X-ray imaging using synchrotron radiation has enabled to observe solidification of metallic alloys in-situ. The observation provides direct information on evolution of microstructure and some defects. In addition, the precise measurement of dendrite tip shape can be used to evaluate physical properties (diffusivity and interfacial energy) with the dendrite growth models.

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A method of accurately measuring the densities of high-temperature liquids levitated by electromagnetic levitation (EML) technique within the static magnetic fields is proposed. The method is based on the electromagnetic effect on the moving electrical conductivity materials. The liquid metal sample levitated by EML technique is oscillating by the electromagnetic force, and also is moving in the coils. For the liquid samples, if we apply a static magnetic field, the Lorentz force by the interaction between the electrical conductive sample and the static magnetic fields reduces the surface oscillation and translational motion of samples. For the effect, we can precisely obtain the correct volume of levitated liquid samples like a solid body. For applying the technique, we can measure the density of high-temperature liquid silicon in the range 1100 to 2000K. Using the technique we succeeded to reduce an order of magnitude compared with previously reported data. From the precise measurement of liquid silicon density, we found that the density has the maximum value in undercooled regions expected from the first principle molecular dynamics (FPMD) simulations. We also performed the structural analysis of liquid silicon by x-ray diffraction combined with the EML technique. Based on these results, we discuss about the temperature dependence of liquid silicon density from the view point of the structure of liquid silicon based on the tetrahedral coordination in the short range order. From these discussions, we show the importance of density measurement of high-temperature liquids for crystal growth simulations and understanding of the liquid structure and properties.

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Surface tension of melt is an important factor to control heat/mass transport caused by Marangoni convection during crystal growth. We introduced recent results of surface tension measurement for molten silicon and silver by oscillating droplet method using electromagnetic levitation under well controlled oxygen partial pressure, Po_2, of measured atmosphere. A very wide temperature range measurement was successfully achieved in this study. The surface tension-temperature coefficient of the melts increases when the Po_2, becomes large. For the molten silver, a boomerang shape temperature dependence of surface tension was experimentally observed at high Po_2; surface tension was increased and then decreased with increasing temperature because the Po_2, becomes less effective. From the experimental data, the surface tension of molten silver was described as functions of both Po_2, and temperature using Szyszkowski model; the measurement condition not only of temperature but also of Po_2, should be specified in future measurement of surface tension..

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Since physico-chemical properties of liquid alloys, molten salts and molten slags affects various phenomena in crystal-growth process, the information on those properties is indispensable to control and design new technical processes. We sometimes, however, come across a situation of lacking those information, and we have to estimate the properties from some fundamental physical quantities. This paper describes some procedures to predict the surface tension of liquid alloys, molten salts and molten slags. In addition, some useful literatures will be given on the prediction of the properties.

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As viscosity is the most fundamental physical property of the metallic liquids in most industrial processes, many efforts have been made to obtain the reliable and accurate values. In this paper, the detail in the actual viscosity measurement by using oscillating cylinder method for high temperature is described. It was made clear that to use the crucible with higher aspect ratio and the excellent temperature uniformity around the crucible are very important. The viscosities of most metals and semiconductors showed good Arrhenius linearity in discord with previous literature values. The viscosities and the activation energies of molten metal generally increase with increasing their melting temperatures although molten semiconductors show considerably lower values than typical metals. Furthermore, it was proposed that primary dependence on the isothermal viscosity of mixture melt should be an additivity of logarithmic viscosity and the interaction between the components may be discussed on the deviation from the logarithmic additivity.

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Viscosity of molten oxide is one of the most important physical properties, which can control the process of metals production and glass-ceramics fabrication at high temperature. However, the viscosity data that have been accumulated since mid-twentieth century is still not enough for trouble-less operation of the production sequences mentioned above. In present paper, we intend to review the definition, and the measuring methods of the viscosity of molten oxides, and also to demonstrate the latest results that we have built. Especially, the addition effect of alkali oxides on the viscosity of alumina containing CaO-SiO_2 based molten oxides, and the non-Newtonian behavior and the crystallization effect on the viscosity of CaO-SiO_2-R_2O molten oxides under liquidus are presented.

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The mathematical modeling of heat flow requires thermophysical properties relevant to heat transfer mechanisms, i.e. conduction, convection and radiation. Emissivity plays a key role in heat transfer analysis by radiation, which becomes more predominant as temperature rises. This paper focuses on emissivities of metallic melts and reviews recent measurement techniques and data for the emissivity.

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Recently, a method for diffusion measurements in molten metals was developed by combining the stable density layering of the samples and the shear cell method, which can suppress natural convection on the ground. Furthermore, it became possible to obtain reproducible reliable data of diffusion coefficients by minimization of the shear convection and the Marangoni convection. The impurity diffusion coefficients in liquid Sn and Pb agreed well with the data obtained under microgravity using the shear cell method. The obtained diffusion coefficients were proportional to the square of the temperature. The possible experimental conditions by this method were discussed and the current problems and the future perspectives were remarked.

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Thermophysical properties of liquid metals are necessary for numerical modeling of crystal growth process. However, measuring thermophysical properties is a difficult task because of existence of convections in liquids and contamination from contact materials. To overcome these experimental difficulties, we have developed the noncontact laser modulation calorimetry using electromagnetic levitation in a dc magnetic field. A dc magnetic field is superimposed to a metallic droplet levitating electromagnetically. Convections and oscillation in the droplet can be well suppressed by the Lorenz force caused by a dc magnetic field. The droplet with suppressed convections is subjected to the modulated laser calorimetry. Heat capacity and thermal conductivity are successfully measured using this method. In this manuscript, the noncontact laser calorimetry is introduced for liquid silicon as an example.

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Recently, a novel method of measuring the thermophysical properties, particularly thermal conductivity, of high-temperature molten materials using the electromagnetic levitation technique has been developed, where this method is based on a noncontact laser AC calorimetry, and entails the superimposing of a static magnetic field to suppress convection in an electromagnetically levitated droplet. Here, the numerical simulation studies are introduced, in which the effect of a static magnetic field on melt convection in the droplet and the measured thermal conductivity have been investigated numerically, in order to determine the optimum conditions for measurement and to estimate the accuracy of the measured value.

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The present work has been carried out to clarify how Cr-ionic species such as Cr^<2+>, Cr^<3+>, and Cr^<4+> ions are incorporated into the Mg_2SiO_4 crystal during the crystal growth, and also how their concentration in the crystal are varied with the oxygen-gas partial pressure in the growth atmosphere. The Cr-doped forsterite (Cr: Mg_2SiO_4) crystal having a dimension of about 35mm in diameter and about 185mm in length was grown by the Czochralski method (called as the Cz one) and by discontinuously changing the oxygen-gas partial pressure in order of 0.03atm, 0atm, and 0.03atm. Furthermore, the Cr: Mg_2SiO_4 crystal having a dimension of about 5mm in diameter and about 35mm in length was grown by the floating zone method (called as the FZ one) under the oxygen-gas pressure of 1atm, to know the concentration distribution of the Cr ionic species in the crystal grown in the un-mixed gas atmosphere of oxygen. The crystal texture observation, the Cr concentration analysis and the optical absorption spectrum measurement were performed on the crystal grown by Cz method and on the one by FZ one (called as the Cz crystal and the FZ one, respectively), and the following results were obtained. As to the Cz crystal, the change in the oxygen-gas partial pressure brought about the contrast change in the crystal texture and the corresponding change in the Cr-ionic species concentration. From the change direction of crystal texture contrast, which is perpendicular to the growth striations, it was made clear that each of Cr-ionic species already existing at its own concentration in the melt is directly incorporated into the growing crystal through the solid-liquid interface. In the case of the FZ crystal, the concentration of the Cr^<4+> ionic species was observed to be remarkably high, in a sharp contrast to those of the Cr^<2+> and the Cr^<3+> ionic species, where the existence of the Cr^<2+> ionic species was not actually recognized, and the Cr^<3+> ionic species was slight in the concentration.

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