International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
J Am Chem Soc. 2011 Jun 22;133(24):9405-12. doi: 10.1021/ja2010362. Epub 2011 May 23.
LiNbO(3) (LN), corundum (cor), and hexagonal (hex) phases of (In(1-x)M(x))MO(3) (x = 0.143; M = Fe(0.5)Mn(0.5)) were prepared. Their crystal structures were investigated with synchrotron X-ray powder diffraction, and their properties were studied by differential thermal analysis, magnetic measurements, and Mössbauer spectroscopy. The LN-phase was prepared at high pressure of 6 GPa and 1770 K; it crystallizes in space group R3c with a = 5.25054(7) Å, c = 13.96084(17) Å, and has a long-range antiferromagnetic ordering near T(N) = 270 K. The cor- and hex-phases were obtained at ambient pressure by heating the LN-phase in air up to 870 and 1220 K, respectively. The cor-phase crystallizes in space group R-3c with a = 5.25047(10) Å, c = 14.0750(2) Å, and the hex-phase in space group P6(3)/mmc with a = 3.34340(18) Å, c = 11.8734(5) Å. T(N) of the cor-phase is about 200 K, and T(N) of the hex-phase is about 140 K. During irreversible transformations of LN-(In(1-x)M(x))MO(3) with the (partial) cation ordering, the In(3+), Mn(3+), and Fe(3+) cations become completely disordered in one crystallographic site of the corundum structure, and then they are (partially) ordered again in the hex-phase. LN-(In(1-x)M(x))MO(3) exhibits a reversible transformation to a perovskite GdFeO(3)-type structure (space group Pnma; a = 5.2946(3) Å, b = 7.5339(4) Å, c = 5.0739(2) Å at 10.3 GPa) at room temperature and pressure of about 5 GPa.
LiNbO(3)（LN）、刚玉（cor）和（In(1-x)M(x))MO(3）的六方（hex）相（x = 0.143；M = Fe(0.5)Mn(0.5)）被制备。它们的晶体结构通过同步加速器 X 射线粉末衍射进行了研究，通过差热分析、磁测量和穆斯堡尔谱研究了它们的性质。LN 相在 6 GPa 和 1770 K 的高压下制备；它在空间群 R3c 中结晶，具有 a = 5.25054(7)Å、c = 13.96084(17)Å，并在 T(N) = 270 K 附近具有长程反铁磁有序。cor 和 hex 相通过在空气中将 LN 相加热至 870 和 1220 K 分别在常压下获得。cor 相在空间群 R-3c 中结晶，具有 a = 5.25047(10)Å、c = 14.0750(2)Å，hex 相在空间群 P6(3)/mmc 中结晶，具有 a = 3.34340(18)Å、c = 11.8734(5)Å。cor 相的 T(N)约为 200 K，hex 相的 T(N)约为 140 K。在 LN-(In(1-x)M(x))MO(3)与（部分）阳离子有序的不可逆转变过程中，In(3+)、Mn(3+)和 Fe(3+)阳离子在刚玉结构的一个晶位中完全无序，然后在 hex 相中再次（部分）有序。LN-(In(1-x)M(x))MO(3)在室温下表现出可逆转变为钙钛矿 GdFeO(3)-型结构（空间群 Pnma；a = 5.2946(3)Å、b = 7.5339(4)Å、c = 5.0739(2)Å，在 10.3 GPa 下）和约 5 GPa 的压力。
