Quantitative nanoscale modulus measurements and elastic imagingof Sn O 2 nanobelts

• Published in: Journal of applied physics 2006-12, Vol.100 (12), p.124308-124308-6
• Main Authors: Zheng, Yuegui, Geer, Robert E., Dovidenko, Katharine, Kopycinska-Müller, Malgorzata, Hurley, Donna C.
• Format: Article
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.2401027

A comparative study of the elastic modulus and uniformity of single-crystal Sn O 2 nanobelts is presented employing two nondestructive techniques based on atomic force microscopy: differential ultrasonic force microscopy (d-UFM) and atomic force acoustic microcopy (AFAM). In mapping mode both techniques revealed a uniform elastic response across the surface of the nanobelts as expected for single-crystal nanostructures. Comparative analyses of the local indentation modulus (probe area ≈ 100 - 400 nm 2 ) were undertaken using both techniques at multiple points on the same Sn O 2 nanobelt exhibiting a (102) surface crystalline orientation as determined by electron backscatter diffraction. Both d-UFM and AFAM exhibited excellent quantitative agreement yielding indentation moduli of 151 ± 14 and 154 ± 18 GPa , respectively. These values are significantly below the expected value of the (102) indentation modulus of 358 GPa for crystalline Sn O 2 determined from the Green's function model of Barnett and Lothe [ Phys. Nors. 8 , 13 ( 1975 )] adapted by Vlassak [ J. Mech. Phys. Solids 51 , 1701 ( 2003 )]. This observation is consistent with recent nanoindentation (destructive) measurements of ( 10 1 ¯ ) oriented Sn O 2 nanobelts that yielded an indentation modulus of 66 ± 10 GPa , well below the expected value of 308 GPa . In addition to confirming the quantitative consistency and overall accuracy of nanoscale modulus measurements using d-UFM and AFAM, the overall trend in these data contradicts recent molecular dynamics studies that call for increased elastic moduli in similar nanobelt structures.