Segregation study and segregation modeling of Ti in Pb[(Mg1/3Nb2/3)0.60Ti0.40]O3 single crystal grown by Bridgman method
Segregation study and segregation modeling of Ti in Pb[(Mg1/3Nb2/3)0.60Ti0.40]O3 single crystal grown by Bridgman method
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DOI：
10.1016/j.materresbull.2005.11.012
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发表时间：
2006-06-15
影响因子：
5.4
通讯作者：
Beylat, L
中科院分区：
文献类型：
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作者：
Benayad, A;Sebald, G;Beylat, L
采用布里奇曼法合成了弛豫铁电0.60Pb(Mg1/3Nb2/3)O-3-0.40PbTiO(3)单晶。通过各种物理化学表征技术观察了沿该晶体长度的偏析。首先，我们注意到晶体结构沿着生长晶体的长度的演变。四方性因子 c/a 从 1.013 增加到 1.020。这种演变与火焰原子吸收光谱法测定的 Ti 含量相关，并且表明这是由于 Ti 浓度沿坩埚的演变造成的。此外，观察到随着Ti含量的增加，四方相的分数连续增加。因此，我们可以将实验数据与标准偏析模型进行比较，从而计算该组合物的有效偏析系数 k(eff)。该系数被发现等于 0.849。沿锭的钛含量的变化导致单晶的介电和压电性能不可避免地波动。由于Ti浓度的增加，铸锭底部的居里点为186℃，顶部为222℃。取向和极化<001>样品的压电系数在1500至250 pC/N之间变化。 (c) 2005 Elsevier Ltd. 保留所有权利。
Relaxor ferroelectric 0.60Pb(Mg1/3Nb2/3)O-3-0.40PbTiO(3) single crystal was synthesized by Bridgman method. The segregation along the length of this crystal was observed by various physico-chemical characterization techniques. First, we note the evolution of the crystalline structure along the length of the as-grown crystals. The tetragonality factor c/a increases from 1.013 to 1.020. This evolution has been correlated with the Ti content determination by flame atomic absorption spectrometry, and it is shown that this is due to the evolution of Ti concentration along the crucible. Furthermore, a continuous increase of the fraction of tetragonal phase with increasing Ti content was observed. Hence, we could compare the experimental data with a standard segregation model and therefore calculate the effective segregation coefficient k(eff) for this composition. This coefficient was found to be equal to 0.849. The variation of the titanium content along the ingot causes an inevitable fluctuation of the dielectric and piezoelectric properties of the single crystal. Due to the increase of Ti concentration, the Curie point was 186 degrees C at the bottom of the ingot and 222 degrees C at the top. The piezoelectric coefficient of oriented and poled < 001 > samples varies from 1500 to 250 pC/N. (c) 2005 Elsevier Ltd. All rights reserved.