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Mn- and Sb-doped PbZrTiO3 (PMSZT) thin-film pyroelectric infrared (IR) detectors have been fabricated on c-oriented YB2Cu3O7−x (YBCO) thin films. The thin-film heterostructure detectors were prepared by pulsed laser deposition on LaAlO3 (100) substrates. The YBCO layer in the PMSZT/YBO heterostructure was used as an atomic template for the epitaxial growth of the PMSZT thin films, as well as a nonsuperconducting electrode and IR reflector in the detector. Mn and Sb doping was used to tune the Pb(Zr,Ti)O3 transition temperature to a lower value (Curie temperature of ∼170 °C), and hence, to modify the pyroelectric and dielectric properties of the pyroelectric material. The PMSZT IR detectors were examined as to their photovoltage and photocurrent in response to IR source temperature, detector temperature, and chopper frequency. The experimental results show that the detector has relatively high IR sensitivity with a detectivity D* of ∼4×108 cm Hz1/2/W, and is capable of operating from room temperature to ∼1...

We present the experimental results of the Ar+ laser- and electric-field-induced diffraction effect in a planar-parallel-aligned nematic liquid crystal film. It is found that only one set of diffraction rings occurs in the second order Fredericksz transition; however, two sets of diffraction rings can occur in the first order Fredericksz transition. The appearance of two sets of rings distinguishes the first order Fredericksz transition from the second order. We propose a theoretical explanation for the phenomenon.

The structure, magnetic transitions, and magnetostriction of TbxDyyNdz(Fe0.9Co0.1)1.93 polycrystalline compounds have been investigated, with the ratio of x, y, and z spanning the line of minimum magnetic anisotropy. Anisotropy compensation with lower Tb content was realized in Tb0.253Dy0.657Nd0.09(Fe0.9Co0.1)1.93 compound. The spin configuration diagram accompanied with different crystal structures was constructed to illustrate the arrangement for the easy magnetization direction and crystal structure. An optimized effect on magnetostriction especially at the relatively low field of 1 kOe (197 ppm) was observed in Tb0.253Dy0.657Nd0.09(Fe0.9Co0.1)1.93 compound, which is about two times larger than that of the sample free of Nd (62 ppm). Meanwhile, the polycrystalline saturation magnetostriction (λs=945 ppm) of Tb0.253Dy0.657Nd0.09(Fe0.9Co0.1)1.93 is even much larger than that of the Ho-doped multicomponent single crystal compound Tb0.2Dy0.22Ho0.58Fe2 (λs=530 ppm). Low content of heavy rare earth Tb, high ...

Mn5Ge3−xAlx ribbons with x=0,0.5, and 1 were prepared by single roller melt-spinning method. Textured structures were observed in these ribbons as a result of fast cooling, with highly ordered columnar grains perpendicular to the surface. The magnetocaloric effect and critical behavior were investigated by dc magnetization measurement. Curie temperatures decrease from 297 K to 283 K as the Al content increases, and the peak entropy changes also decrease from 4.92 J/kg K to 3.0 J/kg K under an external magnetic field change of 3 T. Critical exponents were obtained by modified Arrott plots technique, Kouvel-Fisher method, and critical isothermal analysis. Similar values of exponents of β∼0.37, γ∼1, and δ∼3.8 were obtained for all of the compositions. Moreover, rescaled entropy data for all compositions collapse into a universal curve, revealing universal behavior for the magnetocaloric effect in this series of compounds.

The structure, magnetic properties, and magnetostriction of Pr(Fe1.95B0.05)1.93 alloys prepared by annealing its precursor amorphous ribbons under high pressure were investigated. It was found that Pr(Fe1.95B0.05)1.93 single cubic Laves phase could be obtained only when the pressure is up to 3 GPa. The average grain size about 20 nm is found in the sample synthesized under 6 GPa. A large linear magnetostriction of 541 ppm at 3 kOe is observed in the Pr(Fe1.95B0.05)1.93 compound synthesized under 6 GPa, which is 25% larger than that under 3 GPa. The present work offers an effective method to obtain bulk nanocrystalline magnetostrictive compounds.

The crystal structure, magnetic properties and magnetostriction of polycrystalline magnetostrictive alloys Nd(Fe1−xCox)1.9 were investigated. It was found that the single cubic Laves phase can only be obtained in the samples with x>0.4 by a traditional annealing method. In contrast, the cubic Laves phase exists over the entire composition range studied in the samples annealed under high pressure. Both the Curie temperature and saturation magnetization increase with increasing Co concentration to a maximum at x = 0.2 and then decrease with further increasing x, which could be understood in the frame of rigid band model. The spin phase diagram for Nd(Fe1−xCox)1.9 is constructed to illustrate the arrangement for the easy magnetization direction and crystal structure. The magnetostriction of Nd(Fe1−xCox)1.9 increases with increasing Co concentration and peaks at x = 0.1 and then presents an anomalous behavior when 0.2≤x≤0.6. It is suggested that the external-field-induced lattice strain should be responsible ...

This paper reports results of an experiment involving two‐laser resonance‐enhanced photoionization of benzene. The excitation sources were two frequency‐doubled dye lasers. The first laser pumped the molecule to a selected vibronic level of its first excited singlet state (1B2u), from where it was ionized by a time‐delayed pulse of the second laser. The ion yield depends on the intermediate vibronic state as well as on the wavelength of the ionizing laser. From the structures and intensities of the measured ion spectra we derived vibrational frequencies and molecular parameters of the ground electronic state of the ion to a remarkable accuracy. The contributions of autoionizing Rydberg levels to the ionization cross section can clearly be distinguished from direct ionization. Several resonance peaks were assigned to transitions to vibrational modes within these Rydberg states.

In this analysis we studied the potential field around a perpendicular recording head by a Fourier method. As this potential function obtained is easy to operate, the wavelength response of the head can be calculated and is shown to be similar to that of a ring head for a recorded sine wave. The first term of our expansion of the flux through the head turned out to be sinx/x. This term is nominally not affected by spacing; thus, the head has good reliability. We built some perpendicular recording heads and obtained a reasonably good response curve as illustrated. However, we find the main drawback of such a head, in a standard tape system, lies with the recording process, i.e., a wavelength loss on tape rather than a limitation of the playback head. Since there is no essential difference between sine-wave and digital recording, the analysis can easily be extended to a digital system.