Developments in Ceramic Materials Research

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T. T. Basiev, V. A. Demidenko, K. V. Dykel’skii et al.
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2 θ
c
Figure 7. Characteristic microphotographs of the Ca 0,9Er 0,1F 2,1 particles prepared by sedimentation from
the water solution with reverse dropping into the hydrofluoric acid with further washing in the ethanol –
(a), after the drying at 150 °C – (b) and their XRD, CuK α radiation – (c).
Taking into account that the homogeneity of ceramic samples is sufficiently high, we put
50 impressions on them (as well as on the single crystals). In the single crystals, the
arrangement of diagonals in an impression corresponds to the {110} direction characterized
by the highest hardness. The microhardness H was calculated by the conventional formula H
= KP/d 2 , where P is the indentation load, d is the length of the diagonal for the indenter
impression, K is the factor depending on the shape of the indenter (for the Vickers pyramid, K
= 1.854). The fracture toughness K1C as a function of the indentation load is determined from
the measurements of the linear size of radial cracks (C) arising near the place where the
indentation load is applied.