Transition-metal substitution in PbAlBO4: Synthesis, structural and spectroscopic studies of manganese containing phases
Transition-metal substitution in PbAlBO4: Synthesis, structural and spectroscopic studies of manganese containing phases
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PbAlBO4 中的过渡金属取代：含锰相的合成、结构和光谱研究
DOI：
10.1016/j.materresbull.2012.03.014
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发表时间：
2012
影响因子：
5.4
通讯作者：
Th. M.
中科院分区：
文献类型：
--
作者：
Murshed;Fischer;Gesing;Th. M.
具有平面BO 3基团的莫来石型金属硼酸盐PbAlBO 4是潜在的非线性光学性质的候选者。我们在PbAl 1 − xMnxBO 4的组成中用锰取代了铝，这将有助于调整晶体化学和相关的物理性质。端元PbAlBO 4通过常规固相反应合成; PbAl 1 − xMnxBO 4系列的其他成员通过甘油法制备。在Rietveld精化中应用基本参数方法来描述X射线粉末衍射谱。晶胞参数和原子间键距相对于化学组成x进行了研究。MO 6八面体畸变随平均MO键距线性增加，这与结构中锰原子量的增加有关。用固溶体中Al/Mn比解释了平均晶粒尺寸和微观应变的变化。而经验键价和（BVS）的一个氧原子，桥接的边缘共享MO 6八面体，被发现是欠键，另一个是过键。用离心率参数的绝对值表征了Pb ~（2+）的6s ~ 2孤电子对的立体活性。|Φi|).铅的键价参数（r 0 i）和BVS均呈线性相关，|Φi|.在1000 cm-1和1400 cm-1之间的红外粉末光谱的吸收特征的解卷积需要四个拟合带，这被指定为三角平面BO 3基团的BO伸缩振动。随着PbAl 1 − xMnxBO 4中Al 3+稀释度的增加，几乎所有观察到的模式都向较低的波数移动，证实了固溶体。在远红外区观察到重原子Pb的振动引起的弛豫。
Mullite-type metal borates PbAlBO4with planar BO3groups are potential candidates for nonlinear optical properties. We successively substituted aluminum with manganese in the composition PbAl1−xMnxBO4, which would help tuning the crystal chemistry and related physical properties. The end member PbAlBO4was synthesized by conventional solid state reaction; the other members of the PbAl1−xMnxBO4series were prepared by glycerin method. The fundamental parameter approach was applied in the Rietveld refinements to describe the X-ray powder diffraction profiles. The cell parameters and interatomic bond distances were studied with respect to the chemical composition x. The MO6octahedral distortion linearly increased with the averaged MO bond distance, which is correlated with the increasing amount of manganese atoms in the structure. The change of the average crystal size and microstrain were explained in terms of Al/Mn ratio in the solid solution. While the empirical bond-valence sums (BVS) of one oxygen atom, bridging the edge-sharing MO6octahedron, were found to be under-bonded, the other one was over-bonded. The stereoactivity of the 6s2lone electron pair of the Pb2+cation was characterized in terms of the absolute value of eccentricity parameter (|Φi|). Both bond valence parameter (r0i) and BVS of Pb showed a linear correlation with |Φi|. Deconvolution of the absorption feature of the infrared powder spectra between 1000cm−1and 1400cm−1required four fitted bands, which were assigned to BO stretching vibrations of the trigonal planar BO3groups. With increasing Al3+dilution in PbAl1−xMnxBO4almost all observed modes shifted toward lower wavenumbers confirming the solid solution. The absorptions caused by the vibrations of the heavy atom Pb were observed in the far-IR region.