Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optical properties and hardness of highly a-axis oriented AlN films   This paper reports optical and nanomechanical properties of seldom studied
highly a-axis oriented AlN thin films for the first time. These films were
deposited by reactive DC magnetron sputtering technique at an optimal target to
substrate distance of 180 mm. Bragg-Brentano geometry X-ray and rocking curve
(FWHM = 52 arcsec) studies confirmed the preferred orientation. Spectroscopic
ellipsometry revealed that these films exhibit a refractive index of 1.93 at a
wavelength of 546 nm. The hardness and elastic modulus of these films were 17
GPa and 190 GPa, respectively. The mechanical properties obtained here are much
higher than the earlier reported and therefore can be useful as protective
coating in thermo printing devices, piezoelectric films in bulk acoustic wave
resonators.

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The categories of this paper are: bayes-an
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The categories of this paper are: adap-org
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The categories of this paper are: chem-ph
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The categories of this paper are: econ
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The categories of this paper are: q-bio
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The categories of this paper are: nlin
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The categories of this paper are: nucl-th
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The categories of this paper are: math
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The categories of this paper are: supr-con
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The categories of this paper are: math-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-th
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The categories of this paper are: solv-int
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The categories of this paper are: nucl-ex
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The categories of this paper are: mtrl-th
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The categories of this paper are: hep-lat