= Solution
For a conventional initially random, untextured piezoceramic, orientational averaging suppresses the macroscopic linear response. Electrical poling of <ferroelectric domains> is the usual way to generate a lasting net response. \b[Under that conventional preparation assumption, a ferroelectric constituent is the expected route.]
However, the word polycrystalline alone does not logically require <ferroelectricity>. A deliberately textured aggregate of nonswitchable piezoelectric grains can have a nonzero effective tensor if their orientations and polar directions do not cancel. <Ferroelectricity> means electrically switchable spontaneous polarization, whereas <piezoelectricity> means linear <stress>–charge coupling. Thus the unconditional statement that every polycrystalline piezoelectric must be ferroelectric is too strong.
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