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<p>The effects of substituting Zn<sup>2+</sup> and Ba<sup>2+</sup> for Ca<sup>2+</sup> on the crystal structure, sintering temperature, microstructure, and microwave dielectric properties of (Ca<sub>1 − <i>x</i></sub> M<sub><i>x</i></sub>)VO<sub>6</sub> (M = Zn, Ba) [<i>x</i> = 0.025–0.10] have been studied. X-ray diffraction, along with refinement results, indicate that all the samples had a monoclinic crystal structure with C2/m space group, and the cationic substitutions affect the cell volume of the ceramics while retaining the crystal structure. Both Zn<sup>2+</sup> and Ba<sup>2+</sup> at Ca<sup>2+</sup> in small percentages improved the density and dielectric properties. The (Ca<sub>0.95</sub> Zn<sub>0.05</sub>)V<sub>2</sub>O<sub>6</sub> ceramic sintered at 650&#xa0;°C achieved <i>ε</i><sub><i>r</i></sub> = 10.6, <i>Q</i> × <i>f</i> = 42,400&#xa0;GHz and <i>τ</i><sub><i>f</i></sub> =  − 60&#xa0;ppm/°C, while the (Ca<sub>0.95</sub> Ba<sub>0.05</sub>)V<sub>2</sub>O<sub>6</sub> ceramic sintered at 600&#xa0;°C showed <i>ε</i><sub><i>r</i></sub> = 10.1, <i>Q</i> × <i>f</i> = 46,100&#xa0;GHz, and <i>τ</i><sub><i>f</i></sub> =  − 59&#xa0;ppm/°C. All the (Ca<sub>1 − <i>x</i></sub> M<sub><i>x</i></sub>) VO<sub>6</sub> ceramics exhibited a negative value of <i>τ</i><sub><i>f</i></sub>. The chemical compatibility with metal electrode was investigated by cofiring both ceramics with Aluminium (Al) metal at the optimised sintering temperature. XRD and EDS analysis confirmed the non-existence of reaction between ceramic and metal and formation of any other secondary phases, indicating significant potential of the ceramics for use in ULTCC applications. Furthermore, a 2-section Wilkinson power divider operating in the L band has been designed and fabricated onto the ULTCC ceramic by screen printing techniques using low temperature curable silver epoxy paste. The fabricated power divider showed a maximum insertion loss of 4.8&#xa0;dB and a minimum isolation of 14&#xa0;dB in 1–1.7&#xa0;GHz matching with the simulation.</p>

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(Ca1 − x Mx)V2O6 (M = Zn, Ba) ultra-low temperature co-firable ceramics for microwave power divider applications

  • 期刊论文

  • 发表日期：

    2025年3月8日

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  • B. Masin,
  • K. Ashok,
  • Manoj Joseph,
  • L. Yerrinaidu,
  • K. Jalaja,
  • Femina Beegum,
  • K. Prabhakaran,
  • H. Sreemoolanadhan

摘要

The effects of substituting Zn2+ and Ba2+ for Ca2+ on the crystal structure, sintering temperature, microstructure, and microwave dielectric properties of (Ca1 − x Mx)VO6 (M = Zn, Ba) [x = 0.025–0.10] have been studied. X-ray diffraction, along with refinement results, indicate that all the samples had a monoclinic crystal structure with C2/m space group, and the cationic substitutions affect the cell volume of the ceramics while retaining the crystal structure. Both Zn2+ and Ba2+ at Ca2+ in small percentages improved the density and dielectric properties. The (Ca0.95 Zn0.05)V2O6 ceramic sintered at 650 °C achieved εr = 10.6, Q × f = 42,400 GHz and τf =  − 60 ppm/°C, while the (Ca0.95 Ba0.05)V2O6 ceramic sintered at 600 °C showed εr = 10.1, Q × f = 46,100 GHz, and τf =  − 59 ppm/°C. All the (Ca1 − x Mx) VO6 ceramics exhibited a negative value of τf. The chemical compatibility with metal electrode was investigated by cofiring both ceramics with Aluminium (Al) metal at the optimised sintering temperature. XRD and EDS analysis confirmed the non-existence of reaction between ceramic and metal and formation of any other secondary phases, indicating significant potential of the ceramics for use in ULTCC applications. Furthermore, a 2-section Wilkinson power divider operating in the L band has been designed and fabricated onto the ULTCC ceramic by screen printing techniques using low temperature curable silver epoxy paste. The fabricated power divider showed a maximum insertion loss of 4.8 dB and a minimum isolation of 14 dB in 1–1.7 GHz matching with the simulation.