Transparent phase change actuator

Patent metadata

Field	Value
Publication number	US-11428964-B2
Application number	US-201916545882-A
Country	US
Kind code	B2
Filing date	Aug 20, 2019
Priority date	Aug 20, 2019
Publication date	Aug 30, 2022
Grant date	Aug 30, 2022

Abstract

A transparent optical element may include a layer of an electroactive ceramic disposed between transparent electrodes, such that the electrodes are each oriented perpendicular to a non-polar direction of the ceramic layer. Optical properties of the optical element, including transmissivity, haze, and clarity may be improved by the application of a voltage to the electroactive ceramic, and an associated phase transformation.

First claim

What is claimed is:

1. An optical element, comprising:
a primary electrode layer;
a secondary electrode layer overlapping at least a portion of the primary electrode layer;
an electroactive ceramic disposed between and abutting the primary electrode layer and the secondary electrode layer, wherein:
a top surface of the primary electrode layer and a bottom surface of the secondary electrode layer are each oriented perpendicular to a non-polar direction of the electroactive ceramic; and
the electroactive ceramic, when exposed to an applied field of at least approximately 0.5 MV/m, comprises at least one of: an optical transmissivity within a visible spectrum of at least approximately 50%; bulk haze of less than approximately 50%;

and optical clarity of at least approximately 75%; and
a power source connected to at least one of the primary electrode layer or the secondary electrode layer.

2. The optical element of claim 1 , wherein the electroactive ceramic comprises a rhombohedral phase and each of the primary electrode layer and the secondary electrode layer are oriented perpendicular to a <110>crystallographic direction of the rhombohedral phase or a <100>crystallographic direction of the rhombohedral phase.

3. The optical element of claim 1 , wherein the electroactive ceramic comprises an orthorhombic phase and each of the primary electrode layer and the secondary electrode layer are oriented perpendicular to a <111>crystallographic direction of the orthorhombic phase or a <100>crystallographic direction of the orthorhombic phase.

4. The optical element of claim 1 , wherein the electroactive ceramic comprises a tetragonal phase and each of the primary electrode layer and the secondary electrode layer are oriented perpendicular to a <111>crystallographic direction of the tetragonal phase or a <110>crystallographic direction of the tetragonal phase.

5. The optical element of claim 1 , wherein the electroactive ceramic comprises a transmissivity within the visible spectrum of at least approximately 50% and less than approximately 10% bulk haze.

6. The optical element of claim 1 , wherein the electroactive ceramic, when exposed to an applied field of at least approximately 0.5 MV/m, comprises at least one of:
a relative increase in optical transmissivity of at least approximately 10%;
a relative decrease in bulk haze of at least approximately 25%; and
a relative increase in optical clarity of at least approximately 10%.

7. The optical element of claim 1 , wherein the electroactive ceramic, when exposed to an applied field of at least approximately 0.5 MV/m, undergoes at least one phase transformation selected from a group consisting of:
rhombohedral to orthorhombic;
rhombohedral to tetragonal;
orthorhombic to rhombohedral;
orthorhombic to tetragonal;
tetragonal to rhombohedral; and
tetragonal to orthorhombic.

8. The optical element of claim 1 , wherein the electroactive ceramic comprises a rhombohedral crystal structure having a preferred <111>orientation.

9. The optical element of claim 1 , wherein the electroactive ceramic comprises an orthorhombic or monoclinic crystal structure having a preferred <110>orientation.

10. The optical element of claim 1 , wherein the electroactive ceramic comprises a tetragonal crystal structure having a preferred <100>orientation.

11. The optical element of claim 1 , wherein the electroactive ceramic comprises at least one compound selected from a group consisting of lead titanate, lead zirconate, lead zirconate titanate, lead magnesium niobate, lead zinc niobate, lead indium niobate, lead magnesium tantalate, lead magnesium niobate-lead titanate, lead zinc niobate-lead titanate, lead indium tantalate, barium titanate, lithium niobate, potassium niobate, sodium potassium niobate, bismuth sodium titanate, and bismuth ferrite.

12. The optical element of claim 1 , wherein the electroactive ceramic comprises an RMS surface roughness of less than approximately 5 nm.

13. The optical element of claim 1 , wherein the electroactive ceramic consists essentially of a perovskite ceramic.

14. The optical element of claim 1 , wherein the electroactive ceramic comprises at least a 25% increase in transparency, at least a 25% increase in clarity, and at least a 25% decrease in bulk haze when a voltage is applied to the primary electrode layer.

15. A device comprising the optical element of claim 1 .

16. An optical element, comprising:
a primary transparent electrode layer;
a secondary transparent electrode layer overlapping at least a portion of the primary transparent electrode layer;
a transparent electroactive ceramic layer disposed between and abutting a top surface of the primary transparent electrode layer and a bottom surface of the secondary transparent electrode layer, wherein:
the electroactive ceramic layer comprises a plurality of domains in an absence of an applied voltage between the electrode layers and a single domain when a voltage is applied between the electrode layers; and
the electroactive ceramic layer, when exposed to an applied field of at least approximately 0.5 MV/m, comprises at least one of: an optical transmissivity within a visible spectrum of at least approximately 50%; bulk haze of less than approximately 50%;

and optical clarity of at least approximately 75%; and
a power source connected to at least one of the primary electrode layer or the secondary electrode layer.

17. A method comprising:
forming a primary electrode layer;
forming an electroactive ceramic layer over and abutting a top surface of the primary electrode layer, wherein the electroactive ceramic layer, when exposed to an applied field of at least approximately 0.5 MV/m, comprises at least one of: an optical transmissivity within a visible spectrum of at least approximately 50%; bulk haze of less than approximately 50%; an optical clarity of at least approximately 75%;
forming a secondary electrode layer, wherein a bottom surface of the secondary electrode layer is over and abutting the electroactive ceramic layer and overlapping at least a portion of the primary electrode layer; and
applying a voltage to the primary electrode layer, wherein the electroactive ceramic layer comprises:
a first bulk haze and a first optical clarity prior to applying the voltage, and
a second bulk haze less than the first bulk haze and a second optical clarity greater than the first optical clarity during application of the voltage.

18. The method of claim 17 , wherein applying the voltage induces a rotation of domains within the electroactive ceramic layer.

19. The method of claim 17 , wherein applying the voltage induces a phase change within the electroactive ceramic layer.

20. The method of claim 19 , wherein inducing a phase change within the electroactive ceramic layer comprises undergoing at least one phase change selected from a group consisting of:
rhombohedral to orthorhombic;
rhombohedral to tetragonal;
orthorhombic to rhombohedral;
orthorhombic to tetragonal;
tetragonal to rhombohedral; and
tetragonal to orthorhombic.

Assignees

• Meta Platforms Tech Llc

Inventors

• Wells Spencer Allan
• Smyth Katherine Marie
• Ouderkirk Andrew John

Classifications

• C04B35/472

  based on lead titanates · CPC title

• C04B2235/3201

  Alkali metal oxides or oxide-forming salts thereof · CPC title

• C04B35/491

  based on lead zirconates and lead titanates {, e.g. PZT} · CPC title

• G02F1/0551 Primary

  Constructional details · CPC title

• C04B2235/3298

  Bismuth oxides, bismuthates or oxide forming salts thereof, e.g. zinc bismuthate · CPC title