Nanostructural Free-Volume Effects in Humidity-Sensitive MgO-Al2O3 Ceramics for Sensor Applications

Klym, Halyna; Ingram, Adam; Shpotyuk, O.; Hadzaman, I.; Hotra, O.; Kostiv, Yuriy M.

doi:10.1007/s11665-016-1931-9

Cited by 33 publications

(10 citation statements)

References 45 publications

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“…This process is captured in the nearest environment of spinel phase, as it follows from τ b GE = 0.195-0.235 ns, the values approaching defect-free bulk positron lifetimes in MgAl 2 O 4 ceramics sintered at different T s (Klym et al 2014;Klym et al 2016b). The water sorption is more pronounced in structurally imperfect ceramics sintered at T s = 1100-1200 °C due to irreversible transformations within inner pores between constituting MgO and Al 2 O 3 phases (resulting in increased GE b ~ 1.3-1.5 ns −1 ).…”

Section: Resultsmentioning

confidence: 99%

“…The alumomagnesium MgAl 2 O 4 spinel ceramics were sintered at different temperatures (T s ) of 1100, 1200, 1300 and 1400 °C during 2 h, which are deterministic in their microstructure perfectness, the more detailed description of technological route being presented in Klym et al (2014Klym et al ( , 2016b. In respect to X-ray diffraction measurements, the ceramics prepared at lower T s = 1100-1200 °C are composed of main spinel phase and large amount of additional MgO and Al 2 O 3 phases (up to 12%), while the ceramics sintered at high T s = 1300-1400 °C contain additionally only MgO phase in the amount of 3.5 and 1.5%, respectively.…”

Section: Ceramics Preparation Routementioning

confidence: 99%

“…This decomposition route allows studying only one annihilation channel directly related to watersorption processes, namely the catalytic effect revealed due to preferential Ps decaying in open pores filled with adsorbed water (Filipecki et al 2007). At high-statistical measurements (more than 1 M counts), the best results were obtained with unconstrained x4-term decomposition (Klym et al 2016a;Klym et al 2016b), which allow to study nanopores of more extended sizes, responsible for o-Ps decaying. Each PAL spectrum was processed multiple times owing to slight changes in the number of channels, annihilation background and time shift of the 0-th channel.…”

Section: Pal Spectra Measurement Proceduresmentioning

confidence: 99%

See 2 more Smart Citations

Atomic-deficient nanostructurization in water-sorption alumomagnesium spinel ceramics MgAl2O4

Ingram

2018

Appl Nanosci

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Atomic-deficient nanostructurization in alumomagnesium MgAl 2 O 4 ceramics sintered at 1100-1400 °C caused by water sorption are studied employing positron annihilation lifetime spectroscopy. Detected PAL spectra are reconstructed from unconstrained x4-term decomposition, and further transformed to x3-term form to be applicable for analysis with x3-x2-CDA (coupling decomposition algorithm). It is proved that water-immersion processes reduce positronium (Ps) decaying in largesize holes of ceramics (1.70-1.84 nm in radius) at the expense of enhanced trapping in tiny (~ 0.2 nm in radius) Ps-traps. The water sorption is shown to be more pronounced in structurally imperfect ceramics sintered at T s = 1100-1200 °C due to irreversible transformations between constituting phases, while reversible physical-sorption processes are dominated in structurally uniform ceramics composed of main spinel phase.

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Section: Resultsmentioning

confidence: 99%

Section: Ceramics Preparation Routementioning

confidence: 99%

Section: Pal Spectra Measurement Proceduresmentioning

confidence: 99%

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Atomic-deficient nanostructurization in water-sorption alumomagnesium spinel ceramics MgAl2O4

Ingram

2018

Appl Nanosci

Self Cite

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“…In both cases, the initial components were taken in a molar ratio of 1:1. The maximum sintering temperatures ( T s ) of the MgAl 2 O 4 ceramics in both cases were 1200, 1300, and 1400 °C, duration 2 h. [ 37,42 ] The average density for the studied ceramics was 1.4 g cm −3 .…”

Section: Methodsmentioning

confidence: 99%

Extended Positron–Positronium Trapping Defects in the MgAl₂O₄ Spinel Ceramics

Klym

Hadzaman

Vilá

et al. 2022

Physica Status Solidi (b)

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Extended free‐volume positron trapping defects (positron trapping channel) and nanopores (positronium decaying channel) in the initial and modified MgAl2O4 ceramics sintered at 1200, 1300, and 1400 °C are investigated using positron annihilation lifetime spectroscopy within four‐component fitting procedure. It is established that the number and size of extended defects near grain boundaries (described by the second component) decrease with increasing sintering temperature of ceramics, which correlates with the content of additional phases in the materials. The agglomeration of nanopores occurs in the initial ceramics (described by the third component) and the decrease of number and size of nanopores in the modified ceramics. The corresponding processes of the evolution of nanopores described by the fourth component are reflected mainly in their reduction, except for ceramics sintered at 1400 °C. Such changes are associated with the evolution of porous structure and increased contact area between the grains of ceramics.

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“…Humidity detection has attracted tremendous attention due to its wide and essential application in industry, − environmental protection, , and personal life. − For the last few decades, many materials have been developed to improve the performance of humidity sensors, such as traditional conductive polymers, − ceramics, − metal oxide semiconductors, − carbon based materials, − and so on. However, few of these sensory materials can satisfy the full requirements of simple operation, specific recognition, high sensitivity/stability, and fast response and recovery at the same time.…”

mentioning

confidence: 99%

Missing-Linker 2D Conductive Metal Organic Frameworks for Rapid Gas Detection

Liu

Cheng

et al. 2021

ACS Sens.

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The structural diversity and tunability of metal organic frameworks (MOFs) represent an ideal material platform for a variety of practical scenarios ranging from gas storage/separation to catalysis, yet their application in chemiresistive gas sensing is relatively lacking, due to the requirements of combined electrical conductivity and optimized gas adsorption properties. Here, we report an effective chemical sensing strategy based on missing-linker two-dimensional conductive MOF, with incorporated defects via a simple ligand oxidization method. The multiple hydroxyl defect sites in the conductive 2D missing-linker amorphous Ni-HAB (aNi-HAB) enable rapid adsorption and desorption of water molecules compared to crystalline Ni-HAB (cNi-HAB). As a result, the aNi-HAB sensory device shows good sensitivity, selectivity, linearity, fast response/recovery rate, and excellent stability, which can be further improved by Nafion functionalization. Theoretical investigations including transient current measurement, density functional theory (DFT) calculations, and systematic performance evaluation of isostructural 2D aM-HAB (M = Cu, Fe, Co) MOF showed that unique transport mechanism and adsorption/activation energies originated from hydrogen bonding at defective sites are critical for enhanced humidity response, and further confirmed that defect engineering through missing linker incorporation is a general and effective approach to tune the sensing properties of conductive MOF materials.

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Nanostructural Free-Volume Effects in Humidity-Sensitive MgO-Al2O3 Ceramics for Sensor Applications

Cited by 33 publications

References 45 publications

Atomic-deficient nanostructurization in water-sorption alumomagnesium spinel ceramics MgAl2O4

Atomic-deficient nanostructurization in water-sorption alumomagnesium spinel ceramics MgAl2O4

Extended Positron–Positronium Trapping Defects in the MgAl₂O₄ Spinel Ceramics

Missing-Linker 2D Conductive Metal Organic Frameworks for Rapid Gas Detection

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Nanostructural Free-Volume Effects in Humidity-Sensitive MgO-Al2O3 Ceramics for Sensor Applications

Cited by 33 publications

References 45 publications

Atomic-deficient nanostructurization in water-sorption alumomagnesium spinel ceramics MgAl2O4

Atomic-deficient nanostructurization in water-sorption alumomagnesium spinel ceramics MgAl2O4

Extended Positron–Positronium Trapping Defects in the MgAl2O4 Spinel Ceramics

Missing-Linker 2D Conductive Metal Organic Frameworks for Rapid Gas Detection

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Extended Positron–Positronium Trapping Defects in the MgAl₂O₄ Spinel Ceramics