Results are presented for lattice-parameter and magnetic-susceptibility measurements on a series of solid solutions SmSb"S~". Low-temperature magnetic-susceptibility measurements indicate an inhomogeneous mixed valence for alloys containing low antimony concentrations and a homogeneous intermediate valence at larger concentrations. The susceptibilities of antimony-rich samples illustrate the disappearance of the antiferromagnetic ordering observed in pure SmSb. The alloys of intermediate composition display a nonmagnetic ground state associated with intermediate valence of the samarium cations. The effect of slight sulfur substitution in SmSb on crystalline electric fields is also discussed.
The acoustical behavior of a harpsichord modeled after 17th-century Flemish prototypes was studied using both experimental and analytical techniques. The vibrational modes of its enclosed air volume were measured and found to correspond closely to those predicted by the Jo and J9 solutions to the Bessel equation for a wedge shaped space. A modal analysis of the complete harpsichord revealed that the soundboard has 36 vibrational modes over a frequency range of 0 to 600 Hz, and that there are numerous modes where the instrument's case has a significant amplitude of motion. Additional information is reported showing that the acoustic output of the harpsichord is reasonably flat over a frequency range of 50-2000 Hz. It is concluded that the resonance behavior of both the soundboard and the enclosed air are important to the tone quality of the harpsichord, and that its generally uniform acoustic output results from the excitation of a large number of wood and air modes by the string partials. PACS numbers: 43.75.Mn, 43.75.Gh LIST OF SYMBOLS co circular frequency, radians • viscous damping factor c velocity of sound, m/s A wavelength, m •p, eigenfunction (mode shape coefficient), air •w eigenfunction (mode shape coefficient), soundboard
Results are presented for the lattice parameter and magnetic susceptibility as a function of temperature for a series of solid solutions of SmS with SmP. At room temperature the SmS~"P"alloys with x «0.06 exhibit a metallic appearance and a much smaller lattice constant and magnetic susceptibility as compared with SmS. For x «0.15 the susceptibilities do not show a Curie-law divergence or magnetic ordering. These properties are consistent with the Sm ions being in a homogeneous intermediate-valence state similar to that of SmS under pressure. The intermediate valence estimated from the lattice parameter is 2.8 at x =0.06 and increases toward the pure trivalent value with increasing phosphorous concentration. Also, the color of the alloys changes from gold to red to silver grey. The alloys with 0.03 & x (0.06 exhibit a varying mixture of two distinct phases, the gold intermediate-valence phase and the black phase characteristic of the x (0.03 alloys. The properties of the black phase are consistent with a mixture of Sm + and Sm + ions where Sm ions with one or more P ions as nearest neighbors are trivalent. The 0.04~x «0.08 alloys exhibit a transition from the gold phase to the black phase with decreasing temperature. This transition which is continuous at higher concentrations changes to a discontinuous one near x =0.06 as seen in the temperature variation of the lattice parameter.
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