Single-phase nanocrystalline 4CaO·Al2O3·Fe2O3 powders were prepared directly from the combustion ... more Single-phase nanocrystalline 4CaO·Al2O3·Fe2O3 powders were prepared directly from the combustion reaction using a new cost-effective, time-saving, and environmentally friendly version of solution combustion synthesis. Instead of a single fuel, a fuel mixture of urea and β-alanine was used. It was shown by x-ray diffraction, energy-dispersive x-ray analysis, thermogravimetric analysis, and optical microscopy that this new version of the solution combustion synthesis allows the maximization of the exothermic effect associated with the combustion reaction. On the other hand, it was shown that the traditional version of combustion synthesis involving the use of a single fuel, such as urea or β-alanine, does not ensure the formation of Ca4Al2Fe2O10 unless subsequent thermal treatments are applied. It was suggested that the occurrence of combustion reactions cannot be regarded only in terms of adiabatic temperature, as the kinetic aspects overrule the thermodynamic ones.
the preparation of monocalcium aluminate, CaAl 2 O 4 , via solution combustion synthesis is discu... more the preparation of monocalcium aluminate, CaAl 2 O 4 , via solution combustion synthesis is discussed in a side-by-side evaluation of the single-fuel and fuel-mixture approach. Single-fuel recipes based on urea or glycine, and corresponding metal nitrates, generated low combustion temperatures (480 °C and 748 °C), which did not enable the formation of CaAl 2 O 4. Under identical experimental conditions, urea and glycine fuel mixture generated a much higher combustion temperature (1558 °C), which promoted the formation of single-phase CaAl 2 O 4 directly from the combustion reaction. The as-prepared CaAl 2 O 4 had a crystallite size of 60 nm and a BET surface area of 0.8 m 2 /g. Laser granulometry measurements evidenced that 90 % of the CaAl 2 O 4 particles were smaller than 28 µm. Combustion synthesis of CaAl 2 O 4 powders requires a careful recipe formulation, as single-fuel approach and fuel-mixture approach may lead to different results in terms of combustion reaction evolution and phase composition of the resulted powder.
One-step synthesis of near-infrared reflective brown pigments based on iron-doped lanthanum alumi... more One-step synthesis of near-infrared reflective brown pigments based on iron-doped lanthanum aluminate, LaAl 1-x Fe x O 3 , Dyes and Pigments (2018),
Solution combustion synthesis: A straightforward route for the preparation of chromium-doped lant... more Solution combustion synthesis: A straightforward route for the preparation of chromium-doped lanthanum aluminate, LaAl 1-x Cr x O 3 , pink red pigments, Dyes and Pigments (2018),
Iron oxide/carbon nanocomposites having a mass ratio of 1:5 were prepared using the simple, versa... more Iron oxide/carbon nanocomposites having a mass ratio of 1:5 were prepared using the simple, versatile and environmentally friendly combustion synthesis method. The effect of experimental conditions, such as the fuel nature (urea, citric acid), reaction atmosphere (air, controlled atmosphere) and the time span of thermal treatment (30 and 60 minutes) on the nanocomposites characteristics were studied. Using citric acid as fuel, in the absence of air, maghemite or magnetite can be obtained by extending the time span of thermal treatment from 30 to 60 minutes. The adsorption capacity of the magnetite/carbon nanocomposite was investigated for the removal of two anionic (Acid Orange 7 and Acid Blue 129) and two cationic (Methylene Blue and Rhodamine 6G) dyes from simulated wastewaters. The effect of different parameters such as solution pH, adsorbent dose and contact time on the adsorption process was evaluated. The adsorption mechanism is controlled by electrostatic forces and is highly dependent on the pH. The removal efficiency of anionic dyes decreases while of cationic dyes increases with the increase of the pH value. The adsorption kinetics of the four dyes was described by the pseudosecond order model and the equilibrium data were correlated by the Langmuir isotherm. The capacity of regeneration and reuse of the adsorbent was evaluated in five cycles of adsorptiondesorption. The combination of high adsorption capacity, excellent separation capability, short equilibrium time and high stability, indicates that the as-prepared magnetite/carbon nanocomposite is an excellent adsorbent material for the removal of both anionic and cationic dyes from wastewaters.
The paper deals with a systematic and in the same time original approach of some great importance... more The paper deals with a systematic and in the same time original approach of some great importance problems, concerning the synthesis of high reactivity powders using the combustion method, ensuring the prerequisites for the rational elaboration of the recipes in order to obtain the desired compound. In order to justify the more or less different behavior of some metal nitrates in respect to various fuels, within the paper there has been studied the Interaction between a great number of metal nitrates M(NO 3 ) x (M x+ = Na + , K + , Mg 2+ , Ca 2+ , Sr 2+ , Al 3+ , Cr 3+ , Fe 3+ , Co 2+ ) and a variety of fuels, frequently used in the combustion synthesis method: urea, glycine and β-alanine. Moreover, there has also been studied the heating interaction between the three fuels and HNO 3 . The experimental results suggest that, on one hand, there is a predilection of metal nitrates in respect to certain fuels, and on the other hand, the formation of some complex combinations between the metal cation and the used fuel does not represent the decisive element in the initiation and the subsequent development of the combustion reactions.
The paper deals with the systematization of a great number of literature data concerning material... more The paper deals with the systematization of a great number of literature data concerning material synthesis using the combustion method; it has been tried to clearly make the difference between "self-propagating high temperature synthesis" (SHS) and "combustion synthesis using organic fuels" (CSOF). Experimental results have also been presented concerning the synthesis of different oxide compounds: tricalcic aluminate (3CaO·Al 2 O 3 ), magnesium spinel (MgAl 2 O 4 ) and some perovskite pigments (YAI 0.95 Cr 0.05 O 3 and NdAl 0,95 Cr 0,05 O 3 ) using the combustion method; the starting raw materials were metal nitrates and various fuels: urea, glycine, β-alanine.
Thermal imaging indicates that the urea and glycine fuel-mixture approach represents a better opt... more Thermal imaging indicates that the urea and glycine fuel-mixture approach represents a better option for SrAl2O4preparation than the single-fuel approach.
The paper presents the results concerning the preparation of calcium aluminoferrite solid solutio... more The paper presents the results concerning the preparation of calcium aluminoferrite solid solutions, \ Ca 2 (Fe 1-x Al x ) 2 O 5 by means of combustion synthesis. The resulted powders were characterized by X-ray diffraction, IR spectrophotometry, surface area measurements and setting time. Experimental results indicated that the use of a single fuel (either urea, or β - alanine) does not permit the formation of single phase Ca 2 (Fe 1-x Al x ) 2 O 5 directly from the combustion process. For x < 0.7 the use of a fuel mixtures (urea and β-alanine) facilitates the formation of the designed phases directly from the combustion reaction. The compositions with x ≥ 0.75 are outside the isomorphy limits, and lead to the formation of C 3 A and C 12 A 7 besides the calcium aluminoferrite solid solution. Ca 2 (Fe 1-x Al x ) 2 O 5 solid solutions prepared by using fuel mixtures are highly friable, turning into large surface area powders (6400÷12000 cm 2 /g). The reactivity of these solid solutions with respect to water increases as the Al 2 O 3 content increases.
Maghemite/silica composites were prepared by a facile and effective method. First a stable magnet... more Maghemite/silica composites were prepared by a facile and effective method. First a stable magnetic fluid (MF) was obtained by dispersing in toluene the maghemite nanoparticles, prepared by coprecipitation. Afterwards, maghemite nanoparticles were coated with silica by the hydrolysis and condensation of tetraethylorthosilicate. The structural, surface and magnetic characteristics of the composites were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) and vibrating sample magnetometer (VSM) measurements. Magnetic studies indicated the superparamagnetic behavior of the samples and the decrease of the saturation magnetization with the decrease of the magnetic fluid concentration. SEM images revealed the presence of agglomerated, spherical particles and TEM images showed both separated particles and multiple maghemite particles together, covered with silica layer. The close relationship between the concentration of maghemite nanoparticles and the color of composite materials was confirmed by diffuse reflectance spectroscopy. CIEL n a n b n analysis revealed the change of the composites' color from reddish-brown to light beige by decreasing the concentration of the maghemite nanoparticles. These results demonstrate that the maghemite/silica composites are suitable for the manufacture of magnetic paper with different degrees of whiteness that can be easily correlated with the concentration of the magnetic fluid used for their preparation.
Abstract Highly sinterable CoFe 2 O 4 particles were prepared by a modified solution combustion s... more Abstract Highly sinterable CoFe 2 O 4 particles were prepared by a modified solution combustion synthesis, starting from a stoichiometric mixture of cobalt acetate (instead of cobalt nitrate), iron nitrate and 5-aminotetrazole. The resulted cobalt ferrite powder had large surface area (44 m 2 /g), small crystallite size (11 nm) and a saturation magnetization of 38.9 Am 2 /kg. CoFe 2 O 4 pellets sintered at 1100 °C for 2 h developed a fine compact microstructure, reaching 99% of the theoretical density. After sintering, the saturation magnetization increased to 71.3 Am 2 /kg whilst the coercivity decreased to 21.8 kA/m.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
The paper reveals a new perspective concerning the rational fuel selection and the logical elabor... more The paper reveals a new perspective concerning the rational fuel selection and the logical elaboration of the recipes for the MgAl 2 O 4 solution combustion synthesis. It was shown that Mg(NO 3) 2 Á6H 2 O and Al(NO 3) 3 Á9H 2 O exhibit different behavior with respect to urea, glycine and b-alanine. Urea proved to be the most adequate fuel for Al(NO 3) 3 Á9H 2 O, while b-alanine proved to be the most appropriate fuel for Mg(NO 3) 2 Á6H 2 O. Considering that there is a predilection of metal nitrates with respect to these fuels, in the case of MgAl 2 O 4 combustion synthesis best results were achieved when fuel mixtures (urea and b-alanine, urea and glycine) were used. The use of fuel mixtures allowed the formation of pure, nanocrystalline MgAl 2 O 4 directly from the combustion reaction, without any subsequent annealing step. The use of a single fuel (urea, glycine or b-alanine) led to the formation of an amorphous powder, which required further annealing in order to achieve the formation of crystalline MgAl 2 O 4 .
The reactivity of LiNO3 and Al(NO3)3 with respect to urea and β-alanine was investigated. Experim... more The reactivity of LiNO3 and Al(NO3)3 with respect to urea and β-alanine was investigated. Experimental results proved that β-alanine is a more suitable fuel for LiNO3, whereas urea seems to be more adequate for Al(NO3)3. Based on the different metal nitrate/fuel mixture reactivity, nanocrystalline γ-LiAlO2 powders were prepared by solution combustion synthesis using a fuel mixture of urea and β-alanine.
Single-phase CaZrO3 powder was prepared by heating at 300°C an aqueous solution of Ca(NO3)2, ZrO(... more Single-phase CaZrO3 powder was prepared by heating at 300°C an aqueous solution of Ca(NO3)2, ZrO(NO3)2 and β-C3H7NO2 (molar ratio=3:3:4). TG–DTA analysis indicated that an intense exothermic reaction occurred at 255°C, which lead to the formation of a voluminous white powder. No additional annealing was required, as pure crystalline CaZrO3 resulted directly from the combustion reaction. Although no advanced milling was performed, the specific surface area of the powder was 21.5m2/g. The average crystallite size of CaZrO3 was 23.9nm. After sintering in air at 1400°C for 2h, the pellets – shaped by uniaxial pressing at 200MPa – reached 95% of the theoretical density, had no open pores and were slightly translucent.
... Janbey A, Pati RK, Tahir S et al (2001) J Eur Ceram Soc 21:2285 11. Patil KC, Aruna ST, Miman... more ... Janbey A, Pati RK, Tahir S et al (2001) J Eur Ceram Soc 21:2285 11. Patil KC, Aruna ST, Mimani T (2002) Curr Opin Solid State Mater Sci 6:507 12. ... Kakade MB, Ramanathan S, Ravindran PV (2003) J Alloys Compd 350:123 J Mater Sci (2009) 44:10161023 1023 123
Single-phase nanocrystalline 4CaO·Al2O3·Fe2O3 powders were prepared directly from the combustion ... more Single-phase nanocrystalline 4CaO·Al2O3·Fe2O3 powders were prepared directly from the combustion reaction using a new cost-effective, time-saving, and environmentally friendly version of solution combustion synthesis. Instead of a single fuel, a fuel mixture of urea and β-alanine was used. It was shown by x-ray diffraction, energy-dispersive x-ray analysis, thermogravimetric analysis, and optical microscopy that this new version of the solution combustion synthesis allows the maximization of the exothermic effect associated with the combustion reaction. On the other hand, it was shown that the traditional version of combustion synthesis involving the use of a single fuel, such as urea or β-alanine, does not ensure the formation of Ca4Al2Fe2O10 unless subsequent thermal treatments are applied. It was suggested that the occurrence of combustion reactions cannot be regarded only in terms of adiabatic temperature, as the kinetic aspects overrule the thermodynamic ones.
The preparation of ␣-cordierite powders via combustion route was investigated. Urea, monoethanola... more The preparation of ␣-cordierite powders via combustion route was investigated. Urea, monoethanolamine and triethylenetetramine were used as fuels. The resulting powders were characterized by means of thermal analysis and XRD. Experimental results showed that SiO 2 behaves as an inert material, preventing the formation of 2MgO•2Al 2 O 3 •5SiO 2 directly from the combustion reaction. Using a fuel mixture of urea and monoethanolamine yielded a poorly crystalline powder (MgAl 2 O 4). The phase composition of powders after annealing at various temperatures has shown that the formation of ␣-cordierite occurs indirectly, via the solid state reaction of spinel and cristobalite. After annealing at 1300 • C for 1 h ␣-cordierite is virtually the only crystalline phase in the sample obtained with triethylenetetramine. In the sample prepared by using urea and monoethanolamine fuel mixture ␣-cordierite is the main crystalline phase, alongside traces of spinel and cristobalite. The intermediate formation of-cordierite was not observed.
Single-phase nanocrystalline 4CaO·Al2O3·Fe2O3 powders were prepared directly from the combustion ... more Single-phase nanocrystalline 4CaO·Al2O3·Fe2O3 powders were prepared directly from the combustion reaction using a new cost-effective, time-saving, and environmentally friendly version of solution combustion synthesis. Instead of a single fuel, a fuel mixture of urea and β-alanine was used. It was shown by x-ray diffraction, energy-dispersive x-ray analysis, thermogravimetric analysis, and optical microscopy that this new version of the solution combustion synthesis allows the maximization of the exothermic effect associated with the combustion reaction. On the other hand, it was shown that the traditional version of combustion synthesis involving the use of a single fuel, such as urea or β-alanine, does not ensure the formation of Ca4Al2Fe2O10 unless subsequent thermal treatments are applied. It was suggested that the occurrence of combustion reactions cannot be regarded only in terms of adiabatic temperature, as the kinetic aspects overrule the thermodynamic ones.
the preparation of monocalcium aluminate, CaAl 2 O 4 , via solution combustion synthesis is discu... more the preparation of monocalcium aluminate, CaAl 2 O 4 , via solution combustion synthesis is discussed in a side-by-side evaluation of the single-fuel and fuel-mixture approach. Single-fuel recipes based on urea or glycine, and corresponding metal nitrates, generated low combustion temperatures (480 °C and 748 °C), which did not enable the formation of CaAl 2 O 4. Under identical experimental conditions, urea and glycine fuel mixture generated a much higher combustion temperature (1558 °C), which promoted the formation of single-phase CaAl 2 O 4 directly from the combustion reaction. The as-prepared CaAl 2 O 4 had a crystallite size of 60 nm and a BET surface area of 0.8 m 2 /g. Laser granulometry measurements evidenced that 90 % of the CaAl 2 O 4 particles were smaller than 28 µm. Combustion synthesis of CaAl 2 O 4 powders requires a careful recipe formulation, as single-fuel approach and fuel-mixture approach may lead to different results in terms of combustion reaction evolution and phase composition of the resulted powder.
One-step synthesis of near-infrared reflective brown pigments based on iron-doped lanthanum alumi... more One-step synthesis of near-infrared reflective brown pigments based on iron-doped lanthanum aluminate, LaAl 1-x Fe x O 3 , Dyes and Pigments (2018),
Solution combustion synthesis: A straightforward route for the preparation of chromium-doped lant... more Solution combustion synthesis: A straightforward route for the preparation of chromium-doped lanthanum aluminate, LaAl 1-x Cr x O 3 , pink red pigments, Dyes and Pigments (2018),
Iron oxide/carbon nanocomposites having a mass ratio of 1:5 were prepared using the simple, versa... more Iron oxide/carbon nanocomposites having a mass ratio of 1:5 were prepared using the simple, versatile and environmentally friendly combustion synthesis method. The effect of experimental conditions, such as the fuel nature (urea, citric acid), reaction atmosphere (air, controlled atmosphere) and the time span of thermal treatment (30 and 60 minutes) on the nanocomposites characteristics were studied. Using citric acid as fuel, in the absence of air, maghemite or magnetite can be obtained by extending the time span of thermal treatment from 30 to 60 minutes. The adsorption capacity of the magnetite/carbon nanocomposite was investigated for the removal of two anionic (Acid Orange 7 and Acid Blue 129) and two cationic (Methylene Blue and Rhodamine 6G) dyes from simulated wastewaters. The effect of different parameters such as solution pH, adsorbent dose and contact time on the adsorption process was evaluated. The adsorption mechanism is controlled by electrostatic forces and is highly dependent on the pH. The removal efficiency of anionic dyes decreases while of cationic dyes increases with the increase of the pH value. The adsorption kinetics of the four dyes was described by the pseudosecond order model and the equilibrium data were correlated by the Langmuir isotherm. The capacity of regeneration and reuse of the adsorbent was evaluated in five cycles of adsorptiondesorption. The combination of high adsorption capacity, excellent separation capability, short equilibrium time and high stability, indicates that the as-prepared magnetite/carbon nanocomposite is an excellent adsorbent material for the removal of both anionic and cationic dyes from wastewaters.
The paper deals with a systematic and in the same time original approach of some great importance... more The paper deals with a systematic and in the same time original approach of some great importance problems, concerning the synthesis of high reactivity powders using the combustion method, ensuring the prerequisites for the rational elaboration of the recipes in order to obtain the desired compound. In order to justify the more or less different behavior of some metal nitrates in respect to various fuels, within the paper there has been studied the Interaction between a great number of metal nitrates M(NO 3 ) x (M x+ = Na + , K + , Mg 2+ , Ca 2+ , Sr 2+ , Al 3+ , Cr 3+ , Fe 3+ , Co 2+ ) and a variety of fuels, frequently used in the combustion synthesis method: urea, glycine and β-alanine. Moreover, there has also been studied the heating interaction between the three fuels and HNO 3 . The experimental results suggest that, on one hand, there is a predilection of metal nitrates in respect to certain fuels, and on the other hand, the formation of some complex combinations between the metal cation and the used fuel does not represent the decisive element in the initiation and the subsequent development of the combustion reactions.
The paper deals with the systematization of a great number of literature data concerning material... more The paper deals with the systematization of a great number of literature data concerning material synthesis using the combustion method; it has been tried to clearly make the difference between "self-propagating high temperature synthesis" (SHS) and "combustion synthesis using organic fuels" (CSOF). Experimental results have also been presented concerning the synthesis of different oxide compounds: tricalcic aluminate (3CaO·Al 2 O 3 ), magnesium spinel (MgAl 2 O 4 ) and some perovskite pigments (YAI 0.95 Cr 0.05 O 3 and NdAl 0,95 Cr 0,05 O 3 ) using the combustion method; the starting raw materials were metal nitrates and various fuels: urea, glycine, β-alanine.
Thermal imaging indicates that the urea and glycine fuel-mixture approach represents a better opt... more Thermal imaging indicates that the urea and glycine fuel-mixture approach represents a better option for SrAl2O4preparation than the single-fuel approach.
The paper presents the results concerning the preparation of calcium aluminoferrite solid solutio... more The paper presents the results concerning the preparation of calcium aluminoferrite solid solutions, \ Ca 2 (Fe 1-x Al x ) 2 O 5 by means of combustion synthesis. The resulted powders were characterized by X-ray diffraction, IR spectrophotometry, surface area measurements and setting time. Experimental results indicated that the use of a single fuel (either urea, or β - alanine) does not permit the formation of single phase Ca 2 (Fe 1-x Al x ) 2 O 5 directly from the combustion process. For x < 0.7 the use of a fuel mixtures (urea and β-alanine) facilitates the formation of the designed phases directly from the combustion reaction. The compositions with x ≥ 0.75 are outside the isomorphy limits, and lead to the formation of C 3 A and C 12 A 7 besides the calcium aluminoferrite solid solution. Ca 2 (Fe 1-x Al x ) 2 O 5 solid solutions prepared by using fuel mixtures are highly friable, turning into large surface area powders (6400÷12000 cm 2 /g). The reactivity of these solid solutions with respect to water increases as the Al 2 O 3 content increases.
Maghemite/silica composites were prepared by a facile and effective method. First a stable magnet... more Maghemite/silica composites were prepared by a facile and effective method. First a stable magnetic fluid (MF) was obtained by dispersing in toluene the maghemite nanoparticles, prepared by coprecipitation. Afterwards, maghemite nanoparticles were coated with silica by the hydrolysis and condensation of tetraethylorthosilicate. The structural, surface and magnetic characteristics of the composites were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) and vibrating sample magnetometer (VSM) measurements. Magnetic studies indicated the superparamagnetic behavior of the samples and the decrease of the saturation magnetization with the decrease of the magnetic fluid concentration. SEM images revealed the presence of agglomerated, spherical particles and TEM images showed both separated particles and multiple maghemite particles together, covered with silica layer. The close relationship between the concentration of maghemite nanoparticles and the color of composite materials was confirmed by diffuse reflectance spectroscopy. CIEL n a n b n analysis revealed the change of the composites' color from reddish-brown to light beige by decreasing the concentration of the maghemite nanoparticles. These results demonstrate that the maghemite/silica composites are suitable for the manufacture of magnetic paper with different degrees of whiteness that can be easily correlated with the concentration of the magnetic fluid used for their preparation.
Abstract Highly sinterable CoFe 2 O 4 particles were prepared by a modified solution combustion s... more Abstract Highly sinterable CoFe 2 O 4 particles were prepared by a modified solution combustion synthesis, starting from a stoichiometric mixture of cobalt acetate (instead of cobalt nitrate), iron nitrate and 5-aminotetrazole. The resulted cobalt ferrite powder had large surface area (44 m 2 /g), small crystallite size (11 nm) and a saturation magnetization of 38.9 Am 2 /kg. CoFe 2 O 4 pellets sintered at 1100 °C for 2 h developed a fine compact microstructure, reaching 99% of the theoretical density. After sintering, the saturation magnetization increased to 71.3 Am 2 /kg whilst the coercivity decreased to 21.8 kA/m.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
The paper reveals a new perspective concerning the rational fuel selection and the logical elabor... more The paper reveals a new perspective concerning the rational fuel selection and the logical elaboration of the recipes for the MgAl 2 O 4 solution combustion synthesis. It was shown that Mg(NO 3) 2 Á6H 2 O and Al(NO 3) 3 Á9H 2 O exhibit different behavior with respect to urea, glycine and b-alanine. Urea proved to be the most adequate fuel for Al(NO 3) 3 Á9H 2 O, while b-alanine proved to be the most appropriate fuel for Mg(NO 3) 2 Á6H 2 O. Considering that there is a predilection of metal nitrates with respect to these fuels, in the case of MgAl 2 O 4 combustion synthesis best results were achieved when fuel mixtures (urea and b-alanine, urea and glycine) were used. The use of fuel mixtures allowed the formation of pure, nanocrystalline MgAl 2 O 4 directly from the combustion reaction, without any subsequent annealing step. The use of a single fuel (urea, glycine or b-alanine) led to the formation of an amorphous powder, which required further annealing in order to achieve the formation of crystalline MgAl 2 O 4 .
The reactivity of LiNO3 and Al(NO3)3 with respect to urea and β-alanine was investigated. Experim... more The reactivity of LiNO3 and Al(NO3)3 with respect to urea and β-alanine was investigated. Experimental results proved that β-alanine is a more suitable fuel for LiNO3, whereas urea seems to be more adequate for Al(NO3)3. Based on the different metal nitrate/fuel mixture reactivity, nanocrystalline γ-LiAlO2 powders were prepared by solution combustion synthesis using a fuel mixture of urea and β-alanine.
Single-phase CaZrO3 powder was prepared by heating at 300°C an aqueous solution of Ca(NO3)2, ZrO(... more Single-phase CaZrO3 powder was prepared by heating at 300°C an aqueous solution of Ca(NO3)2, ZrO(NO3)2 and β-C3H7NO2 (molar ratio=3:3:4). TG–DTA analysis indicated that an intense exothermic reaction occurred at 255°C, which lead to the formation of a voluminous white powder. No additional annealing was required, as pure crystalline CaZrO3 resulted directly from the combustion reaction. Although no advanced milling was performed, the specific surface area of the powder was 21.5m2/g. The average crystallite size of CaZrO3 was 23.9nm. After sintering in air at 1400°C for 2h, the pellets – shaped by uniaxial pressing at 200MPa – reached 95% of the theoretical density, had no open pores and were slightly translucent.
... Janbey A, Pati RK, Tahir S et al (2001) J Eur Ceram Soc 21:2285 11. Patil KC, Aruna ST, Miman... more ... Janbey A, Pati RK, Tahir S et al (2001) J Eur Ceram Soc 21:2285 11. Patil KC, Aruna ST, Mimani T (2002) Curr Opin Solid State Mater Sci 6:507 12. ... Kakade MB, Ramanathan S, Ravindran PV (2003) J Alloys Compd 350:123 J Mater Sci (2009) 44:10161023 1023 123
Single-phase nanocrystalline 4CaO·Al2O3·Fe2O3 powders were prepared directly from the combustion ... more Single-phase nanocrystalline 4CaO·Al2O3·Fe2O3 powders were prepared directly from the combustion reaction using a new cost-effective, time-saving, and environmentally friendly version of solution combustion synthesis. Instead of a single fuel, a fuel mixture of urea and β-alanine was used. It was shown by x-ray diffraction, energy-dispersive x-ray analysis, thermogravimetric analysis, and optical microscopy that this new version of the solution combustion synthesis allows the maximization of the exothermic effect associated with the combustion reaction. On the other hand, it was shown that the traditional version of combustion synthesis involving the use of a single fuel, such as urea or β-alanine, does not ensure the formation of Ca4Al2Fe2O10 unless subsequent thermal treatments are applied. It was suggested that the occurrence of combustion reactions cannot be regarded only in terms of adiabatic temperature, as the kinetic aspects overrule the thermodynamic ones.
The preparation of ␣-cordierite powders via combustion route was investigated. Urea, monoethanola... more The preparation of ␣-cordierite powders via combustion route was investigated. Urea, monoethanolamine and triethylenetetramine were used as fuels. The resulting powders were characterized by means of thermal analysis and XRD. Experimental results showed that SiO 2 behaves as an inert material, preventing the formation of 2MgO•2Al 2 O 3 •5SiO 2 directly from the combustion reaction. Using a fuel mixture of urea and monoethanolamine yielded a poorly crystalline powder (MgAl 2 O 4). The phase composition of powders after annealing at various temperatures has shown that the formation of ␣-cordierite occurs indirectly, via the solid state reaction of spinel and cristobalite. After annealing at 1300 • C for 1 h ␣-cordierite is virtually the only crystalline phase in the sample obtained with triethylenetetramine. In the sample prepared by using urea and monoethanolamine fuel mixture ␣-cordierite is the main crystalline phase, alongside traces of spinel and cristobalite. The intermediate formation of-cordierite was not observed.
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