Piezoelectric film, piezoelectric stack, piezoelectric element, and method for producing piezoelectric stack
There is provided a piezoelectric film, being a polycrystalline film comprised of potassium sodium niobate; containing at least one metal element selected from a group consisting of Cu and Mn; and having 1.0 or less ratio of a concentration B of the metal element at grain boundaries of crystals, with respect to a concentration A of the metal element in a matrix phase of the crystals.
1 . A piezoelectric film, wherein the piezoelectric film is sputtered film comprising potassium sodium niobate and Mn;
the piezoelectric film is a polycrystalline film comprising a matrix phase and crystalline grains; and
a ratio of a concentration B of Mn at grain boundaries of the crystalline grains of the polycrystalline film, with respect to a concentration A of Mn in the matrix phase of the polycrystalline film is more than 0 and 1.0 or less.
2 . The piezoelectric film according to claim 1 , wherein the ratio of the concentration B, with respect to the concentration A, is more than 0 and 0.8 or less.
3 . The piezoelectric film according to claim 1 , wherein a total concentration of Mn in the matrix phase at the grain boundaries of the crystalline grains is 0.2 at % or more and 2.0 at % or less relative to an amount of niobium in the polycrystalline film.
4 . The piezoelectric film according to claim 1 , wherein the crystal grains have an average grain size of 100 nm or more.
5 . A piezoelectric stack, comprising:
a substrate;
an electrode film on the substrate; and
a piezoelectric film on the electrode film, the piezoelectric film being a sputtered film comprising of potassium sodium niobate and Mn,
wherein the piezoelectric film is a polycrystalline film comprising a matrix phase and crystalline grains;
80% or more of the crystalline grains of the piezoelectric film are oriented in (001) direction with respect to a surface of the substrate; and
a ratio of a concentration B of Mn at grain boundaries of the crystalline grains of the piezoelectric film, with respect to a concentration A of Mn in the matrix phase of the crystals, is more than 0 and 1.0 or less.
6 . A piezoelectric element, comprising:
a substrate;
a bottom electrode film provided on the substrate;
a piezoelectric film at the bottom electrode film, the piezoelectric film being a sputtered film comprising potassium sodium niobate and Mn; and
a top electrode film on the piezoelectric film,
wherein
the piezoelectric film is a polycrystalline film comprising a matrix phase and crystalline grains;
80% or more of the crystalline grains of the piezoelectric film are oriented in (001) direction with respect to a surface of the substrate; and
a ratio of a concentration B of Mn at grain boundaries of the crystalline grains of the piezoelectric film, with respect to a concentration A of Mn in the matrix phase of the crystals, is more than 0 and 1.0 or less.
7 . A method for producing a piezoelectric stack, comprising:
depositing an electrode film on a substrate; and
depositing by sputtering a piezoelectric film on the electrode film, wherein the piezoelectric film comprises potassium sodium niobate and Mn,
the piezoelectric film is a polycrystalline film comprising a matrix phase and crystalline grains;
80% or more of the crystalline grains of the piezoelectric film are oriented in (001) direction with respect to a surface of the substrate; and
the piezoelectric film has a concentration B of Mn at grain boundaries of the crystalline grains of the piezoelectric film, with respect to a concentration A of Mn in the matrix phase of the piezoelectric film.
8 . The piezoelectric stack according to claim 5 , wherein the ratio of the concentration B, with respect to the concentration A, is more than 0 and 0.8 or less.
9 . The piezoelectric stack according to claim 5 , wherein a total concentration of Mn in the matrix phase and at the grain boundaries of the crystalline grains is 0.2 at % or more and 2.0 at % or less relative to an amount of niobium in the polycrystalline film.
10 . The piezoelectric stack according to claim 5 , wherein the crystal grains have an average grain size of 100 nm or more.
11 . The piezoelectric element according to claim 6 , wherein the ratio of the concentration B, with respect to the concentration A, is more than 0 and 0.8 or less.
12 . The piezoelectric element according to claim 6 , wherein a total concentration of Mn in the matrix phase and at the grain boundaries of the crystalline grains is 0.2 at % or more and 2.0 at % or less relative to an amount of niobium in the polycrystalline film.
13 . The piezoelectric element according to claim 6 , wherein the crystal grains have an average grain size of 100 nm or more.
14 . The method according to claim 7 , wherein the ratio of the concentration B, with respect to the concentration A, is more than 0 and 0.8 or less.
15 . The method according to claim 7 , wherein a total concentration of Mn in the matrix phase and at the grain boundaries of the crystalline grains is 0.2 at % or more and 2.0 at % or less relative to an amount of niobium in the polycrystalline film.
16 . The method according to claim 7 , wherein the crystal grains have an average grain size of 100 nm or more.