Processing and characteristics of transparent Gd₃TaO₇ polycrystalline ceramics

Abstract

Transparent polycrystalline Gd 3 TaO 7 ceramics were successfully developed. A sol-gel process was used to synthesize Gd 3 TaO 7 powder with a uniform composition and an estimated average particle size of 100 nm. Simultaneous thermal gravimetric analysis and differential thermal analysis (TGA/DTA) was used to identify the decomposition sequence as a function of temperature for the assynthesized sol-gel powders. Crystallization was confirmed by X-ray diffraction (XRD) and a single phase was achieved by calcining at 1000°C. The calcined powders were hot-pressed at 1400°C to achieve >96% theoretical density with closed pore structure followed by a hot isostatic pressing at 1400°C at 207 MPa to achieve a fully dense structure. Microstructural characterization shows a uniform grain size distribution with an average grain size of about 7 lm. In-line transmission measurements revealed high transparency in the red and infrared.Thermal conductivity was measured to be >1.6 W/mK at room temperature, decreasing to~1.3 W/mK by 500°C. Dielectric properties remain stable with relative permittivity values just above 200 and loss tangents <0.005 up to 350°C.

Crystallization of glass materials into transparent optical ceramics

“…[15,[17][18][19] Cubic sesquioxide compositions with the general formula of M2O3, such as Y2O3 [20], Sc2O3 [21], Lu2O3 [22], etc., have also been successfully fabricated as high-quality transparent ceramics. Other ceramic systems such as Al2O3 [23], MgO [24], MgAl2O4 [16], ZrO2 [14], or even Lu3NbO7 [25] and Gd3TaO7 [26] with cubic defect-fluorite structures, have also been reported. Non-oxide compositions have also been demonstrated, including nitrides (AlN [27] and AlON [28]), fluorides (MgF2 [29], CaF2 [30], SrF2 [31], and BaF2 [32]), and chalcogenides, such as sulfides (ZnS [33]), selenides (ZnSe [34]), and tellurates (KNbTeO6 [35]).…”

Y3NbO7 transparent ceramic series for high refractive index optical lenses

“…The refractive index and Abbe number data of several representative transparent ceramics are plotted in Figure 5, 3,[4][5][6]9,10 which show negative correlation. 3 The Y 1−x Nb x O 1.5+x transparent ceramic series (x = 0.20, 0.22, 0.24, 0.25, 0.26) with a defect fluorite structure were fabricated by a pressureless pre-sintering (1600°C for 10 h in air) and a HIP (1600°C for 1 h in 200 MPa argon) postsintering treatment.…”

“…6 The A 2 B 2 O 7 7 and A 3 BO 7 8,9 transparent ceramic families (A = rare-earth metals, B = transition metal) generally possess a high refractive index. For example, La 2 Zr 2 O 7 , 6 Y 2 Ti 2 O 7 , 10 and Gd 3 TaO 7 9 transparent ceramics have a refractive index of 2.09, 2.29, and 2.0, respectively. Hence, in the last decade, they are intensively investigated as potential materials for high refractive index lenses.…”

Calculation of Pore Scattering in Transparent Ceramics

“…[6,7] Many studies have been carried out and a variety of noble transparent ceramic materials have been developed, such as Y 2 O 3 , Y 3 Al 5 O 12 , MgAlO 4 , YSZ and so on. [7][8][9][10] Promising laser performance has been reported in various output wavelength, such as 2.7 μm Q-switch Er: Y 2 O 3 ceramic laser, 1.44 μm picosecond Nd: YAG ceramic laser and resonantly pumped eye-safe Er: YAG laser. [11][12][13] However, fabricating high-quality transparent ceramic for large-scale laser application is still challenging, which is necessary for high-power laser applications.…”