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Hafnia (HfO2, hafnium dioxide) is a wide band gap and high-κ material, and the metastable cubic hafnia has a much higher permittivity compared with the normal monoclinic hafnia. Here, we employ a one-step process, the pulsed plasma in liquid (PPL) method to synthesize two types of hafnia nanoparticles (NPs): one which is mainly in cubic phase (cubic: 81.7 at%, monoclinic: 18.3 at%) and the other which is in monoclinic phase. High-resolution transmission electron microscopy images showed that the particles were small (particle size ~3 nm). X-ray absorption fine structure analysis showed no chemical shifts, indicating that the synthetic hafnia NPs contained no oxygen vacancy. The synthetic hafnia NPs mainly in cubic phase showed a much higher relative permittivity than that of the commercial hafnia (monoclinic), and have a larger band gap than the synthetic monoclinic hafnia NPs.

Cerium oxide (CeO2-x) nanoparticles were synthesized using a simple one-step method known as the pulsed plasma in liquid (PPL). XRD analysis showed the production of pure cubic cerium oxide (Fm 3 ‾ m). HRTEM and XANES analysis confirmed the monophase cubic CeO2-x, and exclude the presence of the hexagonal Ce2O3 and/or mix phase of CeO2/Ce2O3 in the particle layers. HRTEM analysis showed that most particles were about 3 nm in diameter. XPS analysis showed that the cerium oxide nanoparticles synthesized by the PPL method had a higher Ce3+ proportion (42.2%) than some commercial powders, and also higher than the previous reported nanoparticles. The present cerium oxide nanoparticles showed high visible light-induced photocatalytic activity in the degradation of methyl orange (MO) and better polishing characteristics of quartz glass, compared to commercial samples. These results may attribute to the high Ce3+-ion content and/or the small particle size.

Herein we report the mass-production of Cl-doped graphene nanodots through the implementation of pulsed plasma on graphite rod in CHCl3 medium. The Cl-doped graphene shows the band gap, which is as...

Under strong gravitational fields, the unique uniaxially distorted crystalline state induces structural changes in compounds other than those caused by high pressure and high temperature. We subjected the hexagonal YMnO3 single crystal to a strong-gravitational field (0.78 × 106 G, 400 °C) and determined the changes in the crystalline structure and physical properties of the recovered metastable sample. According to four-circle single-crystal X-ray diffraction data, the structural analyses indicated changes in the inequivalent nearest-neighbor Mn-Mn and Mn-O bond distances, thereby demonstrating that trimerization distortion occurred in the ab plane under the strong gravitational field. Magnetic measurements indicated that there were changes in the magnetic anisotropy, which were explained by changes in the spin–orbit interaction due to lattice distortion.

Single crystals of synthetic reidite and natural radiation-damaged zircon from Okueyama, Japan were investigated using X-ray diffraction. The pressure-induced zircon–reidite transition is described by the twisting and translations of SiO4 tetrahedra with disappearance of the SiO4–ZrO8 shared edges. The lattice of radiation-damaged zircons expands mainly from α-decays of radioactive elements such as U and Th. Although old radiation-damaged zircons show anomolous lattice distortion, young radiation-damaged zircons do not show such distortions. These distortions are caused by thermal recovery that suppresses the Si4+–Zr4+ repulsion between the SiO4 tetrahedron and ZrO8 dodecahedron. These changes in structure can be understood by considering the cation–cation repulsion between the SiO4–ZrO8 shared edges.

In the study, Si3N4-Al2O3-Y2O3 samples were obtained in two stages. In the first stage, the materials were compacted using different methods: Isostatic Pressing, UHP (Ultra High Pressure), and SC (Shock Compaction). In the second stage, the green body samples obtained were sintered using the free sintering method. Powder mixtures, in wt%, 88 Si3N4 - 6 Al2O3 - 6Y2O3, were based on commercial nano - and micropowders. The parameters of green bodies compaction and sintering processes were optimised using the criteria of highest density, hardness, and Young's modulus. When compared to theoretical density values, the density of green body samples was 58% for the Isostatic Pressing and 82% for UHP and Shock Compaction. The Vickers hardness was measured only for Shock Compacted green body samples and was ~10.8–14 GPa depending on the applied load during the measurement. The largest changes in lattice constant parameters were measured for the Y2O3 phase for the dynamic compaction method (a = 0.02% - 2.26%). The highest relative density was measured for materials which were compacted by UHP method and subsequently free sintered (95%). Young's modulus for UHP and Isostatic green body free sintered samples was 284 GPa and 241 GPa, respectively. The hardness values of samples after free sintering were as follows: 11.7GPa for Isostatic, 14.8 GPa for UHP, and 17.6 GPa for Shock Compaction samples.

Hugoniot data for $\mathrm{Pb}{\mathrm{F}}_{2}$ single crystals were measured for pressures up to 1 TPa through gas gun and laser shock experiments. Experimental results show that $\mathrm{Pb}{\mathrm{F}}_{2}$ transforms to a less compressible phase at 29 GPa and possibly melts at 57 GPa. Quantum molecular-dynamics simulations were also performed to calculated the liquid Hugoniot for $\mathrm{Pb}{\mathrm{F}}_{2}$. The simulated results are in good agreement with the experimental results, supporting the high-pressure phase is liquid. The current study, combined with previous studies on $\mathrm{Ti}{\mathrm{O}}_{2}, \mathrm{Si}{\mathrm{O}}_{2}$, and $\mathrm{Ca}{\mathrm{F}}_{2}$, suggests that for $A{X}_{2}$ compounds, decreasing of Hugoniot slope can be taken as an indication of melting, and the Hugoniot slope approaches 1.2 at ultrahigh pressure.

At the 26th AIRAPT conference in 2017, a task group was formed to work on an International Practical Pressure Scale (IPPS). This report summarizes the activities of the task group toward an IPPS ruby gauge. We have selected three different approaches to establishing the relation between pressure (P) and ruby R1-line shift (Δλ) with three groups of optimal reference materials for applying these approaches. Using a polynomial form of the second order, the recommended ruby gauge (referred as Ruby2020) is expressed by: P[GPa]=1.87(±0.01)×103Δλλ01+5.63(±0.03)Δλλ0, where λ0 is the wavelength of the R1-line near 694.25 nm at ambient condition. In June of 2020, the Executive Committee of AIRAPT endorsed the proposed Ruby2020. We encourage high-pressure practitioners to utilize Ruby2020 within its applicable pressure range (up to 150 GPa), so that pressure data can be directly compared across laboratories and amended consistently as better scales emerge in the future.

The stability of hauerite (MnS2) as compared to that of pyrite (FeS2) can be explained by the long Mn–S distance and departure from the typical pyrite-type structures. The structural differences of MnX2 compounds (X=S, Se, and Te) are the result of spin configurations that are different than those of other MX2 compounds; however, the arrangement of d-electrons and the size of the ions in MnX2 compounds do not clearly explain why Mn2+ in MnX2 does not exist as a low spin state. To investigate the structural differences of MnX2 compounds, we synthesized single-crystal MnTe2 and MnSe2 and performed single-crsytal X-ray diffraction experiments. The single-crystal X-ray diffraction experiments were conducted on MnTe2 [a=6.9513(1) Å, u-parameter=0.38554(2), space group Pa3̅, Z=4], MnSe2 [a=6.4275(2) Å, u-parameter=0.39358(2)], MnS2 [hauerite; a=6.1013(1) Å, u-parameter=0.40105(4), obtained from Osorezan, Aomori, Japan], and FeS2 [pyrite; a=5.4190(1) Å, u-parameter 0.38484(5), obtained from Kawarakoba, Nagasaki, Japan]. The X-ray intensity datasets of these compounds do not show any evidence of symmetry reduction. In MnS2, the S–S distance is 2.0915(8) Å, which is significantly shorter than that of FeS2 (2.1618(9) Å), and the mean square displacement of S (U 11=0.00915(9) Å2) is smaller than that of Mn (U 11=0.01137(9) Å2). The thermal vibration characteristics of MnX2 compounds are significantly different than those of FeS2. Based on structural refinement data, we discuss the low spin state of MnX2 compounds and the structural stability of pyrite-type structures.

Chlorine on graphene (G) matrices was doped by pulsed plasma stimulation on graphite electrode submerged in organochlorine solvents (CH2Cl2, CHCl3, CCl4). The study of work function by Kelvin probe force microscopy (KPFM) measurement clearly indicates that Cl-doped G behave like semiconductor and GG@CHCl3 exhibits the lowest value for the work function. We propose that this report not only represents a new route for tuning the semiconductivity of G but also indicates that doping level of halogen on G based carbon framework can be controlled by pulsed plasma treatment of carbon materials on various organohalogen derivatives.

We present the first experimental results of the growth of Cu6Sn5 and Cu3Sn under an external force field – during the sedimentation process. The results are compared with the proposed model under the combined influence of the Kirkendall effect, backstress and sedimentation. It is shown that Cu3Sn consumes the preformed Cu6Sn5 phase during sedimentation under a strong gravitational field of 779,000 G at 200 °C.

Single crystals of the vanadate garnet Ca2NaCd2V3O12 (dicalcium sodium dicadmium trivanadate) were synthesized using the floating-zone method and the crystal structure was investigated using single-crystal X-ray diffraction. We considered the effectiveness of substitution of the Y-site cation with reference to previous structural studies of vanadate garnets. The structures of vanadate garnets are subject to geometric constraints similar to those of silicate garnets. These constraints force the tetrahedral–dodecahedral shared edge length in vanadate garnets to become shorter than the unshared dodecahedral edge length, as in ugrandite (uvarovite, grossular and andradite) garnets. However, the vanadate garnet Ca2NaCd2V3O12 exhibits the normal structural feature, similar to pyralspite (pyrope, almandine and spessartine) garnets, namely that the dodecahedral–dodecahedral shared edge length is shorter than the unshared dodecahedral edge length. With increasing ionic radius of the Y-site cation, the atomic coordinates x, y and z of oxygen adopt values which satisfy Pauling's third rule.

The phase transformations in Fe have been of technological and sociological importance in the development of human civilization. The α→e (BCC→HCP) martensitic transformation is the best known phase transformation of Fe and has been extensively studied. However, the mechanisms of α→e and e→α transformation upon shock loading and release are not yet understood owing to its short life and reversibility. In this study, we designed experimental and atomic methods for observing the shock-induced phase transformations in [001] and [111] single-crystal Fe, using shock recovery experiments and molecular dynamic simulations. It was found that the orientation relationships in the [001] and [111] single-crystal Fe are consistent with previously proposed transformation mechanisms. The α→e transformation was attributed to the (110) slip system, while the reverse transformation was attributed to the (112) slip system. Furthermore, it was postulated that the rod-like microstructures observed in the shock-recovered samples were caused by the wave interactions during the unloading. However, the rod-like shapes in the [001] Fe were caused by the activation of dislocations in the b1 = ka[11–2] and b2 = ka[112] Burgers vectors. Only the b3 = ka[112] dislocation was activated in the [111] Fe sample.

Through Surface Mechanical Coating (SMC), a plate of pure Cu was successfully coated using of Al-50-wt% Cu during mechanical alloying. Effect of milling time and heat treatment on formation of coat...

Pulsed plasma between two Zn rods submerged into aqueous solution of cetyl trimethylammonium bromide (CTAB) and sodium dodecyl sulphate (SDS) surfactants resulted in formation of pure ZnO nanorods, while the pulsed plasma between two Zn rods in water without surfactant yielded a mixture of ZnO and Zn nanoparticles. Carbon coated ZnO nanorods with about 20 nm thickness and 150 nm length were synthesized by this method using different surfactant materials such as CTAB and SDS. Cu nanoparticles of about 10 nm in size were also synthesized by the pulsed plasma in aqueous solution of 0.2% gelatine as surfactant material. Surfactant materials served as protective and stabilizing agent and induced formation of smaller sized particles with larger surface area, which in turn inhibited excellent antibacterial activity for Escherichia coli (E.coli). Silver nanoparticles stabilized by SDS exhibited much higher antibacterial activity against E.coli than that of without surfactant.

We report the preparation of single-crystal rutile (TiO2) with a unique structure prepared by ultracentrifugation at high temperature (strong gravitational field). Single-crystal rutile was subjected along the c-axis direction to a gravitational field of 0.4 × 106 G at 400 °C, and the uniquely structured single-crystal rutile, which did not conform to Pauling’s third rule, was quenched at ambient conditions. The anisotropy (a/c ratio) of the tetragonal phase increased by 2%. The (Ti–Oa)/(Ti–Ob) and Os/Ou ratios increased by 1.6% and 3%, respectively, and approached 1; Ti–Oa and Ti–Ob are the two Ti–O interatomic distances, and Os and Ou are the shared edge Oa–Oa and the unshared edge Oa–Ob, respectively. This means that the TiO6 octahedral group became isotropic. Os was expanded from its normal size, in contradiction to the usual laws, by the strong gravitational force. Such a structural change has not previously been achieved under high-pressure or high-temperature conditions, and may be related to struc...

FePt alloys are an important class of materials in permanent magnetic applications because of their large uniaxial magnetocrystalline anisotropy and good chemical stability. We have applied the pulsed plasma in liquid method to synthesis nanoparticles. Short duration of pulse and quenching effects of the surrounding liquid limit the size of crystal. That enable synthesis of small size and metastable nanoparticles. In this study, ferromagnetic FePt nanoparticles were successfully synthesized. Face-centered-cubic (FCC) A1-type phase was synthesized from FePt (Fe:PT=50:50, 55:45 in atomic %) alloy rod electrodes using the pulsed plasma in ethanol. The ordered face-centered-tetragonal (FCT) L10-type phase FePt was obtained by annealing the A1-type phase at 400oC for 1 h. The average diameter of L10-type FePt nanoparticles was less than 10 nm. Vibrating Sample Magnetometer (VSM) analysis showed that the coercivity of L10-type nanoparticles was much larger than that of the A1-type phase nanoparticles.

We propose a new method for the hydrothermal decomposition of cellulose using a strong gravitational field to recover useful chemical intermediates. Experiments of decomposition of two kinds of cellulose (microcrystalline and low-crystalline) under a hydrothermal condition were conducted at 250 °C for 6 h to a gravitational field of 0.33 × 106 G generated by a ultracentrifuge rotating at 80,000 rpm using a specially-designed gravity apparatus. Results, of our strong-gravity hydrothermal treatment of celluloses showed that both celluloses types successfully hydrolyzed to form cello-oligosaccharides and glucose, and surprisingly phenolic compounds such as guaiacol derivertives, which are applicable for the chemicals and food industries. Due to synergism of strong gravitational field with physical properties of water under hydrothermal condition, this unique method is anticipated as a benign technique to covert cellulose to cello-oligosaccharides and glucose via hydrolysis, and valuable phenolic compounds via any rearrangement or unique reactions of cellulose or its hydrolysis products.

We report the effect of a strong gravitational field on oriented crystalline perovskite-type manganese oxide La1−x Sr x MnO3 (LSMO). The perovskite-type manganese oxides La1−x Sr x MnO3 (LSMO) have been investigated for giant magnetoresistance (GMR) by controlling the hole-doping level (x). A strong gravitational field can change in crystalline state and the enhancement of usual diffusion. We subjected oriented crystalline La1−x Sr x MnO3 with different grain and grain-boundary (GBs) Sr concentrations to a strong gravitational field and investigated the resulting changes in the A-site cation diffusion and physical properties of the material. Electron probe micro-analysis (EPMA) results showed appearance of the GBs where the Sr concentration was quite high compared with in other GBs. The quantitative analysis at the grain and GBs indicated that cation diffusion was more enhanced than the annealed one. The temperature dependence of the magnetic susceptibility of the gravity samples changed with the Sr concentration in the grains. The temperature dependence of the resistivity curves of the gravity sample showed several abrupt changes, which corresponded to phase transitions at the grains and GBs, which may be caused by composition changes.

A shock-wave compression experiment using synthesized silica gel was investigated as a model for a comet impact event on the Earth’s surface. The sample shocked at 20.7 GPa showed considerable structural changes, a release of water molecules, and the dehydration of silanol (Si–OH) that led to the formation of a new Si–O–Si network structure containing larger rings (e.g., six-membered ring of SiO4 tetrahedra). The high aftershock temperature at 20.7 GPa, which could be close to 800 °C, influenced the sample structure. However, some silanols, which were presumed to be the mutually hydrogen-bonded silanol group, remained at pressures >20.7 GPa. This type of silanol along with a small number of water molecules may remain even after shock compression at 30.9 GPa, although the intermediate structure of the sample recovered was similar to that of silica glass.

We synthesized Pd-Fe series nanoparticles in solid solution using pulsed plasma in liquid with Pd-Fe bulk mixture electrodes. The Pd-Fe atomic percent ratios were 1:3, 1:1, and 3:1, and the particle size was measured to be less than 10 nm by high-resolution transmission electron microscopy (HR-TEM). The nanoparticles showed face-centered cubic structure. The lattice parameter increased with increasing Pd content and followed Vegard&rsquo, s law, and energy-dispersive X-ray spectra were consistent with the ratios of the starting samples, which showed a solid solution state. The solid solution structure and local structure were confirmed by HR-TEM and X-ray absorption fine structure.

In this work, spherical Sn and SnO2 nanoparticles smaller than 5 and 20 nm, respectively, were synthesized using pulsed plasma in deionized water, simply and environmentally friendly. The tetragonal Sn nanoparticles showed good crystallinity and slight increase in lattice parameters. Thermo-gravimetric analysis revealed insignificant weight loss from the particles, indicating their thermal stability up to 500 °C. The Sn nanoparticles then were annealed at 800 °C; in result, cassiterite phase of SnO2 nanoparticles were successfully obtained. Structural and morphological analysis indicated the full oxidation of Sn and size growth of SnO2 nanoparticles upto 20–25 nm. The SnO2 nanoparticles showed good photocatalytic activity in degradation of organic dyes, such as methylene blue and methyl orange.

Impact-induced dehydration of serpentine in primitive meteorites is believed to be a mechanism to provide water in terrestrial planets. Primitive meteorites show a wide range of porosity and it is necessary to know the effect of porosity on the dehydration. In this work we report the dynamic dehydration reaction in powdered samples of antigorite by shock recovery experiments, in which recovered samples were investigated using techniques of X-ray diffractions, electron microscopy, and thermal analyses of shock recovered samples. The present experimental results indicate that the dehydration reaction is weakly pressure-dependent below a peak shock pressure of ∼21 GPa and becomes violent at pressures of 21–60 GPa. The kinetics was found to be dependent on not only peak shock pressure but also the initial porosity and sample amount. We discuss the heterogeneous dehydration reactions based on the phases identified in the recovered samples, more than previously thought.

Single crystals of the vanadate garnet Ca

Pure orthorhombic-phase WO3·H2O nanoparticles with sizes of about 5 nm were synthesized by pulsed plasma in deionized water, in which tungsten electrodes provide the source of tungsten and the water is the source of oxygen and hydrogen. The quenching effect and liquid environment inherent in this pulsed plasma in liquid method resulted in ultra-small particles with lattice lengths (a = 5.2516 A, b = 10.4345 A, c = 5.1380 A) larger than those of reference lattices. The emission lines of W I atoms, W II ions and H I atoms were observed by an optical emission spectrum in order to gather information on the synthetic mechanism. These nanoparticles showed higher absorption in the visible region than did ST-01 TiO2 and Wako WO3 nanoparticles. The WO3·H2O nanoparticles displayed more activity in the photocatalytic test than did the commercial TiO2 sample (ST-01). Also, the absorption edge of WO3·H2O shifted to longer wavelengths in the UV-Vis absorption pattern relative to that of the anhydrous tungsten oxide.

Shock-reshock and shock-release experiments were performed on silicon nitride ceramics above and below its phase transition pressure. Experimental results clearly show the occurrence of elastic-plastic transition and phase transition during initial shock loading. The HEL and phase transition stress are determined as 11.6 and 34.5 GPa, respectively. Below the phase transition stress, the reshock profile consists of the single shock with short rise time, while the release profile shows the gradual release followed by rapid one. Above phase transition stress, reshock and release behavior varies with the initial shock stress. In the case of reshock and release from about 40 GPa, the reshock structure is considerably dispersed, while the release structure shows rapid release. In the reshock profile from about 50 GPa, the formation of the shock wave with the small ramped precursor is observed. And, the release response from same shocked condition shows initial gradual release and subsequent quite rapid one. The...

High temperature phase tungsten carbide and titanium carbide coated with graphitic carbon (WC1−x@C and TiC@C) nanoparticles were synthesized by pulsed plasma in liquid. HRTEM results show that the average size of WC1−x@C and TiC@C nanoparticles are 30 and 35 nm, respectively. Raman spectroscopy revealed well-organized graphitic coatings, which make the nanoparticles stable at higher temperatures and resistant to oxidation. Refinement of the XRD profiles showed larger cell parameters compared to JCPDS cards. Furthermore, thermogravimetric analyses showed the higher thermal stability up to 601 and 543.4 °C, for the WC1−x@C and TiC@C nanoparticles, these are 43% and 36% more compared to the thermal stability of previously reported nanoparticles, which degraded at around 350 °C.

Homogeneous Bi-Pb alloy samples in the ε-phase are treated under mega-gravity centrifugal acceleration field. Atomic sedimentation in solid and associated partial crystallization occurs during the treatment. Small differences of densities in the ε-phase are enhanced under the mega-gravity, and they cause the separation of the ε-phase between fully packed hcp structure of the Bi3Pb7and partially defected hcp structure of the Bi3Pb7-δ. The compositional graded superconducting alloy is obtained in the latter. Partially melt-growth occurs in the latter and microstructure of Pb is formed along the gravity field associating with the formation of highly oriented the (211) phase of Bi3Pb7-δ. The superconductivity parallel to gravity is Pb, and perpendicular to gravity is Bi3Pb7-δas the result. Superconducting properties differs between the separated two phases.

We synthesized onion-like carbon-encapsulated Co, Ni, and Fe (Co-C, Ni-C, and Fe-C) magnetic nanoparticles with low cytotoxicity using pulsed plasma in a liquid. The pulsed plasma is induced by a low-voltage spark discharge submerged in a dielectric liquid. The face-centered cubic Co and Ni, and body-centered cubic Fe core nanoparticles showed good crystalline structures with an average size between 20 and 30 nm were encapsulated in onion-like carbon coatings with a thickness of 2-10 nm. Vibrating-sample magnetometer measurements revealed the ferromagnetic properties of as-synthesized samples at room temperature (Co-C=360 Oe, Fe-C=380 Oe, and Ni-C=211 Oe). Raman-spectroscopy analysis found onion-like carbon shells composed of well-organized graphitic structures. Thermal gravimetric analysis showed a high ___________________*Corresponding author. Tel/Fax: +08052593295. E-mail address: mashimo@gpo.kumamoto-u.ac.jp (T. Mashimo)stability of the as-synthesized samples under thermal treatment and oxidation. Cytotoxicity measurements showed higher cancer cell viability than samples synthesized by different methods.

The α−ɛ phase transition stresses of single-crystal iron under shock compression along the [100], [110], and [111] crystal orientations were measured to be ∼13.3 ± 0.5, 13.5 ± 0.4, and 12.8 ± 0.4 GPa, respectively. Within the uncertainty of the measurement, the phase transition stresses of single crystal iron do not show obvious orientational dependence. These results differ from the simulation studies of the nonequilibrium molecular dynamics. We suggest that single crystal iron loses most shear stress beyond the Hugoniot-elastic-limit and the phase transition happens under a nearly hydrostatic state.

We performed an ultracentrifuge experiment on Bi–Sb alloy. Deformation twins with misorientations of about 90° were observed in the low-gravitational region where grain refinement had not occurred. The twins were thicker than the conventional deformation twins and their thickness was proportional to the gravitational field. We found that the minimum gravitational field required for grain refinement was 0.17 × 106 G at 240°C for periods

Through shock-compression experiments, pressure-density relation of condensed matter can be directly and precisely determined. We have established the high-time-resolution streak photographic system using a long-pulsed dye laser equipped with both the powder gun and two-stage light gas gun. By using them accuracy of the measurement is much improved. We started the Hugoniot-measurement experiments on pressure-scale materials such as Au and MgO up to >200 GPa for the purpose of improvement of the pressure scales. We are now measuring the Hugoniots of Au and MgO as well as those of some metals (Al, Cu, Ta, W, etc.) to determine the Hugoniot data free from the Los Alamos data. In this article, the backgrounds and problems of the various pressure scales are reviewed, and our approach to establish pressure scales by means of the shock-compression at Kumamoto University is described.

Through the measurement of Hugoniot parameters, we can get useful information about high-pressure phase transitions, equations of state (EOS), etc. of solids, without pressure calibration. And, we can discuss the transition dynamics, because the relaxation times of phase transition and compression process are of the same order. We have performed the Hugoniot-measurement experiments on various kinds of compound materials including oxides, nitrides, borides and chalcogenides by using a high time-resolution streak photographic system combined with the propellant guns. The structure-phase transitions have been observed for several kinds of inorganic materials, TiO2, ZrO2, Gd3Ga5O12, AlN, ZnS, ZnSe, etc. The phase transition pressures under shock and static compressions of metals, ionic materials, semiconductors and some ceramics are consistent with each other. Those are not consistent for strong covalent bonding materials such as C, BN and SiO2. Here, the Hugoniot compression data are reviewed, and the shock-induced phase transitions and the dynamics are discussed, as well as the EOS of the high-pressure phase up to evem 1 TPa.

Synthesis of blue amorphous TiO2 and Ti(n)O(2n-1) by the impulse plasma in dielectric liquid is presented. The impulse plasma in liquid enables us to quench from plasma state, by which we can synthesize nanomaterials, metastable materials, etc. By the impulse plasma between titanium rods submerged into water, we have synthesized blue colored amorphous TiO2 nanoparticles suspended in water and black titanium monoxide at the bottom. Different types of titania oxides like Ti3O, TiO, Ti2O3, Ti4O7 were produced by the impulse plasma in different water temperatures (3, 30, 60, and 90 degrees C respectively). High Resolution Transmission Electron Microscopy analysis showed that the amorphous TiO2 contains anatase nanocrystals with less than 10 nm. UV-vis absorption spectra of the blue TiO2 nanoparticles showed higher absorbance of visible light than the commercially available pure anatase nanoparticles.

The graded oxide glasses in binary oxide systems (Si−Ti, Si−V, and Si−Zr) had been prepared by means of a sol−gel method combined with centrifugal processing. In the Si−Ti and Si−V oxide systems, the graded oxide glasses, whose composition continuously changed with dimension in molecular scale, were prepared. The FT-IR analysis showed that infrared absorption peaks of Si−O−Si stretching and bending shifted, and Ti−O−Si or V−O−Si bands appeared with increasing the concentration of Ti or V, respectively. In the Si−Zr oxide system, the graded oxide glass in which the ZrO2 nanocrystals appeared in the high gravity region was prepared.

A visible four-layers structure with anomalous nano-sturucture was formed from a homogeneous -phase Bi3Pb7 intermetallic compound under a strong gravitational field (1.02x106 G, 130°C, 100 hours). In the 4th layer (lowest-gravity region), pure Bi particles precipitate. In the 2nd 3rd layers, composition graded structures, where Pb content increased along the gravity direction, were formed. It was found that the very broad XRD peak appeared in the 2nd layer, which indicated that an amorphous structure was contained.

An atomic-scale graded structure has been formed by sedimentation of substitutional atoms under an ultra-strong gravitational field of 1 million G level in alloys and compounds. In this study, we investigate the sedimentation of impurity atoms in semiconductor materials under a strong gravitational field. High-temperature ultracentrifuge experiments (0.59×106 G, 400°C, 60 hours) have been performed on an InSb single crystal wafer which surface was coated with Ge by means of Physical Vapor Deposition (PVD). It was observed that the penetration depth of diffused Ge atoms under the gravitational field was several times larger than under terrestrial field at the same temperatures.

Ultracentrifuge experiments were performed on the twinned Y1Ba2Cu3O7-x (Y123) single crystal at much lower temperatures than the melting point. Two layers structure with slightly different compositions was observed in the sample ultracentrifuged at 250°C(380,000 G), which might be due to the sedimentation of atoms. In the strong gravity layer, it was found that the Y123 phase disappeared, and unknown XRD peaks appeared. Decomposition occurred in the sample ultracentrifuged at 400°C.

The atomic-scale graded structure of In-Pb alloy was formed by an ultracentrifuge under a gravitational field of 0.81 x 106 g for 100 hours at 150 °C in solid state. The isotope ratio measurements were performed on the centrifuged sample with secondary ion mass spectrometer (SIMS, CAMECA IMS-6f). 206Pb/208Pb and 207Pb/208Pb isotope ratio changed with negative gradient in the direction of centrifugal force approximately 1.5% and 0.8%, respectively. There was a tendency that the heavy 208Pb isotope abundance increased and the light 206Pb isotope abundance decreased in the direction of centrifugal force. Three-isotope diagram of 206Pb/208Pb versus 207Pb/208Pb proved that the isotope fractionation depends on the isotopic mass difference. These results showed that a strong gravitational field not only affected the inter-diffusion but also the self-diffusion in this alloy by causing isotope fractionation effect, which was dependent on the mass-difference.