Two Rare‐Earth Molecular Ferroelectrics with High Curie Temperatures, Large Spontaneous Polarization, Switchable Second Harmonic Generation Effects, and Strong Photoluminescence

Abstract

Smartm ultifunctional molecular ferroelectrics bearing high Curie temperatures and diverse excellent physical properties, such as second harmonic generation (SHG) responses, luminescence, and semiconductivity, among others, have significant applicationsb ut have seldom been documented. Herein, the rare-earth metals Nd and Pr are introduced into as imple molecular system (nBu 4 N) 3 [M(NO 3 ) x (SCN) y ]( nBu 4 N = tetrabutyl ammonium, M = rare-earth metal, nBu = CH 3 CH 2 CH 2 CH 2 ), and two new multifunctional molecular ferroelectrics are obtained:Their distinct heat and dielectric anomaly dependence on temperature verifies that compounds 1 and 2 experience high-temperature para-ferroelectric phase transitions at 408 and 413 K, respectively.S trikingly,b oth molecular ferroelectrics possess large spontaneousp olarizationw ith P s values of 9.05 and 8.50 mCcm À2 ,r espectively,a nd are further characterized by the appearance of multiple intersecting non-1808 domains and polarization switching behavior.I np articular,c ompounds 1 and 2 show good stability with only a small decrease in SHG intensity after switching cycles,s uggesting that they have great potentialfor applicationinnonlinear optical( NLO) switches. Simultaneously,t he rare-earth compounds 1 and 2 present brighty ellow-red andb right green fluorescence, respectively,atr oom temperature. Figure 5. UV/Vis absorptionspectra of compounds 1 (a) and 2 (c), and fluorescence emission spectraofc ompounds 1 (b) and 2 (d).

Successive Phase Transitions and Dual Dielectric Switching in an Organic–Inorganic Hybrid Perovskite

“…Molecular dielectric switches, undergoing transitions between low and high dielectric states, have attracted widespread attention for their promising applications in data storage, varactors, signal processing, data communication, etc. − To obtain such functional materials, constructing phase-transition compounds is a common strategy because they usually display dielectric anomalies near the phase-transition temperatures. , As the phase transition occurs, the structural changes might also bring about interesting physical properties in some cases, such as ferroelectric and ferroelastic properties. − In view of the crystallographic symmetry, structural changes in the ferroelastic phase transition need to meet the severe requirements, which must belong to one of the 94 ferroelastic species deduced by Aizu . Ferroelastic is the mechanical analogue of ferroelectric, and its strain–stress relationship shows hysteresis behavior.…”

Coupling Narrow Band Gap and Switchable SHG Responses in a New Molecule Ferroelectric: Imidazolyl Propylamine Pentabromo Stibium(III)

“…9−12 Although much progress has been achieved in the field of organic−inorganic hybrid ferroelectrics, there is still much space remaining to be explored: 13−16 for example, how to couple the narrow band gap, ferroelectricity, and switchable SHG responses in a ferroelectric molecule and obtain multifunctional ferroelectric devices. 17,18 To the best of our knowledge, to date only a small number of multifunctional molecular ferroelectrics have been discovered because a ferroelectric must meet some necessary conditions such as a , and opened new avenues to explore excellent optoelectronic properties in the anti-perovskite family. 19 Considering the unique photoelectric properties in rare-earth elements, we also assembled the first two rare-earth ferroelectrics (nBu 4 N) 3 [Nd(NO 3 ) 4 (SCN) 2 ] and (nBu 4 N) 3 [Pr-(NO 3 ) 4 (SCN) 2 ], which present bright yellow-red and bright green fluorescence, respectively; however, they have relatively wide band gaps with values of 3.84 and 3.94 eV, respectively.…”

Dielectric switching from a high temperature plastic phase transition in two organic salts with chiral features

“…Solid-solid plastic phase transition materials can be utilized in many interesting fields. [1][2][3][4] Among the available materials, temperature-triggered responsive dielectric switchable materials that can undergo transitions between high and low dielectric states at a phase transition temperature in response to a temperature stimulus are promising materials for use in data communication, signal processing, tunable dielectric devices, etc. [5][6][7][8] The construction of hybrid metal halides is usually an effective strategy for the synthesis of plastic phase transition materials, because they provide great opportunities for obtaining temperature-triggered reversible solidsolid phase transitions.…”