Microwave-Assisted Hydrothermal Synthesis of Zinc-Aluminum Spinel ZnAl2O4

Strachowski, Tomasz; Grzanka, Ewa; Mizeracki, Jan; Chlanda, Adrian; Baran, M.; Małek, Marcin; Niedziałek, M.

doi:10.3390/ma15010245

Cited by 9 publications

(3 citation statements)

References 65 publications

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“…The peaks evidenced at Bragg angles 2θ = 31.23, 36.83, 44.80, 47.85, 49, 55.65° and 59.34, 62.23, and 65.25° were described to the planes (220), (311), (400), (331), (422), (511), (440) and (531), respectively . This result coincides with JCPDS File no.…”

Section: Resultsmentioning

confidence: 99%

Experimental Investigation of Calcium-Doped Zinc Aluminate Nanoparticles as a Promising Material for Microwave Applications

Didde,

Dubey,

Panda

et al. 2023

ACS Omega

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Miniaturization of microstrip patch antennas (MPAs) is vital in applications such as wireless networks, mobile devices, global positioning satellites, and upcoming wireless terminals. This miniaturization has led to a demand for new materials with higher permittivity compared to the existing ones. Zinc aluminate (ZnAl2O4) ceramic is an exceptional and versatile material in this context, thanks to its high dielectric permittivity and low tangent loss, making it suitable for microwave applications. This article explores the feasibility of sol–gel-prepared Ca-doped ZnAl2O4 ceramic nanoparticles to be useful in fabricating a MPA. These nanoparticles were examined using X-ray diffraction, which confirmed their polycrystalline structure, and the morphological investigation evidenced the spherical grains having a mean diameter of 16 nm. The dielectric permittivity of the ZnAl2O4Ca nanoparticles is 21.11, with a tangential loss of 0.0247. A prototype MPA made by using Ca-doped ZnAl2O4 nanoparticles showed a return loss of −20.92 dB at a resonance frequency of 6.8 GHz with a bandwidth of 600 MHz. These results indicate that Ca-doped ZnAl2O4 ceramic nanoparticles possess exceptional dielectric characteristics, which make them a promising candidate for MPA applications.

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Section: Resultsmentioning

confidence: 99%

Experimental Investigation of Calcium-Doped Zinc Aluminate Nanoparticles as a Promising Material for Microwave Applications

Didde,

Dubey,

Panda

et al. 2023

ACS Omega

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“…Currently, magnesium aluminum spinel is the most widely researched and used. In comparison, zinc aluminum spinel has better acid and alkali resistance and higher thermal conductivity [25][26][27][28][29], and its [AlO 6 ] octahedral coordination environment matches well with Cr 3+ ions. It holds promise for the preparation of fluorescent ceramics for high-power/high-brightness WLEDs.…”

Section: Introductionmentioning

confidence: 99%

Spinel-Based ZnAl2O4: 0.5%Cr3+ Red Phosphor Ceramics for WLED

Ji,

Xu,

Qiang

et al. 2024

Materials

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To address the issue of the lack of red light in traditional Ce3+: YAG-encapsulated blue LED white light systems, we utilized spark plasma sintering (SPS) to prepare spinel-based Cr3+-doped red phosphor ceramics. Through phase and spectral analysis, the SPS-sintered ZnAl2O4: 0.5%Cr3+ phosphor ceramic exhibits good density, and Cr3+ is incorporated into [AlO6] octahedra as a red emitting center. We analyzed the reasons behind the narrow-band emission and millisecond-level lifetime of ZAO: 0.5%Cr3+, attributing it to the four-quadrupole interaction mechanism as determined through concentration quenching modeling. Additionally, we evaluated the thermal conductivity and thermal quenching performance of the ceramic. The weak electron-phonon coupling (EPC) effects and emission from antisite defects at 699 nm provide positive assistance in thermal quenching. At a high temperature of 150 °C, the thermal conductivity reaches up to 14 W·m−1·K−1, and the 687 nm PL intensity is maintained at around 70% of room temperature. Furthermore, the internal quantum efficiency (IQE) of ZAO: 0.5%Cr3+ phosphor ceramic can reach 78%. When encapsulated with Ce3+: YAG for a 450 nm blue LED, it compensates for the lack of red light, adjusts the color temperature, and improves the color rendering index (R9). This provides valuable insights for the study of white light emitting diodes (WLEDs).

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“…Therefore, the purpose of the present work is to experimentally investigate the structural, optical, and electrical transport properties of pure and Cu-doped ZnAl 2 O 4 . There are many methods to synthesis ZnAl 2 O 4 such as solid-state reaction, co-precipitation, sol-gel, and hydrothermal [24][25][26][27][28]. In the present work, zinc aluminate is synthesized by hydrothermal method owing to its simplicity and cost-effectiveness.…”

Section: Introductionmentioning

confidence: 99%

Investigation of structural, morphological, thermal, and thermoelectric properties of Zn_1−xCu_xAl₂O₄ (0.0 ≤ x ≤ 0.1)

Radha

Rajkumar

Arivanandhan

et al. 2023

Mater. Res. Express

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Most promising oxide thermoelectric materials such as perovskites, layered oxide materials, Al-doped ZnO, etc., have been reported. In the present work, Zn1-xCuxAl2O4 (0.0≤ x ≤0.1) samples were synthesized by a simple hydrothermal method. The structural, optical, morphological, and TE properties of Zn1-xCuxAl2O4 (0.0≤ x ≤0.1) have been investigated. XRD analysis reveals that ZnAl2O4 has a single-phase cubic structure and Cu is completely dissolved in the ZnAl2O4 lattice. Thermal analysis shows that ZnAl2O4 has high thermal stability up to 1000 °C. From the UV-Vis DRS analysis, the energy band gap of ZnAl2O4 decreased from 3.30 eV to 2.82 eV with increasing the content of Cu. Carrier concentration and mobility of the samples were measured by the Hall effect. The values of a carrier concentration of undoped ZnAl2O4 and Zn0.9Cu0.1Al2O4 are obtained to be 3.836×1013 cm-3 and 3.3×1016 cm-3 at 313 K and 9.6×1013 cm-3 for pure and 5.5×1016 cm-3 for Zn0.9Cu0.1Al2O4 at 673 K. TE properties of the synthesized samples have been analyzed as a function of temperature. With the optimum values of Seebeck coefficient and electrical conductivity, Zn0.9Cu0.1Al2O4 shows the highest power factor of 0.50 μW/mK2 while the pure ZnAl2O4 shows a maximum power factor of 0.19 μW/mK2 at 673 K. The Zn0.9Cu0.1Al2O4 exhibits a relatively high zT of 2.4×10-4 at 673 K, while pure ZnAl2O4 has a zT value of 0.4×10-4 at 673 K. The obtained values reveal the improvement of TE properties by increasing the Cu content in the sample.

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Microwave-Assisted Hydrothermal Synthesis of Zinc-Aluminum Spinel ZnAl2O4

Cited by 9 publications

References 65 publications

Experimental Investigation of Calcium-Doped Zinc Aluminate Nanoparticles as a Promising Material for Microwave Applications

Experimental Investigation of Calcium-Doped Zinc Aluminate Nanoparticles as a Promising Material for Microwave Applications

Spinel-Based ZnAl2O4: 0.5%Cr3+ Red Phosphor Ceramics for WLED

Investigation of structural, morphological, thermal, and thermoelectric properties of Zn_1−xCu_xAl₂O₄ (0.0 ≤ x ≤ 0.1)

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Microwave-Assisted Hydrothermal Synthesis of Zinc-Aluminum Spinel ZnAl2O4

Cited by 9 publications

References 65 publications

Experimental Investigation of Calcium-Doped Zinc Aluminate Nanoparticles as a Promising Material for Microwave Applications

Experimental Investigation of Calcium-Doped Zinc Aluminate Nanoparticles as a Promising Material for Microwave Applications

Spinel-Based ZnAl2O4: 0.5%Cr3+ Red Phosphor Ceramics for WLED

Investigation of structural, morphological, thermal, and thermoelectric properties of Zn1−xCuxAl2O4 (0.0 ≤ x ≤ 0.1)

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Investigation of structural, morphological, thermal, and thermoelectric properties of Zn_1−xCu_xAl₂O₄ (0.0 ≤ x ≤ 0.1)