Surface-treated infrared-absorbing fine particles, surface-treated infrared-absorbing fine particle powder, infrared-absorbing fine particle dispersion liquid in which the surface-treated infrared-absorbing fine particles are used, infrared-absorbing fine particle dispersion, and infrared-absorbing substrate

Surface-treated infrared-absorbing fine particles each comprising:

• an infrared-absorbing fine particle having a crystallite size of 42 nm or more and 60 nm or less;
• and
• a coating layer coated on a surface of the infrared-absorbing fine particle, the coating layer containing:
• a hydrolysis product of a metal chelate compound, or
• a hydrolysis product of a metal cyclic oligomer compound, wherein
• the metal chelate compound or the metal cyclic oligomer compound contains Al,
• the metal chelate compound or the metal cyclic oligomer compound has at least one selected from the group consisting of an ether bond, an ester bond, and an acetyl group, and
• the infrared-absorbing fine particles are represented by a formula MxWyOz, where M is at least one element selected from the group consisting of Cs, K, Rb, Tl, In, Ba, Li, Ca, Sr, Fe, and Sn, W is tungsten, O is oxygen, satisfying 0.2≤x/y≤0.5 and 2.0≤z/y≤3.0.