Diffuse Reflectance Infrared Fourier Transform Spectroscopy of Commercial AlN Powders in Vacuum up to 700°C

Li, Jinwang; Matsumaru, Koji; Ishizaki, Chanel; Ishizaki, Kōzō

doi:10.1111/j.1551-2916.2006.01084.x

Cited by 6 publications

(4 citation statements)

References 29 publications

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“…It is known that Ca 3 N 2 is very moisture-sensitive, and AlN hydrolyzes easily in moist air at room temperature . Thus, CaAlSiN 3 , which contains both Ca−N and Al−N bonds, can also be hydrolyzed in contact with moisture and form an oxide surface layer like in the case of AlN . The surface oxide layer is visible in the high-resolution TEM images (Figure ).…”

Section: Resultsmentioning

confidence: 98%

“…23 Thus, CaAlSiN 3 , which contains both Ca-N and Al-N bonds, can also be hydrolyzed in contact with moisture and form an oxide surface layer like in the case of AlN. 24 The surface oxide layer is visible in the high-resolution TEM images (Figure 12). Because the hydrolysis changes the amount of anions, the resultant composition values for the metal elements are reliable, but those for oxygen and nitrogen can be different from the composition in the nitride lattice, especially for nanocrystals where the surface contribution is significant.…”

Section: Caalsin 3 Formation Without Presynthesis Of Ammonometallatesmentioning

confidence: 99%

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Synthesis of a Multinary Nitride, Eu-Doped CaAlSiN₃, from Alloy at Low Temperatures

et al. 2008

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A multinary nitride, Eu-doped CaAlSiN 3 , which had previously been synthesized at 1600-1800 °C as a red-emiting phosphor material, was obtained at 500-800 °C via the reaction of a CaAlSi alloy with a low concentration of Eu (composition Ca 0.992 Eu 0.008 AlSi) in ammonia in the present study. In supercritical ammonia (100 MPa), CaAlSiN 3 was formed at temperatures g 500 °C both with and without the addition of sodium amide. The addition of sodium amide significantly facilitated the synthesis and prevented the presence of unreacted silicon, which could be due to the formation of sodium ammonometallates as intermediates in the presence of sodium amide. CaAlSiN 3 was synthesized even in an atmospheric ammonia flow, but the crystallinity of the product was rather low. Evidence suggested that CaAlSiN 3 was insoluble in the pressurized sodium amide-ammonia medium under the present conditions, and the prolonged reaction of the alloy in ammonia at the CaAlSiN 3 -forming temperatures (500-800 °C) did not result in an effective improvement of the crystallization. In contrast, well-crystallized samples with plate-and bar-like nanocrystals were synthesized by first converting the alloy at 300-400 °C into sodium ammonometallates and subsequently decomposing the ammonometallates up to 800 °C into CaAlSiN 3 . The products showed a red emission centered at 630-644 nm at a blue excitation of 460 nm. Instead of using sodium amide, the use of sodium azide, which was converted into sodium amide during heating, led to a product of plate-like crystals with significantly reduced oxide (oxide-free in the XRD spectrum) but did not result in an improved light emission. The size and lattice strain were calculated by refining against the XRD patterns, and the elemental composition was obtained via energy dispersive X-ray analysis on single nanocrystals with TEM observations. The synthetic conditionssstructure and compositionslight emission relationships were discussed. The deficiency in calcium was the determining factor for the decreased light emission.

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Section: Resultsmentioning

confidence: 98%

Section: Caalsin 3 Formation Without Presynthesis Of Ammonometallatesmentioning

confidence: 99%

Synthesis of a Multinary Nitride, Eu-Doped CaAlSiN₃, from Alloy at Low Temperatures

et al. 2008

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“…The amount of C8-M required can be approximately estimated by the density of the surface -OH groups of AlN when assuming these hydroxyl groups can be displaced entirely by C8-M. The hydroxyl groups on the AlN surface will usually start to lose around 446.85 °C and cannot be fully removed up to 700 °C but with a very low density [3,7]. Before AlN is tested by TGA, it was added to dry toluene due to the safety procedure.…”

Section: B Surface Functionalisation Of Alnmentioning

confidence: 99%

Influence of the Amount of Silane Coupling Agent on the Dielectric Properties of AlN/Polypropylene Nanocomposites

Wang

Andritsch

2019

2019 IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP)

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In this work, four loading amounts of trimethoxy (octyl) silane (C8-M) were used in preparing C8-M treated AlN/polypropylene nanocomposites. Although the thermal gravimetric analysis shows a significant difference in the amount of C8-M grafted on the AlN surface, and a saturation point can be reached as the amount of C8-M added increases, the AC breakdown strengths of composites present virtually identical results. Similar behaviours can be observed in the real and imaginary permittivity from 0.01 Hz to 100 kHz, although the upturns of the imaginary permittivity at low frequency are observed increasing with the amount of C8-M used. Seemingly contradictory to a previously reported work on epoxy with nanosilica, AlN/polypropylene is largely unaffected by the amount of the silane coupling agent applied during the surface treatment.

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“…If the oxygen is present as AlOOH or Al(OH) 3 , reactions involving hydrogen may also be effective at removing oxygen from AlN powder via the formation of water. In this case, the reactions might involve (1) 2Al(OH) 3 25 supports the probability of reactions 1 and 2 occurring. Similar conclusions were drawn from XPS analysis by Dalmau et al; 19 an oxygen peak characteristic of a hydroxide was reduced by annealing for 6 h from 260 °C to 830 °C under ultrahigh vacuum.…”

Section: Introductionmentioning

confidence: 99%

Native oxide and hydroxides and their implications for bulk AlN crystal growth

Edgar

Nyakiti

et al. 2008

Journal of Crystal Growth

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Oxygen degrades the properties of AlN, thus producing bulk single crystals with low oxygen concentrations is an important goal. Most of the oxygen in bulk AlN single crystals grown by the sublimation-recondensation method originates from the hydroxides and oxides that spontaneously form on the surfaces of the AlN source powder. For a typical AlN powder with an average particle size of 1-2 microns, a 1-3 nm thick oxide and/or hydroxide can account for most of its oxygen (generally on the order of 1.0 wt%) and hydrogen (200-300 ppm). Heating the AlN powder source at 1950 °C for 10 h in a nitrogen atmosphere reduced its surface area by a factor of 160 (due to sintering), the oxygen concentration by 16, and the hydrogen concentration by 67. The difference in these reduction factors suggests some of the oxygen is dissolved into the bulk AlN with this heat treatment. By first annealing the AlN powder at a low temperature (950-1000 °C) for several hours before sintering at 1950 °C, the oxygen and hydrogen concentrations were reduced to lower levels. The low temperature treatment is effective eliminating oxygen and hydrogen from the surface of the powder, while high temperature sintering reduces the specific surface area of the source. The combination of heat treatments produced a source with oxygen and hydrogen concentrations as low as 0.015 wt% O (1.9 x 10 19 atoms O cm -3 ) and 1.7 ppm H (3.4 x 10 18 atoms H cm -3 ). Annealing becomes less effective at removing oxygen and hydrogen with longer heat treatments, suggesting there is a minimum oxygen concentration that can be produced with this method.

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Diffuse Reflectance Infrared Fourier Transform Spectroscopy of Commercial AlN Powders in Vacuum up to 700°C

Cited by 6 publications

References 29 publications

Synthesis of a Multinary Nitride, Eu-Doped CaAlSiN₃, from Alloy at Low Temperatures

Synthesis of a Multinary Nitride, Eu-Doped CaAlSiN₃, from Alloy at Low Temperatures

Influence of the Amount of Silane Coupling Agent on the Dielectric Properties of AlN/Polypropylene Nanocomposites

Native oxide and hydroxides and their implications for bulk AlN crystal growth

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Diffuse Reflectance Infrared Fourier Transform Spectroscopy of Commercial AlN Powders in Vacuum up to 700°C

Cited by 6 publications

References 29 publications

Synthesis of a Multinary Nitride, Eu-Doped CaAlSiN3, from Alloy at Low Temperatures

Synthesis of a Multinary Nitride, Eu-Doped CaAlSiN3, from Alloy at Low Temperatures

Influence of the Amount of Silane Coupling Agent on the Dielectric Properties of AlN/Polypropylene Nanocomposites

Native oxide and hydroxides and their implications for bulk AlN crystal growth

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Synthesis of a Multinary Nitride, Eu-Doped CaAlSiN₃, from Alloy at Low Temperatures

Synthesis of a Multinary Nitride, Eu-Doped CaAlSiN₃, from Alloy at Low Temperatures