Effect of magnetic field in the microhardness studies on calcium hydrogen phosphate crystals

Calcium hydrogen phosphate dihydrate (CaHPO₄·2H₂O, brushite) crystals are grown in gel medium at physiological pH by single diffusion method in the presence of different magnetic field strengths, namely 0, 0.1 and 0.2 Tesla. The results indicate that in the presence of magnetic field, the number of brushite crystals formed at the gel-solution interface reduces and the average size of the crystals increases. This shows that the growth of brushite crystal was favored by magnetism. Vickers and Knoop microhardness studies were carried out on the crystals grown at various magnetic fields. The Vickers (H_V) and Knoop (H_K) microhardness numbers were found to increase with increasing load. The values of Meyer’s index number (n) decrease while the magnetic field strength increases. Nevertheless the n values are greater than 1.6, which shows that the brushite crystals grown under magnetic fields still fall in the soft material category. The brittle index (Bi), yield strength (σ_y) and elastic stiffness constant (c₁₁) were calculated. The Young’s Modulus was calculated using the Knoop hardness value and found to decrease in higher magnetic field strengths.