The role ofγ-C2H5NO2 as a new transient liquid phase in cold sintering process of BaTiO3 composites

Dielectric materials,such as barium titanate(BT)-based materials,have excellent dielectric properties but require high temperatures(above 1300℃)for ceramic fabrication,leading to high costs and energy loss.The cold sintering process(CSP)offers a solution to these issues and is gaining worldwide attention as an innovative fabrication route.In this work,we proposed an alternative organic ferroelectric phase,gamma-glycine(γ-GC),which acts as a transient liquid phase to fabricate high-density composites with barium titanate(BT)at low temperatures through CSP.Our findings show that the density of 15γ-GC/85BT reached 96.7%±1.6%when it was sintered at 120℃for 6 h under 10 MPa uniaxial pressure.Scanning electron microscopy‒energy dispersive X-ray spectroscopy(SEM‒EDS)mappings of the composite suggested thatγ-GC completely underwent the precipitation-dissolution process and,therefore,filled between BT particles.Moreover,X-ray diffraction(XRD)and Fourier-transform infrared spectroscopy(FTIR)confirmed the preservation ofγ-GC without undesired phase transformation.In addition,the ferroelectric and dielectric properties ofγ-GC/BT composites have been reported.The high dielectric constant(εr)was 3600,and the low dielectric loss(tanδ)was 1.20 at 200℃and 100 kHz for the 15γ-GC/85BT composite.The hysteresis loop showed a remanent polarization(Pr)of 0.55µC·cm^(−2)and a coercive field(Ec)of 7.25 kV·cm^(−1).Our findings reaffirmed that an organic ferroelectric material(γ-GC)can act as a transient liquid phase in a CSP that can successfully and sustainably fabricateγ-GC/BT composites at low temperatures while delivering outstandingly high performance.

Unleashing the potential of morphotropic phase boundary based hybrid triboelectric–piezoelectric nanogenerator

Morphotropic phase boundary(MPB)-based ceramics are excellent for energy harvesting due to their enhanced physical properties at phase boundaries,broad operating temperature range,and ability to customize properties for efficient conversion of mechanical energy into electrical energy.In this work,Bi_(1–x)Na_(x)Fe_(1–x)Nb_(x)O_(3)(x=0.20,0.30,0.32 and 0.40,BNFNO abbreviation)based ceramics were synthesized using a solid-state route and blended with Polydimethylsiloxane(PDMS)to achieve flexible composites.Various material characterization and energy harvesting were performed by designing a hybrid piezoelectric(PENG)-triboelectric(TENG)device.The voltage and current of PENG,TENG,and hybrid bearing same device area(2 cm×2 cm)were recorded as 11 V/0.3μA;60 V/0.7μA;110 V/2.2μA.The strategies for enhancing the output performance of the hybrid device were evaluated,such as increased surface area(creating micro-roughness and porous morphology)and increasing electrode size and multi-layer hybrid device formation.The self-powered acceleration monitoring was demonstrated using the hybrid device.Further,the low-frequency-based wave energy is converted into electrical energy,confirming the usage of hybrid PENG-TENG devices as a base for battery-free sensors and blue energy harvesting.