There are few known semiconductors exhibiting both strong optical response and large dielectric polarizability. Inorganic materials with large dielectric polarizability tend to be wide-band gap complex oxides. Semiconductors with a strong photoresponse to visible and infrared light tend to be weakly polarizable. Interesting exceptions to these trends are halide perovskites and phase-change chalcogenides. Here we introduce complex chalcogenides in the Ba-Zr-S system in perovskite and Ruddlesden-Popper structures as a family of highly polarizable semiconductors. We report the results of impedance spectroscopy on single crystals that establish $\mathrm{BaZr}{\mathrm{S}}_3$ and ${\mathrm{Ba}}_3{\mathrm{Zr}}_2{\mathrm{S}}_7$ as semiconductors with a low-frequency relative dielectric constant ${\varepsilon }_0$ in the range 50–100 and band gap in the range 1.3–1.8 eV. Our electronic structure calculations indicate that the enhanced dielectric response in perovskite $\mathrm{BaZr}{\mathrm{S}}_3$ versus Ruddlesden-Popper ${\mathrm{Ba}}_3{\mathrm{Zr}}_2{\mathrm{S}}_7$ is primarily due to enhanced IR mode-effective charges and variations in phonon frequencies along 〈001〉; differences in the Born effective charges and the lattice stiffness are of secondary importance. This combination of covalent bonding in crystal structures more common to complex oxides, but comprising sulfur, results in a sizable Fröhlich coupling constant, which suggests that charge carriers are large polarons.

中文翻译：

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发现高度极化的半导体BaZrS3和Ba3Zr2S7

很少有既显示强光学响应又显示大介电极化率的半导体。具有大的介电极化率的无机材料倾向于是宽带隙复合氧化物。对可见光和红外光具有强烈光响应的半导体往往具有弱极化性。这些趋势的有趣例外是卤化钙钛矿和相变硫属化物。在这里，我们在钙钛矿和Ruddlesden-Popper结构的Ba-Zr-S系统中引入了复杂的硫族化物，作为一类高度极化的半导体。我们报告了建立单晶的阻抗谱的结果$\mathrm{BaZr}{\mathrm{小号}}_3$ 和 ${\mathrm{巴}}_3{\mathrm{锆}}_2{\mathrm{小号}}_7$ 作为具有低频相对介电常数的半导体 ${\varepsilon }_0$在50–100范围内，带隙在1.3–1.8 eV范围内。我们的电子结构计算表明钙钛矿中增强的介电响应$\mathrm{BaZr}{\mathrm{小号}}_3$ 对阵Ruddlesden-Popper ${\mathrm{巴}}_3{\mathrm{锆}}_2{\mathrm{小号}}_7$主要是由于增强的IR模式有效电荷​​以及声子频率沿<001>的变化所致；次生有效电荷和晶格刚度的差异是次要的。晶体结构中共价键的这种结合对复合氧化物更常见，但包含硫，导致相当大的Fröhlich耦合常数，这表明电荷载流子为大极化子。