Surface Structure of Niobium-Doped Potassium Tantalate KTa1-XNbXO3 by Helium Atom Scattering

Abstract

Helium atom scattering experiments have been carried out on the (001) surface of KTaO3 doped with 6, 10 and 15% Nb, produced by cleaving in situ single crystal samples. Several phenomena were observed through He atom diraction measurements, including metastable behavior immediately after cleaving, reconstruction of a fraction of the surface to (21) domains after thermally cycling the surface temperatures, and the distribution of step-heights of terraces at the surface as multiples of the unit cell dimension of 4 A. In addition, a large hysteresis eect was found in the in the azimuth in the variation of surface re ectivity with surface temperature; a much smaller hysteresis eect was found in the azimuth. The hysteresis eects appear for all Nb doping concentrations. Finally, small oscillations in the specular and Bragg diraction intensities near surface temperature 80K were also observed.