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Novel Method to Achieve Temperature-Stable Microwave Dielectric Ceramics: A Case in the Fergusonite-Structured NdNbO 4 System.
- Source :
-
ACS applied materials & interfaces [ACS Appl Mater Interfaces] 2023 Apr 19; Vol. 15 (15), pp. 19129-19136. Date of Electronic Publication: 2023 Apr 05. - Publication Year :
- 2023
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Abstract
- Microwave dielectric ceramics with permittivity (ε <subscript>r</subscript> ) ∼ 20 play an important role in massive multiple-input multiple-output (MIMO) technology in 5G. Although fergusonite-structured materials with low dielectric loss are good candidates for 5G application, tuning the temperature coefficient of resonant frequency (TCF) remains a problem. In the present work, smaller V <superscript>5+</superscript> ions ( r <subscript>V</subscript> = 0.355 Å, with coordination number (CN) = 4) were substituted for Nb <superscript>5+</superscript> ( r <subscript>Nb</subscript> = 0.48 Å with CN = 4) in the Nd(Nb <subscript>1- x </subscript> V <subscript>x</subscript> )O <subscript>4</subscript> ceramics, which, according to in situ X-ray diffraction data, lowered the fergusonite-to-scheelite phase transition ( T <subscript>F-S</subscript> ) to 400 °C for x = 0.2. The thermal expansion coefficient (α <subscript>L</subscript> ) of the high-temperature scheelite phase was +11 ppm/°C, whereas for the low-temperature fergusonite phase, it was + 14 < α <subscript>L</subscript> < + 15 ppm/°C. The abrupt change in α <subscript>L</subscript> , the associated negative temperature coefficient of permittivity (τ <subscript>ε</subscript> ), and the minimum value of ε <subscript>r</subscript> at T <subscript>F-S</subscript> resulted in a near-zero TCF ∼ (+7.8 ppm/°C) for Nd(Nb <subscript>0.8</subscript> V <subscript>0.2</subscript> )O <subscript>4</subscript> (ε <subscript>r</subscript> ∼ 18.6 and Qf ∼ 70,100 GHz). A method to design near-zero TCF compositions based on modulation of τ <subscript>ε</subscript> and α <subscript>L</subscript> at T <subscript>F-S</subscript> is thus demonstrated that may also be extended to other fergusonite systems.
Details
- Language :
- English
- ISSN :
- 1944-8252
- Volume :
- 15
- Issue :
- 15
- Database :
- MEDLINE
- Journal :
- ACS applied materials & interfaces
- Publication Type :
- Academic Journal
- Accession number :
- 37018740
- Full Text :
- https://doi.org/10.1021/acsami.2c23180