Abstract Mean-field models for behavior of ferroelectric (FE) crystals like KH2PO4 (KDP) succeed well in explaining behavior in the paraelectric (PE) phase in which the various phosphate groups HiPO4 (i = 1, 2, or 3) groups are distributed quite randomly. However, they underestimate the spontaneous polarization Ps in the FE phase, in which these groups are distributed quite nonrandomly. Instead, within the background of H2PO4 groups of either “all up” or “all down” polarity along the c axis, there are chains of nonpolar “Slater” H2PO4 groups with an H3PO4 “Takagi” group at one end and an HPO4 “Takagi” group at the other. Explained herein is the “bound charge semiconductor” model for the creation, growth, and interactions of such chains. It is then applied to show how these chains reduce Ps below the value it would have if all groups were H2PO4 groups of the same polarity. Comparison is made with the predictions of Ps for a mean field model.

中文翻译：

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束缚电荷半导体模型比平均场模型更好地解释了 KDP 型晶体自发极化行为

摘要 铁电 (FE) 晶体如 KH2PO4 (KDP) 行为的平均场模型成功地解释了顺电 (PE) 相中的行为，其中分布着各种磷酸基团 HiPO4 (i = 1、2 或 3)相当随机。然而，他们低估了 FE 相中的自发极化 Ps，其中这些基团非常非随机地分布。相反，在沿 c 轴“全部向上”或“全部向下”极性的 H2PO4 基团的背景下，存在非极性的“Slater”H2PO4 基团链，一端带有 H3PO4“Takagi”基团和 HPO4“Takagi” ”另一组。此处解释的是用于此类链的产生、生长和相互作用的“束缚电荷半导体”模型。然后应用它来显示这些链如何将 Ps 降低到低于所有基团都是相同极性的 H2PO4 基团时的值。与平均场模型的 Ps 预测进行比较。