Piezoelectric film and method for manufacturing the same, piezoelectric film element and method for manufacturing the same, and piezoelectric film device
There is provided a piezoelectric film having an alkali niobate-based perovskite structure expressed by a general formula (Na x K y Li z )NbO 3 (0≦x≦1, 0≦y≦1, 0≦z≦0.2, x+y+z=1), wherein the alkali niobate has a crystal structure of a pseudo-cubic crystal, a tetragonal crystal, an orthorhombic crystal, a monoclinic crystal, a rhombohedral crystal, or has a crystal structure of coexistence of them, and when total of K—O bonding and K-Metal bonding is set as 100% in a binding state around K-atom of the alkali niobate, a K—O bonding ratio is 46.5% or more and a K-Metal bonding ratio is 53.5% or less, wherein the Metal indicates a metal atom included in the piezoelectric film.
1. A piezoelectric film having an alkali niobate-based perovskite structure expressed by a general formula (Na x K y Li z )NbO 3 (0≦x≦1, 0≦y≦1, 0≦z≦0.2, x+y+z=1), wherein the alkali niobate has a crystal structure of a pseudo-cubic crystal, a tetragonal crystal, an orthorhombic crystal, a monoclinic crystal, a rhombohedral crystal, or has a crystal structure of coexistence of them, and when total of K—O bonding and K-Metal bonding is set as 100% in a binding state around K-atom of the alkali niobate, a K—O bonding ratio is 46.5% or more and a K-Metal bonding ratio is 53.5% or less, wherein the Metal indicates a metal atom included in the piezoelectric film.
2. The piezoelectric film according to claim 1 , wherein the alkali niobate is included so that the ratio of Nb 5+ is 98.2% or more and the ratio of Nb 2+ is 1.8% or less, when total of Nb 5+ for NbO 3 − bonding and Nb 2+ for NbO bonding resulting from reducting NbO 3 − , is set as 100%.
3. The piezoelectric film according to claim 1 , wherein the alkali niobate is included so that the ratio of Nb 5+ is 61.4% or more and total of the ratios of Nb 2+ , K + , Na + , and Li + is 38.6% or less, when total of Nb 5+ for NbO 3 − bonding, Nb 2+ for NbO bonding resulting from reducting NbO 3 − , K + for K 2 O bonding, Na + for Na 2 O bonding, and Li + for Li 2 O bonding, is set as 100%.
4. The piezoelectric film according to claim 1 , wherein the K—O bonding ratio is calculated as the ratio of intensity of the K—O bonding, with respect to total of intensity of the K—O bonding and intensity of the K-Metal bonding, measured by an X-ray photoelectron spectroscopic analysis.
5. The piezoelectric film according to claim 1 , wherein any one of a crystal layer, an amorphous layer, or a mixed layer mixing the crystal layer and the amorphous layer made of perovskite oxide expressed by a general formula ABO 3 , is included in a part of the alkali niobate,
wherein in the ABO 3 , the A—O bonding ratio is 46.5% or more and the A-Metal bonding ratio is 53.5% or less when total of the A—O bonding and the A-Metal bonding is set as 100% in a binding state around A-atom,
wherein A is one kind or more elements selected from Li, Na, K, Pb, La, Sr, Nd, Ba, and Bi, and B is one kind or more elements selected from Zr, Ti, Mn, Mg, Nb, Sn, Sb, Ta, and In, and O is oxygen.
6. The piezoelectric film according to claim 5 , wherein in the ABO 3 , the ratio of B 5+ is 98.2% or more and the ratio of B 2+ is 1.8% or less, when total of B 5+ for BO 3 − bonding and B 2+ for BO bonding resulting from reducting BO 3 − is set as 100% in a binding state around B-atom.
7. The piezoelectric film according to claim 5 , wherein in the ABO 3 , the ratio of B 5+ is 61.4% or more and total ratios of B 2+ and A + is 38.6% or less, when total of B 5+ for BO 3 − bonding and B 2+ for BO bonding resulting from reducting BO 3 − , and A + for A 2 O bonding is set as 100% in a binding state around B-atom.
8. A piezoelectric film, comprising at least a lower electrode layer, the piezoelectric film of claim 1 , and an upper electrode layer on a substrate.
9. The piezoelectric film according to claim 8 , wherein the upper electrode layer and/or the lower electrode layer is a single electrode layer made of Pt or an alloy mainly composed of Pt, or an electrode layer of a lamination structure including the electrode layer mainly composed of Pt.
10. The piezoelectric film according to claim 8 , wherein the upper electrode layer and/or the lower electrode layer is a single electrode layer made of Pd or an alloy mainly composed of Pd, or an electrode layer of a lamination structure including the electrode layer mainly composed of Pd.
11. The piezoelectric film according to claim 8 , comprising an oxide thin film for coating the piezoelectric film.
12. A piezoelectric film device, comprising a voltage application unit or a voltage detection unit between the lower electrode layer and the upper electrode layer of the piezoelectric film element of claim 8 .