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.

What is claimed is: 
     
         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 1-n Sr n )(Ti 1-x-y Zr x Sn y )O 3  which can be doped;
 wherein 0.0≦n≦0.6, 0.0≦x≦0.6, 0.0≦y≦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≦n≦0.5, 0.05≦x≦0.4, 0.05≦y≦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 2 O 5 ; or a sintering aid selected from one or more of B 2 O 3 , Li 2 O, SiO 2 , Bi 2 O 3 , and PbO; a glass phase filler selected from one or more of B 2 O 3 , Li 2 O, Na 2 O, MgO, Al 2 O 3 , SiO 2 , CaO, V 2 O 5 , Cr 2 O 3 , Co 2 O 3 , ZnO, CuO, Sb 2 O 5 , BaO, and Bi 2 O 3 .