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Biomedical porous NiTi alloys with tailored pore sizes at the same porosity levels (∼50%) were prepared by microwave sintering technique and space holder method. The effects of pore sizes on the microstructure, macrohardness, compressive strength, elastic modulus, superelasticity and corrosion resistance of the porous NiTi alloys were investigated. The results showed that the porosities of the porous NiTi alloys mainly depended on the weight ratio of the NH 4 HCO 3 space holder agents, while the pore sizes mainly depended on the particle sizes of the space holder agents. The porous NiTi alloys mainly consisted of the predominant NiTi phase and the secondary phases Ti 2 Ni and Ni 3 Ti. With increasing the pore sizes of the porous NiTi alloys, the Ti 2 Ni phase and Ni 3 Ti phase increased, while the NiTi phase decreased. The hardness, compressive strength and elastic modulus of the porous NiTi alloys presented “S” type variation tendency with the pore sizes, respectively. The superelasticity of the porous NiTi alloys could reach ∼4% under the pre-strain of 5% as the pore sizes smaller than 294 μm. Moreover, partial shape memory effect was observed for all pore size levels under the experiment conditions. The increase of the pore sizes had adverse effects on the corrosion resistance of the porous NiTi alloys in Hank’s solution.

This paper reports an all-quartz high accuracy MEMS absolute pressure sensor based on high Q double-ended tuning fork (DETF) resonator, which is suitable for application in automotive, petroleum, meteorological, aerospace and spacecraft field. etc. The main parts of the MEMS pressure sensor, including the DETF resonator, diaphragm and back cavity structure, are all fabricated by quartz crystal using MEMS process. These pieces are bonded together as ‘sandwich’ structure to form the absolute pressure sensing unit using glass paste under low temperature and vacuum condition. This process could effectively eliminate the thermal stress effect and form the reference vacuum cavity. The experimental results show that the quality factor of the DETF resonator is up to 61000, the sensitivity is up to 7.35 Hz/kPa in the operating range 0∼250 kPa, the pressure error is only 0.021%FS over the temperature range -40C∼+60C.

Biomedical porous NiTi alloys, being composed of mainly NiTi phase with a little Ti 2 Ni phase and no Ni 3 Ti phase, were fabricated by a microwave sintering technique. They presented an isotropic and three-dimensionally interconnected pore microstructure with the pore size of 20–100 μm. The compressive strength and elastic modulus of the porous NiTi alloy were about 360 MPa and 5.5 GPa, respectively. At the same time, the porous NiTi alloys possessed excellent corrosion resistance in Hank׳s solution. Therefore, the porous NiTi alloys fabricated by the microwave sintering technique would be good candidates for ideal biomaterials, used potentially as the heavy load-bearing hard tissue implants.

Effect of Mn overlayer on the spin reorientation transition (SRT) of Ni/Cu(0 0 1) is investigated in situ by multi-functional techniques such as surface magneto–optic Kerr effect (SMOKE) measurement. It is found that the SRT thickness of Ni/Cu(1 0 0) shifts to thinner Ni thickness by ∼ 0.5 ML after covering the Ni film with 0.5 ML Mn.

Growth of Cr thin films on GaAs(0 0 1) was carried out using molecular beam epitaxy and was investigated by in situ reflection high-energy electron diffraction (RHEED) and ex situ X-ray diffraction (XRD). The results show that there are two competing mechanisms during the growth, and the film structure strongly depends on the growth temperature. The single-crystalline Cr films with the body-centered-cubic (bcc) structure are obtained, with the epitaxial relationship of (0 0 1)[0 0 1] Cr ∥(0 0 1)[0 0 1] GaAs and (0 0 1)[1 0 0] Cr ∥(0 0 1)[1 0 0] GaAs .

A series of rf sputtered [NiCo(1.3 nm)/Cu(tCu)]25 multilayers with tCu=0.5–4.0 nm was prepared and the behavior of interlayer coupling, magnetoresistance, and magneto-optical Kerr effect was studied. A concurrent oscillation in the magnitude of the magnetoresistance and magneto-optical Kerr effect in visible wavelength range as a function of Cu layer thickness was observed. The changes of both the optical and magneto-optical transition due to interlayer coupling may be responsible for the magneto-optical activities.

The growth of single-crystal Co x Mn 1− x alloy on GaAs(0 0 1) has been achieved at room temperature using molecular beam epitaxy. The body-centered-cubic structure is determined by in situ reflection high energy electron diffraction (RHEED). In-plane magnetic anisotropy has been determined using the longitudinal magneto-optical Kerr effect technique.

Single-crystal Fe films of 4 to 33 monolayers (ML) on GaAs (100) prepared by molecular-beam epitaxy were studied by ferromagnetic resonance (FMR). The evolution of both in-plane and out-of-plane anisotropies was observed. The FMR data show a predominant in-plane uniaxial magnetic anisotropy in the films with the thickness t less than 12.7 ML, with an easy axis along the 〈11_0〉 direction. An in-plane fourfold anisotropy due to cubic magnetocrystalline anisotropy starts to appear and coexists with uniaxial magnetic anisotropy when t=8.4 ML, and increases with increasing film thickness. For t=33 ML, the cubic anisotropy constant K1 reaches 28.2×104 erg/cm3, which is 60% of the value for bulk bcc Fe. A strong perpendicular anisotropy in the ultrathin Fe films was observed. For t=4 ML, the perpendicular anisotropy constant is as high as 14.6×106 erg/cm3. It decreases with increasing the thickness t and reaches about 2.1×106 erg/cm3 for 33 ML, while a small fourth-order perpendicular anisotropy appears and incr...

Epitaxial growth of Ni thin films on GaAs(0 0 1) and their magnetic property have been investigated using reflection high energy electron diffraction and magneto-optical Kerr effect. The result shows that a body-centered-cubic (BCC) phase of Ni which does not exist in nature can grow epitaxially up to 2.5 nm on the GaAs(0 0 1) substrate, and it is determined to be ferromagnetic showing a four-fold in-plane magnetic anisotropy with the easy axes along the 〈1 0 0〉 directions.

The two-dimensional nature of surface adsorbate layers of rare earth atoms and of epitaxial interfaces of rare earths on Si(111)-7 × 7 is reflected in the axial symmetry of the local field at the rare earth site. The induced splitting of the ground state of the rare earth is probed by linear polarized X-ray absorption spectroscopy (XAS), which exhibits strong dichroism.

Epitaxial structure of Co on GaAs(0 0 1) is studied by cross section high resolution transmission electron microscope. A bilayer structure is confirmed in the Co thin-film, where a body-centered-cubic (BCC) phase near the interface and a two-domain hexagonal-close-packed (HCP) phase on the top. Using the magneto-optical Kerr effect (MOKE) measurement, the in-plane magnetic anisotropy of the BCC phase is determined as a fourfold symmetry with easy axes along the 〈1 0 0〉 directions. Strongly depending on the growth temperature, the two-domain HCP phase shows either a uniaxial symmetry along the 〈1 1 0〉 direction or a fourfold symmetry with easy axes along the 〈1 0 0〉 directions.

Growth of Fe 1− x Mn x alloys on GaAs (0 0 1) were carried out by molecular beam epitaxy and both α-Fe 1− x Mn x (BCC) and γ-Fe 1− x Mn x (FCC) phases have been achieved. Single-crystalline α-Fe 1− x Mn x thin-film is stabilized with Mn concentration up to 20%, while single-crystalline γ-Fe 1− x Mn x phase is succeeded with Mn concentration higher than 65%. The structure of Fe 1− x Mn x alloys is found to be more complicated for Mn concentration 20% x 1− x Mn x alloys are ferromagnetic at Mn concentration x 1− x Mn x alloys, an ab initio all-electron linearized augmented-plane-wave calculation, using the local-spin-density approximation, has been carried out and a good agreement reached with the experiment.

A series of RF sputtered NiCo/Cu multilayers was prepared and the correlation of the interlayer coupling and magnetooptical Kerr effect (MOKE) was studied. A concurrent oscillation of the magnetoresistance ratio and the maximum Kerr rotation (θ2k+η2k)1/2 with Cu layer thickness was observed. The oscillation of the Kerr rotation is attributed to changes in the band structure related to the antiferromagnetic interlayer coupling, leading to changes in the optical and magnetooptical transitions.

A series of Co/Mn/Co sandwiches was prepared on GaAs(001) surfaces at room temperature via a molecular beam epitaxy (MBE) technique. Reflection high-energy electron diffraction (RHEED) and x-ray-diffraction (XRD) analysis indicated a polycrystalline structure. By standard magnetoresistance measurements, it was found that with a Mn spacer thickness of 8 A, a seldom-seen positive magnetoresistance (PMR) as high as 16% was exhibited at room temperature. The measurement under different geometries of H and I indicated that it was not an anisotropic magnetoresistance (AMR) effect. The MR–H curve displayed no hysteresis in contrast to the magnetometry measurement. An interface effect is proposed as a possible origin of this phenomenon.

Alloy films of Co0.70Mn0.30 were grown on GaAs (001) substrates by molecular beam epitaxy at room temperature. The metastable tetragonally distorted single crystal structure was confirmed by reflection high energy electron diffraction and x-ray diffraction measurement, which exhibited a 2.87 A in-plane lattice parameter. Ferromagnetic resonance measurements and theoretical fitting were performed and showed that, with a Mn capping layer, a uni-directional anisotropy existed. In addition, a fourfold tetragonal magnetocrystalline anisotropy as well as a uniaxial term in the film plane was also confirmed. The hysteresis loops recorded by longitudinal magneto-optical Kerr-effect also demonstrated the existence of different kinds of in-plane magnetic anisotropy. The origins of the anisotropy are explained tentatively.

The electronic and magnetic structures of both face-centered-cubic (FCC) and body-centered-cubic (BCC) Co 1− x Pd x ordered alloys at x =0.25, 0.50, 0.75 have been calculated using the first principles linearized augmented plane-wave (LAPW) method with the local spin density approximation (LSDA). It is found that both FCC-Co 1− x Pd x and BCC-Co 1− x Pd x are ferromagnetic at all the compositions considered above. It is also noticed that the Pd atoms in these situations are strongly spin-polarized, meanwhile magnetic moments of Co are significantly enhanced.

The formation of the Yb/InP(110) interface is studied by synchrotron radiation electron spectroscopy. Chemical reactions at the interface lead to the formation of an intermixed region of ternary composition. At increasing coverages two distinct intermetallic phases grow out of the mixed region: islands of a YbP phase and a layer of metallic YbIn alloy.