Design and Characterization of New Optical Functional Transparent Tellurite Glass-Ceramics

本研究的目的是阐明本课题组所发现的透明碲基微晶玻璃的第二次产生(SHG)的机制。得到了以下结果。1)15K_2O-15Nb_2O_5-70TeO_2微晶玻璃中出现倍频的晶相化学成分大致相当于K(Nb_2O；1/3&gt；Te_&lt；2/3&gt；)_2O_&lt；4.8&gt；，其晶体结构为缺氧萤石型。XNa_2O-(15-x)K_2O-15Nb_2O_5-70TeO_2微晶玻璃的晶相晶格常数随Na_2O含量的增加而线性减小，即Na~(2+)与K~(2+)之间出现固溶体。3)15K_2O-xRO-(15-x)Nb_2O_5-70TeO_2(RO=WO_3，MoO_3)微晶玻璃的抗析晶热稳定性极高，难以形成具有倍频效应的晶相。4)与微晶玻璃内部相比，微晶玻璃表面晶化层产生了较强的二次谐波。5)制备了透明的掺Er^&lt；3+&gt；微晶玻璃，观察到在800 nm激光照射下，由于^4S_&lt；3/2&gt；*^4i_&lt；15/2&gt；产生的550 nm上转换峰。6)从玻璃化转变时的热容变化可以看出，碲基玻璃更容易发生结构单元间的重排。

The purpose of the present study is to clarify the mechanism of the second harmoinic generation (SHG) in transparent tellurite-based glass-ceramics which have been discovered by the present author's group. The following results were obtained. 1) The chemical composition of the crystalline phase showing SHG in 15K_2O-15Nb_2O_5-70TeO_2 glass-ceramics corresponds to K (Nb_<1/3>Te_<2/3>) _2O_<4.8> approximately, and its crystal structure is oxygen-defect fluorite type. This crystal is distorted slightly from cubic, maybe causing SHG.2) The lattice constant of the crystalline phase in xNa_2O- (15-x) K_2O-15Nb_2O_5-70TeO_2 glass-ceramics decreases linearly with increasing Na_2O content, meaning the appearance of the solid solution between Na^+and K^+. The intensity of SHG decreases steeply with increasing Na_2O/K_2O ratio, and the glass-ceramic with x=8 shows no SHG.3) The thermal stability against crystallaization in 15K_2O-xRO- (15-x) Nb_2O_5-70TeO_2, RO=WO_3, MoO_3, is extremely high, and the formation of the crystalline phase showing SHG tend to be difficult. 4) The surface crystallization layr generates strong second harmonic generation compared with the interior of the glass-ceramics. 5) The transparent Er^<3+>-doped tellurite-based glass-ceramics have been fabricated, and the upconversion at 550nm due to ^4S_<3/2>*^4I_<15/2> transition under the irradiation of laser with 800nm wavelength is clearly observed. 6) It is found from heat capacity changes at the glass transition that rearrangements among structural units occurs easily in tellurite-based glasses.