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Spinel phase LiMn₂O₄ is of great interest as cathode materials for lithium-ion batteries. In this study, SHS (Self propagating Hightemperature Synthesis) method to synthesize spinel LiMn₂O₄ directly from lithium nitrate, manganese oxide, manganese and sodium chloride were investigated. The influence of Li/Mn ratio, the heat-treated condition of product have been explored. The resultant LiMn₂O₄ synthesized under the optimum synthesis conditions shows perfect spinel structure, uniform particle size and excellent electrochemical performances.

The preparation of SiC powder by SHS in the system of SiO₂-Mg-C was investigated in this study. The effects of various processing parameters such as the initial pressure of inert gas in reactor, the content of Mg and C in mixture and the size of SiO₂ particles on the synthesis of SiC by SHS methode were investigated. The minimum initial pressure of inert gas in reactor for SHS reaction in this system was 5 atm, and as the pressure increased, and the concentration of unreacted Mg decreased. At 50 atm of the initial inert gas pressure in reactor, the optimum composition for the preparation of pure SiC was SiO₂+2.5Mg-1.2C. SiC powder synthesized in this condition had a mixture of α-SiC and β-SiC with an irregular shape and the particle size of 0.5~0.8 ㎛.

This paper deals with the formation of tungsten carbide sub-micrometer powders from WO 3 + Mg + C + sodium salts (NaCl, Na 2 CO 3 ) system by combustion synthesis technique. The powders were characterized by XRD and FESEM. X-ray data demonstrate the superiority of the NaCl + Na 2 CO 3 combined mixture in the WC formation process. Single phase, sub-micrometer WC powders were synthesized at temperatures as low as 1600 °C. The roles of sodium salts in combustion process were discussed and chemical mechanism of WC formation was proposed. WC powder produced by salt-assisted combustion synthesis technique has a size 0.2–3 μm, crystalline shape and low agglomeration degree.

In this study, a new approach to synthesize nanostructured WC and WC–Co powders is developed. WC and WC–Co powders have been synthesized from WO3–NaN3–C and WO3–Co3O4–NaN3–C green mixtures in which NaN3 was used as a reducing agent. Parametric study of the combustion process including initial concentration of starting materials, samples diameter and the combustion temperature were carried out under argon pressure. The final products are first washed and then examined by XRD and TEM analysis. As a result, phase pure nanostructured WC and WC–Co with the particle sizes of about 50–100 and 50–200 nm were obtained.

Molten salt-assisted self-propagating high-temperature synthesis of nanocrystalline W powder was studied experimentally. The technique involves the reduction of WO 3 in the presence of sodium chloride using three different reducing agents: magnesium (Mg), sodium azide (NaN 3 ), and sodium borohydride (NaBH 4 ). The effects of the mole fraction of sodium chloride on temperature distributions, combustion parameters, phase compositions, and morphology of the final products were determined. The sodium chloride-assisted method reported here has been found to be effective for lowering combustion temperature and producing uniform and spherical W nanopowders of average particle size around 20–200, 100–200, and 20–50 nm. The effect of combustion temperature on tungsten particle size is discussed, and a sketch describing the chemistry of combustion is proposed.

A simple and effective method for the synthesis of LiMn₂O₄ powder as a cathode material for lithium secondary battery is reported. Micrometer size LiMn₂O₄ was prepared by combustion synthesis technique employing initial mixture of 1.1LiNO₃-1.3Mn-0.7MnO₂-1NaCl composition. Parametric study of the combustion process including molar ratio of Mn/MnO₂ and NaCl concentration were carried out under air atmosphere. The combustion products obtained were additionally heat treated at the temperature 900℃ and the washed by distilled water. The results of charging-discharging characteristics revealed that LiMn₂O₄ cell synthesized in the presence of NaCl had a high capacity and much better reversibility than one formed without NaCl. An approximate chemical mechanism for LiMn₂O₄ formation is proposed.

A simple and effective method for the synthesis of PZT powder is reported. Fine spherical powders of PZT [Zr]/[Ti]=52/48 in mol ratio were prepared by solid-state combustion synthesis method based on the reaction of Pb3O4, ZrO2, and TiO2, activated by KClO3+1.5C mixture. The powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and LPSA methods. The PZT powder consists of nearly homogenous and spherical grains with an average diameter of 1 μm. An approximate explanation of spherical shape formation is proposed.

The formation of nanostructured metallic molybdenum from the MoO3–NaBH4–kNaCl system (where k is mole-number of NaCl) is analyzed thermodynamically and investigated experimentally under self-propagating high-temperature synthesis (SHS) mode. The laws of combustion and phase formation and an effect of sodium chloride on the characteristics of Mo powder are discussed. The result shows that mean particle size of Mo produced depends greatly on the amount of sodium chloride, especially the increasing of NaCl concentration leads to a small size Mo powder formation. Mo powder with the particle size at least 20 ∼ 100 nm was synthesized at k = 2. As synthesized Mo powder have been compacted and successfully consolidated to densities exceeding 90% at the temperature of 1700 °C.

B₂O₃-Mg-C계에서 자전연소합성법에 의한 B₄C의 제조가 본 연구에서 조사되었다. B₄C의 제조에 있어 반응기내 불활성 가스의 초기 압력, 혼합물내의 Mg와 C의 함량이 반응성과 반응생성물에 미치는 영향이 조사되었다. 본 반응계에서 자전연소합성 반응이 가능한 반응기내 불활성 가스의 최소 초기 압력은 25기압이었다. 압력이 증가할수록 미반응 Mg의 농도는 감소하였으며 연소온도는 증가하였다. 25기압의 반응기내 초기 불활성 가스 압력에서 순수 B₄C의 제조를 위한 최적조성은 2B₂O₃+6.3Mg+0.94C이었다. 이 조건에서 제조된 B₄C는 부정형으로서 1~3 μm의 입자크기를 가지고 있었다.

BaO₂-TiO₂-환원제-입자제어제계에서 자전연소합성법을 이용한 BaTiO₃ 분말의 제조에 대하여 고찰하였다. 환원제로서 C, Mg를 사용하였고, 입자제어제로서 NaCl을 사용하였다. 자전연소합성법을 이용한 BaTiO₃ 분말의 제조에 있어 최적의 반응계에서 환원제의 종류와 농도, 입자제어제, 반응량의 변화에 따른 생성물의 영향을 조사하였다. 최적의 반응계 및 조성은 Ar 반응 분위기에서 BaO₂+TiO₂+0.11Mg+0.2C+0.75NaCl이었다. 희석제로서 첨가된 NaCl은 연소온도의 조절 뿐 아니라 반응생성물의 입도를 제어하는 효과를 나타냄을 알 수 있었다. 최적의 조건에서 제조된 순수 BaTiO₃ 분말의 입도는 약 0.5 ㎛ 이하였으며, 반응량을 증가시킬수록 균일한 반응성을 나타내었다. 제조된 BaTiO₃ 분말의 유전특성을 측정하기 위하여 1300℃, 2시간동안 대기중에서 소결실험을 행하였고 이때 상온에서의 유전상수는 약 2290이었고, 큐리점(129℃)에서의 유전상수는 약 13800을 나타내었다.

균일하게 혼합된 LiNO₃와 Co 금속분말을 알곤 분위기 하에서 SHS 공정으로 리튬이차전지용 양극활물질인 LiCoO₂ 분말을 합성하였다. 여러 가지 반응변수에 따라 제조된 분말의 특성과 전기화학적 특성평가를 수행하였는데, 반응온도 및 속도와 제조된 분말의 입도는 각각 Li/Co 몰비와 시료의 냉각속도 변화로 제어 가능하였다. Li/Co 몰비가 1.05일 때 최대방전용량인 145mAh/g을 나타냈으며, 10회 충·방전 실험 후 6.4%의 낮은 용량감소를 갖는 비교적 안정된 cycling 특성을 보였다.

Formation rate of tetragonal BaTiO3 powder by hydrothermal synthesis and its dielectric property were studied. Submicron tetragonal BaTiO3 powders were prepared hydrothermally, using Ba(OH)2 · 8H2O, TiO2 (anatase) and KOH as starting chemicals. Characterization via X-ray diffractometry, Field Emission Scanning Electron Microscopy confirmed that increasing calcination temperature (from 1100 to 1300°C) promotes the formation of tetragonal BaTiO3. Tetragonal BaTiO3 ceramics obtained from optimum condition (Tetragonal BaTiO3 powders calcined at 1200°C for 3 h after hydrothermal synthesized at 200°C for 168 h) exhibited submicron size of 0.5–0.7 μm, monodispersed type and high relative permittivity.

The new approach has been developed for the synthesis of nickel (Ni), cobalt (Co) and iron (Fe) powders from the appropriate oxides by the solid combustion method. The reduction was made by sodium azide (NaN 3 ) at the presence of carbon in the argon atmosphere. The variation of combustion temperature and velocity was performed by using alkali metal salt as an inert diluent. The values of combustion parameters were measured and also the temperature distribution in a combustion wave are obtained. The geometric sizes of reactionary zones and the activation energy of the process were estimated. The optimum conditions for single-phase metal powder synthesis were found. Powders fabricated in this way had cubic structure and particles size about 0.5–2.0 μm for Ni, Co and 1–3 μm for Fe. In a number of cases the formation of spherical particles with the average size about 5–15 μm were observed.

The high-temperature combustion mechanism of the BaO2–TiO2–organic compound system [urea, CO(NH2)2; hexamethylenetetramine, C6H12N4] was investigated by the microthermocouple technique. The adiabatic combustion temperatures (Tad) and equilibrium compositions of the final products were calculated by the computer program THERMO. The distribution of the temperature T(x), rate of heat generation Φ(x), and degree of conversion η(x) in the combustion wave were determined. The relative sizes of the combustion zones, the leading stage of the reaction, the kinetic law of components interaction, and parameters (activation energy, pre-exponential factor, braking parameter) were then calculated. Through this method, the optimal conditions for tetragonal BaTiO3 powder synthesis with spherical form and particles size of 2–5 μm were found.

The combustion process of TiO2–Mg and TiO2–Mg–C systems with sodium chloride as an inert diluent was investigated. The values of combustion parameters and temperature distribution on a high-temperature wave according to the amount of sodium chloride were obtained by the thermocoupling technique. The leading stages of combustion processes are found and the sizes of reactionary zones were estimated. It is shown that the introduction of NaCl in an initial mixture promotes the formation of a nanocrystalline structure of the final products. As a result, nanosized titanium, and titanium carbide powders have been successfully obtained.

Nanosized uniform silver powders and colloidal dispersions of silver were prepared from AgNO 3 by a chemical reduction method involving the intermediate preparation of Ag 2 O colloidal dispersion in the presence of sodium dodecyle sulfate CH 3 (CH 2 ) 11 OSO 3 Na as a surfactant. Several reducing agents such as hydrazine hydrate (N 2 H 4 ·H 2 O), formaldehyde (HCOH) and glucose (C 6 H 10 O 5 ) have been found to be preferable in this study from a practical point of view. The silver powder with the 60–120 nm particle size and colloidal dispersion with the particles size 10–20 nm and 0.5–2.0 wt.% concentration were successfully synthesized.

The combustion synthesis process activated by organic polymers (Teflon and polystyrene) in the SiO2/Al/C system is investigated under the counter-current and co-current degassing conditions. It is found that the combustion parameters, i.e. wave velocity and temperature, and final product microstructure are influenced by the degassing mode considered as well as the type and amount of promoters added to the starting mixture. In particular, the combustion wave results to accelerate during its propagation when adopting the forward infiltration configuration and in absence of polystyrene. In addition, under the same degassing condition, the produced gases are found to provide a specific orientation on the growth direction of thread-like SiC crystals during final product formation.

The combustion process of a titanium–carbon system with sodium chloride as an inert diluent was investigated. The combustion laws and microstructure of final products according to diluent content were obtained. It was shown that sodium chloride not only decreases combustion temperature but also makes effective protective shells around primary carbide crystals and keeps this ultrafine structure up to the end of combustion. As a result, nano-sized titanium carbide powders were successfully obtained.

The synthesis of alumina/silicon carbide composites by self-propagating reactions activated by Teflon is investigated. It is shown that small amounts of this material (i.e. 0.20–0.25 wt.%) guarantee the occurrence of self-propagation reactions leading to the formation of a composite. In particular, under argon atmosphere, it consists of well-formed crystals of alumina, fine grained silicon carbide and whiskers-shaped crystallites of SiC. On the other hand, aluminium nitride, silicon carbonitride/silicon cyanide, aluminum oxynitrisilicides and mullite are also found under nitrogen atmosphere. The content of SiC whiskers in the final product increases when powdered polymers (polystyrene, polyethylene, polypropylene) are added to the initial mixture together with Teflon.

This study deals with research on the reduction process of neodymium compounds by electrochemical process. Neodymium fluoride was synthesized from neodymium oxide by chemical reaction, thus prepared neodymium fluoride was used for feed stock of electrolyte for electrowinning based on lithium fluoride electrolyte. Electrochemical properties of neodymium were measured according to the concentration of neodymium ion by cyclic voltammetry at 1050 °C . The performance of the electrowinnig cell was evaluated by chronopotentiometry. Neodymium metal is deposited from electrolyte to cathode. Composition and morphology of the deposits was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Neodymium metal was deposited by molten salt electrorwinning process.

The title phosphor is synthesized by self-sustaining combustion of SrX2 and EuX3 (X: F, Cl, I), micrometer sized Si powder, polytetrafluoroethylene, and urea under 2.0 MPa N2 pressure.

We developed a highly effective and self-sustaining route for synthesizing Sr(2)Si(5)N(8):Eu(2+) red-emitting phosphor particles for use in light emitting diodes (LEDs). The phosphors thus synthesized showed excellent emission characteristics under a blue excitation wavelength of 450 nm, had a uniform particle size distribution, and showed high performance in LED packages.

The self-propagating high temperature synthesis approach was applied to synthesize amorphous boron nanopowders in argon atmospheres. For this purpose, we investigated the characteristics of a thermally induced combustion wave in the B2O3 + α Mg system(α = 1.0-8.0) in an argon atmospheres. In this study, the exothermic nature of the B2O3-Mg reaction was investigated using thermodynamic calculations. Experimental study was conducted based on the calculation data and the SHS products consisting of crystalline boron and other compounds were obtained starting with a different initial molar ratio of Mg. It was found that the B2O3 and Mg reaction system produced a high combustion temperature with a rapid combustion reaction. In order to regulate the combustion reaction, NaCl, Na2B4O7 and H3BO3 additives were investigated as diluents. In an experimental study, it was found that all diluents effectively stabilized the reaction regime. The final product of the B2O3 + α Mg system with 0.5 mole Na2B4O7 was identified to be amorphous boron nano-powders(< 100 nm).

Due to their unique properties, tungsten borides are good candidates for the industrial applications where certain features such as high hardness, chemical inertness, resistance to high temperatures, thermal shock and corrosion. In this study, conditions were investigated for producing tungsten boride powder from tungsten oxide() by self-propagating high-temperature synthesis (SHS) followed by HCl leaching techniques. In the first stage of the study, the exothermicity of the -Mg reaction was investigated by computer simulation. Based on the simulation experimental study was conducted and the SHS products consisting of borides and other compounds were obtained starting with different initial molar ratios of , Mg and . It was found that , Mg and reaction system produced high combustion temperature and radical reaction so that diffusion between W and B was not properly occurred. Addition of NaCl and replacement of with B successfully solved the diffusion problem. From the optimum condition tungsten boride( and WB) powders which has 0.1~0.9 um particle size were synthesized.

Zirconium boride is an artificial or which is rarely found in the nature. ZrB2 is popular in the hard material industry because it has a high melting point, excellent mechanical properties and chemical stability. There are two known methods to synthesize ZrB2. The first involves direct reaction between Zr and B, and the second is by reduction of the metal halogen. However, these two methods are known to be unsuitable for mass production. SHS(Self-propagating High-temperature Synthesis) is an efficient and economic method for synthesizing hard materials because it uses exothermic reactions. In this study, ZrB2 was successfully synthesized by subjecting ZrO2, Mg and B2O3 to SHS. Because of the high combustion temperature and rapid combustion, in conjunction with the stoichiometric ratio of ZrO2, Mg and B2O3; single phase ZrB2 was not synthesized. In order to solve the temperature problem, Mg and NaCl additives were investigated as diluents. From the experiments it was found that both diluents effectively stabilized the reaction and combustion regime. The final product, made under optimum conditions, was single-phase ZrB2 of 0.1-0.9 μm particle size.