Influences of solid–acid catalyst on dimethyl ether steam reforming (DME SR) and DME hydrolysis for hydrogen production were investigated. Series of zeolite (JRC-ZHM20(5), JRC-ZHM90(1) as H-mordenite ...type and JRC-Z5-90H(1) as ZSM-5 type) and of alumina (ALO8, TA1301, TA3301, DK503, NKHD24, NKHO24 and NK324) were used as acidic catalysts for DME hydrolysis. The composite catalysts of the acidic catalyst and CuFe
2O
4 spinel catalyst were employed for DME SR. DME SR activity strongly depended on the acidic catalyst that is active for DME hydrolysis. The hydrolysis of DME, the rate-determining step in DME SR, is equilibrium-controlled. Zeolite exhibited high activity for DME SR at a low temperature range of 200–275
°C, since the hydrolysis could effectively proceed over strong BrØnsted acid-sites approaching its equilibrium. Alumina possessing Lewis acid-sites was active for DME hydrolysis in the higher temperature range from 275 to 450
°C. CO
2 and CO with relatively small amounts of CH
4 were found as primary carbon-containing compounds when alumina was used as the acidic catalyst. In the case of zeolite, besides those carbon compounds, C
3H
8,
i-C
4H
10, and
n-C
4H
10 were detected during SR and hydrolysis of DME. It was found that not only the acid amount of the acidic catalysts, but also the acid strength and the type of acid-site definitely affected the steam reforming and hydrolysis activity. γ-Alumina (ALO8) mixed with CuFe
2O
4 exhibited the highest DME conversion and hydrogen production with optimum reforming temperature at 350–375
°C. Stable activity for DME hydrolysis was attained over ALO8 with high durability for 25
h.
Dielectric ceramics with the compositions of Pb(Mg
1/3
Nb
2/3
) O
3
–Pb(Zn
1/3
Nb
2/3
)O
3
–Pb(Fe
2/3
W
1/3
)O
3
pseudo-ternary system were studied. The ceramics were sintered at 900°C, had high ...dielectric constant (6500) and small change of dielectric constant with temperature (+3%∼-26% relative to 20°C between -25°C to 85°C). The powder processing of these compositions was studied. Pb
2
Nb
2
O
7
phase remained in the ceramics with low calcining temperatures. Multilayer chip capacitors with Ag–Pd internal electrodes were fabricated.
Piezoelectric properties of hot-pressed Pb(Zn
1/3
Nb
2/3
)O
3
–Pb(Sn
1/3
Nb
2/3
)O
3
–PbTiO
3
–PbZrO
3
quaternary ceramics are described. The ceramics exhibited high coupling coefficient and high ...dielectric constant. A small addition of MnO
2
to the quaternary ceramics increased markedly mechanical quality factor (
Q
M
=1400), and coercive field (
E
c
=20 kV/cm). The ceramics made it possible to produce high frequency transducer for large strain and high output voltage.
Dielectric properties of Pb(Mg
1/3
Nb
2/3
)O
3
–PbTiO
3
–Pb(Ni
1/2
W
1/2
)O
3
pseudo-ternary ceramics were studied. The ceramics could be sintered at 1050°C, exhibited high dielectric constant ...(15000∼20000) and high resistivity (10
13
Ω·cm, 27000 Ω·F). A small addition of MnO
2
to these ceramics decreased the dissipation factor and caused a peculiar temperature dependence of dielectric constnt. The characteristics of multilayer chip capacitors made of these ceramics with Ag–Pd electrode are described.
We investigate the thermal-transport properties of the kagome antiferromagnet Cd-kapellasite (Cd-K). We find that a field-suppression effect on the longitudinal thermal conductivityκxxsets in below ...approximately 25 K. This field-suppression effect at 15 T becomes as large as 80% at low temperatures, suggesting a large spin contributionκxxspinκxx. We also find clear thermal Hall signals in the spin liquid phase in all Cd-K samples. The magnitude of the thermal Hall conductivityκxyshows a significant dependence on the sample’s scattering time, as seen in the rise of the peakκxyvalue in almost linear fashion with the magnitude ofκxx. On the other hand, the temperature dependence ofκxyis similar in all Cd-K samples;κxyshows a peak at almost the same temperature of the peak of the phonon thermal conductivityκxxphwhich is estimated byκxxat 15 T. These results indicate the presence of a dominant phonon thermal Hallκxyphat 15 T. In addition toκxyph, we find that the field dependence ofκxyat low fields turns out to be nonlinear at low temperatures, concomitantly with the appearance of the field suppression ofκxx, indicating the presence of a spin thermal Hallκxyspat low fields. Remarkably, by assembling theκxxdependence ofκxyspdata of other kagome antiferromagnets, we find that, whereasκxyspstays a constant in the low-κxxregion,κxyspstarts to increase asκxxdoes in the high-κxxregion. Thisκxxdependence ofκxyspindicates the presence of both intrinsic and extrinsic mechanisms in the spin thermal Hall effect in kagome antiferromagnets. Furthermore, bothκxyphandκxyspdisappear in the antiferromagnetic ordered phase at low fields, showing that phonons alone do not exhibit the thermal Hall effect. A high field above approximately 7 T inducesκxyph, concomitantly with a field-induced increase ofκxxand the specific heat, suggesting a coupling of the phonons to the field-induced spin excitations as the origin ofκxyph.
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