Pyroelectricity
Use the Pyroelectricity multiphysics node () to simulate pyroelectric and electrocaloric effects coupling the variations of temperature and electric polarization in solid dielectrics.
Settings
The Label is the default multiphysics coupling feature name.
The Name is used primarily as a scope prefix for variables defined by the coupling node. Refer to such variables in expressions using the pattern <name>.<variable_name>. In order to distinguish between variables belonging to different coupling nodes or physics interfaces, the name string must be unique. Only letters, numbers, and underscores (_) are permitted in the Name field. The first character must be a letter.
The default Name (for the first multiphysics coupling feature in the model) is pye1.
Coupled Interfaces
This section defines the physics involved in the Pyroelectricity multiphysics coupling. The Electrostatics and Heat Transfer lists include all applicable physics interfaces.
The default values depend on how the Electrostriction node is created.
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If it is added from the Physics ribbon (Windows users), Physics contextual toolbar (macOS and Linux users), or context menu (all users), then the first physics interface of each type in the component is selected as the default.
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If it is added automatically when a Pyroelectricity multiphysics interface has been selected in the Model Wizard or Add Physics window, then the participating Electrostatics and Heat Transfer in Solids interfaces are selected.
You can also select None from either list to uncouple the Pyroelectricity node from a physics interface. If the physics interface is removed from the Model Builder, for example Electrostatics is deleted, then the list defaults to None as there is nothing to couple to.
If a physics interface is deleted and then added to the model again, then in order to reestablish the coupling, you need to choose the physics interface again from the lists. This is applicable to all multiphysics coupling nodes that would normally default to the once present interface. See Multiphysics Modeling Workflow in the COMSOL Multiphysics Reference Manual.
Domain Selection
The domain selection is set by default to all domains, so that all applicable domains are selected automatically. Such domains represent an intersection of the applicable domains under the corresponding Electrostatics and Heat Transfer in Solids interfaces selected in the coupling feature.
In Electrostatics interface, the following two domains are applicable:
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 Charge Conservation, if its material type input is set to Solid. Use this domain feature for solid dielectric materials, for which a linear dependency can be assumed for the electric polarization with respect to the applied electric field.
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Charge Conservation, Piezoelectric. Use this domain feature for solid linear piezoelectric materials.
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 Charge Conservation, Ferroelectric. Use this domain feature for solid ferroelectric or nonlinear piezoelectric materials.
In Heat Transfer in Solids interface, the applicable domains are:
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Solid. Use this domain feature for solid pyroelectric and dielectric materials.
To model solid nonpyroelectric domain, remove such domains from the coupling feature selection.
Coupling Type
From the list, choose one of these coupling types:
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 Pyroelectric effect to include only the change in the material polarization caused by temperature variations.
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 Electrocaloric effect, also known as inverse pyroelectric effect, to include only the heat source due to the polarization variation in time.
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 Fully coupled (default) to include both the direct and inverse pyroelectric effects.
Coupling settings
Enter the Total pyroelectric coefficient pET, which is a vector (SI unit: C/(m2·K)) specified in the selected coordinate system. The default is to take the values From material.
You also can enter the Reference temperature Tref with the default value of 293.15 K.
The total pyroelectric coefficient pET is a coupling coefficient measure at constant stress (unclamped) conditions. When this coupling feature is used as part of The Piezoelectricity and Pyroelectricity Interface, the following relation between different pyroelectric coefficients holds:
where pES is the primary pyroelectric coefficient measured at constant strain (clamped), and the second term is usually called the secondary pyroelectric coefficient with α being the thermal expansion vector and eES being the piezoelectric coupling matrix. The software does all needed conversions automatically.
References for pyroelectricity
1. Newnham R.E., Properties of Materials. Anisotropy, Symmetry, Structure. Oxford University Press, New York, 2005.