Using a highly-spatially-resolved mechanical properties microprobe, the Young’s modulus and hardness of bulk YBa2Cu3O7−x (1:2:3) and YBa2Cu4O8 (1:2:4) have been determined. The Young’s modulus of a superconductor is an important parameter in determining critical grain sizes above which microcracking will occur due to anisotropic thermal stresses that arise during processing. This phenomenon of microcracking has been determined to cause a decrease in the attainable critical current densities in bulk superconductors. The mechanical properties data for these two materials show that the Young’s modulus of 1:2:3 is approximately 35% greater than the modulus of 1:2:4. This along with available anisotropic thermal expansion data for 1:2:3 and 1:2:4 suggests that the critical grain size for 1:2:4 is about 7 times greater than the critical grain size for microcracking in 1:2:3.

In this work, we report on both the microstructural (sp3 carbon atoms content) and the mechanical properties (hardness and elastic modulus) of pulsed laser deposited diamond-like-carbon (DLC) thin films. The sp3 content of the films was determined by analysis of the XPS C 1s core-level signal, and the hardness and elastic modulus were measured by nanoindentation using the continuous stiffness measurement (CSM) technique. By investigating the effect of process parameters, such as deposition temperature and KrF excimer laser intensity on the diamond-like characteristics of the films, we were able to point out that: (1) deposition at 25°C, as opposed to deposition at 300°C, enhances the diamond-like properties of the coatings, (2) the sp3 content increases with laser intensity up to a maximum value of about 60% obtained at 7.0×108 W/cm2 and (3) the hardness and elastic modulus of the coatings both increase with laser intensity as they respectively reach 44 and 375 GPa at 7.0×108 W/cm2. It is finally shown that the observed variations in the hardness value and elastic modulus correlate well with the variations of the sp3 content of the DLC coatings.

Diamond-like-carbon (DLC) thin films have been deposited at room temperature on Si substrates by ablation of a graphite target using a KrF excimer laser at intensities ranging from 0.9×108 W/cm2 to 6.0×109 W/cm2. The microstructure of the films was studied by x-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The macroscopic properties were evaluated by measurement of their optical constants using in-situ laser reflectometry and their hardness using the continuous stiffness measurement technique. Analysis of the XPS C 1s core level spectra of the DLC films shows that their sp3 hybridized carbon atom content increases with laser intensity up to a maximum value of about 60% obtained at 7.0×108 W/cm2. At higher laser intensities, the sp3 content appears to stabilize at about 53%. Such an evolution of the sp3 content can be understood in terms of the subsurface carbon ions implantation model which has been proposed for ion beam deposited films. On the other hand, Raman analysis indicates that an increase in laser intensity leads to the establishment of some long range order of the sp2 domains in the deposited layers. The extinction coefficient k of the deposited layers was found to be correlated to their sp3 content. Finally, it is shown that hardness values as high as 47 GPa can be obtained and that hardness is also correlated to the sp3 content of the films.

In indentation literature, there is support for the proposition that the extents of the elastic and plastic fields scale with the contact radius. For example, in Hertzian contact, the locations of constant-shear-stress lines scale with the contact radius. This idea has significant consequences with respect to measuring substrate-independent properties of thin films. If it is the contact radius that determines the extent of the elastic and plastic fields, then any general rule expressed in terms of the indentation depth is only appropriate for one indenter geometry - the one for which it was determined. In this work, three different indenter geometries were used to measure the hardness of one thin film. For all geometries, hardness results are expressed in terms of both depth and contact radius

Due to its interesting mechanical properties, silicon carbide is an excellent material for many applications. In this paper, we report on the mechanical properties of amorphous hydrogenated or hydrogen-free silicon carbide thin films deposited by using different deposition techniques, namely plasma enhanced chemical vapor deposition (PECVD), laser ablation deposition (LAD), and triode sputtering deposition (TSD). a-SixC1−x: H PECVD, a-SiC LAD, and a-SiC TSD thin films and corresponding free-standing membranes were mechanically investigated by using nanoindentation and bulge techniques, respectively. Hardness (H), Young’s modulus (E), and Poisson’s ratio (v) of the studied silicon carbide thin films were determined. It is shown that for hydrogenated a-SixC1−x: H PECVD films, both hardness and Young’s modulus are dependent on the film composition. The nearly stoichiometric a-SiC: H films present higher H and E values than the Si-rich a-SixC1−x: H films. For hydrogen-free a-SiC films, the hardness and Young’s modulus were as high as about 30 GPa and 240 GPa, respectively. Hydrogen-free a-SiC films present both hardness and Young’s modulus values higher by about 50% than those of hydrogenated a-SiC: H PECVD films. By using the FTIR absorption spectroscopy, we estimated the Si-C bond densities (NSiC) from the Si-C stretching absorption band (centered around 780 cm−1), and were thus able to correlate the observed mechanical behavior of a-SiC films to their microstructure. We indeed point out a constant-plus-linear variation of the hardness and Young’s modulus upon the Si-C bond density, over the NSiC investigated range [(4–18) × 1022 bond · cm−3], regardless of the film composition or the deposition technique.

Using a highly-spatially-resolved mechanical properties microprobe, the Young's modulus and hardness of bulk YBa2Cu3O7-x (1:2:3) and YBa2Cu4O8 (1:2:4) have been determined. The Young's modulus of a superconductor is an important parameter in determining critical grain sizes above which microcracking will occur due to anisotropic thermal stresses that arise during processing. This phenomenon of microcracking has been determined to cause a decrease in the attainable critical current densities in bulk superconductors. The mechanical properties data for these two materials show that the Young's modulus of 1:2:3 is approximately 35% greater than the modulus of 1:2:4. This along with available anisotropic thermal expansion data for 1:2:3 and 1:2:4 suggests that the critical grain size for 1:2:4 is about 7 times greater than the critical grain size for microcracking in 1:2:3.

Diamond and diamond-like films were characterized with a mechanical properties microprobe (MPM) and compared to a natural IIa diamond and single crystal sapphire characterized by the same method. The diamond films were 125 to 375 ..mu..m thick with a fine-grained microstructure (/approximately/20-..mu..m-diam grains). The natural diamond was a IIa quality diamond with the (100) axis normal to the surface. The sapphire used had low dislocation density with the c-axis normal to the surface. The diamond-like carbon film (DLC) was rf glow discharge deposited to a thickness of about 0.2 ..mu..m. Results of the present study are given and future work is discussed. 8 refs., 5 figs.

Amorphous carbon films variously designated as i-C, α-C:H diamond-like or hard carbon films, have interesting optical and mechanical properties and are candidates for wear and corrosion protection in a wide range of applications. Because the depth of penetration by the indenter in normal hardness tests often approaches or exceeds the thickness of the diamond-like coating film, hardness data may reflect large substrate effects. This paper gives the results of ultra-low load microindentation hardness measurements which allow data to be obtained for indentation depths as small as 20 nm. The data also yield information on the elastic modulus of the coatings. Films were obtained from a number of sources and had been prepared by several techniques. The hardness values are in the range of 7 to 15 GPa and depend on the exact preparation parameters. The hardness data will be compared to those obtained by the Knoop technique.