Deformation during Vickers nanoindentation in highly oriented nonlinear optical Ba2TiGe2O8 crystalline layers at glass surface

Abstract

Transparent surface crystallized glasses consisting of c-axis oriented nonlinear optical Ba2TiGe2O8 crystalline layers (~10 μm)at the surface of 40BaO·20TiO2·40GeO2 glass are prepared, and their deformation behaviors are examined from the load/ unload displacement curves obtained with the Vickers nanoindentation technique. It is found that the surface crystalline layers deform easily in small loadings during Vickers nanoindentations in comparison with the precursor glass with a homogeneous random glass structure. The surface crystalline layers subjected to the penetration depth of h = 0.5 μm show a large elastic recovery of ~70% compared with that (49%) in the precursor glass. The sliding (displacement) of about 0.02 μm is observed immediately after the stop of the loading with a loading speed of 5 μm/s in the surface crystallized samples. The present study suggests that the deformation behaviors of the surface Ba2TiGe2O8 crystalline layers in the crystallized glass might be closely related to the assemblage state of highly oriented crystals, in particular, the bonding (i.e., the degree of the adhesion ) among c-axis oriented crystals might be weak.

Morphology and dispersion state of Ba2TiSi2O8 nanocrystals in transparent glass-ceramics and their nanoindentation behavior

“…Because the product of load P (N) and displacement h (m) has a dimension of energy (J), it is possible to estimate consumed energies for elastic deformation and plastic deformation from the area of load/ unload displacement curve [27][28][29][30][31]. The total consumed deformation energy (U t ) is the summation of elastic deformation energy (U e ) and plastic deformation energy (U p ), and the elastic recovery (ER) during unload displacement is calculated as a ratio of U e /U t .…”

Electric field induced structural modification and second order optical nonlinearity in potassium niobium silicate glass

“…Structural modifications may involve either the glass surface or the whole glass matrix, depending on the kind of external anisotropic field. The glass surface can be easily modified by several different methods such as surface crystallization [1,2], ionic exchange [3], ionic implantation [4,5] and poling techniques [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Poling of glasses is performed by applying an intense electric field under particular conditions of irradiation (by UV-laser [17,18] or e-beam [19]) or elevated temperature [20], or by thermal quenching from very high temperatures without applied electric field [21].…”