Project Details
Projekt
Cooling power in lead-free electrocalorics
Applicant
Professor Dr.-Ing. Jürgen Rödel, since 1/2018
Subject Area
Synthesis and Properties of Functional Materials
Term
from 2015 to 2019
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 281244181
The main focus of this project is to investigate the thermal properties of ferroelectric and relaxor materials in order to establish the full set of properties that are necessary to enable a functioning electro caloric (EC) material. In the proposed project the thermal transport properties of ferroelectric material with different types of ferroelectric transitions and dielectric behavior will be investigated in order to understand the inter-related phenomena that will dictate device performance under real operating conditions, including the thermal conductivity, characteristic time constant, and cooling power. This information is essential to specify the electrical and thermal properties that are required of practical EC materials for device applications. The key objectives of the proposed projects are to:1. Determine the thermal transport properties of ferroelectric materials with different order and nature of phase transition, i.e., first- to second-order and normal to relaxor ferroelectric behavior.2. Investigate the impact of electric field on thermal properties.3. Relate electrical losses with the thermal transport properties.4. Understand the mechanisms of losses and their relation to thermal transport properties in an EC application.5. Provide new insight concerning optimum operating conditions, intrinsic equilibrium EC properties, and material measures of EC performance.To achieve these objectives it is necessary to:1. Fully characterize the structure and microstructure of the samples in order to ensure that thermal and electrical properties are measured on samples having suitable physicochemical characteristics /quality.2. Determine the dielectric and polarization response as a function of temperature and electric field.3. Determine electric field-temperature phase diagrams.4. Measure equilibrium EC properties.5. Determine heat capacity, thermal conductivity, and thermal expansion as a function of temperature and electric field.The proposed work will focus on the lead-free perovskite-structured solid solution Ba(Zr,Ti)O3. The experimentally obtained electrical and thermal data will be used as an input to determine the cooling power of different ferroelectric materials. This will allow us toCompare the cooling power of the EC cycle between the ferroelectric materials with first order, second order and diffuse phase transition and ferroelectrics with relaxor behavior. It will provide an insight in the interrelations between the electric and thermal properties which determine the working conditions and ranges EC material. Based on the data gathered together a table with operational conditions characteristic for each investigated ferroelectric system will be created. This will provide valuable information that will assist in selecting an appropriate ferroelectric material for successful implementation of EC material in a solid-state cooling device.
DFG Programme
Priority Programmes
Ehemaliger Antragsteller
Dr. Nikola Novak, until 12/2017
