒, b = 9.8957͑1͒, c = 11.8800͑2͒ Å, ␤ = 119.63͑4͒°, and Z = 4͔. The photoluminescence properties of doped materials, Y 2 Si 4 N 6 C:Ce 3+ and Y 2 Si 4 N 6 C:Tb 3+ , were characterized on the basis of the detailed structural analysis result.In recent years, it has been found that some rare-earth ion-doped metal nitrides and oxynitrides such as Sr 2 Si 5 N 8 :Eu 2+ , CaAlSiN 3 :Eu 2+ , and Eu 3+ -or Ce 3+ -doped ␣-SiAlON show excellent photoluminescence properties, 1-3 which are characterized for shifting of the excitation band of such metal nitrides and oxynitrides to the visible region in contrast to UV excitation of oxide phosphors. This feature allows nitrides and oxynitrides to be good candidates as the phosphors for white light emitting diodes ͑LEDs͒ coupled with a blue LED chip. The crystal field is strengthened when O 2− ions are replaced by N 3− ions to coordinate the active ions such as Eu 3+ or Ce 3+ because the valence state of the N 3− ion is higher than that of the O 2− ion. Consequently, emission bands of the metal nitrides and oxynitrides doped with Ce 3+ or Eu 2+ ion shift to longer wavelengths than those of the corresponding oxide phosphors. Also, the Stokes shift is pointed out as another factor to affect the emission peak positions as it relates to the rigidity of the host lattice.Krevel et al. 4 have studied photoluminescence behaviors of a series of Ce 3+ -doped Y-Si-O-N compounds. For the host lattice of Y 4 Si 2 O 7 N 2 , the emission peak is located at the longer wavelength of about 500 nm. For the Ce 3+ -doped ␣-SiAlON, the emission band shifts much more to about 540 nm, 3 so that one can see yellow light like that of Y 3 Al 5 O 12 :Ce 3+ ͑YAG:Ce 3+ ͒. Recently, yttrium silicon carbonitride, Y 2 Si 4 N 6 C, has been reported as a new compound, 5 but the detailed structure is still unclear. The Ce 3+ -doped Y 2 Si 4 N 6 C prepared from yttrium metal, Si͑NH͒ 2 , and carbon powder is found to emit a yellow band peaking at 590 nm under blue excitation. 6 In this paper, we prepared Y 2 Si 4 N 6 C:M 3+ ͑M = Ce,Tb͒ by using the carbon thermoreduction and nitridation ͑CRN͒ method as usually employed to synthesize Si 3 N 4 or ␤-sialon. 7 The structure of Y 2 Si 4 N 6 C was determined by Rietveld refinement and the photoluminescence properties of Ce 3+ -and Tb 3+ -doped compounds were characterized. ExperimentalSamples of Y 2−x Ce x Si 4 N 6 C ͑0 ഛ x ഛ 0.08͒ and Y 2−x Tb x Si 4 N 6 C ͑0 ഛ x ഛ 0.5͒ were prepared by the CRN method. The starting materials used were Y 2 O 3 ͑99.9%͒, CeO 2 ͑99.9%͒, Tb 4 O 7 ͑99.9%͒, Si 3 N 4 ͑99%͒, and C ͑graphite, 98 + %͒ powders. The appropriate amounts were weighed and then the...

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“…[14,15,18,19] Eu 2+ -and Ce 3+ -doped SrYSi 4 N 7 respectively emit 548-570 nm yellow light and 450 nm blue light when excited at 390 nm. [17,20,21] However, no studies of the evolution of phosphor properties within Sr 1Ày Y 1+y Si 4 N 7Ày C y hosts have been reported. [19] Several studies have proposed that higher covalence is expected in the Y 2 Si 4 N 6 C network owing to the introduction of carbon, so that the thermal stability of photoluminescence in carbidonitridosilicates is expected to be better than that of corresponding SrYSi 4 N 7 type nitrides.…”

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Nanosegregation and Neighbor‐Cation Control of Photoluminescence in Carbidonitridosilicate Phosphors

et al. 2013

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Phosphor materials play a key role in white-light emitting diode (LED) devices based on gallium indium nitride (GaInN). [1][2][3][4][5] Phosphors for white LEDs should have good thermal stability and conversion efficiency and an excitation wavelength range in the UV to blue region (370-460 nm). [3,[6][7][8] The yellow-emitting phosphor (Y,Gd) 3 (Al,Ga) 5 O 12 :Ce 3+ is a well-known commercial example, but the lack of red emission results in cold white light and a low color-rendering index (CRI). [1,7,9,10] Nitride-based materials are more covalent than oxides, which improves thermal stability, and their greater crystal field splitting increases the red emission leading to warmer white light. [1,2,11,12] The chemistry of doped nitride phosphors is often complex and it may be difficult to understand how substitutions tune photoluminescence properties, as the local environment of activator ions may be quite different to the structural average. For example, local O/N ordering driven by the size mismatch between the Eu 2+ activator and the host cations was found to be an important effect in M 1.95 Eu 0.05 Si 5Àx Al x O 8Àx N x (M = Ca, Sr, Ba) phosphors. [12] Herein we demonstrate a new approach to controlling phosphor properties through segregation of activator cations on the nanoscale, as applied to Sr 1Àx Y 0.98+x Ce 0.02 Si 4 N 7Àx C x carbidonitridosilicate phosphors, and we show that overall trends evidence a significant neighboring-cation influence.Two structure types are encountered in the studied system. The SrYSi 4 N 7 (1147) type structure with hexagonal (space group P6 3 mc) symmetry contains a network of cornerlinked N(SiN 3 ) 4 structural units. [13][14][15][16] Sr and Y sites are coordinated by 12 and 6 nitrides, respectively. The related

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M2(Si,Al)4(N,C)7 (M=La,Y,Ca) carbonitrides

Cited by 25 publications

References 15 publications

Nanosegregation and Neighbor‐Cation Control of Photoluminescence in Carbidonitridosilicate Phosphors

Nanosegregation and Neighbor‐Cation Control of Photoluminescence in Carbidonitridosilicate Phosphors

Preparation, Structure, and Luminescence Properties of Y[sub 2]Si[sub 4]N[sub 6]C:Ce[sup 3+] and Y[sub 2]Si[sub 4]N[sub 6]C:Tb[sup 3+]

Nanosegregation and Neighbor‐Cation Control of Photoluminescence in Carbidonitridosilicate Phosphors

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