High-temperature stabilities of YCuO2, BaCu2O2 and Ba2CuO3 from oxide electrolyte e.m.f. measurements

The oxygen potentials in the system YCuO₂/Y₂O₃/Cu and Y₂O₃/YCuO₂/CuO were measured over the ranges 1113–1255 K and 782–1122 K by employing oxide electrolyte galvanic cells with air/platinum as the reference electrode, and the expression $$\Delta G_{f, ox}^o (YCuO_2 )( \pm 0.19)(kJ mol^{ - 1} ) = - 5.346 + 0.00384{\text{ }}T (K)$$ was determined. Similar e.m.f. measurements were carried out on the electrodes BaCuO₂/BaCu₂O₂/Cu₂O and Ba₂CuO₃/BaCuO₂/BaCu₂O₂ were measured over the ranges 1003–1132 K and 1175–1235 K and from the results, the ΔG _f,ox ^o of BaCu₂O₂ and Ba₂CuO₃ were determined to be $$\begin{gathered} \Delta G_{f, ox}^o (BaCu_2 O_2 )(kJ mol^{ - 1} ) = - 25.09 + 0.01548{\text{ }}T (K) \hfill \\ \Delta G_{f, ox}^o (BaCu_2 O_3 )(kJ mol^{ - 1} ) = - 5.79 - 0.07492{\text{ }}T (K) \hfill \\ \end{gathered} $$      

Thermodynamic properties of Pt5La,Pt5Ce,Pt5Pr,Pt5Tb and Pt5 Tm intermetallics

The Gibbs’ energies of formation of Pt₅La, Pt₅Ce, Pt₅Pr, Pt₅Tb and Pt₅ Tm intermetallic compounds have been determined in the temperature range 870–1100 K using the solid state cell: $$Ta,M + MF_3 /CaF_2 /Pt_5 M + Pt + MF_3 ,Ta$$ . The reversible emf of the cell is directly related to the Gibbs’ energy of formation of the Pt₅M compound. The results can be summarized by the equations: $$\begin{gathered} \Delta G_f^ \circ \left\langle {Pt_5 La} \right\rangle = - 373,150 + 6 \cdot 60 T\left( { \pm 300} \right)J mol^{ - 1} \hfill \\ \Delta G_f^ \circ \left\langle {Pt_5 Ce} \right\rangle = - 367,070 + 5 \cdot 79 T\left( { \pm 300} \right)J mol^{ - 1} \hfill \\ \Delta G_f^ \circ \left\langle {Pt_5 Pr} \right\rangle = - 370,540 + 4 \cdot 69 T\left( { \pm 300} \right)J mol^{ - 1} \hfill \\ \Delta G_f^ \circ \left\langle {Pt_5 Tb} \right\rangle = - 372,280 + 4 \cdot 11 T\left( { \pm 300} \right)J mol^{ - 1} \hfill \\ \Delta G_f^ \circ \left\langle {Pt_5 Tm} \right\rangle = - 368,230 + 4 \cdot 89 T\left( { \pm 300} \right)J mol^{ - 1} \hfill \\ \end{gathered} $$ relative to the low temperature allotropic form of the lanthanide element and solid platinum as standard states The enthalpies of formation of all the Pt₅M intermetallic compounds obtained in this study are in good agreement with Miedema’s model. The experimental values are more negative than those calculated using the model. The variation of the thermodynamic properties of Pt₅M compounds with atomic number of the lanthanide element is discussed in relation to valence state and molar volume.     

Surface and grain-boundary energies in yttria-stabilized zirconia (YSZ-8 mol%)

The multiphase equilibration technique has been used to measure the equilibrium angles that develop at the interphase boundaries of a solid-liquid-vapour system after annealing and also the surface (γ_sv)and the grain-boundary, (γ_ss) energies of polycrystalline yttria-stabilized zirconia (8 mol% Y₂O₃). The data was recorded in the temperature range 1573–1873 K. Linear temperature functions were obtained for the surface energy $$\gamma _{SV} (Jm^{ - 2} ) = 1.927 - 0.428x10^{ - 3} T$$ and for the grain-boundary energy $$\gamma _{SS} (Jm^{ - 2} ) = 1.215 - 0.358x10^{ - 3} T$$      

Determination of thermodynamic interactions of poly(l-lactide) and biphasic calcium phosphate/poly(l-lactide) composite by inverse gas chromatography at infinite dilution

Inverse gas chromatography at infinite dilution was applied to determine the thermodynamic interactions of poly(l-lactide) (PLLA) and the composite of biphasic calcium phosphate and PLLA (BCP/PLLA). The specific retention volumes, $ V_{\text{g}}^{0} $ , of 11 organic compounds of different chemical nature and polarity (non-polar, donor or acceptor) were determined in the temperature range of 308–378 K for PLLA and 308–398 K for BCP/PLLA. The weight fraction activity coefficients of test sorbates, $ \Omega_{1}^{\infty } $ , and the Flory–Huggins interaction parameters, $ \chi_{12}^{\infty } $ , were estimated and discussed in terms of interactions of the sorbates with PLLA and BCP/PLLA. Also, the partial molar free energy, $ \Delta G_{1}^{\infty } $ , the partial molar heat of mixing, $ \Delta H_{1}^{\infty } $ , the sorption molar free energy, $ \Delta G_{1}^{\text{S}} $ , the sorption enthalpy, $ \Delta H_{1}^{\text{S}} $ , and the sorption entropy, $ \Delta S_{1}^{\text{S}} $ , were analyzed. A different chromatographic behavior of the two investigated samples, PLLA and BCP/PLLA, was observed. The values of $ \Omega_{1}^{\infty } $ indicated n-alkanes, diethyl ether, tetrahydrofurane (THF), cyclohexane, benzene, dioxane (except for 338 K), and ethyl acetate (EtAc) (except for 338 K) as non-solvents, and chloroform (CHCl₃) as good solvent (except for 378 K) for PLLA. For BCP/PLLA, CHCl₃, EtAc (for 378 K), dioxane (except for 378 K), and THF were indicated as good solvents.     

Sublimation study of BiBr3

Steady-state sublimation vapour pressures of anhydrous bismuth tribromide have been measured by the continuous gravimetric Knudsen-effusion method from 369.3 to 478.8 K. Additional effusion measurements have also been made from 435.4 to 478.6 K by the torsion—effusion method. Based on a correlation of Δ_sub H ₂₉₈ ⁰ and Δ_sub S ₂₉₈ ⁰ , a recommended p(T) equation has been obtained for BiBr₃(s) $$\alpha - {\rm B}i{\rm B}r_3 :log{\text{ }}p = - C\alpha /T - 12.294log{\text{ }}T + 5.79112 \times 10^{ - 3} {\text{ }}T + 47.173$$ with Cα=(Δ _subH ₂₉₈ ⁰ +20.6168)/1.9146×10^-2 $$\beta - {\rm B}i{\rm B}r_3 :log{\text{ }}p = - C\beta /T - 23.251log{\text{ }}T + 1.0492 \times 10^{ - 2} {\text{ }}T + 77.116$$ with Cβ=(Δ _subH ₂₉₈ ⁰ +46.2642)/1.9146×10^-2 where p is in Pa, T in Kelvin, Δ _sub H ₂₉₈ ⁰ in kJ mol^?1. Condensation coefficients and their temperature dependence have been derived from the effusion measurements.     

Reaction diffusion in the Nb-Ge system

Reaction diffusion in the Nb-Ge system was studied in the temperature range 1243 to 1723 K for diffusion couples of (pure solid Nb)-(pure liquid Ge) and (pure solid Nb)-(Ge-37.5wt % Nb liquid alloy). Growth of the NbGe₂, Nb₃Ge₂, Nb₅Ge₃ and Nb₃Ge layers was observed, and the growth rates of all except the Nb₃Ge layer were found to conform to the parabolic law. Growth of the Nb₃Ge layer was observed only along the grain boundaries in the Nb₅Ge₃ layer. Interdiffusion coefficients \(\tilde D\) in the NbGe₂, Nb₃Ge₂ and Nb₅Ge₃ phases were determined by Heumann's method, and the temperature dependence of these was expressed by the Arrhenius equations as follows: $$\tilde D_{{\text{NbGe}}_{\text{2}} } = (6.40_{ - 1.66}^{ + 2.25} \times 10^{ - 6} exp [ - (161 \pm 4) kJ mol^{ - 1} {\text{/RT] m}}^{{\text{2 }}} \sec ^{ - 1} $$ $$\tilde D_{{\text{Nb}}_{\text{3}} {\text{Ge}}_{\text{2}} } = (2.27_{ - 0.60}^{ + 0.82} \times 10^{ - 4} exp [ - (282 \pm 4) kJ mol^{ - 1} {\text{/RT] m}}^{{\text{2 }}} \sec ^{ - 1} $$ and $$\tilde D_{{\text{Nb}}_{\text{5}} {\text{Ge}}_{\text{3}} } = (6.28_{ - 1.93}^{ + 2.78} \times 10^{ - 5} exp [ - (238 \pm 5) kJ mol^{ - 1} {\text{/RT] m}}^{{\text{2 }}} \sec ^{ - 1} $$ In addition to the binary Nb-Ge system, the reaction diffusion of (pure solid Nb)-(Cu-13 wt % Ge liquid alloy) couples was also studied. In this case, only growth of the Nb₅Ge₃ layer containing negligible copper content was observed.     

Surface,grain-boundary and interfacial energies in Al2O3 and Al2O3-Sn,Al2O3-Co systems

Using the multiphase equilibrium method for the measurement of contact angles, the surface and grain-boundary energies of polycrystalline Al₂O₃ in the temperature range of 1473 to 1923 K were determined. Linear temperature functions were obtained by extrapolation for both quantities between absolute zero and the melting point of Al₂O₃. The temperature dependence of the surface and grain boundary energies can be expressed as $$\gamma _{{\rm A}l_2 O_3 } = 2.559 - 0.784 \times 10^{ - 3} T(J m^{ - 2} )$$ and $$\gamma _{{\rm A}l_2 O_3 - Al_2 O_3 = } 1.913 - 0.611 \times 10^{ - 3} T(J m^{ - 2} )$$ respectively. The interfacial energies of Al₂O₃ in contact with the molten metals tin and cobalt revealed a linear dependence on temperature.     

The Influence of Oxygen/Argon Ratio on the Structure and Surface Morphology of GaBa2Cu3O7?δ Films Deposited by RF Magnetic Sputtering

$\mathrm{GaBa}_{2}\mathrm{Cu}_{3}\mathrm{O}_{7\mbox{-}\delta}$ thin films have been grown on CeO₂ cap layer by RF magnetic sputtering with different oxygen/argon partial pressure ratio from 2:1 to 1:5. The CeO₂ cap layers were fabricated by pulse laser deposition (PLD) on YSZ/CeO₂/Ni-5%W alloy substrate and had good properties in structure and surface morphology. We study the relationship between oxygen/argon ratio and the performance of the $\mathrm{GaBa}_{2}\mathrm{Cu}_{3}\mathrm{O}_{7\mbox{-}\delta}$ film in order to find out the optimized deposition condition. The structure and surface morphology of the $\mathrm{GaBa}_{2}\mathrm{Cu}_{3}\mathrm{O}_{7\mbox{-}\delta}$ thin films were measured by X-ray diffraction (XRD), Field emission scanning electron microscope (FE-SEM), Atomic force microscopy (AFM). It was found that the texture and surface performance of $\mathrm{GaBa}_{2}\mathrm{Cu}_{3}\mathrm{O}_{7\mbox{-}\delta}$ film, such as growth orientation, grain roughness, grain size and surface morphology, are deeply affected by the oxygen/argon ratio. And the film??s performance was the best when the oxygen/argon partial pressure ratio is 1:1.     

Transfer Partial Molar Isentropic Compressibilities of (l-Alanine/l-Glutamine/Glycylglycine) from Water to 0.512 {\mathrm{mol}}\!\cdot \!{\mathrm{kg}}^{-1} Aqueous {\mathrm{KNO}}_{3}/0.512\, {\mathrm{mol}}\!\cdot \! {\mathrm{kg}}^{-1} Aqueous {\mathrm{K}}_{2}{\mathrm{SO}}_{4} Solutions Between 298.15 K and 323.15 K

Speeds of sound of (l-alanine/l-glutamine/glycylglycine $\,+\, 0.512\, {\mathrm{mol}}\cdot {\mathrm{kg}}^{-1}$ + 0.512 mol · kg ? 1 aqueous ${\mathrm{KNO}}_{3}/0.512\, {\mathrm{mol}}\cdot {\mathrm{kg}}^{-1}$ KNO 3 / 0.512 mol · kg ? 1 aqueous ${\mathrm{K}}_{2}{\mathrm{SO}}_{4}$ K 2 SO 4 ) systems have been measured for several molal concentrations of amino acid/peptide at different temperatures: $T$ T = (298.15 to 323.15) K. Using the speed-of-sound and density data, the parameters, partial molar isentropic compressibilities $\phi _{\kappa }^{0}$ ? κ 0 and transfer partial molar isentropic compressibilities $\Delta _{\mathrm{tr}} \phi _{\kappa }^{0}$ Δ tr ? κ 0 , have been computed. The trends of variation of $\phi _{\kappa }^{0}$ ? κ 0 and $\Delta _{\mathrm{tr}} \phi _{\kappa }^{0}$ Δ tr ? κ 0 with changes in molal concentration of the solute and temperature have been discussed in terms of zwitterion–ion, zwitterion–water dipole, ion–water dipole, and ion–ion interactions operative in the systems.     

Thermal expansion of copper,silver, and gold at low temperatures

Improvements have been made in a differential dilatometer using the three-terminal capacitance detector. The dilatometer is of copper and has been calibrated from 1.5–34 K in an extended series of observations using silicon and lithium fluoride as low-expansion reference materials. The expansion of silver and gold samples has been measured relative to the dilatometer, while the calibrations themselves have been used to determine the expansion of copper relative to the reference materials. Analyses of six sets of observations indicate that below 12 K the linear expansion coefficient α of copper is represented by $$10^{10} \alpha = (2.1_5 \pm 0.1){\rm T} + (0.284 \mp 0.005){\rm T}^3 + (5 \pm 3) \times 10^{ - 5} T^5 K^{ - 1} $$ corresponding to respective electronic and lattice Grüneisen parameters γ _e =0.9 ₃ and γ ₀ =γ ₁ =1.78. Measurements on oxygen-free silver yield $$10^{10} \alpha = (1.9 \pm 0.2){\rm T} + (1.14 \mp 0.03){\rm T}^3 + (2 \pm 2) \times 10^{ - 4} T^5 K^{ - 1} $$ below 7 K, whence γ _e ? 0.9 ₇ , γ ₀ =γ ₁ =2.23. By contrast, silver containing ca. 0.02 at. % oxygen showed a much larger expansion at the lowest temperatures: below 7 K, 10 ¹⁰ α ～ 7T+1.19T ³ . We have not been able to obtain an unambiguous representation for gold, but find a reasonable fit below 7 K to be $$10^{10} \alpha \simeq (1 \pm 0.5){\rm T} + (2.44 \mp 0.05){\rm T}^3 - (5 \pm 1) \times 10^{ - 3} T^5 K^{ - 1} $$ with γ ₁ ? 2.94 and γ _e ? 0.7 (free-electron value).     

Numerical simulation of burning front propagation

In the context of a numerical experiment, it is shown that the switching wave described by the reaction-diffusion equation can be delayed at a medium inhomogeneity with a thickness Δ and amplitude Δβ for a finite time τ = τ(Δβ, Δ) up to a complete stop at it (τ = ∞). Critical values Δβ _c and Δ _c corresponding to the autowave stop are found. The similarity laws \(\tau \sim (\Delta _c - \Delta )^{ - \gamma _\Delta } \) and \(\tau \sim (\Delta \beta _c - \Delta \beta )^{ - \gamma _\beta } \) are established, and the critical indices and are found. The similarity law is established for critical values of amplitude and width of the inhomogeneity corresponding to the autowave stop Δβ _c ～ Δ _c ^-δ where δ ≈ 1.     

An approximate approach for the calculation ofM s in iron-base alloys

Having estimated the critical driving force associated with martensitic transformation,ΔG ^α→M, as $$\Delta G^{\alpha \to M} = 2.1 \sigma + 900$$ whereσ is the yield strength of austenite atM _s, in MN m^?2, we can directly deduce theM _s by the following equation: $$\Delta G^{\gamma \to {\rm M}} |_{M_S } = \Delta G^{\gamma \to \alpha } + \Delta G^{\alpha \to M} = 0.$$ The calculatedM _s are in good agreement with the experimental results in Fe-C, Fe-Ni-C and Fe-Cr-C, and are consistent with part of the data in Fe-Ni, Fe-Cr and Fe-Mn alloys. Some higher “M _s” determined in previous works may be identified asM _a,M _s of surface martensite or bainitic temperature. TheM _s of pure iron is about 800 K. TheM _s in Fe-C can be approximately expressed as $$M_S (^\circ {\text{C}}) = 520 {\text{--- }}\left[ {{\text{\% C}}} \right]{\text{ }}x 320.$$ In Fe-X, the effect of the alloying element onM _s depends on its effect onT ₀ and on the strengthening of austenite. An approach for calculation of ΔG ^γ→α in Fe-X-C is suggested. Thus dM _s/dx _c in Fe-X-C is found to increase with the decrease of the activity coefficient of carbon in austenite.     

Self-diffusion of14C in polycrystalline β-SiC

The¹⁴C self-diffusion coefficients for both lattice (D _lc ^* ) and grain boundary (D _bc ^* ) transport in high purity CVDβ-SiC are reported for the range 2128 to 2374 K. The Suzuoka analysis technique revealed thatD _bc ^* is 10⁵ to 10⁶ faster thanD _bc ^* ; the respective equations are given by $$\begin{gathered} D_{I c}^* = (2.62 \pm 1.83) \times 10^8 exp\left\{ { - \frac{{(8.72 \pm 0.14)eV/atom}}{{kT}}} \right\}cm^2 sec^{ - 1} \hfill \\ D_{b c}^* = (4.44 \pm 2.03) \times 10^7 exp\left\{ { - \frac{{(5.84 \pm 0.09)eV/atom}}{{kT}}} \right\}cm^2 sec^{ - 1} \hfill \\ \end{gathered} $$ A vacancy mechanism is assumed to be operative for lattice transport. From the standpoint of crystallography and energetics, reasons are given in support of a path of transport which involves an initial jump to a vacant tetrahedral site succeeded by a jump to a normally occupied C vacancy.     

Measurements of Microstructural, Mechanical, Electrical, and Thermal Properties of an Al–Ni Alloy

The Al–7.5 wt% Ni alloy was directionally solidified upwards with different temperature gradients, $G$ ( $0.86\,\text{ K}~{\cdot }~ \text{ mm}^{-1}$ to $4.24\,\text{ K}~{\cdot }~\text{ mm}^{-1})$ at a constant growth rate, $V$ ( $8.34\,\upmu \text{ m}~{\cdot }~\text{ s}^{-1})$ . The dependence of dendritic microstructures such as the primary dendrite arm spacing ( $\lambda _{1}$ ), the secondary dendrite arm spacing ( $\lambda _{2}$ ), the dendrite tip radius ( $R$ ), and the mushy zone depth ( $d$ ) on the temperature gradient were analyzed. The dendritic microstructures in this study were also compared with current theoretical models, and similar previous experimental results. Measurements of the microhardness (HV) and electrical resistivity ( $\rho $ ) of the directionally solidified samples were carried out. Variations of the electrical resistivity ( $\rho $ ) with temperature ( $T$ ) were also measured by using a standard dc four-point probe technique. And also, the dependence of the microhardness and electrical resistivity on the temperature gradient was analyzed. According to these results, it has been found that the values of HV and $\rho $ increase with increasing values of $G$ . But, the values of HV and $\rho $ decrease with increasing values of dendritic microstructures ( $\lambda _{1}, \lambda _{2}, R,$ and $d$ ). It has been also found that, on increasing the values of temperature, the values of $\rho $ increase. The enthalpy of fusion ( $\Delta {H}$ ) for the Al–7.5 wt%Ni alloy was determined by a differential scanning calorimeter from a heating trace during the transformation from solid to liquid.     

Relationship of hardness to load on the indentor and hardness with a fixed diagonal of the indentation

For high-hardness materials, particularly for ceramics, the relationship of hardness to load is revealed very strongly. An equation is proposed for conversion of Vickers hardness from one load to another: $$HV = HV_1 \left( {\frac{P}{{P_1 }}} \right)^{1 - 2/n}$$ where HV and HV₁ are the hardness with loads on the indentor of P and P₁ respectively. The parameter n is determined from the equation P = const dⁿ, where d is the indentation diagonal. The parameter n may also be determined on the basis of a normalized curve of the value of HV/E (E is Young's modulus). The physical nature of the relationship of hardness to load is discussed and the hardness \(HV_{d_f }\) is introduced with a fixed indentation diagonal d_f (and not with a fixed load) calculated using the equation $$HV_{d_f } = HV\left( {\frac{d}{{d_f }}} \right)^{2 - n}$$ . The introduction of \(HV_{d_f }\) makes it possible to unify measurement of microhardness for different materials at different temperatures. Curves are given simplifying conversion of hardness from one load to another and determination of the hardness \(HV_{d_f }\) .     

Anomalous roughness of fracture surfaces in 2D fuse models

We study anomalous scaling and multiscaling of two-dimensional crack profiles in the random fuse model using both periodic and open boundary conditions. Our large scale and extensively sampled numerical results reveal the importance of crack branching and coalescence of microcracks, which induce jumps in the solid-on-solid crack profiles. Removal of overhangs (jumps) in the crack profiles eliminates the multiscaling observed in earlier studies and reduces anomalous scaling. We find that the probability density distribution ${p(\Delta h(\ell))}$ of the height differences ${\Delta h(\ell) = [h(x+\ell) - h(x)]}$ of the crack profile obtained after removing the jumps in the profiles has the scaling form ${p(\Delta h(\ell)) = \langle\Delta h^2(\ell)\rangle^{-1/2} ~f\left(\frac{\Delta h(\ell)}{\langle\Delta h^2(\ell)\rangle^{1/2}}\right)}$ , and follows a Gaussian distribution even for small bin sizes ?. The anomalous scaling can be summarized with the scaling relation ${\left[\frac{\langle\Delta h^2(\ell)\rangle^{1/2}}{\langle\Delta h^2(L/2)\rangle^{1/2}}\right]^{1/\zeta_{loc}} + \frac{(\ell-L/2)^2}{(L/2)^2} = 1}$ , where ${\langle\Delta h^2(L/2)\rangle^{1/2}\sim L^{\zeta}}$ and L is the system size.     

Magnetic Properties of Interacting La0.67Sr0.33MnO3 Nanoparticles

Magnetic nanoparticles of La_0.67Sr_0.33MnO₃ (LSMO) with mean particle sizes of 13, 16, 18, and 21 nm were prepared by the sol?Cgel method. The samples were characterized by X-ray diffraction (XRD) using Rietveld refinement and transmission electron microscope (TEM). Fourier transform infrared (FTIR) transmission spectroscopy revealed that stretching and bending modes are influenced by annealing temperature. Dc magnetization versus magnetic field of the samples was carried out at room temperature. Magnetic dynamics of the samples was studied by the measurement of ac magnetic susceptibility versus temperature at different frequencies and ac magnetic fields. A frequency-dependent peak was observed in ac magnetic susceptibility versus temperature which is well described by Vogel?CFulcher and critical slowing down laws, and empirical $c_{1} = \frac{\Delta T_{f}}{T_{f}\Delta (\log _{10}f)}$ and $c_{2} = \frac{T_{f} -T_{0}}{T_{f}}$ parameters. By fitting the experimental data with Vogel?CFulcher magnetic anisotropy energy and an effective magnetic anisotropy constant have been estimated. The obtained values support the presence of strong interaction between magnetic nanoparticles of LSMO.     

Hypersensitive Transition of Nd(III) Complexes in Liquids Detected by Pulsed-Laser-Induced Photoacoustic Spectroscopy

Laser-induced photoacoustic (PA) spectroscopy for the spectral measurements of extremely weak absorption such as a forbidden transition of lanthanide ions in liquids has been established. In spectroscopy, a pulsed Nd:YAG laser connected with a MOPO series optical parametric oscillator which emits a broad spectrum covering UV and visible regions is used as the excitation source, and the induced PA signals are detected by an optimized PA piezoelectric transducer. The absorption spectra of trivalent lanthanide ions ( $\text{ Pr}^{3+}, \text{ Ho}^{3+}$ , and $\text{ Nd}^{3+})$ in aqueous solutions have been obtained by the detection system with a detection-limit absorbance of $1.3\times 10^{-5}\,\text{ cm}^{-1}$ at room temperature. In addition, the effects of different binding environments on the band shapes and oscillator strengths of the hypersensitive transitions of $\text{ Nd}^{3+}$ ions, i.e., $\text{ Nd}(\text{ CH}_{3}\text{ COO})_{3}$ $\cdot $ $\text{ H}_{2}\text{ O}$ dissolved in $0.1\,{\text{ mol}} \cdot \text{ l}^{-1}$ acetic acid and $\text{ Nd(3-butanedione)}_{3}{\cdot } 2\text{ H}_{2} \text{ O}$ dissolved in triglycol compared with $\text{ NdCl}_{3}$ in $0.1\,{\text{ mol}}\cdot \text{ l}^{-1}$ hydrochloric acid, are observed. The results show that the chemical environment around the lanthanide ions has great impact on 4f–4f transitions, which is rationalized as the impact in terms of ligand (or solvent) special structures and coordination properties.     

A new correlation for the viscosity of gaseous fluorocarbon refrigerants

A new generalized correlation is presented for the low-pressure gaseous viscosity of fluorocarbon refrigerants. The following empirical equation is obtained based on the most reliable experimental data for 16 fluorocarbons: $$\eta \xi = \left( {0.5124T_r - 0.0517} \right)^{0.82} Z_c ^{ - 0.81}$$ where η is the viscosity in μPa·s and ξ is the viscosity parameter defined using the critical temperature T _c in K, the critical pressure P _c in MPa, and the molar mass M in g·mol^?1 as follows: $$\xi = T_c ^{1/6} M^{ - 1/2} P_c ^{ - 2/3}$$ The applicable ranges are 0.6<T _r<1.8 and 0.253<Z _c<0.282. The availability of the correlating equation for both pure fluorocarbons and their mixtures has been investigated based on the experimental data of these authors and those in the literature. It is found that the present correlation is useful for the prediction of the viscosity of pure fluorocarbons and their binary mixtures at atmospheric pressure with mean deviations less than 1.6%.     

Isothermal transformation and decomposition ofβ 1 phase in a CuZnAl alloy

In the present paper, the crystallography of isothermal transformation and decomposition ofβ, phase have been studied by means of transmission electron microscopy and diffraction in the CuZnAl shape memory alloy. It has been proved that the bainite formed inβ ₁, matrix when the samples were transformed isothermally at moderate temperature. The crystallography of the isothermal bainitic transformation is identical to that of martensite in the same system. When the specimens were aged at moderate temperatures for longer time, the bainite and matrix decomposed to equilibrium phases. The decomposition process can be summarized as follows: $$\begin{gathered} bainite (9R) \to 9R + \alpha \left( {fcc} \right) \to \alpha + \beta \left( {bcc} \right) \hfill \\ matrix (B2) \to 2H + B2 \to \beta \left( {bcc} \right) \hfill \\ \end{gathered} $$ There are definite orientation relationships among these phases during the decomposition process and they are shown below: $$\begin{gathered} \left( {111} \right)_\alpha \parallel \left( {001} \right)_B ,\left[ {0\bar 11} \right]_\alpha \parallel \left[ {\bar 110} \right]_B \hfill \\ \left( {111} \right)_\alpha 5^ \circ away from \left( {110} \right)_\beta ,\left[ {0\bar 11} \right]_\alpha \parallel \left[ {1\bar 1\bar 1} \right]_\beta \hfill \\ \left( {110} \right)_M \parallel \left( {001} \right)_{2H} ,\left[ {001} \right]_M \parallel \left[ {010} \right]_{2H} \hfill \\ \end{gathered} $$ Thus, the crystallography of isothermal transformation and decomposition ofβ ₁ phase and the sequence of transitions have been revealed.