Such small-scale cooling is also of interest for on-chip cooling of semiconductor circuits. [6] In 2020, data centers in the United State used an estimated 75 billion kWh, more than 2% of the nation's total energy consumption. Approximately half of this energy was spent on cooling these centers. [7] Advanced cooling technology that directly cools integrated circuits (ICs) (rather than the entire data center) offers an alternative. Furthermore, IC miniaturization has increased the power density of a packaged chip to 10 6 W cm −2 in 2018; power densities continue to rise, and often induce highly nonuniform heat generation. [8] It has been reported that more than 50% of IC failures are related to thermal control; this rate is expected to increase with further miniaturization. [9] Therefore, new approaches for local cooling of IC are needed. [10] Solid-state cooling, a potential solution, is highly compact, efficient, and environmentally friendly. Research involving thermoelectric, electrocaloric, and magnetocaloric effects is promising. [11][12][13] In 2006, large electrocaloric effects were observed in PZT thin films. [14] Unlike magnetocaloric and barocaloric materials, the electrocaloric effect does not require bulky external magnets or pressure apparatus. Electrocalorics enable relatively good energy efficiency that can be further improved via charge recovery. [15,16] Achieving large temperature changes in the electrocaloric material necessitates inducing large field-induced entropy changes. For this purpose, relaxor ferroelectrics are of special interest due to the disordered polarization and polar nanoregions. [17] A potential additional contribution to the entropy change in a ferroelectric-based material is to use high compositional complexity, e.g. through entropy engineering to further disorder the polarization on a local scale. In 2004, entropy stabilization of metallic alloys was introduced. [18,19] In 2015, the concept was broadened to include entropy stabilized oxides. [20] Various entropy stabilized oxides (ESO) have shown high dielectric constants, superior ionic conductivity, and extremely high-temperature stability; that is, entropy stabilization provides an additional approach to property tunability with respect to enthalpy-based compositional design. [21][22][23] In cases where reversible phase transformations have not yet been demonstrated, potential ESO may be called high entropy oxides (HEO). [24] Triggered by the novel concept, several attempts to investigate the electrocaloric effect (ECE) based on HEO have been made. A-site disordered HEO ceramics show good This paper describes two perovskite high entropy oxide (PHEO) compositions: Pb(Hf 0.2 Zr 0.2 Ti 0.2 Nb 0.2 Mn 0.2 )O 3 (Mn PHEO) and Pb(Hf 0.2 Zr 0.2 Ti 0.2 Nb 0.2 Al 0.2 )O 3 (Al PHEO). Powders are prepared by conventional solid state sintering by first pre-reacting the B-site oxides, then adding PbO. Phase pure Mn PHEO powder is obtained following calcination of the mixed powders at 750 °C for 240 min; however, secondary phases persist...