From Structure to Signal: Rare‐Earth‐Optimized Ba ₂ R _2/3 TeO ₆ (R = Pr–Lu) for Advanced WLAN Antennas

ABSTRACT High‐performance microwave dielectric ceramics are pivotal for next‐generation communication devices. In order to achieve this, a series of rare‐earth substituted Ba ₂ R _2/3 TeO ₆ (R = Pr to Lu) ceramics were developed through solid‐state ceramic route, and its structural‐microwave dielectric properties were investigated. Monoclinic structure with the P2 ₁ /n space group is confirmed through XRD and Raman spectroscopy. The 𝜀 _r changes from 16 to 13, and a variation from 16 to −28 ppm/°C, is noted for the temperature coefficient of resonant frequency (τ _f ) as the B‐site cations are replaced from Pr to Lu. The decrease in polarizability and covalency from Pr to Lu may be the prime factor for the decrease in relative permittivity along the series. The Raman modes show a red shift correlating with increased 𝜀 _r . The slight decrease in the octahedral bond valence, especially the B─O bond valence from Pr to Lu, suggests the marginal under‐bonding of the B‐site. Additionally, as the bond valence decreases from Pr to Lu, its 𝜀 _r and τ _f also show a decrease. Further, a truncated triangular patch CDRA is designed and fabricated using Ba ₂ Y _2/3 TeO ₆ , with a resonant frequency, bandwidth, and measured gain of 5.815 GHz, 400 MHz, 3.82 dB respectively for the WLAN applications.