Optimization of pyroelectric figures of merit via magnesia doping in lithium tantalate single crystal

Abstract

This paper reports a series of experiments and optimization based on pyroelectric figures of merit (FoMs), which demonstrate that the proper doping of magnesia (MgO) can improve the thermal performance of lithium tantalate (LiTaO3) in infrared sensors. Starting with MgO-doped LiTaO3 grown by the Czochralski method, the heat capacity, pyroelectric coefficients and dielectric parameters of these single crystals are then investigated systematically. By considering the ultraviolet and infrared spectra, the variation of the electrical parameters and the occupation mechanism of MgO doping could be explained. It is found that the dopant increases the Curie temperature and broadens the operating temperature of pyroelectric devices. Notably, compared with congruent LiTaO3, when the doping concentration reaches 5 mol%, the corresponding voltage responsivity and specific detectivity FoMs are enhanced by ten and two times, respectively.

Pyroelectric Properties and Applications of Lithium Tantalate Crystals

“…The pyroelectric properties are related to the material properties and the subsequent processing of the materials. By doping other ions, the material properties can be changed, reducing the defects inside the crystals and improving the pyroelectric properties [6]. The subsequent processing of materials mainly includes reducing the thickness of the wafers and coating the surface with an absorption layer to improve the pyroelectric properties.…”

“…Pyroelectric detectors are categorized as single-element detectors, two-dimensional Proper doping can improve the thermal properties of LT crystals, resulting in an increase in the T C of the crystals and an increase in the operating temperature range. Tang et al [6] studied Mg-doped LT crystals and found that there is also an optimum point in their pyroelectric properties. When the doping concentration is below 4 mol%, their pyroelectric coefficients are significantly lower than when they are undoped.…”

“…TGS has the largest pyroelectric coefficient (350 µC/m 2 K), but its T C is the smallest, which makes it unsuitable for operation at high temperatures [5]. The LT crystal has a T C of 605 • C and a pyroelectric coefficient of 190 µC/m 2 K, which is twice that of the LN [4,6,7], and it is the best pyroelectric crystal with comprehensive performance. Therefore, LT crystals that can maintain the ferroelectric phase over a wide range of temperatures become one of the best materials for making pyroelectric detectors [6].…”

“…The LT crystal has a T C of 605 • C and a pyroelectric coefficient of 190 µC/m 2 K, which is twice that of the LN [4,6,7], and it is the best pyroelectric crystal with comprehensive performance. Therefore, LT crystals that can maintain the ferroelectric phase over a wide range of temperatures become one of the best materials for making pyroelectric detectors [6]. The optical damage threshold value of the LT crystal is 1500 W/cm 2 , which is nearly 40 times that of the LN crystal, giving LT a higher ability to detect high-power laser radiation than LN [8].…”

Carbon Dioxide Sensor Module Based on NDIR Technology

“…Compared with metal oxide ceramic PZT [6][7][8][9] and BST [10], single-crystal material lithium tantalate generally has better pyroelectric properties. For example, lithium tantalate has the characteristics of a large pyroelectric coefficient, high Curie temperature, high detectivity, and small dielectric constant [11][12][13]. It is an ideal material for preparing pyroelectric sensors, so it has been widely used in pyroelectric detectors.…”