# US 8,541,930 B2 · Piezoelectric component > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,541,930 B2 - Document ID: US8541930B2 - Status: Granted - Kind: B2 - Application number: 13/276,791 - Filed: 2011-10-19 - Published: 2012-03-15 - Granted: 2013-09-24 - Earliest claimed: 2009-05-29 - Assignees: Epcos AG - Applicants: Alexander Glazunov; Oliver Dernovsek - Inventors: Alexander Glazunov; Oliver Dernovsek - Web page: https://patentgrep.com/patent/US8541930B2 ## CPC - H10N 30/508: {adapted for alleviating internal stress, e.g. cracking control layers} - H10N 30/8554: {Lead-zirconium titanate [PZT] based} - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR ## Abstract A piezoelectric component includes a stack of piezoelectric layers arranged one on top of the other and first and second electrode layers arranged therebetween. The stack includes at least one first piezoelectric layer having a first electrical coercive force and directly adjacent thereto at least one second piezoelectric layer having a second electrical coercive force different from the first coercive force. ## Claims ### Claim 1 A piezoelectric component comprising: a stack of piezoelectric layers arranged one above another; and first and second electrode layers arranged between the piezoelectric layers; wherein the stack has a first piezoelectric layer having a first electric coercive field strength and, directly adjacent thereto, a second piezoelectric layer having a second electric coercive field strength different than the first electric coercive field strength; wherein the first piezoelectric layer and the second piezoelectric layer comprise different ceramic materials, different dopants, different dopant concentrations, different particle sizes of starting materials, different layer thicknesses or a combination thereof; wherein the first and second piezoelectric layers comprise a ceramic material formed from a plurality of constituents having respective concentrations and wherein the first and second piezoelectric layers differ in a concentration of at least one constituent; wherein the first and second piezoelectric layers comprise a ceramic material having the same constituents; wherein the ceramic material has, depending on a concentration of at least one first constituent, a morphotropic phase boundary lying between a first structure and a second structure of the ceramic material; and wherein the concentration of a first constituent of the ceramic material in the first and second piezoelectric layers is in each case chosen in such a way that the first piezoelectric layer comprises the ceramic material having the first structure and the second piezoelectric layer comprises the ceramic material having the second structure. ### Claim 2 (depends on 1) The piezoelectric component according to claim 1, wherein the first and second piezoelectric layers differ in exactly one property selected from different ceramic materials, different dopants, different dopant concentrations, different particle sizes of starting materials and different layer thicknesses. ### Claim 3 (depends on 1) The piezoelectric component according to claim 1, wherein the first and second piezoelectric layers comprise ceramic materials produced from starting powders having different particle sizes. ### Claim 4 (depends on 3) The piezoelectric component according to claim 3, wherein the particle size of the starting powders is greater than or equal to 0.3 μm and less than or equal to 2.0 μm, and wherein the difference in the particle sizes of the starting powders is greater than or equal to 0.1 μm and less than or equal to 1.5 μm. ### Claim 5 (depends on 1) The piezoelectric component according to claim 1, wherein the first piezoelectric layer has a first thickness and the second piezoelectric layer has a second thickness that is different from the first thickness. ### Claim 6 (depends on 5) The piezoelectric component according to claim 5, wherein the ratio of the first and second thicknesses is greater than or equal to 1.1 and less than or equal to 3.0. ### Claim 7 (depends on 1) The piezoelectric component according to claim 1, wherein the stack has a sequence of layers arranged directly one above another, and wherein the sequence of layers is formed from the first electrode layer, the first piezoelectric layer, the second electrode layer, the second piezoelectric layer and a further first electrode layer. ### Claim 8 (depends on 1) The piezoelectric component according to claim 1, wherein the stack has a sequence of layers arranged directly one above another, and wherein the sequence of layers is formed from the first electrode layer, the first piezoelectric layer, the second piezoelectric layer and the second electrode layer adjacent to the first electrode layer. ### Claim 9 (depends on 8) The piezoelectric component according to claim 8, wherein the stack has further first piezoelectric layers. ### Claim 10 (depends on 8) The piezoelectric component according to claim 8, wherein the stack has an identical number of first and second piezoelectric layers. ### Claim 11 (depends on 7) The piezoelectric component according to claim 7, wherein the stack has further first piezoelectric layers. ### Claim 12 (depends on 7) The piezoelectric component according to claim 7, wherein the stack has an identical number of first and second piezoelectric layers. ### Claim 13 A method of making a piezoelectric component, the method comprising: producing a plurality of green sheets, each green sheet comprising unsintered ceramic powder; joining the green sheets together with electrode layers; and sintering the green sheets and the electrode layers to form a stack of piezoelectric layers arranged one above another in a stack and first and second electrode layers arranged between the piezoelectric layers; wherein the stack has a first piezoelectric layer having a first electric coercive field strength and, directly adjacent thereto, a second piezoelectric layer having a second electric coercive field strength different than the first electric coercive field strength; wherein the first piezoelectric layer and the second piezoelectric layer comprise different ceramic materials, different dopants, different dopant concentrations, different particle sizes of starting materials, different layer thicknesses or a combination thereof; wherein the first and second piezoelectric layers comprise ceramic materials produced from starting powders having different particle sizes; wherein the particle size of the starting powders is greater than or equal to 0.3 μm and less than or equal to 2.0 μm; and wherein the difference in the particle sizes of the starting powders is greater than or equal to 0.1 μm and less than or equal to 1.5 μm. ### Claim 14 (depends on 13) The method according to claim 13, wherein the first and second piezoelectric layers comprise a ceramic material formed from a plurality of constituents having respective concentrations, and wherein the first and second piezoelectric layers differ in a concentration of at least one constituent. ### Claim 15 (depends on 14) The method according to claim 14, wherein the first and second piezoelectric layers comprise a ceramic material having the same constituents, wherein the ceramic material has, depending on a concentration of at least one first constituent, a morphotropic phase boundary lying between a first structure and a second structure of the ceramic material, and wherein the concentration of a first constituent of the ceramic material in the first and second piezoelectric layers is in each case chosen in such a way that the first piezoelectric layer comprises the ceramic material having the first structure and the second piezoelectric layer comprises the ceramic material having the second structure. ### Claim 16 (depends on 13) The method according to claim 13, wherein the first and second piezoelectric layers are each chosen in such a way that a contact boundary between the first and second piezoelectric layers forms a region for forming load-relieving and/or polarization cracks that runs substantially parallel to the first and second electrode layers. ### Claim 17 (depends on 13) The method according to claim 13, wherein the first and second piezoelectric layers differ in exactly one property selected from different ceramic materials, different dopants, different dopant concentrations, different particle sizes of starting materials and different layer thicknesses. ### Claim 18 (depends on 13) The method according to claim 13, wherein the first piezoelectric layer has a first thickness and the second piezoelectric layer has a second thickness that is different from the first thickness, wherein the ratio of the first and second thicknesses is greater than or equal to 1.1 and less than or equal to 3.0. ### Claim 19 (depends on 1) The piezoelectric component according to claim 1, wherein the first and second piezoelectric layers are each chosen in such a way that a contact boundary between the first and second piezoelectric layers forms a region for forming load-relieving and/or polarization cracks that runs substantially parallel to the first and second electrode layers. ### Claim 20 A piezoelectric component comprising: a stack of piezoelectric layers arranged one above another; and first and second electrode layers arranged between the piezoelectric layers; wherein the stack has a first piezoelectric layer having a first electric coercive field strength and, directly adjacent thereto, a second piezoelectric layer having a second electric coercive field strength different than the first electric coercive field strength; wherein the first piezoelectric layer and the second piezoelectric layer comprise different ceramic materials, different dopants, different dopant concentrations, different particle sizes of starting materials, different layer thicknesses or a combination thereof; wherein the first and second piezoelectric layers comprise ceramic materials produced from starting powders having different particle sizes; wherein the particle size of the starting powders is greater than or equal to 0.3 μm and less than or equal to 2.0 μm; wherein the difference in the particle sizes of the starting powders is greater than or equal to 0.1 μm and less than or equal to 1.5 μm; wherein the first and second piezoelectric layers comprise a ceramic material formed from a plurality of constituents having respective concentrations; wherein the first and second piezoelectric layers differ in a concentration of at least one constituent; wherein the first and second piezoelectric layers comprise a ceramic material having the same constituents; wherein the ceramic material has, depending on a concentration of at least one first constituent, a morphotropic phase boundary lying between a first structure and a second structure of the ceramic material; and wherein the concentration of a first constituent of the ceramic material in the first and second piezoelectric layers is in each case chosen in such a way that the first piezoelectric layer comprises the ceramic material having the first structure and the second piezoelectric layer comprises the ceramic material having the second structure.