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Microwave-hydrothermal (M − H) synthesis of α-Sn(HPO4)2·H2O (α-SnP) was achieved here in as low as 5 min at 194 °C compared to several days by others previously. The use of microwaves in conjunction with the hydrothermal process enhanced the α-SnP synthesis reaction at least by two orders of magnitude. The super fast synthesis was apparently due to localized superheating where nucleation started and the reactions occurred very quickly in the localized superheated spots. The synthesized α-SnP was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). TEM revealed worm-like morphology at both low temperature and short duration of M − H treatment but at higher temperature platy morphology typical of layered phases resulted. The synthetic tin phosphate (α-SnP) phase is potentially useful as a cation exchanger, proton conductor and electrode material.

Anthracite briquettes were developed using mainly waste anthracite fines, plant byproducts of rice hulls and rice hull ash and silicon metal powder as an ecofriendly fuel and as an alternative to conventional coke used in a cupola furnace. Si metal powder reacts with anthracite to form SiC, which provides high mechanical strength to an anthracite briquette when it is exposed to a high temperature in the cupola furnace. Rice hull and rice hull ash, which are agricultural byproducts with high SiO2 content were investigated as partial substitutes for silicon as the former are inexpensive relative to silicon metal. The formation of SiC was investigated under different conditions using X-ray diffraction and transmission electron microscopy. In addition, unconfined compressive strength of the briquettes was measured when the rice hull or ash substituted Si powder partially or completely. When anthracite briquettes prepared with elemental Si powder and either rice hull ash or rice hull powder were pyrolyzed at 1400 °C for 2 h, SiC formed and the briquettes showed high mechanical strength in the range of 2000–4000 kPa, which is enough to keep their structural integrity in a cupola furnace.

Crystalline Co3O4 and Co(OH)(2) were synthesized using Co(NO3)(2) as a precursor by conventional-hydrothermal and microwave-hydrothermal routes, respectively. The Co3O4 phase showed cubic morphologies while the beta-Co(OH)(2) phase exhibited plate-like shapes. The electrochemical performances of Co3O4 and Co(OH)(2) phases were evaluated as electrode materials for lithium-ion battery anodes, cathodes and supercapacitors. Both Co3O4 and Co(OH)(2) phases showed pseudocapacitive performances in Li2SO4 and KOH electrolytes. The Co3O4 and Co(OH)(2) phases were found to be more promising as anodes than as cathodes in lithium-ion batteries. The Co(OH)(2) electrodes showed higher specific capacitances than those of Co3O4 materials. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

The LiMn2O4 electrode materials were synthesized by the conventional-hydrothermal and microwave-hydrothermal methods. The electrochemical performances of LiMn2O4 were studied as supercapacitors in LiNO3 electrolyte and lithium-ion battery cathodes. The microwave-hydrothermal method can synthesize LiMn2O4 electrode materials with reversible electrochemical reaction in a short reaction time and low reaction temperature than conventional-hydrothermal route. The capacitance of LiMn2O4 electrode increased with increasing crystallization time in conventional-hydrothermal route. The results showed that LiMn2O4 supercapacitors had similar discharge capacity and potential window (1.2 V) as that of ordinary lithium-ion battery cathodes. In LiNO3 aqueous electrolyte, the reaction kinetics of LiMn2O4 supercapacitors was very fast. Even, at current densities of 1 A/g and 5 A/g, aqueous electrolyte gave good capacity compared with that in organic electrolyte at a current density of 0.05 A/g.

Fe-based materials, fe2o3, fe3o4, and feooh, were synthesized by the microwave-hydrothermal process in the temperature range of 100-200 degrees c and under very short reaction times of 15 min to 2 h. under microwave-controlled hydrolysis and redox reactions, cube-like fe2o3 was crystallized using fecl3, fe3o4 particles were crystallized from fecl2 and feooh nanorods were crystallized using fecl3. the fe-based materials were fabricated to make anodes and cathodes of lithium-ion battery and supercapacitor electrode materials to study their potential electrochemical applications. the electrochemical results showed that feooh had better anode capacity as lithium-ion batteries than those of fe2o3 and fe3o4. the present results suggest that the microwave-hydrothermally synthesized fe-based materials are promising lithium-ion battery anode materials. (c) 2013 elsevier ltd and techna group s.r.l. all rights reserved.

Nanophase anatase was synthesized by a novel simplified one-pot method using Ti alkoxides and hydrogen peroxide under conventional- and microwave-hydrothermal conditions. The specific surface areas (SSAs) of anatase ranged from 147 to 298 m2/g under different hydrothermal conditions but higher SSAs were obtained under microwave-hydrothermal conditions. The novel method developed here results in nanophase anatase with superior DeNOx properties.

Apparently C-doped and undoped or pure nanoparticles of anatase were synthesized using a microwave hydrothermal process in the temperature range of 140–180 °C for 1 h from several Ti precursors, such as Ti ethoxide, Ti isopropoxide and Ti oxysulfate. Nanoparticles of anatase samples were characterized by powder X-ray diffraction, transmission electron microscopy (TEM) and photocatalytic activity measurements. Results showed that nanoparticles in the size range of 4–17 nm of anatase were obtained in all cases with surface areas in the range of 151–267 m 2 /g. The photocatalytic activity of the prepared titanias was measured using methylene blue (MB) and NO x molecules. Because MB has very strong adsorption on the samples, photocatalytic degradation under either solar light or black light irradiation was found to be very limited. However, the DeNO x abilities of carbon-doped titanias were higher than those of Degussa P25 commercial titania sample and undoped or pure titanias especially under irradiation by long wavelength or visible light (>500 nm).

Parameters such as temperature, time and presence or absence of microwaves affected the particle size and magnetic properties of synthetic magnetite. The presence of microwaves during crystallization significantly increased the particle size of magnetite in a short time with improved magnetic properties. Magnetite samples were characterized by X-ray diffraction, transmission electron microscopy (TEM) and saturation magnetization measurements. The TEM crystal sizes varied from about 40 to 50 nm at room temperature to greater than 50 nm with wider crystal size distribution at higher temperatures. The saturation magnetization values of synthetic magnetites ranged from 57.4 to 89.0 emu/g.

Anatase and Ca, Sr and Ca0.5Sr0.5 hydroxyapatites were synthesized by conventional-hydrothermal (C-H) as well asmicrowave-hydrothermal (M-H)methods.Microwave-assisted reactions led to accelerated syntheses of anatase but no such acceleration of reactions could be detected with the syntheses of hydroxyapatites because the crystallization of the latter materials occurred at very low temperature. Cu and Au metal powders were produced by using glucose, fructose or sucrose as reducing agents under C-H conditions at 160 ℃, where fructose and sucrose were found to be stronger reducing agents than glucose. The crystallinity of all the powders was characterized by powder X-ray diffraction, and morphology and particle sizes were determined by scanning or transmission electron microscopy

LiMn 2 O 4-based materials such as LiMn 2 O 4 and LiMn 1.53 Ni 0.47 O 3.67 were synthesized by both conventional-hydrothermal (CH), microwave-hydrothermal (MH) methods and calcination route. Both reaction temperature and reaction time during MH routes were lower than those of CH routes. LiMn 2 O 4 electrode materials were assembled into lithium-ion battery anodes and their electrochemical performances were studied. The results proved that these LiMn 2 O 4 electrodes can be served as conversion anode materials, and show electrochemical activity during the potential range of 0.01–3.0 V versus Li +/ Li . For LiMn 1.53 Ni 0.47 O 3.67 materials when used as lithium-ion battery anodes, we found that the introduction of Ni can change their electrochemical reaction and thus improve their electrochemical performances.