U.S. patent application number 15/265112 was filed with the patent office on 2017-03-16 for method to enhance the performance of cooling devices utilizing modified barium titanate (bt) electrocaloric ceramic materials.
The applicant listed for this patent is Nascent Devices LLC. Invention is credited to Jianwei CHEN, Ailan CHENG, Haisheng XU.
Application Number | 20170074555 15/265112 |
Document ID | / |
Family ID | 54897475 |
Filed Date | 2017-03-16 |
United States Patent
Application |
20170074555 |
Kind Code |
A1 |
CHENG; Ailan ; et
al. |
March 16, 2017 |
METHOD TO ENHANCE THE PERFORMANCE OF COOLING DEVICES UTILIZING
MODIFIED BARIUM TITANATE (BT) ELECTROCALORIC CERAMIC MATERIALS
Abstract
A method to enhance the performances of cooling devices based on
barium titanate (BT) ceramics is disclosed. Such cooling is
realized by utilizing at least one BT-based ceramics which exhibit
large electrocaloric effect (ECE). The method enhances the large
ECE performances to cover temperature range between -30 C to 80C,
by introducing an invariant critical point where paraelectric phase
and at least one ferroelectric phase of BT-based ceramic
refrigerant coexist.
Inventors: |
CHENG; Ailan; (State
College, PA) ; XU; Haisheng; (Shanghai, CN) ;
CHEN; Jianwei; (Shanghai, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Nascent Devices LLC |
State College |
PA |
US |
|
|
Family ID: |
54897475 |
Appl. No.: |
15/265112 |
Filed: |
September 14, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C04B 2235/3251 20130101;
F25B 21/00 20130101; C04B 2235/3293 20130101; Y02B 30/00 20130101;
C04B 2235/3267 20130101; F25B 2321/001 20130101; C04B 2235/3224
20130101; C04B 2235/3213 20130101; C04B 2235/3275 20130101; Y02B
30/66 20130101; H01L 37/025 20130101; C04B 2235/3229 20130101; C04B
2235/3215 20130101; C04B 35/49 20130101 |
International
Class: |
F25B 21/00 20060101
F25B021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 15, 2015 |
CN |
201510586361.3 |
Claims
1. A cooling device including an electrocaloric (EC) ceramic as at
least one of a refrigerant wherein the EC ceramic possessing a
large electrocaloric effect (ECE) and has chemical composition of
(Ba.sub.1-nSr.sub.n)(Ti.sub.1-x-yZr.sub.xSn.sub.y)O.sub.3 which can
be doped; wherein 0.0.ltoreq.n.ltoreq.0.6, 0.0.ltoreq.x.ltoreq.0.6,
0.0.ltoreq.y.ltoreq.0.6; wherein A-site doping element(s) can be
chosen from Li, Na, K of IA group, Ca of IIA group, Pb of IVA
group, Bi of VA group, Y of IIIB group, La, Ce, Pr, Nd, Pm, Sm of
Lanthanide series of elements, and a combinations of thereof;
wherein B-site doping element(s) can be chosen from Mg of IIA
group, In of IIIA group, Sb of VA group, Cu of IB group, Zn, Cd of
JIB group, Sc of IIIB group, Hf of IVB group, V, Nb, Ta of VB
group, Cr, W of VIB group, Mn of VIIB group, Fe, Co, Ni, Pd of VIII
group, and Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu of Lanthanide series
of elements, and the combinations of thereof.
2. The device of claim 1, wherein 0.0.ltoreq.n.ltoreq.0.5,
0.05.ltoreq.x.ltoreq.0.4, 0.05.ltoreq.y.ltoreq.0.5.
3. The device of claim 1, wherein the doping elements can be chosen
from both ions which have equivalent ionic valence state to ions in
the ceramic base and ions which have non-equivalent ionic valence
state to ions in the ceramic base.
4. The device of claim 1, wherein a total mole percentage of doping
element or doping elements is 0-20% of the ceramic base.
5. The device of claim 1, wherein the BT includes an additive
selected from one or more of MnO2, MgO, CuO, ZnO, and
Sb.sub.2O.sub.5; or a sintering aid selected from one or more of
B.sub.2O.sub.3, Li.sub.2O, SiO.sub.2, Bi.sub.2O.sub.3, and PbO; a
glass phase filler selected from one or more of B.sub.2O.sub.3,
Li.sub.2O, Na.sub.2O, MgO, Al.sub.2O.sub.3, SiO.sub.2, CaO,
V.sub.2O.sub.5, Cr.sub.2O.sub.3, Co.sub.2O.sub.3, ZnO, CuO,
Sb.sub.2O.sub.5, BaO, and Bi.sub.2O.sub.3.
Description
[0001] This application claims the benefit of Chinese Application
No. 201510586361.3 filed Sep. 15, 2015 the entire disclosure of
which is hereby incorporated by reference herein.
FIELD OF THE INVENTION
[0002] The present disclosure is directed to a method to enhance
electrocaloric effect (ECE) performances in modified Barium
Titanate (BT)-based ceramics and hence enhance the performances of
the cooling devices, such as heat pumps, refrigerators and
air-conditioners, based on modified BT ceramics. The present
disclosure relates to fields of refrigeration and thermal
management devices, especially methods to enhance refrigeration
capability in modified BT-based ceramics which exhibit large
ECE.
BACKGROUND
[0003] In a dielectric material, its dipolar orientation can be
changed by applying electric fields upon the material, causing an
adiabatic temperature change or an isothermal entropy change. Such
effect is known as electrocaloric effect (ECE). Upon applying an
electric field, the dipoles in the dielectric material orient with
respect to the electric field, reducing its dipolar entropy,
raising its temperature adiabatically or ejecting heat
isothermally. When the electric field is removed, dipoles return to
its random orientation state, increasing its dipolar entropy,
reducing its temperature adiabatically or absorbing heat
isothermally. Above describes the principle of refrigeration from
electrocaloric effect.
SUMMARY OF THE DISCLOSURE
[0004] This disclosure relates to cooling devices with enhanced
performance which can be achieved by a method that enhances the
performances of the cooling devices based on modified BT ceramics.
The disclosed method enhances the ECE performances of BT-based
ceramics and hence enhances the performance of cooling devices or
refrigerators which are based on at least one of the said ceramics
as refrigerant. With the disclosed method, BT-based ceramics would
exhibit larger ECE which covers temperature range from
-30-80.degree. C.
[0005] To achieve the performance enhancement of cooling devices,
the present disclosure provides a method to enhance ECE
performances of BT-based ceramics. Said cooling devices is based on
at least one BT-based ceramic exhibiting large ECE. Said large ECE
correspond to an induced temperature change
.DELTA.T.gtoreq.3.degree. C., under an electric field E.ltoreq.15
MV/m. Said large ECE occurs over a wide range of temperature from
-30 to 80.degree. C. [0006] Said BT-based electrocaloric ceramic
have compositions of
(Ba.sub.1-nSr.sub.n)(Ti.sub.1-x-yZr.sub.xSn.sub.y)O.sub.3 as base
ceramics or doped
(Ba.sub.1-nSr.sub.n)(Ti.sub.1-x-yZr.sub.xSn.sub.y)O.sub.3 ceramics.
Wherein 0.ltoreq.n.ltoreq.1, 0.ltoreq.x.ltoreq.1 and
0.ltoreq.y.ltoreq.1. Wherein A-site doping element(s) are chosen
from Li, Na, K from IA group, Ca from IIA group, Ph from IVA group,
Bi from VA group, Y from IIIB group, La, Ce, Pr, Nd, Pm, Sm from
Lanthanide series of elements, and the combinations of thereof;
[0007] wherein B-site doping element(s) are chosen from Mg from IIA
group, In from IIIA group, Sb from VA group, Cu from IB group, Zn,
Cd from IIB group, Sc from IIIB group, Hf from IVB group, V, Nb, Ta
from VB group, Cr, W from VIB group, Mn from VIIB group, Fe, Co,
Ni, Pd from VIII group, and Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu from
Lanthanide series of elements, and combinations of thereof. [0008]
Preferably, 0.ltoreq.n.ltoreq.0.5, 0.1.ltoreq.x.ltoreq.0.3 and
0.05.ltoreq.y.ltoreq.0.2.
[0009] Preferably, the doping element can be chosen from ions that
have same valence state as that of replaced base ion; it can also
be chosen from ions that have different valence state as that of
replaced base ion. [0010] Preferably, molar percentages of doping
element or elements is from 0-20% of base ceramics. [0011]
Preferably, in one embodiment of fabrication method of said
electrocaloric ceramic, it comprises procedures as, [0012] (1)
Based on chemical formula of base ceramic
(Ba.sub.1-nSr.sub.n)(Ti.sub.1-x-yZr.sub.xSn.sub.y)O.sub.3 and
doping element types and quantities, weigh corresponding materials
and mix them to form powder. (2) Add solvent into the mixture of
powder and ball mill the mixture. Bake to remove the solvent after
ball mill and then get ball-milled powder. (3) Pre-sinter the said
ball-milled powder to get precursor powder. (4) Add additives,
sintering aids and glass phase additives to the precursor powder
and then add solvent. Perform ball mill to the mixture, Bake to
remove solvent to get raw BT-based electrocaloric ceramic powder.
(5) Press said raw BT-based electrocaloric ceramic powder to form a
raw solid shape from BT-based electrocaloric ceramic powder. (6)
Sinter said pressed BT-based electrocaloric ceramic to get bulk
BT-based electrocaloric ceramic.
[0013] Further, in procedure (4) of above method, wherein the
additives can be chosen from one or more than one from MnO2, MgO,
CuO, ZnO, Sb.sub.2O.sub.5; the sintering aids can be chosen from
one or more than one from B.sub.2O.sub.3, Li.sub.2O, SiO.sub.2,
Bi.sub.2O.sub.3, PbO; glass phase filler can be chosen from one or
more than one from B.sub.2O.sub.3, Li.sub.2O, Na.sub.2O, MgO,
Al.sub.2O.sub.3, SiO.sub.2, CaO, V.sub.2O.sub.5, Cr.sub.2O.sub.3,
Co.sub.2O.sub.3, ZnO, CuO, Sb.sub.2O.sub.5, BaO,
Bi.sub.2O.sub.3.
[0014] The advantage of this invention disclosure lies in the
enhancement of electrocaloric effect in BT-based ceramics to
improve the performances of heat-pumps or refrigerators or cooling
devices that are using BT-based electrocaloric ceramics as at least
one of the refrigerant. To achieve such enhancement, this invention
discloses a method to form invariant critical point at which
paraelectric phase is merged with at least one of the ferroelectric
phases by doping BT-based ceramics to improve their electrocaloric
performances. Thus modified BT-based ceramics exhibit enhanced
electrocaloric performance over a temperature range from -30 to
80.degree. C., where the invariant critical point can be adjusted
to.
[0015] Barium Titanate (BaTiO.sub.3) is a ferroelectric material
with perovskite ABO.sub.3 structure. Wherein both A-site ions and
B-site ions can be substituted, by doping other element, to modify
the material properties, which include various physical and
chemical functional properties. Near paraelectric and ferroelectric
transition temperature, the electric polarization of the material
goes through abrupt change, which enables the material to have
larger electrocaloric effect at nearby temperature range than that
at other temperatures. By doping different elements to BaTiO.sub.3
ceramics, we substitute ions in A-site and B-site and hence modify
the electrocaloric effect of the modified material to have better
performances at a temperature range of -30-80.degree. C., Thus the
performances of the cooling devices which are based on one or more
BT-based cooling agent/refrigerant would have better cooling
performance at the temperature range of -30-80.degree. C.
[0016] The disclosed BT-based electrocaloric ceramics are modified
by ion substitution of either or both A-site and B-site where
doping ions were added by composite-doping method, donor/acceptor
doping method, precursor doping methods and etc. The phase diagram
of BT-based ceramics can be adjusted by doping A-site and/or B-site
ions with both donor and acceptor ion, thus optimize stability of
coexistence of multi-phases in the BT-based ceramics and thus
improve the electrocaloric effect in the material.
[0017] The BT-based ceramics made from the method in present
invention disclosure exhibit larger electrocaloric effect in a
temperature range of -30-80.degree. C. than that at other
temperature ranges. In -30-80.degree. C., electrocaloric induced
temperature change .DELTA.T.gtoreq.3K under an electric field
E.ltoreq.15 MV/m.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Reference is made to the attached drawings, wherein elements
having the same reference numeral designations represent similar
elements throughout. Understanding that these drawings describe
only several embodiments of the disclosure and are, therefore, not
to be considered limiting of its scope and wherein:
[0019] FIG. 1. The electric field induced temperature change as a
function of electric field for Ba(Ti.sub.0.8Zr.sub.0.2)O.sub.3.
[0020] FIG. 2 show the temperature change for the doped material,
0.8[Ba(Ti.sub.0.82Zr.sub.0.18)O.sub.3]-0.2[Ba(Ti.sub.0.9Sn.sub.0.1)O.sub.-
3]. It is clear that Sn-doped BZT showed much better EC response
compared with pure BZT.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0021] The present disclosure provides a method to enhance the
performances of a heat-pump/refrigerator that is operating a
BT-based ceramics exhibiting large electrocaloric effect as at
least one of the cooling agent (refrigerant). Said large
electrocaloric effect is referring to at an interested temperature
range, where most of cooling devices are working at, the
electrcaloric effect induced temperature change is larger than that
at other temperature ranges. To be specific, said electrocaloric
effect induced temperature change .DELTA.T.gtoreq.3K under an
electric field E.ltoreq.15 MV/m in a temperature range of
-30-80.degree. C.
[0022] Wherein BT-based electrocaloric ceramic have compositions of
(Ba.sub.1-nSr.sub.n)(Ti.sub.1-x-yZr.sub.xSn.sub.y)O.sub.3 as base
ceramics or a complex ceramic comprising
(Ba.sub.1-nSr.sub.n)(Ti.sub.1-x-yZr.sub.xSn.sub.y)O.sub.3 as base
ceramics and other elements as dopant doped into the base ceramic.
Wherein 0.ltoreq.n.ltoreq.1, 0.ltoreq.x.ltoreq.1 and
0.ltoreq.y.ltoreq.1. In addition, 0.ltoreq.n.ltoreq.0.5,
0.ltoreq.x.ltoreq.0.5 and 0.ltoreq.y.ltoreq.0.5. Preferably,
0.1.ltoreq.n.ltoreq.0.4, 0.1.ltoreq.0.1x.ltoreq.0.3 and
0.05.ltoreq.y.ltoreq.0.2.
[0023] Wherein A-site doping element or doping element composition
can be chosen from one or a combination from Li, Na, K from IA
group, Ca from IIA group, Pb from IVA group, Bi from VA group, Y
from IIIB group, La, Pr, Nd, Pm, Sm from Lanthanide series of
elements; wherein B-site doping element(s) can be chosen from one
or a combination from Mg from IIA group, In from IIIA group, Sb
from VA group, Cu from IB group, Zn, Cd from IIB group, Sc from
IIIB group, Hf from IVB group, V, Nb, Ta from VB group, Cr, W from
VIB group, Mn from VIIB group, Fe, Co, Ni, Pd from VIII group, and
Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu from Lanthanide series of
elements. For instance, the composition of base ceramics is
(Ba.sub.1-nSr.sub.n)(Ti.sub.1-x-yZr.sub.xSn.sub.y)O.sub.3, with
A-site doping element of Ce, Bi, B and B-site doping element Mn and
Co.
[0024] Said doping element can be chosen from ions which have same
equivalent valance state of ions in base ceramics, such as
Ca.sup.2+, Mn.sup.4+, Ce.sup.4+, Hf.sup.4+. Pb.sup.2+; they can
also be chosen from element ions that has different valance state
of ions on base ceramics, such as Co.sup.3+, Nb.sup.5+, Sb.sup.5+,
La.sup.3+ and W.sup.6+.
[0025] In addition, said doping elements composition can be an ion
composition that has same valance state in total as that of ion in
base ceramics, such as, Na.sub.1/2.sup.+,
Mn.sub.1-m.sup.4+Ce.sub.m.sup.4+ (0.ltoreq.m.ltoreq.1),
Mg.sub.1/3.sup.2+Nb.sub.2/3.sup.5+,
Fe.sub.1/2.sup.3+Nb.sub.1/2.sup.5+; they can also be chosen from an
ion composition that has different equivalent valance state in
total from that of ions in base ceramics, such as
Co.sub.1/2.sup.3+Hf.sub.1/2.sup.4+,
La.sub.1/2.sup.3+W.sub.1/2.sup.6+,
Mn.sub.1/4.sup.4+La.sub.1/4.sup.3+Sb.sub.1/8.sup.5+Ta.sub.1/8.sup.5+Ho.su-
b.1/8.sup.3+Yb.sub.1/8.sup.3+.
[0026] In addition, in said doping element or element composition,
the mole percentage of doping ions or ion compositions is 0-20%.
For instance, in a BT-based electrocaloric ceramics, mole
percentage of doped elements or element compositions is 3%.
[0027] In addition, said additives can be chosen from one or more
than one from MnO.sub.2, MgO, CuO, ZnO, and Sb.sub.2O.sub.5; Proper
addition of the additives may reduce the dielectric loss and
electric conductivity. The said sintering aids can be chosen from
one or more than one from B.sub.2O.sub.3, Li.sub.2O, SiO.sub.2,
B.sub.2O.sub.3, and PbO. The purpose of the said sintering aids may
reduce the sintering temperature of the ceramics. Glass phase
additives can be chosen from one or more than one from
B.sub.2O.sub.3, Li.sub.2O, Na.sub.2O, MgO, Al.sub.2O.sub.3,
SiO.sub.2, CaO, V.sub.2O.sub.5, Cr.sub.2O.sub.3, Co.sub.2O.sub.3,
ZnO, CuO, Sb.sub.2O.sub.5, BaO, and Bi.sub.2O.sub.3. Addition of
said glass phase additives not only can reduce sintering
temperature, but also effectively reduce porosity of sintered
ceramics and thus enhance density and breakdown strength, resulting
in an improved electrocaloric performances.
[0028] In one embodiment of the present disclosure, a method of
utilizing BT-based electrocaloric ceramic,
Ba(Zr.sub.0.2Ti.sub.0.8)O.sub.3, to enhance performances of cooling
devices based on such electrocaloric ceramics is provided. Said
BT-based electrocaloric ceramic, Ba(Zr.sub.0.2Ti.sub.0.8)O.sub.3,
is comprising of ceramic, Ba(Zr.sub.0.2Ti.sub.0.8)O.sub.3, and
doping elements Mn, Ce; the composition of doping ions is
Mn.sub.0.4.sup.4+Ce.sub.0.6.sup.4+; the mole percentage of the
doping ion composition is 2% of mole quantity of base ceramics.
[0029] In one embodiment of present disclosure, a method of
utilizing BT-based electrocaloric ceramic,
(Ba.sub.0.8Sr.sub.0.2)(Ti.sub.0.85Zr.sub.0.1Sn.sub.0.05)O.sub.3, to
enhance performances of cooling devices based on such
electrocaloric ceramics is provided. Said BT-based electrocaloric
ceramic,
(Ba.sub.0.8Sr.sub.0.2)(Ti.sub.0.85Zr.sub.0.1Sn.sub.0.05)O.sub.3, is
comprising of ceramic,
(Ba.sub.0.8Sr.sub.0.2)(Ti.sub.0.85Zr.sub.0.1Sn.sub.0.05)O.sub.3,
and doping elements Mn, Co, Nb, Sin, Eu, Gd, Tb, Dy, Ho, Er; the
composition of doping ions is
Mn.sub.0.1Co.sub.0.1Nb.sub.0.1Sm.sub.0.1Eu.sub.0.1Gd.sub.0.1Tb.sub.0.1Dy.-
sub.0.1Ho.sub.0.1Er.sub.0.1; the mole percentage of the doping ion
composition is 2% of the mole quantity of base ceramics.
[0030] FIG. 1 shows the temperature change as a function of
electric field for Ba(Ti.sub.0.8Zr.sub.0.2)O.sub.3. FIG. 2 show the
temperature change for the doped material,
0.8[Ba(Ti.sub.0.82Zr.sub.0.18)O.sub.3]-0.2[Ba(Ti.sub.0.9Sn.sub.0.1)O.sub.-
3]. It is clear that Sn-doped BZT showed much better EC response
compared with pure BZT.
[0031] Only the preferred embodiment of the present invention and
examples of its versatility are shown and described in the present
disclosure. It is to be understood that the present invention is
capable of use in various other combinations and environments and
is capable of changes or modifications within the scope of the
inventive concept as expressed herein. Thus, for example, those
skilled in the art will recognize, or be able to ascertain, using
no more than routine experimentation, numerous equivalents to the
specific substances, procedures and arrangements described, herein.
Such equivalents are considered to be within the scope of this
invention, and are covered by the following claims.
* * * * *