Synthesis Of Aluminum Nitride Research Articles

Carbothermal synthesis of aluminium nitride at elevated nitrogen pressures

This paper is the first part of an investigation of carbothermal nitridation of alumina at elevated nitrogen pressure. The effect of some process parameters on nitridation rate was studied at different temperatures (1300–1700 °C) and pressures (0.1–5 MPa). The experiments were performed in a graphite furnace permitting a controlled nitrogen flow through the sample holder, and continuous measurement of CO in the outlet gas. The products were characterized by X-ray diffraction, BET and elemental analyses. The nitridation rate was found to be a function of the process parameters. For a suitable temperature and pressure, e.g. 1600 °C and 1 MPa, pure AIN was obtained after just 1 h, with very low residual oxygen content (0.4 wt%). At a high gas-flow rate (⩾5 I min−1), the optimum range of pressure was 0.5–1 MPa at 1550–1700 °C. The nitridation was hampered by even small amounts of CO added to the system. No intermediate phases formed under the experimental conditions studied. Thermodynamic calculations on the Al-O-C-N system were performed in a search for explanations of the results.

Carbothermal synthesis of aluminium nitride at elevated nitrogen pressures

The particle size and morphology of AlN product powders from carbothermal synthesis have been studied by scanning electron microscopy, surface-area measurement and microarea elemental analysis. AlN powders with widely variable grain size and morphology could be produced by varying the pressure, gas-flow rate and alumina type. Discrete AlN particles (∼0.5-3 μm) were obtained by using fine γ-Al 2 O 3 as starting material at 1600 o C over the pressure and gas-flow rate ranges 0.1-5 MPa and 1-10 l min -1 . When coarse α-Al 2 O 3 was used as raw material, large aggregates of AlN particles normally formed, unless the reaction was run at high nitrogen pressure (5 MPa) and low gas-flow rate (1 l min -1 )

Effect of RF Bias on Low-Temperature Synthesis of Aluminium Nitride Film by Hollow Cathode Discharge-Type Ion Plating

The effects of RF bias potential on the synthesis of aluminium nitride (AlN) film on a glass substrate using the hollow cathode discharge (HCD) ion plating technique, and on some properties of the film were investigated. The deposits were characterized by X-ray diffraction and scanning electron microscopy. The AlN films prepared with application of RF bias potential were superior in flatness to those prepared without applying of RF bias potential, but excess RF bias voltage to the substrate caused the film to come off not just from the substrate, but also with peeling of the glass substrate surface. The Vickers microhardness of film consisting of AlN single phase was estimated to be about 2300 kg/mm2. The film density was increased by applying RF bias voltage, its value being close to the theoretical value.

Electrochemical synthesis of ceramic materials. 2. Synthesis of aluminum nitride (AlN) and an AlN polymer precursor: chemistry and materials characterization

A simple electrochemical method for the preparation of AlN and other metal nitride ceramic precursors is described. Constant-current eletrolysis in a cell containing a NH 4 Br/NH 3 electrolyte solution and Al electrodes yields a solid mixture consisting primarily of Al(NH 3 ) 6 Br 3 and [Al(NH 2 )(NH)] n after excess NH 3 is removed

Electrochemical Synthesis of Aluminum Nitride in Liquid Ammonia Electrolyte Solutions

ABSTRACTAn electrochemical method for the preparation of high purity metal nitride ceramic precursors is described. Constant current electrolysis of an electrolyte solution containing NH3 and NH4Br at an Al electrode yields a solid mixture consisting of Al(NH3)6Br3 and [Al(NH2)(NH)]n after evaporation of excess NH3. Calcination of this mixture above 800 C in flowing NH3 results in sublimation of Al(NH3)6Br3 and conversion of the ceramic polymer precursor, [Al(NH2)(NH)]n, to pure, high surface area AlN. Here we discuss some electrochemical aspects of the polymer precursor synthesis, precursor processing parameters, and materials characterization of the AlN powder before and after sintering.

High pressure combustion synthesis of aluminum nitride

We report initial results on the synthesis of monolithic aluminum nitride by burning Al–AlN mixtures in high pressure nitrogen. The objective is to synthesize economically large, near-theoretical density AlN parts. In this work, we begin with compacted mixtures of 10 μm Al and 3 μm AlN powder formed into 7.62 cm diameter by 3.81 cm thick disks having densities up to 60% of theoretical. Then, at N2 pressures up to 180 MPa (26 000 psi), we ignite the disk on one face. The fraction of Al converted to AlN, density, and severity of macroscopic cracking vary with N2 pressure and heat transfer from the sample. Presently, products are inhomogeneous, showing regions of relatively high porosity, regions with no porosity but with AlN in a matrix of Al, and regions of nearly theoretical density AlN.

Measurement of sputtering yields induced by molecular nitrogen bombardment of aluminum

Several authors have shown recently that is is possible to synthesize aluminum nitride (AIN) by direct nitrogen implantation into aluminum. The AlN layer has already been characterized (depth profiling, phase formation, etc.) by means of several techniques including Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), nuclear reaction analysis (NRA) and Rutherford backscattering spectrometry (RBS). However, no data about sputtering yields during molecular and atomic nitrogen implantation into aluminum are currently available. The aim of this work is to measure the aluminum and nitrogen sputtering yields of evaporated thin aluminum films (4000 Å) on carbon, bombarded with 100 keV 15N + 2 at doses ranging from 5 × 10 16 to 1.5 × 10 18 N 2 +/cm 2. We have used nuclear reaction analysis (NR backscattering spectrometry (RBS) and quartz-crystal microbalance techniques. We have compared our data with those obtained by two models: transport of ions in matter (TRIM) and TRIM-dynamic (TRIDYN). Additionally, an attempt is made to determine the Al and N component sputtering yields within the resolution of the applied techniques. It is shown that the sputtering yields strongly depend on the contamination of the sample surface.

特集 「無機材料の合成を支える技術とその評価」 液体アンモニア中の火花放電による窒化アルミニウムの合成

液体アンモニア中にアルミニウムペレットを充填し,液体アンモニア温度0～130℃,放電電圧2 .5～11kV,放電サイクル1～2/sで火花放電反応を行わせることにより,結晶子径29～43nm,平均凝集粒径4.5～8.7μmの窒化アルミニウム粉末が得られた。生成粉末中にはAINとともにA1が含まれ,単一相AINの直接合成はできながった。なお,液体アンモニア温度の上昇および出発原料として用いるアルミニウムペレットの粒径の減少により,AIN含有率が増加し,AIN粒径が減少した。粉末を900～1200℃ の窒素雰囲気でか焼することにより,AIの溶融による粉末の凝結を起こすことなく粉末中のAlを窒化することができた。

Low-temperature synthesis of aluminium nitride via liquid-liquid mix carbothermal reduction

Low-temperature synthesis of aluminium nitride via liquid-liquid mix carbothermal reduction

Ammonothermal synthesis of aluminum nitride

This paper describes and discusses the preparation of aluminium nitride by ammonothermal reaction of aluminium with ammonia using potassium amide as transporting agent. Crystals of aluminium nitride are grown in the temperature range of 500 to 600°C and at ammonia pressures of 2 kbar. KNH 2 is removed from the reaction product by extraction with liquid ammonia. Single crystals of aluminium nitride predominantely grow in the direction of the crystallographic c-axis. Dense layers of single crystals up to a thickness of 1 mm can be produced.

Thermal Conversion of Preceramic Polyiminoalane Precursors to Aluminum Nitride: Characterization of Pyrolysis Products

This study introduces a new method for the synthesis of aluminum nitride by pyrolysis of a polymeric precursor. Metallic aluminum is electrolytically dissolved in an electrolyte containing a primary amine. Subsequent drying and heating enables the formation of a polymeric, gellike intermediate polyiminoalane compound. Calcining in ammonia atmosphere at 850°C results in aluminum nitride powder with a mean crystallite size of about 30 nm.

Carbothermal Synthesis of Aluminum Nitride

A synthetic route is described for making carbothermally reduced powders from colloidal oxide precursors trapped in a polymer matrix. The entrapping resin, which is formed by polymerization of a monomer dissolved in the colloid, serves both to minimize particle agglomeration during reaction and as the source of carbon for reduction. Following reduction, the remaining carbon matrix is removed by oxidation. This strategy was used to synthesize aluminum nitride powder via trapping of colloidal alumina in poly(furfuryl alcohol) resin.

Growth dynamics of aluminum nitride and aluminum oxide thin films synthesized by ion-assisted deposition

Some aspects of the dynamics of thin-film synthesis of aluminum nitride and aluminum oxide produced by ion-assisted deposition have been deduced from in situ measurements by ellipsometry, photometry, and ion scattering spectroscopy. Measurements obtained during the etching of aluminum films by nitrogen and oxygen ion beams have established the thickness of the synthesized layer and the rate of compound formation. Some of these measurements have been compared with a theoretical model which predicts the time evolution of the synthesized surface layer as well as the steady-state layer thickness. The breakdown voltage and variation of capacitance with applied voltage of aluminum oxide films prepared by ion-assisted deposition are also presented. Furthermore, the optical properties of ion-assisted AlN and Al2O3 in the visible region are given.

The Synthesis of Aluminum Nitride from Aluminum Hydride

ABSTRACTThe reaction between ammonia and aluminum hydride (AIH3) was investigated as a possible synthetic route to aluminum nitride (AIN), using tetrahydromran (THF) as the solvent. When an excess of ammonia was employed, a white powder was obtained which was converted to AIN by calcination. However, when a stoichiometric amount of ammonia was used, a soluble intermediate was obtained. This intermediate polymerized slowly at room temperature via a condensation reaction involving the elimination of hydrogen to give a gel that could be converted to AIN.

Measurement of temperature in the reactor during the plasma-chemical synthesis of aluminum nitride

Measurement of temperature in the reactor during the plasma-chemical synthesis of aluminum nitride

Sound velocity and elastic and thermal characteristics of crystalline oxygen and nitrogen (15–50°K): Bezuglyi, P.A., Tarasenki, L.M., Ivanov, Y.S. Soviet Physics—Solid State, Vol 10, No 7 (January 1969) pp 1660–1664 (1032)

After nearly a century since the first synthesis of aluminum nitride (AlN), III-nitride semiconductors have become one cornerstone of modem optoelectronic and electronic devices thanks to a spectacular research and development in the last 20 years. The nitrides of group III metal elements commonly referred to as aluminum nitride (AlN), gallium nitride (GaN), indium nitride (InN), and their alloys, all of which are compounds of nitrogen—the smallest group V element in the Periodic Table and an element with one of the highest values of electronegativity. III-nitride semiconductors crystallize in their most stable form into a wurtzite crystallographic structure with nitrogen atoms forming a hexagonal close packed (hep) structure and the group III atoms occupying half of the tetrahedral sites available in the hep lattice. III-nitrides are polar crystals as they do not have a center of symmetry. They thus possess many other potentially useful properties such as piezoelectricity, pyroelectricity, and non-linear optical properties. Long regarded as a scientific curiosity, III-nitrides have now earned a most respected place in the science and technology of compound semiconductors, as well as modem electronic and optoelectronic devices.

Investigation of the ultrasonic parameters of m-cresol and ethylene glycol as a function of the state parameters of the medium: Soviet Physics—Acoustics, Vol 14, No 1 (July–September 1968) pp 94–96 (1031)

After nearly a century since the first synthesis of aluminum nitride (AlN), III-nitride semiconductors have become one cornerstone of modem optoelectronic and electronic devices thanks to a spectacular research and development in the last 20 years. The nitrides of group III metal elements commonly referred to as aluminum nitride (AlN), gallium nitride (GaN), indium nitride (InN), and their alloys, all of which are compounds of nitrogen—the smallest group V element in the Periodic Table and an element with one of the highest values of electronegativity. III-nitride semiconductors crystallize in their most stable form into a wurtzite crystallographic structure with nitrogen atoms forming a hexagonal close packed (hep) structure and the group III atoms occupying half of the tetrahedral sites available in the hep lattice. III-nitrides are polar crystals as they do not have a center of symmetry. They thus possess many other potentially useful properties such as piezoelectricity, pyroelectricity, and non-linear optical properties. Long regarded as a scientific curiosity, III-nitrides have now earned a most respected place in the science and technology of compound semiconductors, as well as modem electronic and optoelectronic devices.