Alumina powder and method of producing the same, and stack and method of producing the same

A stack comprising:

• a substrate;
• and
• an alumina layer containing an alumina powder satisfying the following expressions:
• 0.7TX≤TA≤1.3TX;
• (Expression 1)
• 0.7TX≤TB≤1.3TX;
• (Expression 2)
• and
• 0.7TX≤TC≤1.3TX, (Expression 3)
• where TX represents a mean value of a peak height TA of a peak A in a particle size distribution of 0.3 μm or more to less than 1.2 μm, a peak height TB of a peak B in a particle size distribution of 0.7 μm or more to less than 3 μm, and a peak height TC of a peak C in a particle size distribution of 3 μm or more to less than 20 μm,
• wherein the alumina powder comprises α-alumina having a crystal structure represented by a hexagonal closest packing structure, and a content of the α-alumina is 34% by mass or more, and
• wherein peak height TA or peak height TC is the largest among the peak heights TA, TB, and TC
• wherein, in a cross-sectional view perpendicular to a planar view of the substrate, a surface of the alumina layer which faces the substrate has an arithmetic mean roughness Ra of 0.08 μm or more to 0.20 μm or less, where the arithmetic mean roughness Ra is represented by the following Formula 1:
• Ra
• =
• 1
• L
• ⁢
• ∫
• 0
• L
• ❘
• "\[LeftBracketingBar]"
• f
• ⁡
• (
• x
• )
• ❘
• "\[RightBracketingBar]"
• ⁢
• dx
• Formula
• ⁢
• 1
• where in Formula 1, L represents a whole measurement length and is 8 μm or more to 16 μm or less, x represents a measurement position, and f (x) represents a function of a measurement waveform,
• wherein the alumina powder comprises α-alumina having a crystal structure represented by a hexagonal closest packing structure, and a content of the α-alumina is 34% by mass or more, and
• wherein the substrate is a plastic film.