Effect of Na ions on the thermal expansion coefficient and hardness of KDP crystals

Na ion is a kind of common impurity in the growth progress of KDP crystal.Effect of Na ions on the properties of crystals were investigated.KDP crystals were grown from a solution by the point seed technique.The results show that thermal expansion coefficient of KDP crystals in the z direction is increased with the creasing Na+ contentration in the solution.The hardness of(001) face is greater than the(100) face.When the Na+ doped contentration is low,the hardness of all directions are increased significantly.With the Na+ contentration increasing,the hardness of KDP crystal all directions are reduced.