Piezoelectric Ceramics Material Design and Their Applications

1Lead-based Piezoelectric Ceramics

Various PZT-relaxor compositions
High energy transduction properties for energy harvester and sensors
High strain properties for actuators
Low temperature sintering technic
Suitable for mass production
Templated grain growth proccess for future technology

2Lead-Free Piezoelectric Ceramics

Various NKN-based compositions
Innoxuous and eco-friendly material
High piezoelectric charge constant for sensors
High strain properties for actuators
For replacing lead-based ceramics

3Application : Piezoelectric Actuator

Multilayer processing technic with high strain materials
Development of haptic actuators and piezoelectric speakers
Know-how of industrialization for haptic actuators and piezoelectric speakers

4Application : Piezoelectric Energy Harvester

Energy harvest from wasted mechanical vibrations
Harvester designing and fabricating technic with high energytransducting materials
Development of knock sensor with lead-free ceramics

Piezoelectric / Dielectric Thin films

1Synthesis of the inorganic nanosheets

Various Dion-Jacobson layered perovskite structure
Easily exfoliation using soft-chemical method
Large aspect ratio
Various thickness of the nanosheets (0.3 ~ 2.5nm)

2Application : Dielectric properties

Deposition method using polarity of nanosheets
Applied to various shapes of substrates
Fast deposition time
Good crystallinty

3Langmuir-Blodgett process for ultra-thin film

Powerful process for making ultra-thin film
Various thickness can be adjusted according to the number of layers to be stacked
High crystalline such as single crystal
Good dielectric properties for MLCC and FET

4Piezoelectric Thin films using 2-D inorganic nanosheets seed-layer

Various nanosheets seed layer available
Adjustable crystal direction according to seed direction
Low-temperature process (~350_oC)
Apply to polymer substrate
High piezoelectric strain constan

New Generation Memories (ReRAM) and Neuromorphic Device

1Oxide Thin Film Memristor for ReRAM

Deposition of various oxide materials
Fine resistive switching properties with a ON/OFF ratio of 10³
Reliable retention & endurance properties
Filament model with oxygen vacancy presented as a resistance switching mechanism

2Self-powered ReRAM with Nanogenerator

Self-powered ReRAM driven by nanogenerator trying to use same material
Enough output voltage of nanogenerator to drive ReRAM device (> ±1V)
Reliable retention & endurance properties

3Neuromorphic Characteristic for Artificial Synapse

Memristor mimicking biological synapse
Multi-level characteristic of ReRAM memristor
Analog memory characteristic with consecutive DC bias & AC pulses
Change of synaptic weight & decay time with various numbers of spikes
Change of synaptic weight with frequency of spikes
Change of synaptic weight with timeing of arbitrary pulses mimicking biological spikes

ZnS Nanoparticle and Ceramics for Infrared Lens Application

1ZnS materials

wide band gap II-VI semiconductor
Cubic sphalerite structure (< 1020 °C)/hexagonal wurtzite(~ 1020 °C) structure
High transparency at the infrared wavelengths
High density / toughness

2ZnS nanopowder with Hydrothermal method

Low temperature synthesis
Easily synthesized ZnS nanopowders with hydrothermal method
Control the ZnS nanopowder shape and grain size depend on S/Zn ratio

3ZnS Ceramics for infrared-ray application

Homogeneous cubic phase
ZnS ceramics with yellowish-brown color and transparent at visible range
Large grain size / high density (>99%)
High transmittance (>70%, 6 ~ 12um, T: 3mm)
Application for the IR-thermal camera / Night vision / military service

Others

1Structural properties of Al₂O₃ for LTCC

XRD patterns of Al₂O₃ + CuO, TiO₂ with different sintering conditions and various amount of sintering aids
All of XRD patterns show Al₂O₃ phase without any secondary phases
SEM image of bar-type Al₂O₃ with respect to the amount of CuO, TiO₂ sintering aids
High strength and thermal conductivity due to large grain sizes without unnecessary phase

2Strength and Thermal conductivity of Al2O3 for LTCC

Density enhancement by sintering aids
3-Point bending strength of Al₂O₃ with respect to sintering aids contents and sintering conditions
Thermal conductivity of Al₂O₃ with respect to sintering aids contents and sintering conditions