Investigating and predicting the magnetization of bulk superconducting materials and developing practical magnetizing techniques is crucial to using them as trapped field magnets (TFMs) in engineering applications. The pulsed field magnetization (PFM) technique is considered to be a compact, mobile and relative inexpensive way to magnetize bulk samples, requiring shorter magnetization times (on the order of milliseconds) and a smaller and less complicated magnetization fixture; however, the trapped field produced by PFM is generally much smaller than that of slower zero field cooling (ZFC) or field cooling (FC) techniques, particularly at lower operating temperatures. In this paper, the PFM of two, standard Ag-containing Gd-Ba-Cu-O samples is carried out using two types of magnetizing coils: 1) a solenoid coil, and 2) a split coil, both of which make use of an iron yoke to enhance the trapped magnetic field. It is shown that a significantly higher trapped field can be achieved using a split coil with an iron yoke, and in order to explain these how this arrangement works in detail, numerical simulations using a 2D axisymmetric finite element method based on the H-formulation are carried to qualitatively reproduce and analyse the magnetization process from both electromagnetic and thermal points of view. It is observed that after the pulse peak significantly less flux exits the bulk when the iron core is present, resulting in a higher peak trapped field, as well as more overall trapped flux, after the magnetization process is complete. The results have important implications for practical applications of bulk superconductors as such a split coil arrangement with an iron yoke could be incorporated into the design of a portable, high magnetic field source/magnet to enhance the available magnetic field or in an axial gap-type bulk superconducting electric machine, where iron can be incorporated into the stator windings to 1) improve the trapped field from the magnetization process, and 2) increase the effective air-gap magnetic field.

The phase stability of Li7La3Zr2O12 (LLZ) was investigated using high temperature X-ray diffraction (HT-XRD). An Al-free tetragonal LLZ phase transformed into a non-quenchable cubic phase around 650 °C. The phase transformation process between the tetragonal phase and the new cubic phase showed perfect reversibility. The thermal analysis showed a pair of endothermic and exothermic peaks around 640 °C that is in good agreement with the phase transformation process observed in the HT-XRD study. The non-quenchable high temperature cubic phase showed high ionic conductivity with extraordinarily low activation energy (0.117 eV). The tetragonal phase showed another phase transformation to a low temperature (LT) cubic phase around 150-200 °C in air by absorbing CO2 into the structure. The preferred temperature for the CO2 absorption process was around 200 °C and the absorbed CO2 was extracted once the temperature reached 450 °C or above resulting in the phase transformation back to the tetragonal phase. On the other hand the high temperature (HT) cubic phase which shows high ionic conductivity was stabilized by Al substitution. A Li-poor LLZ containing impurity phases such as La2Zr2O7 and La2O3 effectively reacted with γ-Al2O3 resulting in the formation of a pure Al-stabilized cubic LLZ, while the stoichiometric LLZ took a much longer time to complete the Al-substitution. The result suggested that the formation of Li vacancies is the primary step in the formation of the Al-stabilized cubic phase.

Investigating, predicting and optimising practical magnetization techniques for charging bulk superconductors is a crucial prerequisite to their use as high performance 'psuedo' permanent magnets. The leading technique for such magnetization is the pulsed field magnetization (PFM) technique, in which a large magnetic field is applied via an external magnetic field pulse of duration of the order of milliseconds. Recently "giant flux leaps" have been observed during charging by PFM: this effect greatly aids magnetization as flux jumps occur in the superconductor leading to magnetic flux suddenly intruding into the centre of the superconductor. This results in a large increase in the measured trapped field at the centre of the top surface of the bulk sample and full magnetization. Due to the complex nature of the magnetic flux dynamics during the PFM process simple analytical methods, such as those based on the Bean critical state model (CSM), are not applicable. Consequently, in order to successfully model this process, a multi-physical numerical model is required, including both electromagnetic and thermal considerations over short time scales. In this paper, we show that a standard numerical modelling technique, based on a 2D axisymmetric finiteelement model implementing the H-formulation, can model this behaviour. In order to reproduce the observed behaviour in our model all that is required is the insertion of a bulk sample of high critical current density, J c. We further explore the consequences of this observation by examining the applicability of the model to a range of previously reported experimental results. Our key conclusion is that the "giant flux leaps" reported by Weinstein et al. and others need no new physical explanation in terms of the behaviour of bulk superconductors: it is clear the "giant flux leap" or flux jump-assisted magnetisation of bulk superconductors will be a key enabling technology for practical applications.

A Schottky ultraviolet photodiode using a (0001) ZnO single crystal grown by the hydrothermal growth method is reported. The photodiode consisted of a semitransparent Pt film for the Schottky electrode and an Al thin film for the Ohmic electrode. The photodiode had polarity dependences on current-voltage characteristics and on responsivity. In the case of the Schottky electrode on the zinc surface, the responsivity was 0.185A∕W at a wavelength of 365nm. On the other hand, the responsivity was 0.09A∕W for an oxygen surface. The results are attributed to the polarity dependences of surface chemical reactivity and the surface state density on ZnO surfaces.

NASICON-type Li 1+x Al x Ge 2-x (PO 4 ) 3 solid state lithium ionic conductors were synthesized by a sol-gel method using citric acid and ethylene glycol. The obtained precursors were sintered at various temperatures and the NASICON-type single phase was observed in a range of x = 0-0.6. The highest electrical conductivity was obtained for Li 1.4 Al 0.4 Ge 1.6 (PO 4 ) 3 sintered at 900 • C for 11 h in air. The total conductivity was 1.22×10 −3 S cm −1 at 25 • C, and the bulk and grain boundary conductivities were estimated by impedance profile analysis to be 1.70×10 −3 and 4.30×10 −3 S cm −1 , respectively. Sintered pellets of Li 1.4 Al 0.4 Ge 1.6 (PO 4 ) 3 were immersed in distilled water, saturated LiCl aqueous solution, and a saturated LiCl and LiOH aqueous solution at 50 • C for one week; X-ray diffraction patterns of these samples dried at 220 • C under vacuum showed no significant change from that of the pristine sample. The electrical conductivity of Li 1.4 Al 0.4 Ge 1.6 (PO 4 ) 3 was decreased to 1.4×10 −4 S cm −1 at 25 • C by immersion in distilled water, while immersion in the saturated LiCl aqueous solution increased the conductivity to 4.95×10 −3 S cm −1 at 25 • C. Li 1.4 Al 0.4 Ge 1.6 (PO 4 ) 3 was stable in the saturated LiCl and LiOH aqueous solution. Li 1.4 Al 0.4 Ge 1.6 (PO 4 ) 3 was unstable in contact with Li metal and Li-In alloy, but was stable in contact with Li 7 Ti 5 O 12 .

In order to take advantage of the high specific capacitance of pseudo-capacitive oxides that can only be realized in aqueous electrolytes and at the same time utilize the low electrode potential of lithium that can only be operated in non-aqueous 75 environment, we have exploited the use of a water stable multilayered Li electrode, 19,20 initially developed as the anode for an aqueous rechargeable Li-air battery. This new advanced hybrid EC can be operated using a mild aqueous electrolyte providing specific energy exceeding that of LICs and potentiaally 80 comparable to LiBs. Cell voltage as high as 4.3 V can be realized when MnO2 is used as the positive electrode.The multi-layered Li electrode consists of lithium metal, a LISICON-type solid glass ceramic (Li1+x+y(Ti,Ge)2−xAlxSiyP3−yO12 (x~0.25, y~0.3); Ohara Inc., Japan, hereafter denoted as LTAP) as 85 the water-stable solid electrolyte, and a buffer layer consisting of polyethylene oxide with Li(CF3SO2)2N polymer electrolyte (PEO-LiTFSI) between the lithium metal and the solid electrolyte. These 3 layers were sealed leaving a 5 mm x 5 mm window cut out for the solid electrolyte (LTAP) to come into contact with the 90 aqueous electrolyte. Figure 1 illustrates the cell configuration of

J J n c c where E c (=10 −4 V m −1 ) is the reference electric field and J c (=4.8 × 10 8 A m −2 ) is the critical current density under zero field, which is a typical J c value at T s = 50 K for the REBaCuO bulk [7]. J c is assumed to be independent of applied magnetic field [7]. For an 'infinite disk bulk' with the same O.D., not the 'infinite ring bulk', the fully magnetized trapped field is estimated to be B z * = μ 0 J c R = 19.30 T (R: radius of the disk bulk) by 2 Supercond. Sci. Technol. 30 (2017) 085008 H Fujishiro et al

We have magnetized the EuBaCuO ring bulk reinforced by a stainless steel ring during fieldcooled magnetization (FCM) at 50 K under the magnetic fields from 6.3, 7.3 or 8.3 T, in which the ring bulk was broken at the intermediate step of FCM from 8.3 T. To discuss the fracture behavior of the bulk, we have performed the numerical simulation using a three dimensional finite element method for the bulk with realistic superconducting characteristics, and obtained both the electromagnetic hoop stress, , FCM s q during FCM and thermal hoop stress, , cool