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The structure and magnetic properties of LaFe11.6Si1.4/Ce40Co60 bulk composites prepared by hot pressing sintering (HPS), followed by high-temperature diffusion annealing, were investigated. During the HPS process, the La(Fe,Si)13 alloy powder particles combined with Ce40Co60 binder and a porous structure with high mechanical strength were obtained. The addition of Ce40Co60 can also promote the peritectic reaction. Annealing has important effects on the magnetocaloric properties due to the diffusion of Ce and Co into the La(Fe,Si)13 phase during annealing. HPS samples were annealed at 1373 K for 24 h, and a table-like magnetocaloric effect, exhibiting a constant high magnetic entropy change (− ∆SM) of ~ 4.0 J/(kg K) in a commercially useful temperature region of 28 K (236–264 K), was obtained for a field change of 2 T. The values of full width at half maximum of (− ∆SM)–T plots (ΔTFWHM) and enhanced refrigeration capacity for the composites are 55 K and 173 J/kg, respectively, for a field change of 2 T. The composites exhibit high compressive strength of up to 312 MPa. The present results indicate that LaFe11.6Si1.4/Ce40Co60 bulk composites can meet the requirement of near room temperature magnetic refrigeration based on the Ericsson cycle.

Two-dimensional (2D) bilayer Janus pellicle (denoted as BJP) of concurrent double aeolotropic electrical conduction, superparamagnetism and luminescence is designed and constructed via electrospinning by using one-dimensional (1D) nanofibers and Janus nanoribbons as constructive units. The BJP comprises top-down two layers tightly bonded together. The top layer is a left-right structured Janus film which consists of Janus nanoribbons array as left and right side, and further, arrangement orientations of Janus nanoribbons in the two sides are perpendicular, leading to double aeolotropic conduction, and the conduction ratio reaches 108 times. The down layer is a non-array luminescent film made of nanofibers. Under the excitation by 291 and 294 nm light, red luminescence of the left side of the top layer and green luminescence of down layer in BJP are respectively achieved. The maximum saturation magnetization of the top layer can reach 21.45 (emu/g). By rolling the 2D BJP into the tube respectively with the ways of rolling from left to right or from up to down, three-dimensional (3D) dual-wall Janus-type tube with the Janus-type tube as outer or inner and the homogeneous tube as inner or outer is obtained.

We report on a novel processing route to prepare La0.8Ce0.2(Fe0.95Co0.05)11.8Si1.2/Cu bulk composites by low-temperature hot pressing. With increasing copper content, the compressive strength of the composites first decrease and then increase owing to the buffering effect of copper, but the magnetocaloric effect reduces to some extent. Copper addition improves the thermal conductivity of the composites, which compensates for the decrease in thermal conductivity due to porosity. A relatively large entropy change of 5.75–7.19 J/(kg K) at 2 T near the Curie temperature (249 K), good thermal conductivity of 7.51–15.55 W/(m·K), and improved compressive strength of 151.1–248.0 MPa make these composites attractive magnetic refrigeration materials. NRF (Natl Research Foundation, S’pore)

A comparative study was performed to examine the co(cross)-polarized reflection and transmission characteristics of multilayer omega(chiro)ferrite slabs, with or without a backing soft and hard surface (SHS), respectively. The omegaferrite models examined here can be described by the Dmitriev's continuous groups of the symmetry: C ∞v (C ∞), C 2v (C 2), C 2v (Cs )1, and C 2v (C s )2. Based on various numerical experiments, some generalized relations governing the co(cross)-polarized reflection and transmission coefficients are found, which are related to the biasing dc magnetic field as well as the orientation of all omega(chiro)ferrite particles, but independent of the incident wavelength, slab thickness or its loss.

The distortion of pulse waves propagating in some shielded composite ferrite microstrip transmission lines (FMTLs) is studied in this paper. The mathematical treatment is based on the Galerkin's method in the spectral domain and the fast Fourier transformation (FFT). The hybrid effects of the biasing magnetic dc field intensity and its orientation on the pulse wave distortion are examined and compared. It is shown that the pulse distortion can be effectively reduced by changing the biasing field intensity or orientation.

The propagation of pulse waves in coplanar waveguides (CPWs) is investigated, and these CPWs are assumed to be fabricated on a single-layer low-temperature co-fired ceramic (LTCC) substrate. The input pulse wave can be a Gaussian pulse or a sinusoidally modulated Gaussian pulse. Based on the standard Galerkin's method in the spectral domain, combined with fast Fourier transform (FFT), the pulse waveform and delay in CPWs are demonstrated and compared for LTCCs with different permittivities. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 32–34, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10816