Powder and solid composition

A titanium-containing metal oxide powder that satisfies the following requirements 1 and 2:

• requirement 1:
• |dA (T)/dT| satisfies 10 ppm/° C. or more at at least one temperature T1 in a range of −200° C. to 1200° C.
• where A is (a-axis (shorter axis) lattice constant of a crystal in the powder)/(c-axis (longer axis) lattice constant of the crystal in the powder), and each of the lattice constants is obtained by X-ray diffractometry of the powder;
• dA(T)/dT represents differentiation of A(T) by T (temperature), |dA(T)/dT| represents an absolute value of dA(T)/dT, and |dA(T)/dT|=|A(T+50)−A(T)|/50;
• requirement 2:
• a particle diameter D50 at a cumulative frequency of 50%, a particle diameter D10 at a cumulative frequency of 10%, and a particle diameter D90 at a cumulative frequency of 90% in a volume-based cumulative particle diameter distribution curve obtained by a laser diffraction scattering method satisfy the following conditions (I) and (II):
• (I) a ratio of D10 to D50 (D10/D50) is 0.05 or more and 0.45 or less, and
• (II) D90 is 0.5 μm or more and 70 μm or less.