Enhanced Pyroelectric Response of Lithium Niobate Crystals for Infrared Detection Applications

This work addresses the low pyroelectric coefficient that limits the practical application of lithium niobate (LN) crystals. A defect modulation process based on reduction annealing treatment is proposed. This reduction annealing treatment increased the pyroelectric coefficient of LN crystals maximally to 3.362 × 10^-4 C/m²K. At room temperature, the voltage responsivity figure of merit (F_V) and detectivity figure of merit (F_D) were both improved more than three-fold. All material properties exceeded those of commercial lead zirconate titanate (PZT) ceramic. This process achieves the simultaneous modulation of high pyroelectric coefficients and low impedance in LN crystals. Based on the LN crystals with optimized properties, pyroelectric infrared detectors (center wavelength 9.4 μm) without external matching resistors were prepared. The response voltage of the detector reached 2.8 times that of commercial PZT detectors while exhibiting lower noise, and has achieved practical applicability. This work provides a simple and efficient method for developing environmentally friendly, low-cost, high-sensitivity pyroelectric infrared detectors. It also establishes the foundations for the application of LN crystals in emerging pyroelectric detection fields.