Improper ferroelectrics for pyroelectric detection of infrared radiation

Abstract

The a b s e n c e o f d i e l e c t r i c d i v e r g e n c e i n i m p r o p e r f e r r o e l e c t r i c s makes i t p o s s i b l e t o o b t a i n a h i g h p y r o e l e c t r i c f i g u r e of m e r i t n e a r their t r a n s ition t e m p e r a t u r e . R e s u l t s o f m e a s u r e m e n t s c a r r i e d o u t a s a f u n c t i o n o f t e m p e r a t u r e on r e p r e s e n t a t i v e s o f three c l a s s e s o f i m p r o p e r ferroelect r i c s : r a r e -e a r t h m o l y b d a t e s , p r o p i o n a t e s , and b o r a c i t e s , show t h a t i n e a c h o f these the f i g u r e o f merit rises t o a p e a k v a l u e w h i c h i s s u p e r i o r t o t h a t of t r i g l y c i n e s u l f a t e . A n a l y s i s ofthe e x p e r i m e n t a l r e s u l t s u s i n g a Landau t y p e f r e e -e n e r g y model y i e l d s a n e s t i m a t e of the optimum f i g u r e o f m e r i t o b t a i n a b l e .

Ultrahigh Pyroelectric Figures of Merit Associated with Distinct Bistable Dielectric Phase Transition in a New Molecular Compound: Di‐n‐Butylaminium Trifluoroacetate

“…It is emphasized that the maximum M 2 value of 1 is also obtained near the phase transition temperature, which reaches up to ≈16 × 10 −2 cm 3/2 J −1/2 , being an order of magnitude larger than that of TGS. To assess the experimental figures, we further performed theoretical calculations using a thermodynamic model on the basis of Gibbs free‐energy expression for improper ferroelectrics . As shown in Figure , the fitting traces agree fairly well with experimental results, and display a consistent tendency with the peak value at T c .…”

Response to Comment on “Improper molecular ferroelectrics with simultaneous ultrahigh pyroelectricity and figures of merit”

“…A single rotational mode (primary order parameter) was found to induce improper ferroelectricity in perovskite oxides ( 8 ). Similar coupling terms of the Landau type free energy model can be found in improper ferroelectrics including rare-earth molybdates, propionates, and boracites ( 9 ). More recently, improper ferroelectric di- n -butylaminium trifluoroacetate used the same form of the equation ( 10 ).…”

Improper ferroelectricity and piezoelectric responses in rhombohedral (A,A′)B2O6perovskite oxides

“…However, it is possible to avoid this problem if the spontaneous polarization is induced by only a single rotational mode, making such materials improper rather than hybrid-improper ferroelectrics. Materials of this nature could find use in high-temperature electronic applications such as sensors [23].…”

“…such as sensors. 22 Our previous work has shown that although both inphase and out-of-phase rotations are required to lift inversion symmetry in [001]-ordered double perovskites, only out-of-phase rotations, which are described by a single mode, are needed if the A-sites are ordered along the [111] direction (the difference in cation ordering is shown in Fig. 1).…”