2 research outputs found
Mechanical Properties of a New Hybrid Inorganic–Organic Framework: A Nanoindentation, High-Pressure X‑ray Diffraction, and Computational Study
The comprehensive mechanical properties of a new synthesized
3D
hybrid inorganic–organic framework (TPrA)Cu2(dca)5 (TPrA+ = N(C3H7)4+, tetrapropylammonium; dca– = N(CN)2–, dicyanamide) have been studied via experimental
approaches and first-principles calculations. The nanoindentation
test demonstrates that Young’s moduli (E)
and the hardness within the 2D [Cu2(dca)4] layers
are respectively 65 and 70% larger than the direction normal to the
2D planes, and the framework of (TPrA)Cu2(dca)5 is prone to cleavage along the 2D [Cu2(dca)4] layers to lead to discrete displacement bursts in the initial loading
part of the load-indentation depth (P-h) curve of
the direction. The bulk modulus of (TPrA)Cu2(dca)5 is 6.97 GPa within a pressure scope of 0 to 3.36
GPa, which
is comparable to those from porous MIL-47 and ZIF-8. The high anisotropy
of Young’s moduli of 31.8 and the shear moduli of 45.0 provided
via first-principles calculations are an order of magnitude larger
than those from many known porous and dense frameworks but close to
those of 2D hybrid systems. The broad range of Poisson’s ratio
of (TPrA)Cu2(dca)5 indicates its very anisotropic
response behavior when under the uniaxial and shearing stress. The
results of nanoindentation, synchrotron high-pressure X-ray diffraction,
and first-principles calculations synergistically indicate that the
3D architecture of (TPrA)Cu2(dca)5 has the potential
to cleavage into 2D nanosheets under the uniaxial or shearing stress.
Further high-resolution microscopic characterization directly confirms
the successful exfoliation of the 3D framework of (TPrA)Cu2(dca)5 into 2D nanosheets via simple surfactant-free solvent-mediated
sonication and demonstrates that the (−102) plane is the cleavage
plane
Chiral Two-Dimensional Hybrid Organic–Inorganic Perovskites for Piezoelectric Ultrasound Detection
Hybrid organic–inorganic perovskites (HOIPs) have
exhibited
striking application potential in piezoelectric energy harvesting
and sensing due to their high piezoelectricity, light weight, and
solution processability. However, to date, the application of piezoelectric
HOIPs in ultrasound detection has not yet been explored. Here, we
report the synthesis of a pair of chiral two-dimensional piezoelectric
HOIPs, R-(4-bromo-2-butylammonium)2ÂPbBr4 and S-(4-bromo-2-butylammonium)2ÂPbBr4 [R-(BrBA)2PbBr4 and S-(BrBA)2PbBr4], which show low mechanical strength and significant piezoelectric
strain coefficients that are advantageous for mechanoelectrical energy
conversion. Benefiting from these virtues, the R-(BrBA)2PbBr4@PBAT and S-(BrBA)2PbBr4@PBAT [PBAT = poly(butyleneadipate-co-terephthalate)] composite films show prominent underwater ultrasound
detection performance with a transmission effectivity of 12.0% using
a 10.0 MHz probe, comparable with that of a polyvinylidene fluoride
(PVDF) device fabricated in the same conditions. Density functional
theory calculations reveal that R-(BrBA)2PbBr4 and S-(BrBA)2PbBr4 have a beneficial acoustic impedance (5.07–6.76 MRayl)
compatible with that of water (1.5 MRayl), which is responsible for
the facile ultrasound-induced electricity generation. These encouraging
results open up new possibilities for applying piezoelectric HOIPs
in underwater ultrasound detection and imaging technologies