Ferroelectric, And Suitable Method And Use Therefor

Abstract

The invention relates to a ferroelectric, which has a piezoelectric material having a hafnium proportion of 2% or less, to the use of a ferroelectric of this type in energy generation and for implementation in memory, processor and sensor technologies, to the use of a ferroelectric, in which use energy demand is lowered by superconductivity, and to a method for producing a ferroelectric, in which method a sintering method is used.

Claims

1. A ferroelectric which comprises a piezoelectric material having a hafnium fraction of 2% or less.

2. The ferroelectric as claimed in claim 1, where a dielectric loss factor for the ferroelectric is 0.2% or less for a dielectric constant ε of more than 1000 and a piezoelectric effect d33 of more than 300.

3. The ferroelectric as claimed in claim 1, comprising a two-phase or multiphase material.

4. The ferroelectric as claimed in claim 1, wherein for a given electrical loss, the ferroelectric attains an at least 50% increase in a relative dielectric constant and/or in a piezoelectric effect d33.

5. The ferroelectric as claimed in claim 1, wherein for a given relative dielectric constant, the ferroelectric attains an at least 50% reduction in an electrical loss.

6. The ferroelectric as claimed in claim 1, wherein for a given piezoelectric effect d33 attains an at least 50% reduction in an electrical loss.

7. The ferroelectric as claimed in claim 1, wherein the ferroelectric has a thickness of at least 5 nanometers up to 4 cm.

8. The ferroelectric as claimed in claim 1, wherein the piezoelectric material is a PZT or a BZT.

9. (canceled)

10. A device comprising the ferroelectric as claimed in claim 1, wherein the device is a memory device, as processor, or a sensor.

11. (canceled)

12. A method for producing the ferroelectric as claimed in claim 1, wherein a sintering method is used.

13. The method as claimed in claim 12, where producing takes place using a ZrO.sub.2 powder.

14. (canceled)

15. A superconductor comprising the ferroelectric of claim 1.

16. An actuator comprising the ferroelectric of claim 1.

Description

EXAMPLE 1: IMPROVEMENT IN THE DIELECTRIC CONSTANT AND IN THE PIEZOELECTRIC EFFECT

[0021]

TABLE-US-00001 Del-Piezo QPM PZT #1 DL-40 with Hafnium Material hafnium 0.6% fraction <0.01% relative dielectric constant ε 350 1574 dielectric losses tan δ 0.3% 0.2% piezoelectric effect d33 145  361

EXAMPLE 2: IMPROVEMENT IN THE DIELECTRIC LOSSES

[0022]

TABLE-US-00002 Del-Piezo QPM PZT #1 DL-45HD with Hafnium Material hafnium 0.6% fraction <0.01% relative dielectric constant ε 1550 1574 dielectric losses tan δ 0.5% 0.2% piezoelectric effect d33  360  361

EXAMPLE 3: IMPROVEMENT IN THE DIELECTRIC LOSSES

[0023]

TABLE-US-00003 Standard APC QPM PZT #1 Material 841 with Hafnium Material hafnium 0.6% fraction <0.01% relative dielectric constant ε 1375 1374 dielectric losses tan δ 0.4% 0.2% piezoelectric effect d33  300  315

[0024] Examples 2 and 3 show that the material of the present application with reduced hafnium fraction, presently less than 0.01%, with comparable values of the piezoelectric properties such as relative dielectric constant and of the piezoelectric effect d33, produces significantly lower dielectric loss. In this case the dielectric loss reduces by at least 50% or more, for example.

EXAMPLE 4: FURTHER-IMPROVED DIELECTRIC LOSSES

[0025]

TABLE-US-00004 QPM PZT #2 Hafnium Material fraction <0.01% relative dielectric constant ε 1347 dielectric losses tan δ 0.1% piezoelectric effect d33  300

[0026] Example 4 illustrates that a dielectric loss of 0.1% is also achievable according to material composition, this being the case with virtually the same piezoelectric properties such as relative dielectric constant and the piezoelectric effect, and shows a further halving of the losses for only slightly lower values for the relative dielectric constant and the piezoelectric effect.

[0027] In addition to the reduction in the loss factor, the ferroelectric can also be converted to the state of superconduction, through reduction in or even removal of hafnium, in order to achieve a further significant lowering of the energy losses in corresponding applications, as in the case of electrical components or circuits, for example. It is common knowledge that the superconductivity of a material is related to the formation of or presence of a rhombohedral phase. This relationship was recognized in research into the interface between lanthanum aluminate and strontium titanate. Accordingly, this material, consisting of lanthanum aluminate and strontium titanate, undergoes transition to a rhombohedral phase at below 30 kelvins, causing its electrical resistance to drop steadily as the temperature falls. The superconductivity occurs at below 200 millikelvins.

[0028] In accordance with the present application, therefore, the reduction in or the removal of hafnium promotes the development of a rhombohedral phase at room temperature, thereby enabling high-temperature superconduction.

[0029] A corresponding superconductivity is evident, for example, in a compound QPM PZT with the elements lead Pb, strontium Sr, zirconium Zr, titanium Ti, iron Fe, lanthanum La, aluminum Al and nickel Ni, having a hafnium fraction of below 0.01%.

[0030] FIG. 1 indicates the extent to which the rhombohedral structure or phase has been significantly increased as a result of a reduction in the hafnium fraction. The measurement took place on the basis of common diffractometer measuring methods, as described for example in the book “Rietveld Refinement, Practical Diffraction Pattern Analysis using TITOPAS” by Dinnebier, Leineweber, Evans, 2018, and was carried out in the Debye-Scherrer geometry, with the intensity being determined relative to the diffraction angle theta. The respective phases are determined in folded form from the total intensity signal measured.

[0031] The ferroelectrics of the present application can be used fundamentally in acceleration sensors, rotation-rate, pressure and force sensors, and ultrasonic sensors, microbalances and knock sensors in motor vehicle engines, and also actuators or micromechanical actuator elements, examples being piezoelectric motors (squigglers), ultrasonic motors, for lens autofocusing or watch drives, for example; in the area of micropositioning and nanopositioning systems, the scanning tunneling microscope, the scanning electron microscope and the atomic force microscope are piezoelectrically driven systems. In valve technology, noteworthy components include automobile injection nozzles (production start 2000 for diesel engines), proportional pressure regulators and printheads of inkjet printers. Pickups, electroacoustic delay lines as in older PAL or SECANT color televisions, batteryless radio equipment (switches) and optical modulators are likewise piezoelectric components. Supply equipment uses many of the stated components. The piezoelectric crystal is utilized, moreover, for the purpose of generating cold atmospheric-pressure plasma, which is employed in particular for surface activation, microbial reduction and odor abatement in medicine.