This 14th volume in the series covers the latest results in the field of Defects and Diffusion in Semiconductor. The issue also includes some original papers: An Experimental Study of the Thermal Properties of Modified 9Cr-1Mo Steel; Physico-Mechanical Properties of Sintered Iron-Silica Sand Nanoparticle Composites: A Preliminary Study; Defect and Dislocation Density Parameters of 5251 Al Alloy Using Positron Annihilation Lifetime Technique; A Novel Computational Strategy to Enhance the Ability of Elaborate Search by Entire Swarm to Find the Best Solution in Optimization of AMCs; Synthesis and Characterization of Novel Nanoceramic Magnesium Ferrite Material Doped with Samarium and Dysprosium for Designing – Microstrip Patch Antenna; ZnO Varistor Defective Gd and Pr Ions; Injecting CO2 and Pumping Out Saline Formation Water Simultaneously to Control Pressure Build-Up while Storing CO2 in Deep Saline Aquifers; Studying the Effect of Low α-Radiation Doses on CR-39 Polymers Using Positron Annihilation Lifetime and Mechanical Properties.