We report the crystal structures and physical properties of trilayer nickelates Nd₄Ni₃O₁₀ and Nd₄Ni₃O₈. Measurements of magnetization and electrical resistivity display contrasting behaviors in the two compounds. Nd₄Ni₃O₁₀ shows a paramagnetic metallic behavior with a metal-to-metal phase transition (T*) at about 162 K, as revealed by both magnetic susceptibility and resistivity. Further magnetoresistance and Hall coefficient results show a negative magnetoresistance at low temperatures and the carrier type of Nd₄Ni₃O₁₀ is dominated by hole-type charge carriers. The significant enhancement of Hall coefficient and resistivity below T* suggests that effective charge carrier density decreases when cooling through the transition temperature. In contrast, Nd₄Ni₃O₈ shows an insulating behavior. In addition, this compound shows a paramagnetic behavior with the similar magnetic moment as that of Nd₄Ni₃O₁₀ derived from the Curie-Weiss fitting. This may suggest that the magnetic moments in both systems are contributed by Nd³⁺ ions. By applying pressures up to about 49 GPa, the insulating behavior is still present and becomes even stronger under a high pressure. Our results suggest that the different Ni configurations (Ni^1+/2+ or Ni^2+/3+) and the changes of coordination environment of Ni sites may account for the contrasting behaviors in trilayer nickelates Nd₄Ni₃O₁₀ and Nd₄Ni₃O₈.

我们报告了三层镍酸盐Nd ₄ Ni ₃ O ₁₀和Nd ₄ Ni ₃ O ₈的晶体结构和物理性质。磁化强度和电阻率的测量显示了两种化合物的对比行为。Nd ₄ Ni ₃ O ₁₀表现出顺磁金属行为，在162 K左右具有金属到金属的相变（T *），如磁化率和电阻率所揭示。进一步的磁阻和霍尔系数结果表明，在低温和Nd ₄ Ni ₃ O的载流子类型下为负磁阻₁₀是由空穴型电荷载流子主导。霍尔系数和低于T *的电阻率的显着提高表明，当冷却至转变温度时，有效电荷载流子密度会降低。相反，Nd ₄ Ni ₃ O ₈显示出绝缘行为。另外，该化合物显示出与源自居里-魏斯拟合的Nd ₄ Ni ₃ O ₁₀具有相似磁矩的顺磁行为。这可能表明两个系统中的磁矩都是由Nd ³⁺贡献的。离子。通过施加高达49 GPa的压力，绝缘性能仍然存在，并且在高压下甚至变得更强。我们的结果表明，不同的Ni构型（Ni ^{1 + / 2 +}或Ni ^{2 + / 3 +}）和Ni位的配位环境的变化可能解释了三层镍酸盐Nd ₄ Ni ₃ O ₁₀和Nd _4中的对比行为。Ni ₃ O ₈。