T is possible to produce a perfect crystalline solid that does not contain any vacancies?

All crystalline solids contain vacancies. In fact, vacancies is one of the properties of a crystalline solids, for their presences is what creates their random (entropic) design. Furthermore, it is near impossible to create any solid matter that does not contain vacancies/defects. Vacancies can be created by the absence of an atom during matter creation; thermal vibrations can create such a defect as well.