Structures of K(0.05)Na(0.95)NbO3 (50-300 K) and K(0.30)Na(0.70)NbO3 (100-200 K).
Structures of K(0.05)Na(0.95)NbO3 (50-300 K) and K(0.30)Na(0.70)NbO3 (100-200 K).
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DOI：
10.1107/s0108768109011057
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发表时间：
2009-06
期刊：
影响因子：
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通讯作者：
N. Zhang;A. M. Glazer;D. Baker;P. Thomas
中科院分区：
文献类型：
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作者：
N. Zhang;A. M. Glazer;D. Baker;P. Thomas
报道了利用中子粉末衍射数据对潜在的无铅压电材料K(x)Na(1 - x)NbO₃（x = 0.05，x = 0.3）在低温下进行的里特韦尔德（Rietveld）精修。确定两种成分的结构都具有菱面体对称性，空间群为R3c，倾斜系统为a(-)a(-)a(-)。发现两种结构中的一些结构参数存在显著差异，特别是NbO₆八面体应变随温度的变化。K(0.05)Na(0.95)NbO₃在300 K时的图谱显示菱面体相和单斜相共存，这表明相界接近室温；K(0.30)Na(0.70)NbO₃的相界约在180 K。
Rietveld refinement using neutron powder diffraction data is reported for the potential lead-free piezoelectric material K(x)Na(1-x)NbO3 (x = 0.05, x = 0.3) at low temperatures. The structures were determined to be of rhombohedral symmetry, space group R3c, with the tilt system a(-)a(-)a(-) for both compositions. It was found that some of the structural parameters differ significantly in the two structures, and particularly the NbO6 octahedral strains as a function of temperature. The 300 K profile for K(0.05)Na(0.95)NbO3 shows the coexistence of rhombohedral and monoclinic phases, which indicates that the phase boundary is close to room temperature; the phase boundary for K(0.30)Na(0.70)NbO3 is found to be at approximately 180 K.