High-performance, high-temperature piezoelectric BiB₃O₆ crystals

High-performance piezoelectric materials are desirable for piezoelectric sensing applications. In this paper, piezoelectric α-BiB₃O₆ (BIBO) crystals were explored for high temperature sensing. Dielectric, piezoelectric and electromechanical properties were evaluated by using the impedance method, from which the piezoelectric charge coefficients were determined to be d₁₄ = 10.9, d₁₆ = 13.9, d₂₁ = 16.7, d₂₂ = 40.0, d₂₃ = 2.5, d₂₅ = 4.3, d₃₄ = 18.7 and d₃₆ = 13.0 pC/N, with corresponding piezoelectric voltage coefficients g₁₄ = 122, g₁₆ = 144, g₂₁ = 225, g₂₂ = 538, g₂₃ = 34, g₂₅ = 58, g₃₄ = 165 and g₃₆ = 121 × 10^-3 V m N^-1 at room temperature (RT). Of particular significance is that the receiving sensitivity of BIBO crystals was found to be 47.2 pm² N^-1, nearly one order of magnitude higher than that of LiNbO₃ crystals. Moreover, the BIBO crystals were found to possess a high mechanical quality factor Q_m (13000 at RT and >1000 at 600 °C), low dielectric loss (<0.1% at RT and 15% at 600 °C and 1 kHz), high electrical resistivity (∼2.5 × 10⁸ Ω cm at 600 °C) and high temperature stability of piezoelectric coefficients (variations <±10%). All these properties demonstrate that BIBO crystals are promising for piezoelectric sensing over a broad temperature range.