Piezoelectric material filler, composite piezoelectric material, composite piezoelectric device, composite piezoelectric material filler, and method for producing alkali niobate compound

A method for producing an alkali niobate compound represented by ANbO3 having a ratio ((Li+Na+K)/Nb) of the total number of moles of alkali metal elements to the number of moles of Nb of 0.995 to 1.005 in terms of atoms, wherein A is an alkali metal element containing Na and K and optionally Li, the method comprising:

• a first step of dry-mixing alkali compounds and a niobium compound in an amount giving a ratio ((Li+Na+K)/Nb) of the total number of moles of alkali metal elements to the number of moles of Nb of 0.900 to 1.000 hi terms of atoms and a difference of a ratio (K/(Na+K)) of the number of moles of K to the total number of moles of Na and K from a ratio (K/(Na+K)) of the number of moles of K to the total number of moles of Na and K in the alkali niobate compound as a production object falling within ±0.015, to prepare a first firing raw material;
• a second step of firing the first firing raw material at 500 to 750° C., to obtain a first fired product;
• a third step of dry-mixing alkali compounds with the first fired product in an amount giving a ratio ((Li+Na+K)/Nb) of the total number of moles of alkali metal elements to the number of moles of Nb of 0.995 to 1.005 in terms of atoms and a difference of a ratio (K/(Na+K)) of the number of moles of K to the total number of moles of Na and K from a ratio (K/(Na+K)) of the number of moles of K to the total number of moles of Na and K in the alkali niobate compound as a production object falling within ±0.010, to prepare a second firing raw material;
• and
• a fourth step of firing the second firing raw material at 500 to 1000° C., to obtain the alkali niobate compound.