New negative temperature coefficient ceramics in Ca0.9Y0.1MoO4–CeNbO4 system

Liu, Yafei; Zhang, Bo; Fu, Zhilong; Chang, Aimin

doi:10.1016/j.matlet.2020.127319

Cited by 9 publications

(12 citation statements)

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“…When the Ca site is substituted by Eu, it will immobilize the [MoO 4 ] cluster with its coordination, thus inhibiting the transformation of EuNbO 4 from tetragonal to monoclinic crystal system during the cooling process, which effectively ensures the stability of the crystal structure and uniform distribution of elements in the solid solution. 14 Figure 2A illustrates the XPS spectrum of CENMO ceramics at room temperature, where we observed only Ca, Eu, Nb, Mo, and O. The positions of the individual characteristic peaks were assigned to the elements 39,40 The peak centered at 530.08 eV is attributed to the Eu-O bond in CENMO, which indicates that the oxygen ion in the ceramic is bound to the europium ion; the peak located around 531.68 eV is the chemical state of the sample with adsorbed oxygen.…”

Section: Resultsmentioning

confidence: 99%

“…Both EuNbO 4 and CaMoO 4 phases are tetragonal scheelite structures at high temperatures, while EuNbO 4 undergoes a reversible phase transition from tetragonal to monoclinic phase during cooling. When the Ca site is substituted by Eu, it will immobilize the [MoO 4 ] cluster with its coordination, thus inhibiting the transformation of EuNbO 4 from tetragonal to monoclinic crystal system during the cooling process, which effectively ensures the stability of the crystal structure and uniform distribution of elements in the solid solution 14 …”

Section: Resultsmentioning

confidence: 99%

“…18,19 On the other hand, the transfer of polaron changes the concentration of electrons. 20 In addition, solid solution ceramics based on the Ca-Ln-Nb-M-O can be modulated in various ways to improve their electrical conductivity, such as adjusting the content of solid solution components, 14 doping with rare earth ions, 21 optimizing the sintering process, and compounding with low resistance phases, 22 all of which can effectively increase the practical application of these ceramic materials.…”

Section: Introductionmentioning

confidence: 99%

“…Lanthanides with variable valence have better conductive properties for Ln-based oxide ceramics. 14 Meanwhile, the electron of the unfilled 4f orbital in the Ln-based ions forms a spectral item by spin-orbital coupling, and the luminescence comes from the transition of the excited state electrons between the different spectral items. 5 The study of photoluminescence and electrical properties is valuable and necessary for the practical applications of Ln-based oxide ceramics.…”

Section: Introductionmentioning

confidence: 99%

“…The polaron conductivity and luminescent mechanisms of the lanthanides (Ln) derived from 4 f ‐4 f transition have been studied for the past few decades 1–5 and gained extensive attention in various fields, such as thin‐film crystals, 6 multifunctional ceramics, 7,8 laser emitters, 9 photocatalysts, 10,11 gas phase sensors, 12,13 and so on. Lanthanides with variable valence have better conductive properties for Ln‐based oxide ceramics 14 . Meanwhile, the electron of the unfilled 4 f orbital in the Ln‐based ions forms a spectral item by spin‐orbital coupling, and the luminescence comes from the transition of the excited state electrons between the different spectral items 5 .…”

Section: Introductionmentioning

confidence: 99%

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Photoluminescence and conductive properties of CaEuNbMoO₈ solid‐solution ceramics

et al. 2022

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Solid‐solution ceramics show a potential in the field of electronic devices. In particular, it is necessary to investigate the photoluminescence and conductive properties of CaEuNbMoO8 (CENMO) solid solution ceramics. It is demonstrated that the sintered ceramics appear as CaMoO4 phase with scheelite structure. The results of X‐ray photoelectron spectroscopy show that the abnormal reduction of Eu3+→Eu2+ occurs in the ceramics, which is due to the formation of VCa′′$V_{Ca}^{^{\prime\prime}}$ vacancy caused by the substitution of Ca2+ by Eu3+, making it act as electron donors. The change of local symmetry of Eu3+ ions in ceramics results in a strong red fluorescence, and the charge transition between Eu, Nb, and Mo ions and O ions in the host lattice results in the near‐ultraviolet (near‐UV) excitation. As a result, CaEuNbMoO8 ceramic materials have promising applications in both near‐ultraviolet excited light‐emitting diodes and thermistors.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Photoluminescence and conductive properties of CaEuNbMoO₈ solid‐solution ceramics

et al. 2022

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A Metal Nanoparticle Thermistor with the Beta Value of 10 000 K

Zhao

Guo

Wang

et al. 2022

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NTC thermistor, metallic oxide powders are mixed with a binder and sintered under high temperature (T ≈400-1450 °C). This step is not energy efficient and, even worse, prevents its use in fields requiring low-temperature processing, e.g., a flexible thermistor. In addition, with the increasing demand for high sensitivity, further improving the performance of ceramic thermistors faces great challenges. Composites of conductive filler in the insulating matrix have been used to improve the sensitivity of the temperature sensor, because the conducting pathways can be disconnected/connected upon swelling/shrinking. However, the temperature window is really small since it has to work near the melting point of crystalline regions. [1] Inspired by the ultrasensitive temperature/heat perception of living creatures, ion-conductive materials have recently attracted considerable attention. [2] For example, a composite of plant cells and carbon nanotubes shows a record high temperature sensitivity due to the increase of "free" conducting calcium cation concentration upon heating. [2b] Various ionic conductive materials (hydrogel, [3] ionic liquid, [2c,4] iongel, [5] etc.) combined with different output modes (resistance, [5a,6] capacitance, [7] voltage, [8] etc.) enable these devices with not only high thermal sensitivity, but also multiple functionalities (flexible, [5b,9] stretchable, [6b,7a] self-healing, [3a,10] etc.), displaying potential applications in electronic skins, prostheses, robots, etc. However, these ionic devices usually require sophisticated fabrication procedures and many of them suffer from poor stability due to the involvement of solvent. Up to now, the widely used NTC thermistor based on these ion-conductive materials with ultra-high sensitivity has been scarcely demonstrated.Metal nanoparticles, because of their physical and chemical attributes, have long been used as elements for sensing various physical (pressure, [11] humidity, [12] temperature, [13] etc.), chemical (organic vapors, [14] metal cations, [15] anions, [16] etc.), and biological (oligonucleotides, [17] proteins, [18] cells, [19] etc.) signals and/or species. Compared with other sensing applications, detecting temperature with metal nanoparticles is usually less efficient. This is due to the measured low activation energy (≈tens of meV), [20] indicating insensitive of their conductance to temperature. It is feasible to adjust the temperature coefficient and sensitivity of metal nanoparticles by various ligand treatments. [21] This method shows a limited increase of the activation energy (100-200 meV) by just tuning the interparticle distance. However, when these nanoparticles are functionalizedThe thermistor, typically made from metallic oxides, is a type of resistor whose electrical resistance is dependent on its temperature. Despite the wide usage, the limitations of ceramic thermistors become increasingly apparent as devices with improved performances are sought and as new applications emerge. Herein, a thermistor that is s...

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New simultaneously doped pyrochlore compounds (Ca1−xCex)2(ZrxNb1−x)2O7 negative temperature coefficient ceramics

Zhang

Xie

Zhang

et al. 2021

J Mater Sci: Mater Electron

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New negative temperature coefficient ceramics in Ca0.9Y0.1MoO4–CeNbO4 system

Cited by 9 publications

References 12 publications

Photoluminescence and conductive properties of CaEuNbMoO₈ solid‐solution ceramics

Photoluminescence and conductive properties of CaEuNbMoO₈ solid‐solution ceramics

A Metal Nanoparticle Thermistor with the Beta Value of 10 000 K

New simultaneously doped pyrochlore compounds (Ca1−xCex)2(ZrxNb1−x)2O7 negative temperature coefficient ceramics

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New negative temperature coefficient ceramics in Ca0.9Y0.1MoO4–CeNbO4 system

Cited by 9 publications

References 12 publications

Photoluminescence and conductive properties of CaEuNbMoO8 solid‐solution ceramics

Photoluminescence and conductive properties of CaEuNbMoO8 solid‐solution ceramics

A Metal Nanoparticle Thermistor with the Beta Value of 10 000 K

New simultaneously doped pyrochlore compounds (Ca1−xCex)2(ZrxNb1−x)2O7 negative temperature coefficient ceramics

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Product

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About

Photoluminescence and conductive properties of CaEuNbMoO₈ solid‐solution ceramics

Photoluminescence and conductive properties of CaEuNbMoO₈ solid‐solution ceramics