Dynamical scaling analysis using the Lillie Number for vitrification of deeply supercooled glycerol

Thermal response was measured for a deeply supercooled glycerol specimen by applying calorimetric temperature scanning rate spectroscopy, cooling the specimen from liquid at a slow constant cooling rate until glass transition was observed. The effective fraction of glass as a function of temperature was determined and a new definition of glass transition temperature, T_gC, as the temperature at which the effective glass fraction to be 0.5 was presented. The relation between this and the cooling rate showed the Arrhenius behavior. The effective glass fraction curves shifted linearly as a function of ln(cooling rate). When T was scaled to the Lillie Number, the glass fraction lay on a master curve, which was successfully fitted with a Kohlrausch–Williams–Watts function. The Kohlrausch exponent, the relaxation time as a function of temperature and the kinetic fragility index were determined. The results were compared with literature values.     

Observation of multiple phase transitions in some even n-alkanes using a high resolution and super-sensitive DSC

The phase transitions of even n-alkanes, n-C₃₄H₇₀, n-C₃₆H₇₄, n-C₄₀H₈₂ and n-C₄₂H₈₆ with high purity have been measured using a high resolution and super-sensitive DSC. A new transition in the low temperature phase was observed in all the samples in the heating run. The surface freezing phenomenon was observed by thermal measurement for the first time in all the samples both in the heating and in the cooling run. The difference of the thermal behaviors between the heating and cooling run was also observed in all the samples.     

Experimental Determination of a Third Derivative of G. (III): Differential Pressure Perturbation Calorimetry (II)

Earlier we constructed a differential pressure perturbation calorimeter, in order to determine directly a third derivative of the Gibbs energy G, the partial molar entropy-volume cross fluctuation density of solute B, ^SVd_[(B)\dot]^{\mathit{SV}}\delta_{\dot{\mathrm{B}}}, in a binary aqueous solution of B. Our attempt was basically successful, as described elsewhere (J. Solution Chem. 39:431–440, 2010). However, the uncertainty of the results for ^SV δ _B was several percent. One of the purposes of our direct experimental determination was to obtain a fourth derivative quantity graphically with some confidence. For this purpose, data of the third derivative quantity are necessary with uncertainties of less than one per cent. Various difficulties that we had on the first generation apparatus were attended to, and a new apparatus was constructed. The new experimental results for aqueous 2-butoxyethanol are found to be at least several-fold better. Hence, we were able to evaluate the fourth derivative quantity for the first time. The physical meaning of the fourth derivatives may become clearer in comparative studies when such data become available for aqueous solutions of other solutes including mono-ols and poly-ols. A project is underway to that effect.     

Experimental Determination of Third Derivative of the Gibbs Free Energy, <Emphasis Type="Italic">G</Emphasis> II: Differential Pressure Perturbation Calorimetry

We have been evaluating third derivative quantities of the Gibbs free energy, G, by graphically differentiating the second derivatives that are accessible experimentally, and demonstrated their power in elucidating the mixing schemes in aqueous solutions. Here we determine directly one of the third derivatives of G, the partial molar entropy-volume cross fluctuation density of 2-butoxyethanol (BE) in the BE–H₂O system, ^SV δ _BE . The difference of the heats of compression were directly determined using two identical cells and applying the same pressure change to both cells concurrently. Both cells are filled with sample solutions having a small appropriate difference in mole fraction. The results indicated that this method is feasible with the prior knowledge of the thermal expansivity of the solution to within a few per cent accuracy. If the volumes of the two cells are identical within the order of 0.01%, the method provides the required results to within 0.1% without the thermal expansivity data. This success opens a possibility of evaluating the fourth derivative graphically, which is expected to provide much more detailed information about the molecular processes in aqueous solutions.     

Simultaneous Observation of Hyperfine Multistage Transitions of BaTiO3 with Thermal Analysis and Thermal Expansion

A new method to measure heat flux and thermal expansion simultaneously with a temperature resolution of milli-Kelvin is presented to observe the multistage transitions. At least six thermal anomalies are observed between 402 and 403 K in BaTiO₃ simultaneously in heat flux and thermal expansion in the cooling process. The correspondence of the anomalies observed in the two physical properties is excellent. This revised version was published online in July 2006 with corrections to the Cover Date.     

Melting and freezing behaviors of prototype ionic liquids, 1-butyl-3-methylimidazolium bromide and its chloride, studied by using a nano-Watt differential scanning calorimeter

1-Butyl-3-methylimidazolium bromide ([bmim]Br) and its chloride ([bmim]Cl) are representative prototypes of ionic liquids. We investigated the melting and freezing behaviors of [bmim]Br and [bmim]Cl by using a homemade differential scanning calorimeter (DSC) with nano-Watt stability and sensitivity. The measurements were carried out at heating and cooling rates slow enough to mimic quasi-static processes. Their thermal behaviors of melting and freezing show characteristic features such as a wide pre-melting range and excessive supercooling and individual behaviors of single crystals even for the same substance. The melting temperatures of [bmim]Br and [bmim]Cl were determined from the broad DSC traces and discussed in relation to the crystal structure. We suggest that the observed characteristics are due to the dynamics of the cooperative change between gauche-trans (GT) and trans-trans (TT) conformations of the butyl group in the [bmim]+ cation.     

Dynamical scaling and ultrasonic attenuation in 4He near Tλ

Ultrasonic attenuation in ⁴He near T_λ has been measured at frequencies between 10.9 MHz and 163 MHz. The attenuation above T_λ is described by a scaling function as $\text{α∝ω}{}^{\mathrm{x}}\text{F(}\text{ε}\text{ω}{}^{\mathrm{Y}}\text{)}$, and which proves the dynamical scaling hypothesis.     

Effect of the magnetic field on the melting transition of Ga and In by nW-stabilized DSC

The melting transition of Ga and In was measured by using a nW-stabilized differential scanning calorimeter working in a magnetic bore. The magnetic effect on the thermometer was about 18 mK at 5 T, which was corrected for the measurement of the magnetic effect on the melting transition of Ga and In. The melting temperatures of Ga and In with the magnetic field of 5 T were obtained to be 8.3 and 10.2 mK, respectively higher than those without the magnetic field. These results show that the solid phase to be relatively more stable under the magnetic field. The calculated temperature shifts of the melting transition due to the magnetic field using the magneto-Clapeyron equation and the reference data of magnetic susceptibility were negative values for both Ga and In, being contradictory to the experimental results.