다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Synthesis methods for nanosized hydroxyapatite with diverse structures.

https://dr.ntu.edu.sg/bitstream/10356/101824/1/A%20comprehensive%20review%20on%20the%20progress%20of%20lead%20zirconate-based%20antiferroelectric%20materials.pdf

A comprehensive review on the progress of lead zirconate-based antiferroelectric materials

Since the last decades, non-precious metal catalysts (NPMC), especially iron based electrocatalysts show sufficient activity, potentially applicant in oxygen reduction reaction (ORR), however they only withstand considerable current densities at low operating potentials. On the other hand iron based electrocatalysts are not stable at elevated cathode potentials, which is essential for high energy competence, and its remains difficult to deal. Therefore, via this research a simple approach is demonstrated that allows synthesis of nanosize Fe-doped mayenite electride, [Ca24Al28O64]4+·(e−)4 (can also write as, C12A7−xFex:e−, where doping level, x = 1) (thereafter, Fe-doped C12A7:e−), consist of abundantly available elements with gram level powder material production, based on simple citrate sol-gel method. The maximum achieved conductivity of this first time synthesized Fe-doped C12A7:e− composite materials was 249 S/cm. Consequently, Fe-doped C12A7:e− composite is cost-effective, more active and highly durable precious-metal free electrocatalyst, with 1.03 V onset potential, 0.89 V (RHE) half-wave potential, and ~5.9 mA/cm2 current density, which is higher than benchmark 20% Pt/C (5.65 mA/cm2, and 0.84 V). The Fe-doped C12A7:e− has also higher selectivity for desired 4e− pathway, and more stable than 20 wt% Pt/C electrode with higher immunity towards methanol poisoning. Fe-doped C12A7:e− loses was almost zero of its original activity after passing 11 h compared to the absence of methanol case, indicates that to introduce methanol has almost negligible consequence for ORR performance, which makes it highly desirable, precious-metal free electrocatalyst in ORR. This is primarily described due to coexistence of Fe-doped C12A7:e− related active sites with reduced graphene oxide (rGO) with pyridinic-nitrogen, and their strong coupling consequence along their porous morphology textures. These textures assist rapid diffusion of molecules to catalyst active sites quickly. In real system maximum power densities reached to 243 and 275 mW/cm2 for Pt/C and Fe-doped C12A7:e− composite, respectively.

/pdf/fe-doped-mayenite-electride-composite-with-2d-reduced-155zacujpr.pdf

Fe-doped mayenite electride composite with 2D reduced Graphene Oxide: As a non-platinum based, highly durable electrocatalyst for Oxygen Reduction Reaction.

There has been a resurgence of complex oxides of late owing to their ferroelectric and ferromagnetic properties. Although these properties had been recognized decades ago, the renewed interest stems from modern deposition techniques that can produce high quality materials and attractive proposed device concepts. In addition to their use on their own, the interest is building on the use of these materials in a stack also. Ferroelectrics are dielectric materials that have spontaneous polarization in certain temperature range and show nonlinear polarization–electric field dependence called a hysteresis loop. The outstanding properties of the ferroelectrics are due to non-centro-symmetric crystal structure resulting from slight distortion of the cubic perovskite structure. The ferroelectric materials are ferroelastic also in that a change in shape results in a change in the electric polarization (thus electric field) developed in the crystal and vice versa. Therefore they can be used to transform acoustic wav...

Processing, Structure, Properties, and Applications of PZT Thin Films

Band-gap energies of sol-gel-derived SrTiO3 thin films were studied in terms of annealing temperature and film thickness. The band-gap energies of highly crystallized films were comparable to those of single crystals reported, whereas for poor-crystallized films, their band-gap energy values were much larger than those of single crystals. The larger band-gap energy shift was believed to be mainly due to both quantum size effect and existence of amorphous phase in thin films. The band-gap energies also showed a strong dependence on film thickness. There was a critical film thickness (∼200 nm), above which the films had band-gap energies close to those of crystals or bulks, but below that, the values shifted largely, which can be attributed to the influence of crystallinity of thin films. Such a thickness effect of band-gap energy should be of high interest in optical device applications.

Band-gap energies of sol-gel-derived SrTiO3 thin films

A series of new compounds, Ba 1−x R 2x/3 Nb 2 O 6 (RNd, Eu, Gd, Tb, Dy, Ho and Er) with tetragonal tungsten bronze (TTB) structure were synthesized. For Ba–R–Nb–O system, single phase TTB was obtained when X =0·25. To understand the formation condition of these TTB type compounds, two tolerance factors for TTB, t A1 and t A2 , were proposed against the coordination polyhedra around A1 and A2 site cations, respectively. One of the factors was at least a requisition to stabilize crystal structure for all TTB type compounds. Ba 1− x R 2 x /3 Nb 2 O 6 showed ferroelectric characteristics and the Curie temperature, T c , increased as the decrease of the ionic radius of rare earth cations. These new compounds have potential to be candidates to apply ferroelectric random access memory (FRAM).

Synthesis and dielectric properties of Ba1-xR2x/3Nb2O6(R : Rare earth) with tetragonal tungsten bronze structure

An XPS study of the nucleation and growth behavior of an epitaxial Pb(Zr,Ti)O3/MgO(100) thin film prepared by MOCVD

The structure stability of perovskite-type compounds has been quantitatively estimated by applying bond valence calculations to Pb(Mg1/3Nb2/3)O3 (PMN) and Pb(Zn1/3Nb2/3)O3 (PZN). The bond valence calculations revealed that the bond strength between oxygen and cations in the pyrochlore-type compounds is greater than that in the perovskite PMN. It is found that the absolute value of the bond valence sum of oxygen, |VO|, for a PZN single crystal is smallest in reported Pb-containing perovskite-type compounds, corresponding to the fact that it is impossible to synthesize PZN by solid-state reaction under atmospheric pressure. The calculated amount of additives required for stabilizing PZN under atmospheric pressure agreed well with the experimental values.

Estimation of Phase Stability in Pb(Mg1/3Nb2/3)O3 and Pb(Zn1/3Nb2/3)O3 Using the Bond Valence Approach

Sandwich structured (Bi, La)4Ti3O12/Pb(Zr, Ti)O3/(Bi, La)4Ti3O12 thin films were fabricated on Pt/Ti/SiO2/Si substrates, with the intention of simultaneously utilizing the advantages of both (Bi, La)4Ti3O12 (BLT) and Pb(Zr, Ti)O3 (PZT) thin films such as non-fatigue behaviours of BLT and good ferroelectric properties of PZT Both BLT and PZT layers were prepared by a chemical solution deposition technique The experiments demonstrated that the sandwich structure showed fatigue-free characteristics at least up to 1010 switching bipolar pulse cycles under 8 V and excellent retention properties The sandwich structured thin films also exhibited well-defined hysteresis loops with a remanent polarization (2Pr) of 88 µC cm-2 and a coercive field (Ec) of 47 kV cm-1 The room-temperature dielectric constant and dissipation factor were 210 and 0031, respectively, at a frequency of 100 kHz These results suggest that this sandwich structure is a promising material combination for ferroelectric memory applications

http://iopscience.iop.org/article/10.1088/0022-3727/35/3/101/pdf

Naoki Wakiya

Papers

Band-gap energies of sol-gel-derived SrTiO3 thin films

Synthesis and dielectric properties of Ba1-xR2x/3Nb2O6(R : Rare earth) with tetragonal tungsten bronze structure

An XPS study of the nucleation and growth behavior of an epitaxial Pb(Zr,Ti)O3/MgO(100) thin film prepared by MOCVD

Estimation of Phase Stability in Pb(Mg1/3Nb2/3)O3 and Pb(Zn1/3Nb2/3)O3 Using the Bond Valence Approach

Ferroelectric properties of sandwich structured (Bi, La)4T3O12/Pb(Zr, Ti)O3/ (Bi, La)4Ti3O12 thin films on Pt/Ti/SiO2/Si substrates