Bak John D, Wright John C
Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
J Phys Chem B. 2005 Oct 6;109(39):18391-9. doi: 10.1021/jp053032n.
Erbium-doped barium titanate crystals were studied by laser-induced fluorescence spectroscopy. Thirteen spectroscopically distinct erbium ion sites were found. The relative concentrations of the different sites changed as a function of the crystal and its preparation and treatment. One major site was present in all crystals. The site distribution was changed either by growing codoped crystals with donor (La3+) and acceptor (Sc3+) ions or by changing the temperature and partial pressure of the oxygen in the annealing atmosphere. Equilibrium calculations were done to simulate the defect distributions that result from the charge compensation of the erbium ions. Comparison with the observed dependence of the site spectral intensities indicated that the erbium enters the lattice on barium sites. We assigned the dominant site to an erbium ion on a barium site that is locally compensated by a barium vacancy, whereas the other lower-intensity sites corresponded to erbium ions that are locally compensated by an electron and a more complex center of an erbium, a barium vacancy, and a hole. The spectra of one sample showed that its defects were different and were characteristic of a sample that had not equilibrated. The new sites in this sample were assigned to erbium entering the lattice on a titanium site, which was then locally compensated by an oxygen vacancy or a hole. Heating equilibrated the sample and changed the erbium to a barium site.
采用激光诱导荧光光谱法对掺铒钛酸钡晶体进行了研究。发现了13个光谱特征不同的铒离子位点。不同位点的相对浓度随晶体及其制备和处理方式而变化。所有晶体中都存在一个主要位点。通过生长掺杂施主（La3+）和受主（Sc3+）离子的共掺杂晶体，或通过改变退火气氛中氧气的温度和分压，可以改变位点分布。进行了平衡计算，以模拟铒离子电荷补偿导致的缺陷分布。与观察到的位点光谱强度依赖性进行比较表明，铒进入晶格中的钡位点。我们将主要位点归因于钡位点上的铒离子，该位点由钡空位局部补偿，而其他低强度位点对应于由电子以及铒、钡空位和空穴组成的更复杂中心局部补偿的铒离子。一个样品的光谱表明其缺陷不同，是一个未达到平衡的样品的特征。该样品中的新位点归因于铒进入晶格中的钛位点，然后由氧空位或空穴局部补偿。加热使样品达到平衡，并将铒转变到钡位点。
