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Crystal structure and phonon modes of disorder induced Ba2Li1-xTe1+xO5.5+δ (x =0, 0.1, 0.2) double perovskite based microwave dielectrics
Materials Research Bulletin ( IF 5.4 ) Pub Date : 2020-12-28 , DOI: 10.1016/j.materresbull.2020.111190
V.L. Vilesh , G. Subodh

An extensive investigation that correlates structural and microwave dielectric properties of oxygen deficient double perovskites, Ba2Li1-xTe1+xO5.5+δ (x = 0, 0.1, 0.2) is reported for the first time. Even though XRD data supports a pseudocubic structure for Ba2Li1-xTe1+xO5.5+δ ceramics, a detailed investigation using Raman and FTIR spectra followed by Rietveld refinement indicates the most likely space group is P21/n for all compositions. Further, temperature dependent Raman spectra illustrate the thermal stability of the compositions between −180°C to 400°C. XPS studies of sintered ceramics confirm more than 95% of Te in 6+ oxidation state. The compounds exhibit maximum densification at 950°C with the addition of 1 wt% B2O3. Ba2Li0.8Te1.2O6 ceramics have temperature stable microwave dielectric properties of εr = 16.9, Q × f = 15410 GHz and τf = −3.7 ppm/°C and it does not react with Ag electrodes at 940°C, which makes it a suitable candidate for low temperature co-fired ceramics applications.



中文翻译:

Ba 2 Li 1-x Te 1 + x O 5.5 +δ(x = 0,0.1,0.2)双钙钛矿基微波电介质的无序晶体结构和声子模

首次广泛报道了与缺氧的双钙钛矿Ba 2 Li 1-x Te 1 + x O 5.5 +δ(x = 0,0.1,0.2)的结构和微波介电性能相关的研究。尽管XRD数据支持Ba 2 Li 1-x Te 1 + x O 5.5 +δ陶瓷的伪立方结构,但使用拉曼光谱和FTIR光谱以及Rietveld精炼进行的详细研究表明,最可能的空间群是P2 1 / n对于所有成分。此外,温度依赖性拉曼光谱说明了组合物在-180℃至400℃之间的热稳定性。XPS对烧结陶瓷的研究证实,在6+氧化态下,Te的含量超过95%。加入1wt%的B 2 O 3,化合物在950℃下显示出最大的致密化。Ba 2 Li 0.8 Te 1.2 O 6陶瓷具有温度稳定的微波介电性能ε[R= 16.9,Q × f = 15410 GHz和τF = -3.7 ppm /°C,并且在940°C时不会与Ag电极反应,这使其非常适合用于低温共烧陶瓷应用。

更新日期:2020-12-28
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