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The Japanese national project started on standardization of the test method of the DC critical current of superconducting cables. A round robin test of critical current measurement is carried out to survey underlying problems for the standardization. The sample cables are made of Bi-2223 tapes and the inner core conductor has two layers and the outer shield conductor is composed of a single layer. The diameter of the shield layer is about 40 mm and the length of the cable is 2.00 m. The critical current was determined by the electric field criterion of 1 μV/cm. The n value is also measured for the inner core and the outer shield conductor. Three institutes participated in the test for two sample cables. The obtained experimental relative standard deviation for the critical current at 77.30 K is in the range of 0.2 to 1.3%, and is sufficiently small. Hence, it can be said that the present method that is widely used is suitable as a standard test method. On the other hand, the experimental relative standard deviation of the value is in the range of 2.8 to 18.6%, which is relatively large. This is caused by the measurements done at different temperatures.

A large-scale demonstration test of a triaxial high-temperature superconducting (HTS) cable for a practical cable system was performed in a chemical plant of a private company. The 200 m-long HTS (REBCO: REBa2Cu3O7-δ) triaxial cable, which was manufactured by connecting 3 cables using 2 joints via a snake-shaped layout, was laid approximately 5 m higher than ground level, and the cable was cryocooled by circulating liquid nitrogen. For the preverification test, the rise-up test of the liquid nitrogen and the development of technology for bending the cable, joining it, as well as laying and installing it, were conducted. No leakage of liquid nitrogen at the terminal due to damage caused by heat shock or liquid nitrogen drop impact was observed. The pressure required for the liquid nitrogen to achieve a 5 m height was from 27.5 to 33 kPa, which is in good agreement with the calculated pressure of 33.6 kPa. The cooling rate was well controlled, and the desired level of 4 K/h was achieved. The economic challenges and methods of achieving market penetration were also discussed. The goal was to realize a superconducting cable for practical applications, and it was thought that the energy and costs necessary for cryocooling could be drastically reduced by using the existing cold system in the plant. In this way, it is expected HTS cables can achieve low costs and high energy-saving effects and penetrate markets in the future.

A new ternary layered pnictide, Li1−xSn2+xP2, was synthesized by a solid-state reaction and its properties were examined to explore its potential as a multifunctional material. The compound crystallizes in a layered structure in the Rm space group (no. 166) with buckled honeycomb Sn–P layers separated by mixed-occupation Li/Sn layers. Crystal structure analysis by synchrotron X-ray diffraction showed that the substitution degree of Li by Sn is x = 0.38. The local ordering of Li/Sn occupation was demonstrated using 31P nuclear magnetic resonance analysis. The thermal and electrical transport properties are significantly affected by this local ordering. The lattice thermal conductivity of Li1−xSn2+xP2 was found to be relatively low (1.2 W m−1 K−1 at 525 K). The room-temperature electrical resistivity of Li1−xSn2+xP2 was found to be 0.3–0.4 mΩ cm and metallic conductivity was observed down to 0.5 K. First-principles calculations demonstrated that the electronic structure and Fermi energy of Li1−xSn2+xP2 are significantly dependent upon x. Moreover, the electronic structure of Li1−xSn2+xP2 is different from that of the related compound NaSn2As2, which shows a superconducting transition. Electrochemical measurements using a single-particle technique demonstrated the activity of Li1−xSn2+xP2 as an anode material for rechargeable Li-ion batteries.

We investigated the chemical pressure effects on structural and electronic properties of SnTe-based material using partial substitution of Sn by Ag0.5Bi0.5, which results in lattice shrinkage. For Sn1-2x(AgBi)xTe, single-phase polycrystalline samples were obtained with a wide range of x. On the basis of band calculations, we confirmed that the Sn1-2x(AgBi)xTe system is basically possessing band inversion and topologically preserved electronic states. To explore new superconducting phases related to the topological electronic states, we investigated the In-doping effects on structural and superconducting properties for x = 0.33 (AgSnBiTe3). For (AgSnBi)(1-y)/3InyTe, single-phase polycrystalline samples were obtained for y = 0-0.5 by high-pressure synthesis. Superconductivity was observed for y = 0.2-0.5. For y = 0.4, the transition temperature estimated from zero-resistivity state was 2.4 K, and the specific heat investigation confirmed the emergence of bulk superconductivity. Because the presence of band inversion was theoretically predicted, and the parameters obtained from specific heat analyses were comparable to In-doped SnTe, we expect that the (AgSnBi)(1-y)/3InyTe and other (Ag,In,Sn,Bi)Te phases are candidate systems for studying topological superconductivity., 18 pages, 9 figures, supplemental data is included

The Ising magnet $\mathrm{Sm}{\mathrm{Pt}}_{2}{\mathrm{Si}}_{2}$ undergoes an antiferromagnetic (AFM) transition at ${T}_{\mathrm{N}1}$ = 5.6 K, but the magnetic moments of some Sm ions remain disordered even below ${T}_{\mathrm{N}1}$. Here, we report the results of measurements of thermal expansion, magnetostriction, and dc magnetization of $\mathrm{Sm}{\mathrm{Pt}}_{2}{\mathrm{Si}}_{2}$ in the temperature range from 0.26 to 7 K. The magnetization and thermal expansion results show clear irreversible phenomena at temperatures below ${T}_{\mathrm{g}}\phantom{\rule{4pt}{0ex}}\ensuremath{\approx}$ 2.4 K. These results suggest that the partially disordered state of the Sm ions becomes a cluster spin glass below ${T}_{\mathrm{g}}$ and coexists with the AFM long-range order. However, unlike the conventional coexistence of spin glass and antiferromagnetism, the isothermal magnetization process at 0.26 K shows a hysteresis curve with almost no remanent magnetization. This observation suggests that the cluster spin glass state is an unusual state with a short relaxation time at zero field.

We propose an efficient way of increasing the entropy of mixing in high-entropy-alloy-type compounds, which can be achieved by multi-site alloying. As an example of this concept, we report the synthesis and observation of polycrystalline samples of new high-entropy-alloy-type metal chalcogenides (Ag,In,Pb,Bi)Te1-xSex (x = 0.0, 0.25, and 0.5) with a NaCl-type structure. The samples were synthesized using high pressure synthesis. Superconductivity with transition temperatures of 2.7, 2.5, and 2.0 K was observed with x = 0.0, 0.25, and 0.5, respectively. To investigate the multi-site alloying effect on the entropy of mixing (ΔSmix) for the examined samples, we calculated the total ΔSmix for two crystallographic sites. For the samples with x = 0.25 and 0.5, ΔSmix reaches 1.89R and 2.00R, respectively, which exceed the ΔSmix of 1.79R for a simple (single-site) high-entropy alloy containing six different elements.

We investigated the chemical pressure effects on structural and electronic properties of SnTe-based material using partial substitution of Sn by Ag0.5Bi0.5, which results in lattice shrinkage. For Sn1−2x(AgBi)xTe, single-phase polycrystalline samples were obtained with a wide range of x. On the basis of band calculations, we confirmed that the Sn1−2x(AgBi)xTe system is basically possessing band inversion and topologically preserved electronic states. To explore new superconducting phases related to the topological electronic states, we investigated the In-doping effects on structural and superconducting properties for x = 0.33 (AgSnBiTe3). For (AgSnBi)(1−y)/3InyTe, single-phase polycrystalline samples were obtained for y = 0–0.5 by high-pressure synthesis. Superconductivity was observed for y = 0.2–0.5. For y = 0.4, the transition temperature estimated from zero-resistivity state was 2.4 K, and the specific heat investigation confirmed the emergence of bulk superconductivity. Because the presence of band inversion was theoretically predicted, and the parameters obtained from specific heat analyses were comparable to In-doped SnTe, we expect that the (AgSnBi)(1−y)/3InyTe and other (Ag, In, Sn, Bi)Te phases are candidate systems for studying topological superconductivity.

A new ternary layered pnictide, Li1-xSn2+xP2, was synthesized by a solid-state reaction and its properties were examined to explore its potential as a multifunctional material. The compound crystallizes in a layered structure in the R-3m space group with buckled honeycomb Sn-P layers separated by mixed-occupation Li/Sn layers. Crystal structure analysis using synchrotron X-ray diffraction showed that the substitution degree of Li by Sn (x) is approximately 0.3. Local ordering of Li/Sn occupation was demonstrated using 31P nuclear magnetic resonance analysis. The lattice thermal conductivity of Li1-xSn2+xP2 was found to be relatively low (1.2 Wm−1K−1 at 525 K). The room-temperature electrical resistivity of Li1-xSn2+xP2 was found to be 0.3-0.4 mohm cm and metallic conductivity was observed down to 0.5 K. First-principles calculations demonstrated that the electronic structure and Fermi energy of Li1-xSn2+xP2 are significantly dependent upon x. Electrochemical measurements using a single-particle technique demonstrated the activity of Li1-xSn2+xP2 as an anode material for rechargeable Li-ion batteries.

Recently CeOBiS2 system without any fluorine doping is found to show superconductivity posing question on its origin. Using space resolved ARPES we have found a metallic phase embedded in the morphological defects and at the sample edges of stoichiometric CeOBiS2. While bulk of the sample is semiconducting, the embedded metallic phase is characterized by the usual electron pocket at X point, similar to the Fermi surface of doped BiS2-based superconductors. Typical size of the observed metallic domain is larger than the superconducting correlation length of the system suggesting that the observed superconductivity in undoped CeOBiS2 might be due to this embedded metallic phase at the defects. The results also suggest a possible way to develop new systems by manipulation of the defects in these chalcogenides with structural instability.

Nanoparticles of e-Fe2O3 in an amorphous silica matrix were prepared by the sol–gel method without using a precursor. X-ray diffraction patterns reflect a completely amorphous state for the samples even after heat-treated up to 600 °C, while at higher temperatures the formation of crystalline iron oxide phases was observed. Transmission electron microscopy analysis showed a wide size distribution of nanoparticles from 3±0.5 to 46±0.8 nm. The occurrence of e-Fe2O3 particles depends on several factors like annealing temperature, particle size and iron concentration in initial chemicals. Based on the 57Fe Mossbauer spectra, three octahedral and one tetrahedral iron site were identified for e-phase. The optimized conditions for the preparation of e-Fe2O3 rich sample were confirmed and ~ 90% of the e-Fe2O3 phase was obtained with the particle size of 15±0.6 nm. The high coercivity of ~ 1.18 T at room temperature was confirmed for our nanoparticle system.

The viscoelastic properties of poly(methyl methacrylate) (PMMA)/grafted poly(butyl acrylate) (PBA) nanoparticle systems were investigated. The rubber particles consist of PBA core (60 nm in diameter) and grafted PMMA shell. The grafting degree, defined as the weight ratio of grafted PMMA to PBA particles, ranges from 0.8 to 1.5. Two series of samples, A series with 7.5 wt.% of PBA content and B series with 12 wt.% of PBA content, were used. The systems exhibited fast and slow relaxation process, the former reflecting the relaxation of the matrix PMMA chains and the latter being attributed to grafted PBA particles. For A series samples, time-temperature superposition (TTS) was held well over the frequency (ω) and temperature (T) ranges measured. However, for B series samples, TTS was not satisfied at low ω due to the particle-particle interaction of grafted PBA particles, although the samples obeyed TTS at high ω associated with the relaxation with entanglement of matrix PMMA. At high T and low ω region, the B series samples showed a sol-gel transition at elevating T and the critical gel behavior characterized with a power-law relationship, G′ = G″/tan(nπ/2) ∝ ωn, was observed. This behavior suggested formation of a self-similar, fractal structure of grafted PBA particles. The critical gel temperature (T gel) and the critical exponent (n) were determined for the B series samples. TEM observations revealed that as-prepared A and B samples had well-dispersed particles but the B samples after viscoelastic measurements had fragmented networks of the PBA particles, confirming that the sol-gel transition occurred for the PMMA/grafted PBA systems at elevating T.

We report the Se substitution effects on the crystal structure, superconducting properties, and valence states of self-doped BiCh2-based compound CeOBiS2-xSex. Polycrystalline CeOBiS2-xSex samples with x = 0-1.0 were synthesized. For x = 0.4 and 0.6, bulk superconducting transitions with a large shielding volume fraction were observed in magnetic susceptibility measurements; the highest transition temperature (Tc) was 3.0 K for x = 0.6. A superconductivity phase diagram of CeOBiS2-xSex was established based on Tc estimated from the electrical resistivity and magnetization measurements. The emergence of superconductivity in CeOBiS2-xSex was explained with two essential parameters of in-plane chemical pressure and carrier concentration, which systematically changed with increasing Se concentration., Comment: 15 pages, 8 figures

We have for the first time succeeded in growing single crystals of Eu 3 Bi 2 S 4 F 4 by CsCl-flux method and performed magnetic property measurements. Magnetization measurements ascertained that the antiferromagnetic transition appears at T N = 2.2 K. The effective moment estimated from a Curie–Weiss (CW) fitting above 150 K is smaller than the free ion value for Eu 2 + , indicating that the average valence of Eu ions deviates from divalent. Weak magnetic anisotropy develops below 20 K. From CW fitting at low temperatures, we found the difference in Curie Weiss temperature between H ∥ [001] and H ⊥ [ 100 ] , indicating the anisotropy of magnetic interaction between Eu ions. In the magnetization curve at 2 K (below T N ), a metamagnetic anomaly appears only for the [001] direction around 0.7 T. Since this anomaly disappears above T N , this transition originates from the spin flip of Eu magnetic moments by applying magnetic field. This finding indicates that the ordered moments in the antiferromagnetic state are parallel to the [001] direction, being consistent with the anisotropic Weiss temperature, which is 20% larger for this direction.

Recently, we reported the observation of superconductivity at ~0.5 K in a La2O2M4S6-type (M: metal) layered compound La2O2Bi3AgS6, which is a layered system related to the BiS2-based superconductor system but possesses a thicker Bi3AgS6-type conducting layer. In this study, we have developed the La2O2Bi3AgS6-type materials by element substitutions to increase the transition temperature (Tc) and to induce bulk nature of superconductivity. A resistivity anomaly observed at 180 K in La2O2Bi3AgS6 was systematically suppressed by Sn substitution for the Ag site. By the Sn substitution, Tc increased, and the shielding volume fraction estimated from magnetization measurements also increased. The highest Tc (=2.3 K) and the highest shielding volume fraction (~20%) was observed for La2O2Bi3Ag0.6Sn0.4S6. The superconducting properties were further improved by Se substitutions for the S site. By the combinational substitutions of Sn and Se, bulk-superconducting phase of La2O2Bi3Ag0.6Sn0.4S5.7Se0.3 with a Tc of 3.0 K (Tconset = 3.6 K) was obtained.

Superconducting transition temperature (Tc) reported in SnAs-based layered compound NaSn$_2$As$_2$ varies from 1.2 to 1.6 K, implying that its superconductivity is critically sensitive to non-stoichiometry. Here, we demonstrate that Na-doping on the Sn site (Na$_{1+x}$Sn$_{2-x}$As$_2$) is effective in enhancing superconductivity, leading to Tc = 2.1 K for x = 0.4. First-principles calculation indicates that such a doping, or Na$_{\rm Sn}$ antisite defects, is energetically favored over other cation vacancies. Our results pave the way for increasing Tc of layered tin pnictide superconductors., 21 pages, 9 figures, 1 Table

The relationship between the local structure and magnetic properties of iron phosphate glass xFe2O3 • (100-x) P2O5 abbreviated as xFeP prepared by a sol-gel method has been investigated. From the Mossbauer spectroscopy results, it was found that iron ions are present in FeIII(distorted octahedral) and FeII(octahedral) coordination. HAADF-STEM images and elemental mapping results revealed that iron and phosphorus are uniformly dispersed in the system. It is clear from the magnetic susceptibility results that only 50FeP glass heat-treated at 200°C shows spin glass behavior and all other glasses are superparamagnetic at low temperatures. The Weiss temperatures (θw) obtained for all the glasses were negative, suggesting that the interaction between the magnetic moments is antiferromagnetic. In these samples, the higher the proportion of FeIII ions, the higher the frustration of the entire system is. The [FeIII] / [Fetotal] molar ratio decreases as the heat-treatment temperature increased.

We report on the substitution effect of Indium (In) at the Ag site of layered oxychalcogenide La2O2Bi3Ag1-xInxS6. The Tc decreases with increasing In concentration. A hump in the normal state resistivity at an anomaly temperature (T*) near 180 K was observed for all the samples. The anomaly in the resistivity at T* is indicating the possible occurrence of a charge-density-wave (CDW) transition. The T* does not markedly change by In doping. The x dependence of Seebeck coefficient suggests that carrier concentration does not change by In doping. The EDX analysis indicates small amount of Bi deficiency, which suggests that the Bi site is slightly substituted by In. The CDW transition is robust against the In substitution at Ag site, while Tc is decreasing due to the Bi site substitution by In. On the basis of those analyses, we propose that the suppression of superconductivity in the In-doped La2O2Bi3Ag1-xInxS6 system is caused by negative in-plane chemical pressure effect and partial substitution of In for the in-plane Bi site., 7 pages, 4 figures, to appear in proceedings of ISS2018

La2O2Bi2Pb2S6 is a layered Bi-based oxychalcogenide with a thick four-layer-type conducting layer. Although La2O2Bi2Pb2S6 is a structural analogue of La2O2Bi3AgS6, which is a superconductor, insulating behavior has been observed in La2O2Bi2Pb2S6 at low temperatures, and no superconductivity has been reported. Herein, we demonstrate superconductivity in La2O2Bi2Pb2S6-xSex via partial substitution of Se in the S sites. Owing to the Se doping, the normal state electrical resistivity of La2O2Bi2Pb2S6-xSex at low temperatures was dramatically suppressed, and superconductivity was observed at a transition temperature (Tc) of 1.15 K for x = 0.5. Tc increased with increasing Se concentration: Tc = 1.9 K for x = 1.0. The emergence of metallicity and superconductivity was explained via in-plane chemical pressure effects that can suppress local disorder and carrier localization, which are commonly observed in two-layer-type BiS2-based systems., Comment: 11 pages, 6 figures

The two-dimensional quadratic lattice magnet, bis(glycolato)cobalt(II) ([Co(HOCH2CO2)2]), showed antiferromagnetic ordering at 15.0 K and an abrupt increase in magnetisation at H = 22 600 Oe and 2 K, thereby acting as a metamagnet. Heat capacity measurements revealed that the associated entropy change ΔS around the transition temperature was evaluated to be 6.20 J K−1 mol−1 and that the Co(II) ion had the total angular momentum of J = 1/2 at low temperatures. Neutron diffraction studies suggested that the magnetic moment vectors of the Co(II) ions had an amplitude of 3.59μB and were not aligned in a fully antiparallel fashion to those of their neighbours, which caused canting between the magnetic moment vectors in the sheet. The canting angle was determined to be 7.1°. Canting induced net magnetisation in the sheet, but this magnetisation was cancelled between sheets. The magnetisations in the sheets were oriented parallel to the magnetic field at the critical magnetic field.

We have been developing triaxial superconducting cable supprted by New Energy and Industrial Technology Development Organization (NEDO) since 2015. The target thereof is replacement for Isolated Power Bus (IPB) which has capacity of 22kV-10kA. We manufactured prototype 15m-long 3kA cable and one set of terminations. The cable used in house YBa 2 Cu 3 O 7−d (YBCO) tapes made by MOD (Metal-organic deposition) process. In ordwe to checki electrical insulation strengeth, AC and lightning impluse break down tests were performed with 600mm-long model cables in liquid nitrogen at atmospheric pressur. We designed cable, and withstand voltage test and partial dischage test were perfomed. The specifications thereof were AC voltage of 52kV for 30minutes and lightning impulse of positive and negative 125kV each in 10times, and partial discharge of 36kV. Thereafter, we designed triaxial terminations. Heat insulation thereof needs both heat and electical insulation characters. To check both insulation characteristics, we produced one-phase model termination. As a result, application of vacuumed insulation for high voltage parts was difficult, so that atmospheric pressure and solid insulation were applied for heat insulation part. In this condition, the system met the withstand voltage test. We assembled a triaxial superconducting cable and termination and cooling system, and system tested based on CIGRE TB 538.

We have investigated the microdomain structure and viscoelastic properties of polystyrene-block-poly(ethylene-co-(ethylene-propylene)-block-polystyrene copolymer (SEEPS-1)/paraffinic oil (Oil-1) blends. The SAXS results revealed that, with increasing oil content, the structures change from a lammelar microdomain for SEEPS-1/Oil-1 = 100/0 to a hexagonally packed cylindrical microdomain for SEEPS-1/Oil-1 = 75/25 blend, and furthermore change to a spherical microdomain packed in a cubic lattice for SEEPS-1/Oil-1 = 50/50 and 25/75 blends. SEEPS-1/Oil-1 = 100/0 and 75/25 blends held each same microdomain structure below 300 °C. In contrast, SEEPS-1/Oil-1 = 50/50 and 25/75 blends, respectively, exhibited order-disorder transition temperature (T ODT) at 210–220 °C and 150–160 °C. Below T ODT, the microdomain structures did not change. Corresponding to the SAXS observations, the viscoelastic responses showed that the dynamic storage modulus G′, respectively, is proportional to ω1/2, ω1/4∼ω1/3, and ω0 at low frequencies for SEEPS-1/Oil-1 = 100/0, 75/25, and 50/50 and 25/75, indicating lamellar, cylindrical, and spherical microdomains The time-temperature superposition was applicable on the ordered state, and the activation energy obtained from the shift factors was roughly independent of blend composition (in other words, microdomain structure), suggesting that the viscoelastic responses are due to the presence of defects of long range order of microdomain structures.

Electrical resistivity, magnetic susceptibility, and specific heat measurements on single crystals of La$Tr_{2}$Al$_{20}$ ($Tr$ = Ti, V, Nb, and Ta) revealed that these four compounds exhibit weak-coupling superconductivity with transition temperatures $T_{\rm c}$ = 0.46, 0.15, 1.05, and 1.03 K, respectively. LaTi$_{2}$Al$_{20}$ is most probably a type-I superconductor, which is quite rare among intermetallic compounds. Single-crystal X-ray diffraction suggests "rattling" anharmonic large-amplitude oscillations of Al ions (16$c$ site) on the Al$_{16}$ cage, while no such feature is suggested for the cage-center La ion. Using a parameter $d_{\rm GFS}$ quantifying the "guest free space" of the cage-center ion, we demonstrate that nonmagnetic $RTr_{2}$Al$_{20}$ superconductors are classified into two groups, i.e., (A) $d_{\rm GFS} \ne 0$ and $T_{\rm c}$ correlates with $d_{\rm GFS}$, and (B) $d_{\rm GFS} \simeq 0$ and $T_{\rm c}$ seems to be governed by other factors., Comment: 5 pages, 5 figures. To appear in J. Phys. Soc. Jpn

We have succeeded in growing single crystals of SmIr2Si2 by Sn-flux method. A single-crystal structure determination has revealed that the single crystals have the tetragonal ThCr2Si2- type crystal structure (I4/mmm, #139). The residual resistivity ratio RRR (=ρ300K/ρ2K) is 270, indicating the high quality of the samples. The electrical resistivity shows metallic behavior with slight downward curvature. A kink structure appearing at 37.8K indicates the existence of a phase transition. It is expected that investigations on the magnetism of SmIr2Si2 single crystals will help to understand the strongly-correlated electron physics of “partially magnetically-disordered (paramagnetic)” Sm ions in a magnetically ordered state, suggested recently in SmPt2Si2 [K. Fushiya et al, J. Phys. Soc. Jpn. 83, 113708 (2014)].

We have succeeded in growing SmxLa1-xTa2Al20 single-crystals, and performed electronic transport measurements to investigate the characteristic features of conduction electron scattering relevant to the field-insensitive – logT dependence of the resistivity. We have found that the – logT dependence of the resistivity remains in a Sm-dilute compound with x = 0.01. This finding provides clear evidence for that the – logT dependence is caused by a local single-ion Kondo effect. We have measured magnetoresistance (MR) of SmTa2Al20 up to 14 T and confirmed that the positive MR continues to develop with decreasing temperature even at 0.5K, evidencing a large deviation from Kohler's rule. This fact indicates that strong wave-vector dependence of conduction-electron scattering by 4f electrons still remains at 0.5K in the magnetically ordered state.

Synchrotron-Radiation-based $^{\mathrm {149}}$ Sm Mossbauer spectroscopy was applied to Sm intermetallics, SmBe13 and SmTi2Al20. Temperature dependence of the Mossbauer parameters in SmBe13 indicate the Sm valence state is purely trivalent. SmBe13 also showed second-order Doppler shift in synchrotron-radiation-based $^{\mathrm {149}}$ Sm Mossbauer spectroscopy. The Mossbauer parameters obtained in SmTi2Al20 suggest that the Sm valence is fluctuating and the magnitude of the magnetic moment is reduced by hybridization between 4f and conduction electrons and/or effect of crystal electric field.

High-entropy-alloy-type tellurides M-Te, which contain five different metals of M = Ag, In, Cd, Sn, Sb, Pb, and Bi, were synthesized using high pressure synthesis. Structural characterization revealed that all the obtained samples have a cubic NaCl-type structure. Six samples, namely AgCdSnSbPbTe5, AgInSnSbPbTe5, AgCdInSnSbTe5, AgCdSnPbBiTe5, AgCdInPbBiTe5, and AgCdInSnBiTe5 showed superconductivity. The highest transition temperature (Tc) among those samples was 1.4 K for AgInSnSbPbTe5. A sample of AgCdInSbPbTe5 showed a semiconductor-like transport behavior. From the relationship between Tc and lattice constant, it was found that a higher Tc is observed for a telluride with a larger lattice constant., 9 pages, 4 figures

We have investigated the crystal structure and physical properties of LaO1-xFxBiSSe to reveal the intrinsic superconductivity phase diagram of the BiCh2-based layered compound family. From synchrotron X-ray diffraction and Rietveld refinements with anisotropic displacement parameters, we clearly found that the in-plane disorder in the BiSSe layer was fully suppressed for all x. In LaO1-xFxBiSSe, metallic conductivity and superconductivity are suddenly induced by electron doping even at x = 0.05 and 0.1 with a monoclinic structure. In addition, x (F concentration) dependence of the transition temperature (Tc) for x = 0.2-0.5 with a tetragonal structure shows an anomalously flat phase diagram. With these experimental facts, we have proposed the intrinsic phase diagram of the ideal BiCh2-based superconductors with less in-plane disorder., 21 pages, 6 figures, 3 supplemental materials

We have investigated Se substitution effect to superconductivity of an optimally-doped BiS2-based superconductor Eu0.5La0.5FBiS2. Eu0.5La0.5FBiS2-xSex samples with x = 0-1 were synthesized. With increasing x, in-plane chemical pressure is enhanced. For x = 0.6, 0.8, and 1, superconducting transitions with a large shielding volume fraction are observed in magnetic susceptibility measurements, and the highest Tc is 3.8 K for x = 0.8. From low-temperature electrical resistivity measurements, a zero-resistivity state is observed for all the samples, and the highest Tc is observed for x = 0.8. With increasing Se concentration, characteristics of electrical resistivity changes from semiconducting-like to metallic, suggesting that the emergence of bulk superconductivity is linked with the enhanced metallicity. A superconductivity phase diagram of the Eu0.5La0.5FBiS2-xSex superconductor is established. Temperature dependences of electrical resistivity show an anomalous two-step transition under high magnetic fields. Hence, the resistivity data are analyzed with assuming in-plane anisotropy of upper critical field., 23 pages, 16 figures (including 10 supplemental materials), 2 tables as supplemental materials

Sn0.8Ag0.2Te is a new superconductor with Tc ~ 2.4 K. The superconducting properties of Sn0.8Ag0.2Te have been investigated by specific heat measurements under magnetic fields. Bulk nature of superconductivity was confirmed from the amplitude of the specific heat jump at the superconducting transition, and the amplitude is consistent with fully-gapped superconductivity. Upper critical field was estimated from specific heat and electrical resistivity measurements under magnetic fields. The Hall coefficient was positive, suggesting that the Ag acts as a p-type dopant in Sn0.8Ag0.2Te., 11 pages, 5 figures

Linear viscoelastic properties of carbon black (CB) suspensions in a mixture of a rosin-modified phenol resin-type varnish (Varnish-1)/an alkyd resin-type varnish (Varnish-2), which exhibited a sol–gel transition on an increase in CB concentration, were investigated from 30°C to 80°C. The viscoelastic properties were reversible from 30°C to 60°C. In contrast, at temperatures above 60°C, the storage (G′) and loss (G″) moduli were irreversible and increased significantly with increasing temperature. This increase in the moduli is due to a change of the dispersion state to agglomerated state by heating. The agglomerated state was held, when the suspensions were lowered at 30°C. However, the G′ and G″ recovered to the original values upon shearing. This heat-induced gelation should be a universal feature for suspensions of weakly attractive particles. The temperature and shearing histories of the suspensions were discussed in relation to adsorption of polymeric component in the varnish on the CB particles.

HTS current leads have been prepared by the TFA-MOD processed YBCO tapes 5 mm in width and around 120 μm in overall thickness. The YBCO superconducting thin layer with 1.5 μm is formed on the oxide buffer layers deposited on Hastelloy substrate tape. The critical current of the YBCO tapes is around 100 A at 77 K in self-field. A current lead unit is composed of a GFRP board and five YBCO tapes soldered to Cu cap at both ends. The transport current of the ten current lead units ranges from 536 A to 408 A at 77 K in liquid nitrogen. The YBCO current lead is assembled from the ten current lead units in parallel. The transport current of 4,000 A at 77 K was stably carried with no voltage generation on the YBCO tapes of the assembled current lead for ten minutes. Furthermore, the trans port current of 5,000 A was successfully applied with voltage of around 200 μV on YBCO tapes. The heat leakage of the assembled YBCO current lead with 150 mm in length between 77 K and 4.2 K is estimated to be 470 mW. Therefore, the heat load of it at transport current of 4000 A corresponds to 0.12 W/kA, which is one order of magnitude smaller than that of conventional Cu current lead. The small heat load results from high current performance and low thermal conductivity in the present YBCO current lead.

Blend systems of polystyrene-block-poly(ethylene-co-(ethylene-propylene))-block-polystyrene (SEEPS) triblock copolymer with three types of hydrocarbon oil of different molecular weight were prepared. The E″ curves as a function of temperature exhibited two peaks; one peak at low temperature (≅ −50°C), arising from the glass transition of the poly[ethylene-co-(ethylene-propylene)] (PEEP) phase and a high temperature peak (≅ 100°C), arising from the glass transition of the polystyrene (PS) phase. The glass transition temperature (Tg) of the PEEP phase shifted to lower temperature with increasing oil content. The shifted Tg depended on the types of oil and was lower for the low molecular weight oil. The Tg of PS phase of the present blend system, were found to be constant and independent of the oil content, when molecular weight of the oil is high. However, for the lower molecular weight oil, the Tg of the PS phase also shifted to lower temperatures. This fact indicates that the oil of high molecular weight is merely dissolved in the PS phase. The E′ at (75°C, at which temperature both of PEEP and PS phases are in glassy state, was found to be independent of oil content. In contrast, at 25°C, at which temperature the PEEP phase is in rubbery state, the E′ decreased sharply with increasing oil content. This result indicates that the hydrocarbon oil was a selective solvent in the PEEP phase. It mainly dissolved in the PEEP phase, although slightly dissolved into the PS phase as well, when molecular weight of oil is low. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

149Sm synchrotron-radiation-based Mossbauer spectroscopy was performed in a heavy fermion compound SmOs4Sb12. A small recoil-free fraction due to the low Einstein temperature at the Sm site inhibit...

We grew high-quality single crystals of the pyrite-type compounds CuS2 and CuSe2 under a pressure of 5 GPa and studied their superconducting and Fermi surface properties by measuring their electric...

Strongly-correlated electron states emerging in cubic Sm-based compounds, e.g., SmOs4Sb12 and Sm Tr2Al20 (Tr: transition metal elements), have anomalous characteristics, like magnetic-field-insensitive heavy-fermion behaviors and strongly mixed valence of Sm ions. In this paper, we compare key physical parameters of these compounds. The results reveal the existence of the following novel features: (i) the electronic specific heat coefficient γ shows a significant inverse correlation with the effective magnetic moment μeff (γ∼1/μeff2), and (ii) largely enhanced γ appears in intermediate Sm valance states around ∼ +2.8. Other remarkable features are the absence of enhanced Pauli paramagnetism at low temperatures and largely suppressed μeff (down to ∼0.1 μB). These are quite different from those of Ce-based heavy-fermion compounds, pointing to an unconventional mechanism for the formation of Sm-based heavy quasiparticles, possibly caused by complex hybridization processes associated with multi-4 f-electrons of a Sm ion.

Uniaxial elongational viscosity of SiO2/(acrylic polymer/epoxy (AP/EP)) suspensions with various SiO2 volume fractions (ϕ) in a blend of acrylic polymer and epoxy was investigated at various temperatures (T). The matrix polymer ((AP/EP) blend) contained 70 vol.% of EP. At ϕ ≤ 35 vol.% at T ≤ 80°C, where the suspensions were in sol state, strain-hardening behavior was observed. This strain hardening of the suspensions is attributable to the elongational flow properties of (AP/EP) medium. At critical gel state (ϕ = 35 vol.% and T = 100°C) and in gel state (ϕ ≥ 40 vol.%), the elongational viscosity exhibited the strain-softening behavior. These results strongly suggest that the strain softening results from the strain-induced disruption of the network structure of the SiO2 particles therein.

Linear and nonlinear viscoelasticity of an adhesion material for integrated circuit chips were investigated to control the processability. The material consists of acrylic polymer (AP) and epoxy oligomer (EP). EP content in AP/EP blend is 70 vol %. From the linear viscoelasticity, it was found that the iso-free volume state of AP/EP blend was 20°C lower than that of AP and the entanglement molecular weight Me of AP/EP was three times higher than that of AP. Nonlinear stress relaxation modulus G(t,γ) showed that the time-strain separability, G(t,γ) = G(t)h(γ), was applicable at long time above a characteristic time τk, where G(t) is linear relaxation modulus and h(γ) is the damping function. The τk value was estimated to be 10 s for AP/EP and below 0.1 s for AP at an iso-free volume state. (h(γ) for AP and AP/EP behaved like a usual linear homopolymer.) The time evolution of the elongational viscosity ηE(t) of each sample showed that AP/EP system exhibited strong strain hardening at , although AP did not show strain hardening at strain rate measured, when the data were compared at an iso-free volume state. These results strongly suggest that the strain hardening behavior of AP/EP is attributable to enhancement of the stretch of AP polymer chains by diluting EP oligomer chains. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Large deformation, nonlinear stress relaxation modulus G(t, γ) was examined for the SiO2 suspensions in a blend of acrylic polymer (AP) and epoxy (EP) with various SiO2 volume fractions (ϕ) at various temperatures (T). The AP/EP contained 70 vol.% of EP. At ϕ ≤ 30 vol.%, the SiO2/(AP/EP) suspensions behaved as a viscoelastic liquid, and the time-strain separability, G(t, γ) = G(t)h(γ), was applicable at long time. The h(γ) of the suspensions was more strongly dependent on γ than that of the matrix (AP/EP). At ϕ = 35 vol.% and T = 100°C, and ϕ ≥ 40 vol.%, the time-strain separability was not applicable. The suspensions exhibited a critical gel behavior at ϕ = 35 vol.% and T = 100°C characterized with a power law relationship between G(t) and t; G(t) ∝ t − n . The relaxation exponent n was estimated to be about 0.45, which was in good agreement with the result of linear dynamic viscoelasticity reported previously. G(t, γ) also could be approximately expressed by the relation $G(t,\gamma) \propto t^{-n^{\prime}}$ at ϕ = 40 vol.%. The exponent n ′ increased with increasing γ. This nonlinear stress relaxation behavior is attributable to strain-induced disruption of the network structure formed by the SiO2 particles therein.

In this study, novel cubic compounds RRu2SnxZn20−x (R = La, Pr, and Nd) were synthesized using the self-flux and melt-growth methods. Single-crystal X-ray structural analysis and measurements of el...

A poly(vinyl chloride) $(\mbox{PVC,}\;{\rm M}_{\rm w} =102\times 10^3)$ di-octyl phthalate (DOP) gel with PVC content of 20 wt.% was prepared by a solvent evaporation method. The dynamic viscoelsticity and elongational viscosity of the PVC/DOP gel were measured at various temperatures. The gel exhibited a typical sol–gel transition behavior with elevating temperature. The critical gel temperature (Tgel) characterized with a power–law relationship between the storage and loss moduli, G′ and G″, and frequency ω, ${G}^\prime={G}^{\prime\prime}{\rm /tan}\;\left( {{n}\pi {\rm /2}} \right)\propto \omega ^{n}$ , was observed to be 152°C. The elongational viscosity of the gel was measured below the Tgel. The gel exhibited strong strain hardening. Elongational viscosity against strain plot was independent of strain rate. This finding is different from the elongational viscosity behavior of linear polymer solutions and melts. The stress–strain relations were expressed by the neo-Hookean model at high temperature (135°C) near the Tgel. However, the stress–strain curves were deviated from the neo-Hookean model at smaller strain with decreasing temperature. These results indicated that this physical gel behaves as the neo-Hookean model at low cross-linking point, and is deviated from the neo-Hookean model with increasing of the PVC crystallites worked as the cross-linking junctions.