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This paper demonstrates how glass has provided one of the earliest, and still rare, examples of controlled use of science at the nanolevel in a well-established gigatechnology. The glass community—from the Venetian glass makers (and the science of luminaries such as Michael Faraday and Isaac Newton) down through major industrial successes such as glass–ceramics—are examples of excellent nanoengineers practicing clever applications of manipulation of matter at the nano and subnano scale. This paper describes the evolution of the understanding of nanoheterogeneity of the structure (and composition of virtually all useful glasses) that has been the key evolutionary “invention” in this process. It then makes the case that glass (and polymer) technology has an enormous advantage over all of the nanomaterial technologies that are confronted with the enormous barrier of assembling large numbers of very small particles into useful products on a large scale, as recognized by the recently anointed patron saint of the present nanofever, Richard Feynman, in his only paper in the field. Finally, this paper introduces glass scientists to a radically new opportunity via a totally new way to convert crystalline matter into glasses (noncrystalline solids)—for all scientists interested in the glassy state.

Amorphous silicon–germanium alloys with 70% Si and 30% Ge have been formed by rapid heating in a pure E-field in a single mode 2.45 GHz microwave cavity. The synthesis of amorphous Si–Ge alloy by all conventional processing is difficult. This polarized microwave process provides another striking example of its unique abilities: producing bulk amorphous Si–Ge alloys. The microwave fabricated amorphous Si0.7Ge0.3 alloy composition exhibited relatively high Seebeck coefficient with high potential of its application in high efficient thermoelectric materials.

One of the most important factors for advanced ceramic preparation is the nature of powders. This article is a review and overview of powder preparation and properties and explains ideal powders for advanced ceramics. In addition, hydrothermal powders that are close to ideal powders are described along with hydrothermal processing.

A new device designed by the senior author of the current paper was examined and tested in the Materials Research Laboratory of The Pennsylvania State University. The device consists of an unconventionally driven magnetron whose directional output is conditioned by filters and a tailored horn antenna. Although the origin of the radiation is an ordinary 600 W magnetron, the modified radiation is not contained by either a Faraday cage or by microwave shielding. It interrupts the operation of electronic devices, shutting them off without apparent harm to the circuitry. The radiation was observed to pass through or circumvent a one inch block of aluminium. Lastly, it unexpectedly attenuated in the building ventilation ducts which were completely outside of the directional field, resulting in the heating of and off-gassing from sealant in the duct flanges.

Silicon and germanium alloys have been formed for the first time by heating powdered mixtures of 75%Si and 25%Ge in just 2 min in the H field in a single mode 2˙45 GHz microwave cavity. As is well known, alloy formation in conventionally heated silicon–germanium mixtures is difficult, even when processed for much longer time durations at the same temperature. Further, any oxide contaminants, if present in the starting material or formed during heating, somehow, appear on the surface of the specimen after microwave treatment.

Most natural waters are probably “ultra dilute”: aquasols. While the composition of such waters is routinely characterized thoroughly with respect to composition, very little attention has been paid to the solid phases which are certainly suspended in most, if not all, such. Our recent work having established the importance of the structure of water on its properties, [[1]; R. Roy, W.A. Tiller, I. Bell, M.R. Hoover; Mater Res Innov. 9 (2005) 577.] we have examined the structures of many waters with easily demonstrated (e.g. silver aquasols) or long-claimed (e.g. homeopathic remedies) biological effects. The results show that such materials can be easily distinguished from the pure solvent, and from each other, by the use of UV–VIS and Raman spectroscopy, while FTIR is insensitive to these differences. This opens up a whole new field of endeavor for inorganic materials scientists interested in biological effects.

The key stumbling block to serious consideration of homeopathy is the presumed ‘‘implausibility’’ of biological activity for homeopathic medicines in which the source material is diluted past Avogadro’s number of molecules. Such an argument relies heavily on the assumptions of elementary chemistry (and biochemistry), in which the material composition of a solution, (dilution factors and ligand‐receptor interactions), is the essential consideration. In contrast, materials science focuses on the three-dimensional complex network structure of the condensed phase of water itself, rather than the original solute molecules. The nanoheterogenous structure of water can be determined by interactive phenomena such as epitaxy (the transmission of structural information from the surface of one material to another without the transfer of any matter), temperature‐pressure processes during succussion, and formation of colloidal nanobubbles containing gaseous inclusions of oxygen, nitrogen, carbon dioxide, and possibly the remedy source material. Preliminary data obtained using Raman and Ultra-Violet‐Visible (UV‐VIS) spectroscopy illustrate the ability to distinguish two different homeopathic medicines (Nux vomica and Natrum muriaticum) from one another and to differentiate, within a given medicine, the 6c, 12c, and 30c potencies. Materials science concepts and experimental tools offer a new approach to contemporary science, for making significant advances in the basic science studies of homeopathic medicines. Homeopathy (2007) 96, 175–182.

We first establish the literature on the use of ultradilute aquasols as extraordinary, powerful, bactericidal inorganic agents equal to most commercial antibiotics. These findings provide the rationale for a major role for inorganic materials scientists to contribute the insights unique to their field for new, safer health vectors. The focus of this preliminary paper is exclusively on the materials science of 2-phase stable sols at ultradilute concentrations near 1 at.-ppm. We analyze the solid and liquid phases for the first time in detail using standard materials science analysis tools. The solid phase is analyzed using DTA, TGA, XRD, SEM, and TEM, and the liquid water phase is analyzed using FTIR, UV–VIS, and Raman spectroscopy. There are at least three crystalline phases in the system Ag–O: Ag, Ag2O, and Ag4O4, which are stable in air. In an aqueous environment between 0 and 100uC there is evidence that various combinations of metal, oxides, and possible ‘oxy-hydroxide’ complexes exist. Similarly, data from Raman and UV–VIS spectroscopy show definite changes in the structure of the water host. These results, in a preliminary way, are parallel to the many empirical observations made by physicians for the last 100 years on the use of metallic silver and water in various combinations for human health.

A series of ferrites was prepared using the microwave method, starting with hematite as precursor in the Ni1−xZnxFe2O4 (x = 0–1) system. After synthesis, the NiZn ferrite samples were irradiated with a microwave field for 90 s. X-ray diffraction (XRD) measurements were performed to yield the lattice constant as function of the amount x of Zn substitution, before and after irradiation. The lattice parameter was found to increase much slower with increasing x for the microwave irradiated specimens. Mossbauer spectroscopy was performed at room temperature and spectra were analyzed using the binomial distribution. For x = 0.4, 0.5 and 0.6 the resonance lines are much sharper for the irradiated samples and indicate that a microwave-induced recrystallization of the NiZn ferrites occurs in the composition range specified.

Two series of xerogels (desiccated hydrogels), one consisting of single phases and the other of two phases, were prepared from organic and inorganic precursors in the system Al2o3-Sio2. The effect of these nanostructural differences in the xerogel powders on the energy content and behavior on heating were studied using DTA, powder X-ray diffraction, and ultrafast heating on a strip furnace. The results demonstrate that diphasic xerogels are substantially different materials from single-phase xerogels of the same composition.

Beside chromium carbide and chromium nitride, chromium sesquioxide Cr 2 O 3 is a new candidate for hard and protective coatings. The reported bulk microhardness of Cr 2 O 3 is 29.5 GPa according to Samsonov (1982) and 28GPa according to Robertson and Manning (1990), making it second among all oxides, even above sapphire. The Mohs hardness is 8. The hardest oxide is the high pressure form of SiO 2 , stishovite, with 35 GPa (Haines and Lager (1998).

Results of a study of phase equilibria in the system CaO–TiO2–SiO2 are presented. A prominent feature of the liquidus surface is a large two-liquid region which appears on the equilibrium diagram as a broad band extending from the SiO2-CaO side to the SiO2-TiO2 side of the triangle. Evidence for the liquid immiscibility and the significance of the resulting large high-temperature liquidus region in silicate technology are discussed. Representative paths of crystallization of liquids in the system under equilibrium conditions are outlined. It is shown that solid solution in the system is virtually nonexistent except for the small-scale substitution of Ti4+ for Si4+ in wollastonite. Indices of refraction of glasses are given. Composition and temperature are listed for the twelve liquidus ternary invariant points.

Using single-crystal electron diffraction data it has been possible to demonstrate more directly the existence of considerable order in dehydroxylated kaolinite and halloysite. The two-dimensional (a-b) plane structure of dehydroxylated kaolinite is very similar to that of kaolinite. This phase, appropriately described by the term “metakaolinite,” decomposes first at about 825°C., γ-Al2O3 being the chief crystalline product. In the case of halloysite the γ-Al2O3 appears first at about 650°C. The products observed on the dehydroxylation of kaolinite depend to a large extent on the particle size of the sample used. Electron microscope studies of dehydroxylated material and the same material treated under very mild hydrothermal conditions show that the main phenomena accompanying dehydroxylation apparently are disalignment along the c-axis, the appearance of discontinuities in the sheets themselves (not visible directly in the crude image of the electron microscope), and the reduction of the effective particle size. The cause of the exothermic peak cannot be the formation of γ-Al2O3 but is assigned to the formation of mullite which is not necessarily detected in an X-ray powder pattern.

The system BaO-TiO2 was investigated using quenching, strip-furnace, and thermal techniques. Five compounds were found to exist in the system: Ba2TiO4, BaTiO3, BaTi2O5, BaTi3O7, and BaTi4O9. Of these, only barium metatitanate (BaTiO3) melts congruently (at 1618°C.). The dititanate melts incongruently at 1322° C. to yield BaTiO3 and liquid; the trititanate melts at 1357°C. to yield BaTi4O9 and liquid; the tetra-titanate melts to TiO2 and liquid at 1428° C. The nature of melting of the orthotitanate could not be determined accurately because of the high temperature involved and the rapid reaction with platinum. The two eutectics in the system occur between Ba2TiO4 and BaTiO3 at 1563°C. and between BaTi2O5 and BaTi3O7 at 1317°C. The temperature of the cubic-hexagonal transition in barium metatitanate was determined as 1460°C. and the transition has been shown to be reversible. The transition temperature is raised sharply by the addition of a small percentage of TiO2 although the extent of solid solution is quite limited. Some applications to the manufacture of titanate bodies and to the growth of single crystals of barium metatitanate are discussed.

This paper provides an interdisciplinary base of information on the structure of liquid water. It begins with a synthesis built on the information base on the structure 5 of noncrystalline, inorganic, covalently-bonded condensed liquid phases, such as SiO2, S, Se, P, and H2O, which exists in the materials science literature. The data for water are analyzed through the prism of well-established algorithms in materials research: the connection of properties to structure; the pressure-temperature (P-T) phase diagrams; the phenomenon of epitaxy; the phenomenon of liquid-liquid phase separation; the stability of two phase colloids; and, the recently discovered effects of weak magnetic and electric fields on the structure of simple inorganic oxides. A thorough combing of the literature of the condensed matter properties reflecting structural features of essentially pure water obtained via the normal processes of preparing homeopathic remedies, provides another rich data base. The examination of these data through the standard materials science paradigms leads to the following conclusion: Many different structures of liquid water must exist within the range of observations and processes encountered near ambient conditions. A typical sample of water in these experimental ranges no doubt consists of a statistical-mechanical-determined assemblage of monomers and oligomers (clusters) of various sizes up to at least several hundred H2O units. The importance of the structural similarity of SiO2 and OH2 is very relevant to the structure of the latter as well as to the probability of epitaxy in controlling at least the region contiguous to the silicate glass surfaces of many common containers. The most distinctive feature of bonding in liquid water is not only the “well-known hydrogen bonds, but the necessary presence of a wide range” of van der Waals bonds between and among the various oligomeric (cluster) structural units. It is this range of very weak bonds that could account for the remarkable ease of changing the structure of water, which in turn could help explain the half-dozen well-known anomalies in its properties. In its subtler form, such weak bonds would also allow for the changes of structure caused by electric and

Jacques Ellul, by far the most significant author in the serious discussions on the interface between religion and technology, is apparently not known to the science-and-religion field. The reason is the imprecise use of the terminology. In scientific formulation the relationship can be summarized as technology /religion:: science/theology. The first pair are robust three-dimensional templates of most human experience; the second pair are linear, abstract concerns of a minority of citizens. In the parallel community—now well developed throughout academia—of science, technology, and society, where the technology/religion matters have been discussed more than the science/religion pair, John Caiazza's point that “techno-secularism is the real problem” has been front and center for some decades. Among the theologians most aware of this, Raimundo Panikkar, Langdon Gilkey, and Huston Smith, Smith is the one who has taken the case much further than Caiazza, recognizing the danger of the real theological challenge from the religion of scientism and actively working against it. I write from a unique background among those involved in this debate—that of being deeply embedded simultaneously both in the modern science and technology establishment and in the reform of the religious enterprise for fifty years. I make the case that matters are worse than even Smith posits. He shows that scientism as a fundamentalist modern secularism serves the exact function of the theology behind the practiced religion of America and the West, that is, technology. An unexpected ray of hope has appeared in the sudden emergence of whole-person healing (also known as complementary and alternative medicine), which is used regularly by well over half the population. This reintroduction of the spiritual dimension into this key technology of health will certainly be a major turning point.

Fine, monophasic silicon carbide powder has been synthesized by direct solid-state reaction of its constituents namely silicon and carbon in a 2.45 GHz microwave field. Optimum parameters for the silicon carbide phase formation have been determined by varying reaction time and reaction temperature. The powders have been characterized for their particle size, surface area, phase composition (X-ray diffraction) and morphology (scanning electron microscope). Formation of phase-pure silicon carbide can be achieved at 1300 °C in less than 5 min of microwave exposure, resulting in sub-micron-sized particles. The free energy values for Si + C → SiC reaction were calculated for different temperatures and by comparing them with the experimental results, it was determined that phase-pure silicon carbide can be achieved at around 1135 °C.

This paper reports a new phenomenon—decrystallization of a solid by 1–5 eV photons, in a few seconds. A polycrystalline, 20 μm thick layer of CVD diamond on a WC substrate was exposed to two simultaneous pulsed laser beams 308 nm excimer, and 1.06 μm Nd:YAG in air ambient. The rough surface was ablated and smoothed, but the upper exposed half of the diamond layer was shown by Raman spectroscopy and X-ray diffraction to have been transformed to a non-crystalline phase. The 1332 cm − 1 Raman peak disappeared, demonstrating that lattice periodicity had been destroyed. Interestingly, the atomic disorder was gradually relaxed during five years at room temperature, and the Raman signature reappeared. The effect of decreasing intensity of diamond Raman peak has been demonstrated in single-crystal diamond. The distorted diamond lattice relaxed upon annealing in hydrogen plasma. The combination of pressure waves and the heating and cooling cycles is responsible for the creation and subsequent freezing of the atomic disorder, all in the solid state. The metastable states are introduced when atoms in the perfect lattice become displaced from the equilibrium positions. This is the process we term decrystallization—to distinguish it from glass formation, which requires the intermediary liquid state.

The application of microwave technology to a diverse range of materials and processes has resulted in a wide spectrum of materials that are commercially processed using microwaves, from the heating of food to the vulcanisation of rubber to the sintering of specialty ceramics. Microwave sintering of elemental or alloy metal powders has gained significance in recent times as a novel processing method since it offers many advantages over the conventional sintering method. Despite substantial R&D investment in this area in the past two decades, no competitive microwave technology has yet emerged for powder metallurgy (PM) sintering. In sharp contrast, because it is 'obvious' that microwaves are reflected by metals, it is not uncommon to be unable to locate many journal papers or literature, wherein metal powders have been sintered in a microwave field. This paper reports the improved mechanical properties and microstructural development of microwave sintered copper and nickel steel PM parts as compare...

WC/Co samples sintered in a microwave field differ radically in terms of phases, chemistry, and microstructure when compared with conventionally sintered samples. Microstructural investigations by TEM showed that in microwave sintered material the cobalt phase dissolved nearly no tungsten, whereas in conventionally sintered samples up to 20 wt.% tungsten was dissolved in the cobalt binder phase. Besides, smaller WC grains and finer and more uniform distribution of cobalt binder were observed in microwave sintered samples. This resulted in a harder material, which also exhibited better resistance towards both corrosion and erosion. Microwave sintered samples also have a three-dimensional uniform shrinkage, whereas conventionally sintered samples showed a greater vertical shrinkage. It is possible to microwave sinter WC/Co at lower surface temperature and in much shorter times than normally needed in a conventional furnace to obtain the same degree of densification.

Carbothermal reduction and nitridation of TiO2 was performed in a 2 kW, 2.45 GHz microwave furnace. Carbon, generally added for the removal of oxygen from TiO2 lattice also served as the low-temperature susceptor in these experiments. At temperatures >1200°C, the mixtures started reacting vigorously (self-burn), which was never observed with the respective pure compounds. In the self-burning state, the minimum duration required for complete titanium nitride transformation was ∼20 min with stoichiometric amounts of carbon. With excess C, the transformation duration dropped to just 1 min. CO removal and subsequent Ni fixation occur more directly in microwave-induced reactions than in conventional nitridation procedures. Intermediate formation of successive Magneli phases (Ti2nO2n−1) was not found in the microwave-induced reactions. The combination of microwave processing and combustion makes this route of economical interest.

A new hybrid sintering process has been developed by replacing all but one laser by microwaves in the existing simultaneous multiple laser process (SIMPLE). Microwave energy has been used to preheat the material before laser radiation, and the synergism between microwave and laser energies could effectively heat the material to temperatures of 1700°C and beyond in just a few minutes. Using this process, rapid sintering of 3Y–ZrO2 (3Y–TZP) pellets has been achieved in a few minutes. Microstructural investigations reveal that the microwave–laser hybrid sintered pellets of 3Y–ZrO2 have nanograins averaging about 20 nm. The microwave–laser hybrid sintering process can clearly be a new approach for fabrication of nanoceramics and nanocomposites.

A series of ferrites was prepared using microwave sintering, starting with both hematite and magnetite precursors in the Ni1−xZnxFe2O4 (x=0−1) system. X-ray diffraction measurements were performed to yield the lattice constant as function of the amount x of Zn substitution. For both hematite and magnetite series, the lattice parameter was found to increase with increasing x. Mossbauer spectroscopy was performed at room temperature and spectra were analyzed using the binomial distribution. The hyperfine magnetic field of the octahedral sublattice was found to decrease with increasing the number of Zn nearest neighbors for all values of the substitution level. The area of the tetrahedral sublattice decreases with increasing x and the sublattice area of the octahedral sites increases correspondingly for both series of samples, as a result of substitution of iron by zinc in the tetrahedral sites. The hyperfine magnetic field of the tetrahedral sublattice was found to decrease as function of Zn amount x, for both hematite and magnetite series. However, in most cases, the hyperfine magnetic fields for the magnetite series are slightly less than those corresponding to the hematite series.

Highly doped n-type silicon powder responds aggressively to a 2.45-GHz microwave E-field, whereas it remains unperturbed in the H-field. In the E-field, after about 30 s of treatment, the silicon powder attained submelting temperatures and thus coagulated to a bulk solid piece. X-ray diffraction analysis of the surface and the cross section of this solid material failed to show any detectable peaks, ascertaining the fact that the material had decrystallized. The Raman spectra of the material had broad and shallow peaks quite different from the thin, sharp lines exhibited by Si wafer. It appears that the E-field treatment has considerably distorted the lattice structure creating lattice strains throughout the sample. These lattice strains were relieved by grinding (recrystallized).

We have identified the high microwave susceptibility of the sodium di-hydrogen phosphate monohydrate (NHPM), NH2PO4·H2O. This acid phosphate of sodium can be heated to >900°C when exposed to 2.45 GHz microwave radiation. Using NHPM and microwave energy, a novel single-step synthesis of many important crystalline NZP compounds has been accomplished in a very short time. Interestingly, the combination of microwaves and nonstoichiometric oxide precursors for the preparation of NZP materials is found to reduce the reaction temperatures and enhance the reaction kinetics further. The microwave synthesis method is found to be simple and fast, minimizing the loss of volatile chemical species from the reaction. A microwave-assisted procedure for the rapid sintering of NZP compounds has also been demonstrated. Densification (>97%) has been achieved in

Ultralow dielectric constant values were measured on Ni–Zn ferrites prepared using Fe2O3 as a starting material and sintered in a microwave field. Significant differences in microstructure, magnetic, and dielectric properties were observed between microwave-sintered Ni–Zn ferrites prepared using Fe3O4 (T34) and those starting with Fe2O3 (T23) ingredients. Higher magnetization values observed in T23 ferrite are attributed to large grain size, possibly containing abundant domain walls and the presence of fewer Fe2+ ions. The ultralow dielectric constant values observed on T23 ferrites show that this procedure is highly suitable to prepare Ni–Zn ferrites for high-frequency switching applications.

Ni1−xZnxFe2O4 with x=0.0–1.0 in steps of 0.2 have been densified to >95% of theoretical both by conventional and microwave sintering procedures. Comparison studies were performed on these samples sintered at 1275 °C for 30 min. Microstructural study revealed large, but fewer pores in the microwave sintered specimens and small, but substantially more pores in the case of conventionally sintered specimens. Magnetic properties measurements showed lower coercivity and higher magnetization values for microwave sintered specimens. Lower coercivity values observed in microwave sintered specimens are attributed to larger grain size and higher magnetization values may be explained by the contribution of the ‘microwave field’ to the ‘uncoupling spin effect’. Most significantly samples sintered in a microwave field, generally, showed lower dielectric constant values compared with the samples sintered conventionally, making microwave sintering particularly suitable for high frequency applications.

We demonstrate in this paper that common crystalline phases can be made noncrystalline and hard magnets can be converted to soft magnets in the solid state in several seconds at temperatures far below the melting points. New crystal structures and magnetic structures of ferromagnetic oxides (ferrites such as BaFe12O19, CoFe2O4, Fe3O4, and ZnFe2O4, etc.) are formed by reacting either the stoichiometric mixture of oxides or the preformed phase-pure crystalline material in a pure H field (or E field) at microwave (2.45 GHz) frequencies. These major changes in the magnetic properties as well as major structural phase changes are caused by the magnetic field.

Transparent alumina samples have been successfully prepared by microwave sintering processing. In comparison to the conventional sintering processing, microwave sintering to transparent alumina can be achieved at lower sintering temperature and shorter sintering time. It was also found that the microwave heating could substantially increase the conversion rate of polycrystalline alumina to single crystalline sapphire, to improve the transparency and other properties of the transparent alumina samples.

A silent revolution has occurred in the most highly industrialized countries. This is the utilization and acceptance of various healing practices (which for convenience has often been labeled as “alternative medicine,” a.k.a. “whole person healing”) by an enormous fraction of the population. Moreover, this population cohort is much wealthier and better educated than the average citizen. It is no longer possible for this generation in the Western world to ignore or denigrate the medicine and healing practices used by hundreds of millions in other cultures. What is obviously needed is a retreat from the innate skeptical reaction of much of the stance of western medicine, the development of a mutual respect for other cultures and their achievements, and a genuinely open, scientific and wholistic approach to the issues, especially in this context, to other practices of whole person healing.

Science and religion are incommensurable: one cannot use centimeters to measure volume. Science's proper cognate is theology. Science and theology are human activities that are basically conceptual (partly fallible) frameworks for explaining experience. Religion and technology, by contrast, involve and control or limit human practice and experience: they involve “sensate” reality—people and things. The study of the interaction of these four terms (or any two) must use the terms more precisely. Science as practiced today has become scientism, another theology. Technology is, without any doubt, the world's most powerful and fastest growing religion. Minor squabbles among theologies, including science, must continue, but it is the tensions between technology and the established religions that will define this century. Battles on three fronts are already clear: the environment, globalization, and economic gaps. But whole–person healing, the replacement for high–tech reductionist modern medicine, is the most significant, because it will undermine science, which has hitched its wagon to this falling star. The end of fundamental science is upon us, because it has been so successful. Science will be increasingly applications–driven, and it will be judged by results. Here, it has met its nemesis in wholeperson healing that incorporates integrative medicine. Scientists must now reconsider their role in society. It will not be easy to accept a humbler position. Moreover, the vague allusions to spirituality by scientists need a more authentic commitment to praxis in lifestyle.

Inspite of overwhelming evidence showing that a variety of solid state reactions were radically different when performed in a multimode microwave chamber compared to conventional heating some still question whether there is direct link to the radiation field. The present study has been conducted, for the first time ever, in a single mode TE103 cavity at 2.45 GHz. A large variety of materials have been reacted as ≈1 cm φ, 2 mm thick samples within the same cavity, at the positions of the E field and H field maxima. Enormous differences are shown to occur for certain families of common ceramic phases depending only on which of the E or H fields were used. The most extraordinary effects and sharpest differences (noted to date) between reactions at the E and H nodes have been found in ferroic oxides. Phases such as Fe3O4 or binary compounds such as BaFe12O19 are rendered non-crystalline to XRD in a few seconds in the H field, although they show no bulk evidence for melting. The microstructures are unique, showing smooth glass-like regions with regular waves parallel to each other. In the E field node the identical pellet components react completely and form large euhedral crystals of a single phase. The phenomenon of de-crystallization or formation of nano-glasses was confirmed for all the 3d ferrite phases. The magnetic properties of these decrystallized ferro-magnetic phases also show remarkable changes from the original very hard, transforming to very soft, magnets.

While the enormous increase in kinetics during the synthesis and sintering of complex ceramics in a microwave field is now well established, there are less examples where synthesis and sintering to high density have been demonstrated in one single step. In this communication, we report the simultaneous synthesis and sintering of NiAl 2 O 4 from NiO+Al 2 O 3 powder mixture in just 15 min in a 2.45-GHz microwave field. The “anisothermal reaction” condition that was achieved in a microwave field appears to be responsible for the observed enhancement in the reaction kinetics of NiAl 2 O 4 formation.

Using a 2.45 GHz wave-guided cavity, in a single mode TE103 excitation, we were able to physically locate compacted 5 mm pellets of samples separately at the H (magnetic) node (where the E field is nearly zero), or the E (electric) node (where H field is nearly zero). A preliminary survey of a variety of metals, (Cu, Fe, Co..) ceramics (ZnO, etc.), and composites, (WC-Co, ZnO-Co) showed remarkable differences in their heating behaviors. The results establish conclusively that the magnetic field interaction contributes greatly to microwave heating of common materials in a manner, previously neglected in most theories of microwave heating, albeit still to be understood.

Pure aluminum nitride (AIN) has been successfully sintered to highly translucent form by microwave sintering at 1850°C with a dwelling time of 30–60 minutes. The results showed that the sintering temperature should be at least 1850°C or higher to get reasonable translucency in the AIN sample by the microwave sintering process. On the other hand, the conventional sintering method requires much longer sintering time to obtain a translucent AIN ceramics.

The experimental achievement of reacting two phases that are held at two different temperatures—the anisothermal reaction condition—is a radical innovation in materials chemistry. Details on the synthesis of Yttrium Iron Garnet (Y3Fe5O12), Barium Ferrite (BaFe12O19), and Nickel Aluminate (NiAl2O4) in 1–10 min in a microwave field are provided. The starting precursor oxides were chosen such that they include a low and a high microwave absorbing phases. When these mixtures are exposed to a 2.45-GHz multimode microwave field the highly absorbing powder particles act as (micro)heat sources and the low absorbing powder particle act as (micro)heat sinks, and create the “anisothermal heat distribution,” a hitherto never attained phenomenon in materials science. A comparison study carried out comparing conventional reactions of the same phases suggested that the “anisothermal heating phenomenon” is also responsible for the very rapid reactions and product formations. Model experiments performed with an Y2O3/Fe3O4 diffusion couple showed a unidirectional diffusion of Fe species into Y2O3, forming a different sequence of intermediate phases.

Microwave processing has gained worldwide acceptance as a novel method for heating and sintering a variety of materials from food to rubber to specialty ceramics, as it offers specific advantages in terms of speed, energy efficiency, process simplicity, novel and improved properties, finer microstructures, and lower environmental hazards. In the present paper, microwave sintering of modulus of rupture (MOR) bar samples of PM copper steel (MPIF FC-0208 composition) and the comparative evaluation of the mechanical properties using both microwave and conventional sintering techniques has been reported.The starting powder characteristics and the processing details of copper steel bar samples sintered in a conventional furnace and in an in house modified commercial microwave oven has been covered at length. In this study, the sintering temperature used typically ranged between 1100 and 1300°C, soaking time ranged from 5 to 20 min, and the atmosphere was controlled using flowing forming gas (mixture of ...

The framework zirconium phosphates with incorporated La 3+ and NH 4 + cations were synthesized via mechanical activation of solids followed by the hydrothermal treatment. Their phase composition, local bulk structure, surface properties and microstructure appear to be defined both by the structure of amorphous zirconium phosphates formed via mechanical activation of solids depending on precursors acidity and reactivity and by the pH-dependent mechanism of subsequent crystallization during hydrothermal treatment.

Results of the systematic study of the synthesis of highly dispersed framework zirconium phosphates stabilized by ammonium, lanthanum, aluminum, manganese, and cobalt cations are summarized. The synthesis involves the mechanochemical activation of a mixture of solid reactants (salts) or the sol–gel process each followed by the hydrothermal treatment (HTT) of obtained precursors in the presence of surfactants. The genesis of dispersed systems under investigation is studied by modern physical methods providing information on the state of the bulk and surface of the systems. It is found that the local structure of sol nanoparticles and zirconium phosphate crystalline nuclei arising from mechanochemical activation products depends on the nature of initial substances. This, in its turn, makes different crystallization mechanisms possible during the HTT process: the dissolution/precipitation mechanism or the mechanism of oriented mating of primary particles. The crystallization mechanism in HTT and the reaction system composition influence the nature of resulting complex zirconium phosphate phases, their thermal stability, dispersity, and porous structure parameters. The relationship between the bulk structure parameters of framework zirconium phosphates, which are controlled by varying the chemical composition and conditions of synthesis, and the surface characteristics of the systems (the strength and concentration of different Lewis and Br@nsted sites) is studied. It is shown that systems based on framework zirconium phosphates are promising catalysts for paraffin (pentane and hexane) isomerization, the selective oxidation of methane by oxygen into synthesis gas at short contact times, and the oxidative dehydrogenation of propane into propylene.

In this study, a large batch of commercial alumina abrasive grit was successfully microwave sintered using a continuous microwave sintering technique. The properties of the microwave sintered grit product can be easily controlled by adjusting the sintering temperature and the feed rate. In comparison of the conventionally sintered product, the microwave sintered material exhibited better abrasive and mechanical properties. Microscopic examination revealed a much finer microstructure of the microwave processed material than for the conventional product.

Simultaneous treatment by three pulsed lasers (excimer, Nd-YAG, and CO 2 ) of a ferrosilicon alloy in the QQC process resulted in a 50-μm layer of a non-crystalline phase in the middle of the workpiece.

Structural features and surface properties of framework zirconium phosphates synthesized via mechanochemical activation (MA) and sol–gel (SG) route were studied using XRD, TEM, 31P MAS NMR, IR and ESR spectroscopy and compared with their catalytic performance in the reaction of hexane isomerization. A high initial isomerization activity of crystalline zirconium phosphates prepared via MA can be determined by a larger share of the strong Lewis centers probed by TEMPON test molecule.