Among existing pyroelectric materials, inorganic polar oxides exhibit large pyroelectric coefficients. However, their pyroelectric performance is severely limited by the high dielectric constants due to the inverse relationship between pyroelectric figures of merit (FOMs) and dielectric constants. On the other hand, organic pyroelectric materials, while having lower dielectric constants and losses, suffer from poor stability, which greatly restricts their application. Regarding the above issues, we present a novel class of polar oxides, Ba₆Pb_3.2(PO₄)₆Cl₂ (BPPC) and Ba₆(Bi_0.5Na_0.5)₄(PO₄)₆Cl₂ (BBNPC), derived from a previously unreported transformation of non-polar apatite structures. These materials exhibit exceptionally low dielectric constants (∼10) and losses (∼0.002), (room-temperature, 10 kHz frequency) combined with high stability. Notably, BPPC demonstrates outstanding pyroelectric performance, with a pyroelectric coefficient of 110 μC m⁻² K⁻¹. The pyroelectric figures of merit (FOMs) for BPPC (room-temperature, 10 kHz frequency, F_v = 0.7 m² C⁻¹, F_D = 17.0 × 10⁻⁵ Pa^1/2, F_E = 5.12 × 10⁻¹¹ m³ J⁻¹) surpass those of most existing inorganic pyroelectrics and approach the performance of leading organic materials. This pioneering doping strategy, leveraging size differentiated atomic substitution to induce spontaneous polarization, opens new avenues for designing high-performance polar oxides with potential applications in ferroelectric, piezoelectric, and photonic technologies. Our findings significantly expand the scope of polar functional materials beyond traditional perovskite-type oxides.

中文翻译：

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具有优异热释电性能的新型极性氧化物：Ba6Pb3.2（PO4）6Cl2 中掺杂诱导的极性转变


在现有的热释电材料中，无机极性氧化物表现出较大的热释电系数。然而，由于热释电品质因数 （FOM） 和介电常数之间存在反比关系，它们的热释电性能受到高介电常数的严重限制。另一方面，有机热释电材料虽然具有较低的介电常数和损耗，但稳定性较差，这极大地限制了其应用。关于上述问题，我们提出了一类新型极性氧化物，Ba₆Pb_3.2（PO₄）₆Cl₂ （BPPC） 和 Ba₆（Bi_0.5Na_0.5）₄（PO₄）₆Cl₂（BBNPC），来源于以前未报道的非极性磷灰石结构的转变。这些材料具有极低的介电常数 （∼10） 和损耗 （∼0.002）（室温，10 kHz 频率）以及高稳定性。值得注意的是，BPPC 表现出出色的热释电性能，热释电系数为 110 μC ^{m-2 K-1}。BPPC（室温，10 kHz 频率，F_v = 0.7 m² C^−1，F _D = 17.0 × 10⁻⁵ Pa^1/2，F _E = 5）的热释电品质因数 （FOM）。12 × ^10-11 m^{3 J-1}）超过了大多数现有的无机热释电体，并接近领先有机材料的性能。这种开创性的掺杂策略利用尺寸差异化原子取代来诱导自发极化，为设计高性能极性氧化物开辟了新的途径，在铁电、压电和光子技术中具有潜在应用。我们的发现显着扩展了极性功能材料的范围，超越了传统的钙钛矿型氧化物。