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The discovery of the quantum Hall effect (QHE).sup.1,2 in two-dimensional electronic systems has given topology a central role in condensed matter physics. Although the possibility of generalizing the QHE to three-dimensional (3D) electronic systems.sup.3,4 was proposed decades ago, it has not been demonstrated experimentally. Here we report the experimental realization of the 3D QHE in bulk zirconium pentatelluride (ZrTe.sub.5) crystals. We perform low-temperature electric-transport measurements on bulk ZrTe.sub.5 crystals under a magnetic field and achieve the extreme quantum limit, where only the lowest Landau level is occupied, at relatively low magnetic fields. In this regime, we observe a dissipationless longitudinal resistivity close to zero, accompanied by a well-developed Hall resistivity plateau proportional to half of the Fermi wavelength along the field direction. This response is the signature of the 3D QHE and strongly suggests a Fermi surface instability driven by enhanced interaction effects in the extreme quantum limit. By further increasing the magnetic field, both the longitudinal and Hall resistivity increase considerably and display a metal-insulator transition, which represents another magnetic-field-driven quantum phase transition. Our findings provide experimental evidence of the 3D QHE and a promising platform for further exploration of exotic quantum phases and transitions in 3D systems. Evidence of the three-dimensional quantum Hall effect and a magnetic-field-driven quantum phase transition are observed in zirconium pentatelluride crystals., Author(s): Fangdong Tang [sup.1] , Yafei Ren [sup.2] , Peipei Wang [sup.1] , Ruidan Zhong [sup.3] , John Schneeloch [sup.3] , Shengyuan A. Yang [sup.4] , Kun Yang [sup.5] [sup.6] [...]

The anode materials that have been developed for solid oxide fuel ceils (SOFCs) are vulnerable to deactivation by carbon buildup (coking) from hydrocarbon fuels or by sulfur contamination (poisoning). We report on a mixed ion conductor, Ba[Zr.sub.0.1][Ce.sub.0.7][Y.sub.0.2-x][Yb.sub.x][O.sub.3-[delta]] , that allows rapid transport of both protons and oxide ion vacancies. It exhibits high ionic conductivity at relatively Low temperatures (500[degrees] to 700[degrees]C). Its ability to resist deactivation by sulfur and coking appears linked to the mixed conductor's enhanced catalytic activity for sulfur oxidation and hydrocarbon cracking and reforming, as well as enhanced water adsorption capability.

A new structure is proposed that is composed of reflector plated mounted in front and in back of the transducer at an angle of 45[degree], so that acoustic waves from front and back of the transducer are combined to form a single main beam. The analysis has shown that far field directivity has become sharper and acoustic pressure output is doubled.

The design, fabrication and measurements of very high frequency kerfless linear arrays prepared from PZT film and PZT bulk material are described. The analysis has shown that the PZT ceramic sheet has a center frequency of 128 MHz with a poorer bandwidth but a better sensitivity.

A study was conducted to examine the [Si.sub.3][N.sub.4]/Zr[O.sub.2] split charge trapping layer (SCTL) by multibit-cell Flash memory using Fowler-Nordheim (F-N) method. Findings reveal that the 2-bit (2-b) charge storage is accomplished by physical data node separation for the SCTL rather than charge injection control.

The power generation characteristics of stiff lead zirconate titanate (PZT) ceramics and the equivalent circuit through extensive experiments are analyzed. The application of PZT elements in a total knee replacement (TKR) implant is outlined.

The effect of partial substitutions of Zr by Hf in the perovskite-type crystalline structure of PbZr[O.sub.3] is determined. The crystalline structure of pure PbZr[O.sub.3] and PbHf[O.sub.3] perovskites, the phase diagram of the Pb[Zr.sub.1-x][Hf.sub.x][O.sub.3] family is described.

The sol-gel process is used for producing Nd-Mn-doped lead zirconate titanate (PZT) fibers. The measurements of the piezoelectric coefficient at superimposed electric field have proved the blocking of strain switching and the cyclation experiments with sesquipolar load has shown a pronounced linearity of the strain loops.

A 2-step approach is described for preparing tetragonal perovskite Pb[Zr.sub.0.1][Ti.sub.0.9][O.sub.3] submicro/nano wires in gram scale and with over 95% wire content. Enhanced piezoelectric response relative to sputtered epitaxial Pb[Zr.sub.0.2][Ti.sub.0.8][O.sub.3] film has shown pronounced electro-mechanical and ferroelectric behavior and the domain structure of the as-prepared perovskite PZT wires is confirmed by both piezoresponse force microscopy (PFM) and transmission electron microscopy examinations.

The electric field-induced phase transformation behavior in lanthanum-doped lead zirconate titanate ceramics is examined by polarization versus electrical field (P-E) measurements carried out from room temperature to 130 [degree]C and under hydrostatic pressures. The ([Pb.sub.1-z][La.sub.x])[([Zr.sub.0.90][Ti.sub.0.10]).sub.1-x/4)[O.sub.3] (PLZT) compositions have displayed ferroelectric and antiferroelectric behavior over the ranges of temperature and hydrostatic pressure.

A piezoelectric micromotor is developed for producing a triple-axis or multi-degree-of-freedom (DOF) micromotor. The results have shown that the micromotor is capable of generating rotation about an arbitrary axis.

A laboratory X-ray diffractometer (XRD) is used for measuring the structural changes in tetragonal La-doped PZT ceramics under the application of static and dynamic electric fields in situ. The field dependence of the lattice strains is described in terms of misfit strains between the differently oriented grains under the application of cyclic electric fields.

Ferroelectric thin-film devices based on lead titanate zirconate are examined for integrated capacitors. Piezoelectric thin films with piezoelectric coupling coefficients and high breakdown voltages as well as excellent lifetimes are examined for galvanic switches and thin-film switches with first-contact resistance measurements and high switching speeds are shown.

The strain coupling, microstructural evolution, and functional properties of a series of BaTi[O.sub.3] (BTO) films with different second-phase oxide additions, Ti[O.sub.2], MgO, Zr[O.sub.2], [Sm.sub.2][O.sub.3] and [Y.sub.2][O.sub.3] (YO), is studied. The studies have shown that the strain state in BTO is tuned by different additions and compared with BFO, which is switched from tensile for a pure film on STO to compressive by the presence of the second phase (SmO).