Dielectric and Pyroelectric Properties of Ammonium Hydrogen-DL-Malate Monohydrate, NH4(C4H5O5) H2O

1987 ◽  
Vol 42 (1) ◽  
pp. 57-66 ◽  
Author(s):  
Silvia Fleck ◽  
Michael C. Böhm ◽  
Alarich Weiss
Keyword(s):  
Dipole Moment ◽  
Room Temperature ◽  
Pyroelectric Coefficient ◽  
Crystallographic Direction ◽  
Dielectric Tensor ◽  
Dielectric Measurements ◽  
Angular Variation ◽  
Pyroelectric Properties ◽  
Self Consistent ◽  
Ammonium Hydrogen

The dielectric and pyroelectric properties of ammonium hydrogen-DL-malate monohydrate NH⊕ (⊖OOCCHOHCH2COOH) • H20 were studied as a function of temperature and crystallographic direction. The components of the dielectric tensor at room temperature are within the limits 5.9 ≦ ε≦ 8.6. The pyroelectric coefficient |p| increases from ≈ 18 μC m-2 K-1 at T= 100 K to 32 μC m-2 K-1 at room temperature. The angular variation of p in the ac-plane of the crystal with symmetry Cc is ≈ 10°.Using an INDO procedure which includes crystal field effects in a self-consistent way (SCEF) the charge distribution in the solid was calculated. With the therefrom resulting dipole moment and together with the dielectric measurements the pyroelectric coefficient |p| and the change of |p| with temperature was calculated. Experiment and theoretical result agree satisfactory.

Pyroelectric Properties of the Plt(10) Thin Film on the P-Doped Poly Silicon

1996 ◽  
Vol 433 ◽  
Author(s):  
Seong Jun Kang ◽  
Yung Sup Yoon ◽  
Dong Il Kim
Keyword(s):  
Thin Film ◽  
Dielectric Constant ◽  
Curie Temperature ◽  
Room Temperature ◽  
Sol Gel ◽  
Pyroelectric Coefficient ◽  
Pyroelectric Properties ◽  
Gel Method ◽  
Sol Gel Method ◽  
Poly Silicon

AbstractWe have studied the pyroelectric properties of the PLT(10) thin film deposited on a p-doped poly-Si electrode by using the sol-gel method. Measurement of the dielectric constant as a function of temperature shows the typical characteristics of a ferroelectric. The dielectric constant reaches a maximum at 295°C, which can be thought of as the Curie temperature. The PLT(10) thin film on p-doped poly-Si fabricated in this research shows excellent pyroelectric properties. The pyroelectric coefficient and the fiqures of merit, Fv and FD at room temperature are measured as 5.76 × 10−8 C/cm2 °C, 1.17 × 10−10C-cm/J and 0.93 × 10−8C-cm/J, respectively.

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.

Intrinsic doping limit and defect-assisted luminescence in Cs4PbBr6

2019 ◽  
Author(s):  
Young-Kwang Jung ◽  
Joaquin Calbo ◽  
Ji-Sang Park ◽  
Lucy D. Wahlley ◽  
Sunghyun Kim ◽  
...  
Keyword(s):  
First Principles ◽  
Room Temperature ◽  
Stokes Shift ◽  
Green Luminescence ◽  
Counter Ions ◽  
Self Consistent ◽  
Deep Ultraviolet ◽  
Halide Perovskite ◽  
Related Compounds ◽  
Level Analysis

Cs<sub>4</sub>PbBr<sub>6 </sub>is a member of the halide perovskite family that is built from isolated (zero-dimensional) PbBr<sub>6</sub><sup>4-</sup> octahedra with Cs<sup>+</sup> counter ions. The material exhibits anomalous optoelectronic properties: optical absorption and weak emission in the deep ultraviolet (310 - 375 nm) with efficient luminescence in the green region (~ 540 nm). Several hypotheses have been proposed to explain the giant Stokes shift including: (i) phase impurities; (ii) self-trapped exciton; (iii) defect emission. We explore, using first-principles theory and self-consistent Fermi level analysis, the unusual defect chemistry and physics of Cs<sub>4</sub>PbBr<sub>6</sub>. We find a heavily compensated system where the room-temperature carrier concentrations (< 10<sup>9</sup> cm<sup>-3</sup>) are more than one million times lower than the defect concentrations. We show that the low-energy Br-on-Cs antisite results in the formation of a polybromide (Br<sub>3</sub>) species that can exist in a range of charge states. We further demonstrate from excited-state calculations that tribromide moieties are photoresponsive and can contribute to the observed green luminescence. Photoactivity of polyhalide molecules is expected to be present in other halide perovskite-related compounds where they can influence light absorption and emission. <br>

Intrinsic doping limit and defect-assisted luminescence in Cs4PbBr6

2019 ◽  
Author(s):  
Young-Kwang Jung ◽  
Joaquin Calbo ◽  
Ji-Sang Park ◽  
Lucy D. Wahlley ◽  
Sunghyun Kim ◽  
...  
Keyword(s):  
First Principles ◽  
Room Temperature ◽  
Stokes Shift ◽  
Green Luminescence ◽  
Counter Ions ◽  
Self Consistent ◽  
Deep Ultraviolet ◽  
Halide Perovskite ◽  
Related Compounds ◽  
Level Analysis

Cs<sub>4</sub>PbBr<sub>6 </sub>is a member of the halide perovskite family that is built from isolated (zero-dimensional) PbBr<sub>6</sub><sup>4-</sup> octahedra with Cs<sup>+</sup> counter ions. The material exhibits anomalous optoelectronic properties: optical absorption and weak emission in the deep ultraviolet (310 - 375 nm) with efficient luminescence in the green region (~ 540 nm). Several hypotheses have been proposed to explain the giant Stokes shift including: (i) phase impurities; (ii) self-trapped exciton; (iii) defect emission. We explore, using first-principles theory and self-consistent Fermi level analysis, the unusual defect chemistry and physics of Cs<sub>4</sub>PbBr<sub>6</sub>. We find a heavily compensated system where the room-temperature carrier concentrations (< 10<sup>9</sup> cm<sup>-3</sup>) are more than one million times lower than the defect concentrations. We show that the low-energy Br-on-Cs antisite results in the formation of a polybromide (Br<sub>3</sub>) species that can exist in a range of charge states. We further demonstrate from excited-state calculations that tribromide moieties are photoresponsive and can contribute to the observed green luminescence. Photoactivity of polyhalide molecules is expected to be present in other halide perovskite-related compounds where they can influence light absorption and emission. <br>

scholarly journals Preparation and the Microwave and Infrared Spectra of Vinyl Ketene

1979 ◽  
Vol 34 (11) ◽  
pp. 1269-1274 ◽  
Author(s):  
Erik Bjarnov
Keyword(s):  
Dipole Moment ◽  
Gas Phase ◽  
Infrared Spectra ◽  
Room Temperature ◽  
Normal Modes ◽  
Spectroscopic Constants ◽  
Electrical Dipole ◽  
Electrical Dipole Moment ◽  
Vacuum Pyrolysis ◽  
Modes Of Vibration

Vinyl ketene (1,3-butadiene-1-one) has been synthesized by vacuum pyrolysis of 3-butenoic 2-butenoic anhydride. The microwave and infrared spectra of vinyl ketene in the gas phase at room temperature have been studied. The trans-rotamer has been identified, and the spectroscopic constants were found to be Ã= 39571(48) MHz, B̃ = 2392.9252(28) MHz, C̃ = 2256.0089(28) MHz, ⊿j = 0.414(31) kHz, and ⊿JK = - 34.694(92) kHz. The electrical dipole moment was found to be 0.987(23) D with μa = 0.865(14) D and μb = 0.475(41) D. A tentative assignment has been made for 17 of the 21 normal modes of vibration

Al1-x ScxN Thin Film Structures for Pyroelectric Sensing Applications

MRS Advances ◽  
2016 ◽  
Vol 1 (39) ◽  
pp. 2711-2716 ◽  
Author(s):  
V. Vasilyev ◽  
J. Cetnar ◽  
B. Claflin ◽  
G. Grzybowski ◽  
K. Leedy ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Pyroelectric Coefficient ◽  
X Ray Diffraction ◽  
Ir Detectors ◽  
Pyroelectric Properties ◽  
X Ray ◽  
Sensing Applications ◽  
Pyroelectric Material ◽  
Deposited Films

ABSTRACTAlN thin film structures have many useful and practical piezoelectric and pyroelectric properties. The potential enhancement of the AlN piezo- and pyroelectric constants allows it to compete with more commonly used materials. For example, combination of AlN with ScN leads to new structural, electronic, and mechanical characteristics, which have been reported to substantially enhance the piezoelectric coefficients in solid-solution AlN-ScN compounds, compared to a pure AlN-phase material.In our work, we demonstrate that an analogous alloying approach results in considerable enhancement of the pyroelectric properties of AlN - ScN composites. Thin films of ScN, AlN and Al1-x ScxN (x = 0 – 1.0) were deposited on silicon (004) substrates using dual reactive sputtering in Ar/N2 atmosphere from Sc and Al targets. The deposited films were studied and compared using x-ray diffraction, XPS, SEM, and pyroelectric characterization. An up to 25% enhancement was observed in the pyroelectric coefficient (Pc = 0.9 µC /m2K) for Sc1-xAlxN thin films structures in comparison to pure AlN thin films (Pc = 0.71 µC/m2K). The obtained results suggest that Al1-x ScxN films could be a promising novel pyroelectric material and might be suitable for use in uncooled IR detectors.

scholarly journals Growth, Optical and Microhardness Studies of 2-Aminothiazole- 3, 5-Dinitrobenzoic Acid Complex

2019 ◽  
Vol 1 (1) ◽  
pp. 42-45
Author(s):  
Tamiloli Devendhiran ◽  
Keerthika Kumarasamy ◽  
Mei–Ching Lin
Keyword(s):  
Room Temperature ◽  
Grown Crystal ◽  
Optical Transmittance ◽  
Dielectric Measurements ◽  
Slow Evaporation ◽  
X Ray Diffraction ◽  
Acid Complex ◽  
X Ray ◽  
Slow Evaporation Technique ◽  
Evaporation Technique

Single crystals of 2-Aminothiazole 3,5-Dinitrobenzoic acid has been synthesized and good quality optical crystals were grown by slow evaporation technique at room temperature. The crystallinity nature of the grown crystal was confirmed from X-ray diffraction technique. An optical transmittance study was also carried out by UV – Vis spectra. FTIR spectra confirm the presence of functional groups in the grown crystal. The dielectric measurements were carried out in the range of 50Hz to 2MHz. The dielectric constant was seen to increase exponentially at lower frequencies. The microhardness studies were carried out using Vickers hardness indenter. Photoluminescence study shows that maximum emission occurs at 435nm.

Dielectric Properties and Raman Spectroscopy in Ca-Substituted Na0.5Bi0.5TiO3 Ferroelectric Ceramics

2011 ◽  
Vol 324 ◽  
pp. 298-301 ◽  
Author(s):  
Roy Jean Roukos ◽  
Olivier Bidault ◽  
Julien Pansiot ◽  
Ludivine Minier ◽  
Lucien Saviot
Keyword(s):  
Raman Spectroscopy ◽  
Dielectric Properties ◽  
Room Temperature ◽  
Rhombohedral Phase ◽  
Xrd Analysis ◽  
Solid State Reaction Method ◽  
Ferroelectric Ceramics ◽  
Dielectric Measurements ◽  
X Ray Diffraction ◽  
X Ray

Lead free Na0.5Bi0.5TiO3 (NBT) and (Na0.5Bi0.5TiO3)1-x(CaTiO3)x (NBT-CT) piezoelectric ceramics with the perovskite structure were studied. The NBT and NBT-CT samples were synthesized using a solid-state reaction method and characterized with X-ray diffraction (XRD), Raman spectroscopy and dielectric measurements for several compositions (x = 0, 0.07, 0.15) at room temperature. The XRD analysis showed a stabilization of a rhombohedral phase at a low concentration of Ca (0 < x <0.15), whereas Raman spectra reveal a strong modification for the sample with x = 0.15. The dielectric properties of these ceramics were studied by measuring impedance in the 79-451K temperature range for unpoled and field cooling with an electric field (FC) conditions.

Strong Polarity and Bond Characterization of Nanostructured Silicon Nitride Solids

1992 ◽  
Vol 286 ◽  
Author(s):  
Lide Zhang ◽  
Chimei Mo ◽  
Tao Wang ◽  
Cunyi Xie
Keyword(s):  
Silicon Nitride ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Bond Properties ◽  
Dielectric Measurements ◽  
X Ray ◽  
Nanostructured Silicon ◽  
Spin Resonance ◽  
Measuring Frequency

ABSTRACTNanostructured silicon nitride solids (NANO–SSNS) were investigated by x–ray photoelectron spectroscopy (XPS), electron spin resonance (ESR) and dielectric measurements. It is found that the dielectric constant of NANO–SSNS depends strongly on the measuring frequency, f. When f<100Hz, at room temperature it is forty times as much as that of conventional Si3N4. ESR measurements show that a large number of unbinding electrons exist in interfaces. This suggests that the NANO–SSNS possess strong polarity. The study on the bond properties indicates that a large number of unsaturated and dangling bonds exist in interfaces of NANO–SSNS.

The Physical and Molecular Properties of New Low Melting Nematics with Negative Dielectric Anisotropy

1999 ◽  
Vol 54 (6-7) ◽  
pp. 448-452 ◽  
Author(s):  
R. Dąbrowski ◽  
J. Jadżyna ◽  
J. Dziaduszek ◽  
Z. Stolarz ◽  
G. Czechowski ◽  
...  
Keyword(s):  
Dipole Moment ◽  
Physical Properties ◽  
Temperature Dependence ◽  
Carboxylic Acids ◽  
Order Parameter ◽  
Room Temperature ◽  
Dielectric Anisotropy ◽  
Molecular Dipole ◽  
Nematic Order ◽  
Moment Vector

Abstract The paper presents some basic physical properties (static electric permittivities, refraction indices, density and viscosity) of 2-chloro-4-n’-alkylphenyl esters of 4-n-alkylbicyclo[2,2,2] octane-1-carboxylic acids (n’=7, n = 5 and 7) which are, at room temperature, nematics with a negative dielectric an-isotropy. On the basis of temperature dependence of the principal static permittivities ε‖(T) and e⊥(T) of the nematics, using the Maier-Meier equations, the angle between the dipole moment vector and the long axis of mesogenic molecules, the apparent molecular dipole moment square pl μ2app(T), and the nematic order parameter S(T) were determined.

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