Is it possible to dope Ca ions in an NaCl crystal to produce a vacancy defect? I was just reading about defects and doping in solids and read about the defect in  ionic crystal ($\ce{NaCl}$). There were examples of $\ce{SrCl2}$. Could this also occur with $\ce{CaCl2}$?
A peek at the NaCl - CaCl2 phase diagram (say at FactSage) will show you that NaCl can hold quite a reasonable fraction of CaCl2 in the NaCl crystal. In contrast, CaCl2 has very limited to no solubility of NaCl.