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This paper presents an exact analysis of deformation and stress field in a finite cylinder under axisymmetric boundary conditions. The problem is formulated based on the state space formulation for transversely isotropic piezoelectric media. Upon the separation of variables method, we get a set of general solutions spanning over the complete solution space to cover all axisymmetric boundary conditions. Furthermore, a rigorous solution which satisfies the end conditions is determined by using eigenfunction expansion. Numerical results show that the local effect is significant but confined to boundary layer near the fixed end where the displacement and stress are remarkably different from those of other regions.

A novel eigenvector expansion method under the symplectic system is introduced for boundary condition problems of thermo-viscoelastic materials. On the basis of the state space formalism and the use of the Laplace integral transform, the general solutions of the governing equations, zero and non-zero-eigenvalue eigenvectors, are obtained analytically. Since the eigenvectors are expressed in concise analytical forms, the adjoint symplectic relation in the Laplace domain is generalized to the time domain. Using this method, various boundary conditions and the particular solution of non-homogeneous governing equations can be conveniently described by combinations of the eigenvectors.

The effects of argon pressure on the microstructure and magnetic properties of the sputtered FeCoSiB amorphous films were investigated. At low deposition pressure the samples show flat and dense surface, while those at higher pressure show columnar growth with rough surface. The formation of the columnar grains results in the perpendicular magnetic anisotropy due to the shape anisotropy. Stripe magnetic domains were observed in the latter samples. Both the magnetic contrast in magnetic force microscope images and the coercivity of FeCoSiB films increase first and then decrease with the increasing of the sputtering pressure. It is suggested that the columnar grains introduce shape anisotropy which plays an important role in tuning the magnetic behaviors of the FeCoSiB films with the sputtering pressure.

In this paper, barium hexaferrite thick films with thickness of 80 microns were prepared on alumina substrates by screen printing method for applications in self-biased planar microwave devices. The influences of sintering temperature on the microstructures and magnetic properties of barium ferrite (BaM) thick films were investigated. The results show that with the increase of sintering temperature, the grain size increases and the porosity of the BaM thick films decreases. When the sintering temperature is below 1200 °C, the BaM thick films show magnetic properties with coercive force of about 3.5 kOe and magnetization at 20 KOe (4πM20kOe) of about 1750 Gs. When the sintering temperature is greater than 1200 °C, the magnetic properties deteriorate remarkably and exhibit a coercive force of 0.4 kOe and 4πM20kOe of about 480 Gs due to the over-sintering and diffusion of Al atoms into the BaM thick films. A new non-ferromagnetic phase Al13Ba7 is formed, which is detected by XRD.

Ag -doped La 0.7 Ca 0.3 MnO 3 (LCMO) films were prepared on silicon substrate by RF magnetron sputtering. The dependences of transport properties on annealing temperature were explored. It is shown that the resistivity of the samples decreases and the metal–insulator transition temperature shifts to higher temperature with the increase in annealing temperature. Two metal–insulator transition temperatures are presented in the R – T plots of Ag -doped LCMO films, which can be explained by the Ag 1+ substitution of La 3+ to form La 1-x Ag x MnO 3 compound. Compared with LCMO thin films, Ag -doping can observably improve the TM-I and decrease the resistivity of the samples.

BaFe 12 O 19 ferrite thick films were screen-printed and sintered at 1150°C under pressure (hot press sintering). The effects of the hot press sintering on the properties of barium hexaferrite thick films were investigated. The X-ray diffraction pattern shows improvement of the (00l) texture under pressure. The porosity size of the hot press sintering samples decreases obviously and the surface compactness is improved as the pressure is increased. The films are quite anisotropic with magnetic easy axis perpendicular to the film plane. The largest remanence ratio achieved is 0.75 under the highest pressure of 4 MPa.

The effects of tensile and compressive stress on the magnetic domains of amorphous FeCoSiB films are investigated. It is observed that the unstressed sample consists of irregular domains while the stressed samples show stripe domains. With the increase of the tensile stress, the stripe domain of the stressed films tends to align parallel to the direction of the stress, while with the increase of the compressive stress the stripe domain of the stressed films tends to align perpendicular to the direction of the stress. The magnetic domain and its evolution under the stress are explained by introducing the magnetoelastic anisotropy induced by the stress.

The effect of stress on the magnetic domain and anisotropy of FeCoSiB amorphous films is investigated. It is observed that the unstressed sample consists of irregular domain while the stressed samples show the strip domain. The strip domain of the sample under tensile stress aligns parallel to the direction of the stress while that of the sample under compressive stress aligns perpendicular to it. The variation of the magnetic domain is explained with the magnetoelastic anisotropy induced by the stress, which has been verified by the hysteresis loops, remanences and the anisotropy field. It is also obtained that the stress-induced anisotropy increases with the increase of the stress. The effects of the stress on the magnetic properties of the FeCoSiB films have been discussed.

We report the effects of oxygen content on the transport properties of La 0.7 Ca 0.3 MnO 3-δ thin films grown epitaxially on LaAlO 3 (001) substrates by RF magnetron sputtering. The as-deposited thin films were annealed and treated by oxygen plasma to improve the oxygen content. We observe that the La 0.7 Ca 0.3 MnO 3-δ films annealed at 850°C is highly oriented growth on (001) LAO substrate. However, the XRD patterns of the samples annealed at lower than 850°C show no distinct diffraction peaks. This evidence indicates that the samples annealed at lower than 850°C are still amorphous or nanocrystalline. The La 0.7 Ca 0.3 MnO 3-δ films without oxygen plasma do not suffer insulator to metal transition at the temperature range from 213 to 293 K. But, at the same temperature range, for the 650°C, 750°C, and 850°C annealed samples with oxygen plasma treatment show an insulator to metal transition at 239 K, 239 K, and 257 K, respectively. Moreover, compared to without oxygen plasma treatment, the resistivity of the sample with oxygen plasma treatment is dramatically decreased. These results imply that the insulator to metal transition is strongly determined by the ratio of Mn 4+/ Mn 3+ and the oxygen content of the films. The increases of the ratio of Mn 4+/ Mn 3+ and the oxygen content lead to a higher insulator to metal transition temperature.

The driving field of the magnetostrictive thin film actuator should be as small as possible in order to develop miniature devices. The aim of this paper is to reduce the driving field by varying the structural and the material parameters of the substrate of the cantilever in the actuator based on the finite element calculation. The influences of the geometric and the material parameters on the reference driving field have been studied. The results show that the reference driving field is sensitive to the length of the cantilever, the thickness of both the magnetostrictive film and the substrate, and also the Young's modulus of the substrate. The length of the cantilever should be long enough. In order to achieve a small driving field, the thickness of both the magnetostrictive film and the substrate should be carefully designed according to the ratio of the Young's modulus of the substrate to that of the film.

Simple and effective model is demanded which enables the design and structural optimization of the microwave MEMS switch efficiently. For this purpose the microwave behaviors of series metal cantilever MEMS switch have been modeled by “simple” circuit in this paper. The microwave characteristics have been calculated and compared with the experiment data based on the developed model. The results show that the microwave characteristics of series metal cantilever MEMS switch can be described very well with this model. Based on this model, the influences of the structural parameters of the switch on the microwave characteristics have been discussed extensively.

In this paper, the influences of depositing angles on TbFe film magnetic and magnetostrictive characteristics were discussed. TbFe films were deposited by DC magnetron sputtering. With the decrease of depositing angles from 900 to 150, TbFe film in-plane magnetization measured at 1600kA.m-1 external field is greatly increased. With the decrease of depositing angles from 900 to 150, the magnetostrictive saturation field is decreased. TbFe film in-plane magnetostriction is improved when depositing angles are changed from 900 to 150. Magnetic domain structures detected by MFM indicates that film easy magnetization direction is gradually changed from perpendicular to parallel with the decrease of depositing angles. The variation of film magnetic and magnetostrictive performances can be explained by the oblique anisotropy associated with columnar grain morphology of the films.

In this paper, the influences of annealing temperature on TbFe magnetostrictive film magnetic and magnetostrictive characteristics were discussed. TbFe films were prepared by RF magnetron sputtering. XRD patterns indicate that polycrystalline films consisting mainly of a-Fe and TbFe2 Laves phase could be obtained through rapid cycle annealing process (RCAP) at higher annealing temperature. Grain sizes could be controlled through varying annealing temperature. From film hysteresis loops measured by VSM, it has been found that the annealing treatment can improve TbFe film in-plane magnetization at 1600 kA.m-1 external field, and decrease in-plane coercivity. Magnetostriction of annealed TbFe films measured by optical cantilever deflectometer is better than as-deposited films at 40 kA.m-1 external magnetic field.

In this paper, magnetostrictive film of TbFe x is fabricated by DC magnetron sputtering. Influence of the argon pressure to the film composition is studied both experimentally and theoretically. The results show that the argon pressure can change the composition of the film in relatively large range: When the gas pressure is increased from 0.2 to 0.6 Pa , the atomic contents of iron decrease from 69% to 55%. The as-deposited film spontaneous magnetization changes from perpendicular to parallel to the film plane when the iron contents decrease which is indicated by magnetic force microscopy. The studies also suggest that decrease of the plasma temperature and increase of the substrate and target distance can enhance the composition control capability of gas pressure variation.

In this paper, micromagnetic simulation is used to study the magnetostrictive and magnetic character of a TbFe 2 /Fe multilayer. The influence of magnetic easy-axis orientation, thickness of the TbFe 2 layer and number of layers of the multilayer are examined in detail. According to our numerical results, some general rules to improve the performances of magnetostrictive multilayers are determined which can be stated as: perpendicular easy-axis orientation of two kinds of sub-layer, proper magnetostrictive layer thickness, and more film layers.

FeCoSiB/Cu/FeCoSiB sandwich layers were deposited on flexible substrate to develop flexible stress/strain sensors. The influence of stress on the impedance of the multilayers is reported. The results show that the variation of the impedance increases with the increase in deflection of the free end of the cantilever. A relative change in impedance of 6.4% is obtained in the FeCoSiB(1.5 μm)/Cu(0.25 μm)/FeCoSiB(1.5 μm) sandwich layers at 1 MHz with deflection of 2 mm. The stress impedance effects are sensitive to the frequency of the current and the thickness of both FeCoSiB and Cu layers. The stress impedance effect increases with the increase in the thickness of FeCoSiB or Cu layers. The stress impedance effect increases slightly with the increase in frequency and decreases with the further increase in frequency, which can be understood by the stress and frequency-dependent permeability of magnetic films.

The effect of stress on the magnetic properties of FeCoSiB amorphous films is investigated. It has been observed that the unstressed sample is isotropic in the film plane. The samples under tensile stress show clear easy axis along the stress while the samples under compressive stress show easy axis perpendicular to the stress axis. With increasing of the tensile stress, the coercivity of the films decreases monotonically. The coercivity increases with increase of the compressive stress when the stress is not large and then decreases with further increase of the compressive stress. The variation of the coercivity with stress is understood by taking into account the influences of stress on the rotational and wall displacement magnetization reversal processes.