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首页> 外文期刊>Journal of Crystal Growth >Top seeded solution growth of KHo(WO_4)_2 single crystals
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Top seeded solution growth of KHo(WO_4)_2 single crystals

机译：KHo（WO_4）_2单晶的顶晶种溶液生长

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Monoclinic KHo(WO_4)_2 single crystals have been grown by means of the Top Seeded Solution Growth method from K_2W_2O_7 self-flux containing up to 30 mol% of the crystallized compound. KHo(WO_4)_2 seed was selected from small crystals obtained by spontaneous crystallization and used to grow the first bulky KHo(WO_4)_2 crystal, from which seeds perpendicular to {111} and {110} planes, used in subsequent experiments, were cut out. Crystals grown on these seeds are designated in this paper as 111 and 110 crystals, respectively. Properly chosen thermal conditions allowed growth of crystals with one dominating crystallographic plane forming the bottom of the 111 crystals. Under conditions of very low temperature gradients, growing crystals developed bottoms consisting of several crystallographic planes, while a slightly steeper temperature gradient led to cracking of the growing crystals due to high anisotropy of thermal expansion coefficients, which is characteristic of all double tungstates. It was found that 111 KHo(WO_4)_2 single crystals were much bulkier than 1 1 0 ones, which had a rectangular cross-section elongated in the c direction. The bottom of 111 KHo(WO_4)_2 crystals was built of one (111) plane, while in 110 crystals additional planes appeared that could not be eliminated by increasing the temperature gradient because such an increase led to cracking of crystals. As-grown 111 and 110 KHo(WO_4)_2 single crystals were of good quality, free from such defects as bubbles, cracks, and inclusions. The morphology of KHo(WO_4)_2 single crystals was investigated. Miller's indices of crystallographic faces (h k l) and edge indices [u v w] were found. Positions of the crystallographic axes a, b, and c in relation to growth faces and edges were found as well. The refractive indices and optical axes have been determined. The investigations of absorption spectra of KHo(WO_4)_2 single crystals were performed in a wide spectral range (4000-40,000 cm~(-1)) at the temperature range 1.1 up to 300 K. The trichroism of KHo(WO_4)_2 was confirmed experimentally. This means that optical absorption is characterized by three different, independent spectra attributed to three main optical directions.
机译：单晶型KHo（WO_4）_2单晶已通过顶部种子溶液生长法从K_2W_2O_7自助熔剂中生长，该助熔剂含有高达30 mol％的结晶化合物。从自发结晶获得的小晶体中选择KHo（WO_4）_2晶种，并将其用于生长第一个大块KHo（WO_4）_2晶体，从中切出用于后续实验的垂直于{111}和{110}平面的晶种出来。这些种子上生长的晶体在本文中分别称为111和110晶体。适当选择的热条件可使晶体生长，其中一个主要的晶面构成111个晶体的底部。在非常低的温度梯度条件下，生长的晶体形成的底部由几个晶体学平面组成，而温度梯度稍陡则由于热膨胀系数的高各向异性而导致生长的晶体破裂，这是所有双钨酸盐的特征。结果发现，111 KHo（WO_4）_2单晶比1 1 0单晶大得多，后者具有沿c方向伸长的矩形截面。 111 KHo（WO_4）_2晶体的底部由一个（111）平面构成，而在110晶体中，出现了其他平面，这些平面无法通过增加温度梯度来消除，因为这样的增加会导致晶体破裂。长成的111和110 KHo（WO_4）_2单晶质量好，没有气泡，裂纹和夹杂物等缺陷。研究了KHo（WO_4）_2单晶的形貌。发现了晶面的米勒指数（h k l）和边缘指数[u v w]。还发现了结晶轴a，b和c相对于生长面和边缘的位置。已经确定了折射率和光轴。在温度范围1.1至300 K的宽光谱范围（4000-40,000 cm〜（-1））中进行了KHo（WO_4）_2单晶的吸收光谱研究。KHo（WO_4）_2的三色性为实验证实。这意味着光吸收的特征在于归因于三个主要光学方向的三个不同的独立光谱。

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