摘要:

A type of electrorheological (ER) system, denoted the magnetic materials-based electrorheological fluids, is introduced. The solid particles of this system are 40–50 &mgr;-microspheres obtained by the sol–gel processing of a ferroelectric material containing a ferromagnetic component. Since the solid material is magnetic, the presence of a small magnetic field, such as that from a small permanent magnet, can suspend the microspheres in liquid. The incorporation of a small amount of magnetic materials thereby solves the long standing problem of particle sedimentation in ER fluids. It is found that this type of ER fluid is very stable and exhibits a strong ER effect at low electric field. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120108

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We report the formation of nanosize ferromagnetic MnAs crystallites imbedded in low-temperature grown GaAs usingMn+ion implantation and subsequent annealing. The structural and magnetic properties of the crystallites have been characterized by transmission electron microscopy, electron beam induced x-ray fluorescence, and superconducting quantum interference device magnetometry. After an optimized thermal annealing at 750 °C, MnAs crystallites of 50 nm in size are formed. These nanomagnets show room temperature ferromagnetism. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120109

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We are optimizing thin films of perovskite manganese oxides for bolometric applications. We have studied the relevant material characteristics of several members of this family namely,La0.7Ba0.3MnO3,La0.7Sr0.3MnO3,La0.7Ca0.3MnO3,andNd0.7Sr0.3MnO3.Here, we discuss issues related to the choice of material, the influence of deposition parameters, and postdeposition heat treatments on the relevant characteristics such as the resistivity-peak temperature(Tp)and the temperature coefficient of resistance (TCR). For a given material, a higher peak temperature implies a larger temperature coefficient of resistance. In contrast, on comparing different material systems, the TCR tends to decrease asTpincreases. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120427

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Temperature effects on charge retention characteristics of integratedSrBi2(Ta,Nb)2O9thin film capacitors were examined in the temperature range of 27–150°C. The decay in remanent polarization at 27°C was linear in logarithmic time from10−3to105 swith a decay rate of0.24 &mgr;C/cm2per decade. The elevation of storage temperature resulted in an instantaneous decrease in remanent polarization, while the decay rate at elevated temperatures after the instantaneous decrease was as small as that at 27°C. The instantaneous decrease in remanent polarization caused by elevating the temperature was explained by the temperature dependence of spontaneous polarization in the vicinity of the second order transition temperature. The development of asymmetry in the hysteresis loop during high temperature storing indicates that the logarithmic time dependence of the decay in remanent polarization is due to redistribution of space charges rather than polarization reversal. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120110

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The bistability problem, common to scanning microscopes employing lateral dithering of the probe for image formation (i.e., shear force microscope) or probe-sample distance control (i.e., near-field optical microscope) is shown to stem from the two nearly degenerate vibration degrees of freedom possessed by a laterally dithered fiber. Controlling the fiber vibration direction by means of a four-sectioned piezo was found to be a simple and effective solution of the problem. An image of a microtubule is presented to demonstrate the improved imaging ability. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120111

出版商:AIP    

年代:1997

数据来源: AIP

ISSN:0003-6951    

DOI:10.1063/1.120565

出版商:AIP    

年代:1997

数据来源: AIP