A theory as the basis for solving nonlinear boundary value problems is described. A new analysis is presented for nonlinear reflection, which reveals that there is a two-dimensional spatial increase of the second-harmonic wave. The accretion along the propagation direction is the result of the self-interaction of the primary wave; the one in the wave front is due to the boundary restriction.
In this article, we address the nonlinear properties of bulk acoustic waves in anisotropic solids. While ordinary driving waves are obtained by means of the quasiwave mode concept in the discussion on propagation problems, we focus our analysis on the driving wave satisfying the resonant condition which exhibits the characteristics of three-dimensional spatial accumulation. Then a theory as the basis for solving nonlinear boundary value problems is developed. The novel analysis is presented for nonlinear reflection of bulk acoustic waves at a free surface of a generally anisotropic solid, which reveals that the surface may generate freely propagating second-harmonic waves, and that the reflective second-harmonic waves increase two dimensionally in the bulk. This technique can also be applied to wave reflection problems at other kinds of planar boundaries. Some numerical calculation is carried out for the case in an isotropic solid. 0 1995 American Institute of Physics.
5 at.% Mn-doped and undoped, 200 nm thick BaTiO3 thin films have been grown under different oxygen partial pressures by pulsed laser deposition on Pt/sapphire substrates. X-ray diffraction (XRD) measurements reveal the same polycrystalline single-phase perovskite structure for all the thin films despite the different oxygen partial pressure, while their preferred orientation strongly depends on the oxygen partial pressure. The 5 at. % Mn-doping decreases the dielectric loss of the Mn-doped BaTiO3 thin films, however, their relative permittivity is also decreased. Ferroelectricity has been probed on the Mn-doped and undoped BaTiO3 thin films grown under relatively high oxygen partial pressure. A ferromagnetic coupling of the Mn dopant ions has been probed at room tempetature on the Mn-doped BaTiO3 thin films prepared under low oxygen partial pressure and is understood in terms of the bound magnetic polaron model.
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