E. Kester et al., Measurement of Young's modulus of nanocrystalline ferrites with spinel structures by atomic force acoustic microscopy, J PHYS CH S, 61(8), 2000, pp. 1275-1284
Using Atomic Force Acoustic Microscopy, the Young's moduli of two thin film
s of nanocrystalline ferrites with spinel structures have been measured as
a function of the oxidation temperature on a nanoscale. There is an overall
decrease of the Young's moduli as a Function of the oxidation temperature
with an intermediate minimum and maximum. These measurements corroborate th
e existence of chemical gradients From the surface layer to the interior of
the films occurring during the oxidation process in the gamma-phase. They
lead to stress gradients which influence the Young's modulus and the coerci
vity H-c. In our measurement technique, we measure the flexural resonance f
requencies of an atomic force microscope cantilever and exploit their depen
dence on the rip-sample contact forces, here an elastic contact described b
y Hertzian contact theory. The technique has been extended allowing quantit
ative measurements using a self-consistent calibration. Comparison to nanoi
ndentation measurements have been made. We discuss possible nonlinear effec
ts occurring in the contact which may lend AFAM itself to measure nonlinear
parameters on a nanoscale. (C) 2000 Elsevier Science Ltd. All rights reser
ved.