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Load<br />

(N)<br />

Chapter VIII Micro-hardness studies…<br />

Table (8.1): Values of Vickers micro-indentation hardness in (MPa) at different loads<br />

Pure<br />

KDP<br />

for pure and amino acid doped KDP crystals<br />

KDP + L-histidine KDP + L-threonine KDP + DL-methionine<br />

0.3 % 0.4 % 0.5 % 0.3 % 0.4 % 0.5 % 0.3 % 0.4 % 0.5 %<br />

0.294 1884.5 1854.23 1838.34 1831.34 1864.93 1862.32 1852.32 1861.87 1859.87 1849.17<br />

0.491 1652.9 1632.46 1624.47 1622.81 1643.86 1640.86 1639.12 1647.27 1638.17 1630.19<br />

0.588 1515.2 1395.59 1392.82 1385.12 1404.22 1394.22 1381.51 1400.54 1391.54 1389.04<br />

0.686 1416.6 1349.12 1348.5 1333.71 1352.44 1342.44 1335.21 1352.96 1349.26 1339.11<br />

0.784 1358.4 1320.58 1320.11 1315.05 1324.58 1320.12 1319.11 1323.21 1318.03 1315.93<br />

0.981 1296.3 1294.56 1292.19 1288.93 1294.56 1289.51 1288.09 1292.41 1288.01 1284.25<br />

One can notice that, for particular applied load, the Vickers micro-<br />

hardness decreases as the amount of doping of particular amino acid<br />

increases. This indicates that the doping of amino acids reduces the Vickers<br />

micro-hardness for a particular load.<br />

Suthar [62] has observed that as the amount of doping of Mn +2 and<br />

Cu +2 increases, the Vickers micro-hardness value decreases for Calcium levo-<br />

tartrate tetrahydrate crystals at high load region. The doping of metallic<br />

impurity facilitated the slip mechanism and made the samples softer.<br />

Hv (In MPa)<br />

1900<br />

1800<br />

1700<br />

1600<br />

1500<br />

1400<br />

1300<br />

1200<br />

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0<br />

Load P (in N )<br />

Figure: 8.5a Plot of H v Vs load for pure and L-histidine doped KDP crystals.<br />

299<br />

Pure KDP<br />

KDP + 0.3 wt. % L-histidine<br />

KDP + 0.4 wt. % L-histidine<br />

KDP + 0.5 wt. % L-histidine

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