scholarly journals Enhanced Pyroelectric Performance of Lead-Free Zn-Doped Na1/2Bi1/2TiO3-BaTiO3 Ceramics

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 87
Author(s):  
Satyanarayan Patel ◽  
Kodumudi Venkataraman Lalitha ◽  
Nishchay Saurabh
Keyword(s):  
Figure Of Merit ◽  
Room Temperature ◽  
Temperature Stability ◽  
Mechanical Quality Factor ◽  
Lead Free ◽  
Figures Of Merit ◽  
Undoped Material ◽  
Threefold Increase ◽  
Mechanical Quality ◽  
Independent Behavior

Lead-free Na1/2Bi1/2TiO3-BaTiO3 (NBT-BT) has gained revived interest due to its exceptionally good high power properties in comparison to commercial lead-based piezoelectrics. Recently, Zn-modified NBT-BT-based materials as solid solution and composites have been reported to exhibit enhanced depolarization temperatures and a high mechanical quality factor. In this work, the pyroelectric properties of Zn-doped NBT-6mole%BT and NBT-9mole%BT ceramics are investigated. The doped compositions of NBT-6BT and NBT-9BT feature a relatively stable pyroelectric property in a wide temperature range of ~37 K (300–330 K) and 80 K (300–380 K), respectively. A threefold increase in detector figure of merit is noted for 0.01 mole Zn-doped NBT-6mole% BT at room temperature in comparison to undoped NBT-6mole%BT and this increase is higher than those of major lead-free materials. A broad range of the temperature-independent behavior for the figures of merit was noted (303–380 K) for Zn-doped NBT-6mole% BT, which is 30 K higher than the undoped material. The large pyroelectric figures of merit and good temperature stability renders Zn-doped NBT-BT an ideal candidate for pyroelectric detector and energy harvesting applications.

Microstructure and Piezoelectric Properties of [(K0.5Na0.5)1-xLix](Nb1-yTay)O3 Lead-Free Piezoelectric Ceramics

2010 ◽  
Vol 156-157 ◽  
pp. 1522-1527
Author(s):  
Bei Xu ◽  
Feng Gao ◽  
Bo Li ◽  
Liang Liang Liu ◽  
Zhen Qi Deng
Keyword(s):  
Room Temperature ◽  
Composition Range ◽  
Piezoelectric Properties ◽  
Piezoelectric Ceramics ◽  
Mechanical Quality Factor ◽  
Lead Free ◽  
Mechanical Quality ◽  
Curie Temperature Tc ◽  
Room Temperature Dielectric Constant ◽  
Tetragonal Phase Transition

Li+ and Ta5+ modified lead-free piezoelectric ceramics [(K0.5Na0.5)1-xLix](Nb1-yTay)O3 have been prepared by an ordinary sintering technique. Effect of Li+ and Ta5+ on microstructure and piezoelectric properties of the ceramics was systematically studied. A morphotropic phase boundary between orthorhombic and tetragonal phases is identified in the composition range of (0.02≤x≤0.04, 0.15≤y≤0.25), which can enhance electrical properties of [(K0.5Na0.5)1-xLix](Nb1-yTay)O3 ceramics. The Curie temperature TC of these ceramics is lower than that of pure (K0.5Na0.5)NbO3 ceramics, but the temperature of orthorhombic to tetragonal phase transition TO-T of the former is higher than that of the latter. TC and TO-T both decrease as the content of Ta5+ increases. With the addition of Li+ increasing, TC increases. The optimal piezoelectric properties are obtained at (x, y)=(0.03, 0.20): piezoelectric constant d33 is 192pC/N; the electromechanical coefficient of the planar mode kp is 44%; room temperature dielectric constant εr is 1049, and the corresponding mechanical quality factor Qm is 49.

Electrical Properties and Figures of Merit for New Chalcogenide-Based Thermoelectric Materials

1997 ◽  
Vol 478 ◽  
Author(s):  
Jon L. Schindler ◽  
Tim P. Hogan ◽  
Paul W. Brazis ◽  
Carl R. Kannewurf ◽  
Duck-Young Chung ◽  
...  
Keyword(s):  
Thermoelectric Materials ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Figures Of Merit ◽  
Lattice Symmetry ◽  
Thermoelectric Refrigeration ◽  
Polychalcogenide Flux ◽  
P Type

AbstractNew Bi-based chalcogenide compounds have been prepared using the polychalcogenide flux technique for crystal growth. These materials exhibit characteristics of good thermoelectric materials. Single crystals of the compound CsBi4Te6 have shown conductivity as high as 2440 S/cm with a p-type thermoelectric power of ≈ +110 μV/K at room temperature. A second compound, β-K2Bi8Se13 shows lower conductivity ≈ 240 S/cm, but a larger n-type thermopower ≈ −200 μV/K. Thermal transport measurements have been performed on hot-pressed pellets of these materials and the results show comparable or lower thermal conductivities than Bi2Te3. This improvement may reflect the reduced lattice symmetry of the new chalcogenide thermoelectrics. The thermoelectric figure of merit for CsBi4Te6 reaches ZT ≈ 0.32 at 260 K and for β-K2Bi8Se13 ZT ≈ 0.32 at room temperature, indicating that these compounds are viable candidates for thermoelectric refrigeration applications.

Physical and Electrical Properties of Lead-Free (Bi0.5Na0.5)TiO3–(Bi0.5K0.5)TiO3 Ceramics

2011 ◽  
Vol 239-242 ◽  
pp. 3240-3243 ◽  
Author(s):  
Chun Huy Wang
Keyword(s):  
Solid Solution ◽  
Coupling Coefficient ◽  
Piezoelectric Properties ◽  
Coupling Factor ◽  
Mechanical Quality Factor ◽  
Lead Free ◽  
Solution System ◽  
Solid Solution System ◽  
Mechanical Quality ◽  
Quality Factor Q

Extending the investigations on (Bi0.5Na0.5)TiO3-based solid solution for lead-free piezoelectric ceramics, this paper consider the complex solid-solution system (Bi0.5Na0.5)TiO3–(Bi0.5K0.5)TiO3[BNT-BKT]. (Bi0.5Na0.5)TiO3with 7~ 30 mol% (Bi0.5K0.5)TiO3ceramics have been prepared following the conventional mixed oxide process. A morphotropic phase boundary (MPB) between rhombohedral (R) and tetragonal (T) was found at the composition 0.82BNT-0.18BKT with correspondingly enhanced piezoelectric properties. The electromechanical planar coupling factor is higher for compositions near the MPB. The mechanical quality factor (Qm), planar coupling coefficient (kp) and thickness coupling coefficient (kt) of 0.82BNT-0.18BKT ceramics were 125, 28.8% and 47.4%, respectively.

Improved Thermoelectric Properties of SixGe1−x by the “Nanoparticle-in-Alloy” Approach

2009 ◽  
Author(s):  
Shidong Wang ◽  
Natalio Mingo
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Power ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Waste Heat ◽  
Fold Increase ◽  
Thermoelectric Power Factor ◽  
Figures Of Merit

We theoretically find that embedding silicide nanoparticles in SixGe1-x alloys is able to considerably improve the figure of merit (ZT). We have computed the thermal conductivity as a function of the sizes of NiSi2 and CoSi2 nanoparticles. We find that the optimal nanoparticle diameters minimizing the composite’s thermal conductivity are 6.9 nm for NiSi2 and 12.6 nm for CoSi2 at room temperature. We provide validity ranges of nanoparticle volume fractions that will not reduce the thermoelectric power factor, but will considerably decrease the thermal conductivity. Embedding NiSi2 or CoSi2 nanoparticles in SixGe1-x may lead to a 5-fold increase of figure of merit (ZT ∼ 0.5) at room temperature and 2.8 times increase (ZT ∼ 2.0) at 900 K. The proposed materials with high figures of merit are promising candidates to be used in integrated micro refrigerators in chips and thermoelectric power generation and waste heat recovery.

scholarly journals Pyroelectric properties of 91.5Na0.5Bi0.5TiO3–8.5K0.5Bi0.5TiO3 lead-free single crystal

2021 ◽  
Author(s):  
Bo Zhang ◽  
Renbing Sun ◽  
Fang Wang ◽  
Tangfu Feng ◽  
Pengna Zhang ◽  
...  
Keyword(s):  
Single Crystal ◽  
Frequency Dependence ◽  
Room Temperature ◽  
Pyroelectric Coefficient ◽  
Lead Free ◽  
Oriented Crystal ◽  
Depolarization Temperature ◽  
Pyroelectric Properties ◽  
Figures Of Merit ◽  
Crystallographic Orientations

The dielectric and pyroelectric performances of 91.5Na[Formula: see text]Bi[Formula: see text]TiO3–8.5K[Formula: see text]Bi[Formula: see text]TiO3 lead-free single crystal were investigated. The depolarization temperature of the crystal is about 153[Formula: see text]C. Among the [Formula: see text]001[Formula: see text], [Formula: see text]110[Formula: see text], and [Formula: see text]111[Formula: see text] crystallographic orientations, the [Formula: see text]111[Formula: see text]-oriented crystal possesses the highest pyroelectric coefficient and the largest figures of merit, and the values of [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text]are 5.63× 10[Formula: see text] C/m2 ⋅ K, 0.06 m2/C, and 21.5 [Formula: see text]Pa[Formula: see text] for the [Formula: see text]111[Formula: see text]-oriented crystal at room temperature. The [Formula: see text]and [Formula: see text]exhibit weak frequency dependence in the range of 100–300 Hz. With the increase of the temperature, the value of [Formula: see text]increases, while the [Formula: see text] value of [Formula: see text] decreases from 18[Formula: see text]C to 103 [Formula: see text]C.

Effects of Mn-Doping on the Piezoelectric and Ferroelectric Properties of (Na0.8K0.2)0.5Bi0.5TiO3 Ceramics

2008 ◽  
Vol 368-372 ◽  
pp. 69-71 ◽  
Author(s):  
Xiang Ping Jiang ◽  
Long Zhu Li ◽  
Fu Lan Jiang ◽  
Yan Yan Zheng ◽  
Li Hua Liu
Keyword(s):  
Solid State ◽  
Dielectric Loss ◽  
Grain Growth ◽  
Remnant Polarization ◽  
Piezoelectric Properties ◽  
Ferroelectric Properties ◽  
Mechanical Quality Factor ◽  
Lead Free ◽  
Mn Doping ◽  
Mechanical Quality

Lead-free piezoelectric ceramics of (Na0.8K0.2)0.5Bi0.5TiO3+x wt.% Mn (abbreviated as NBKT-x% Mn, x=0~0.5) were synthesized by solid-state reaction. The grain growth of the ceramics was restrained by Mn-doping at a certain extent. The mechanical quality factor Qm increases and the dielectric loss tanδ decreases with the increase of Mn-doping. Best piezoelectric properties were obtained for the composition of NKBT-0.2%Mn: d33=158 pC·N-1, tanδ=2.9% at 1 kHz, Qm=110 and kp=30%. The P-E loops show that remnant polarization Pr and coercive field Ec decrease slightly with the amount of the Mn2+ increasing up to 0.2wt.% and then increase as the content of Mn2+ increases further. NKBT-0.5wt. % Mn exhibits strong ferroelectricity with remnant polarization Pr = 38μC/cm2.

Effect of Low-Temperature Frit on the Sintering Behavior and Properties of 0.95K0.49Na0.51NbO3-0.05LiSbO3 Lead-Free Piezoceramics

2011 ◽  
Vol 412 ◽  
pp. 290-293
Author(s):  
Zhu Mei Wang ◽  
Yue Ming Li ◽  
Run Run Li ◽  
Zong Yang Shen ◽  
Yan Hong
Keyword(s):  
Low Temperature ◽  
Electromechanical Coupling ◽  
Sintering Temperature ◽  
Mechanical Quality Factor ◽  
Lead Free ◽  
Piezoelectric Response ◽  
Electromechanical Coupling Coefficient ◽  
Sintering Behavior ◽  
Mechanical Quality ◽  
Reduced Temperature

The effects of low-temperature frit Li2O-Na2O-K2O-B2O3-SiO2-CaO-BaO-ZnO (abbreviated as BS) on the sintering behavior and electrical properties of 0.95K0.49Na0.51NbO3- 0.05LiSbO3 (abbreviated as KNN-LS) lead-free piezoceramics were investigated. The sintering temperature of the KNN-LS ceramics can be reduced from 1080 °C to 1000 °C due to the addition of BS frit. For the 0.5 wt% BS-doped KNN-LS ceramics, which are sintered at reduced temperature of 1000 °C for 2 h, remain relatively high piezoelectric constant d33 (195 pC/N) and planar electromechanical coupling coefficient kp (40.7%). In addition to other optimization effects, such as reduction of dielectric loss from 3.6% to 2.7% and increment of mechanical quality factor Qm from 48 to 70, this BS frit was experimentally proved to be good for low temperature sintering of KNN-based ceramics while maintaining high piezoelectric response.

High-Power Piezoelectric Characteristics of Sr2Bi4Ti5O18-Ca2Bi4Ti5O18-Based Ferroelectric Ceramics

2011 ◽  
Vol 485 ◽  
pp. 93-96 ◽  
Author(s):  
Yoji Noumura ◽  
Shigeki Sato ◽  
Yuji Hiruma ◽  
Hajime Nagata ◽  
Tadashi Takenaka
Keyword(s):  
High Power ◽  
Mechanical Quality Factor ◽  
Power Measurement ◽  
Lead Free ◽  
Ferroelectric Ceramics ◽  
Vibration Velocity ◽  
Lead Free Ceramics ◽  
Mechanical Quality ◽  
Mn Doped ◽  
Piezoelectric Characteristics

The high-power piezoelectric characteristics of lead-free piezoelectric ceramics, based on a bismuth layer-structured ferroelectric, MnCO3-doped (Sr0.7Ca0.3)2Bi4Ti5O18(abbreviated as SCBT0.3 + Mnxwt%), were studied. SCBT0.3 + Mnxwt% lead-free ceramics showed an extremely high mechanical quality factor (Qm) of more than 3000 in the (33) vibration mode under small-amplitude vibration. The high-power piezoelectric characteristics of SCBT0.3 + Mnxwt% were measured using the high-power measurement method based on frequency sweep driving under a constant voltage condition. It was found that the vibration velocityv0-pof SCBT0.3 + Mn 0.2 wt% linearly increased up to approximately 3.0 m/s. Therefore, the Mn-doped SCBT0.3-based ceramics are a promising candidate for lead-free high-power applications.

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