The number of rank holders can vary depending on different factors, such as the region, academic institutions, and the specific ranking criteria being considered.
Rankings in the field of Physical Chemistry and Materials can include academic rankings of universities or research institutions, rankings of individual researchers or scientists, or rankings based on scientific publications and citations. These rankings are typically conducted by independent organizations, research institutions, or academic bodies.
To obtain the most up-to-date and accurate information on the number of rank holders in the PCM field, I recommend referring to recent academic rankings, publications, or reports from reputable sources, such as scientific journals, university rankings, or research organizations specializing in the field of Physical Chemistry and Materials.