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Synthesis and structure-property relations in xMoO(3)-0.6B(2)O(3)-(0.4-x)K2O (0.010 = x = 0.295) glasses

机译:xMoO(3)-0.6B(2)O(3)-(0.4-x)K2O(0.010 <= x <= 0.295)玻璃中的合成和结构性质关系

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摘要

Glasses having compositions xMoO(3)-0.6B(2)O(3)-(0.4X)K2O (0.010 <= x <= 0295)(G1-G4: x:: 0.01, 0.105, 0.200, 0.295) are prepared by sal-gel method. Powder X-ray diffraction (XRD) patterns ensure clean glassy phase in the samples. Glass transition temperature, T-g, is found to be similar to 609-625 K in the glasses. IR spectroscopic results show the presence of trigonal [BO3/2], tetrahedral [BO4/2](-), octahedral [OMoO5//2](2-), and trigonal [BOn+1(3-n)/2](n-)(n = 1, 2,3) units with free oxygens in the glasses. The glasses exhibit hysteresis loops at 300 K with fairly low values of loop areas and coercivities which indicate soft ferromagnetic nature of the glasses. Calculated values of the Mo5+ (4d(1)) small polaron exchange integrals from the obtained Weiss constant at 300 K are found to be -0.052 eV in the glasses. Observed electron paramagnetic resonance (EPR) lineshapes at 7,105 and 300 K are isotropic in nature isi general. The observed &so-values similar to 1.90 +/- 0.001-1.93 +/- 0.001 indicate that the paramagnetic molybdenyl, MoO3+(4d(1)), ions are in octahedral coordination with tetragonal distortion. Optical absorption broad band similar to 238-311 nm is due to charge transfer phenomenon and the broad and weak band -750 nm in the glass G4 is due to the B-2(2g) ( I d(xy)> B-2(1g) (Id(x)(2) -y(2)>) transitions in Mo5+ (4d(1)) ions in distorted octahedral coordination. (C) 2015 Elsevier B.V. All rights reserved.
机译:制备具有xMoO(3)-0.6B(2)O(3)-(0.4X)K2O(0.010 <= x <= 0295)(G1-G4:x :: 0.01,0.105,0.200,0.295)的玻璃通过sal-gel方法。粉末X射线衍射(XRD)图案可确保样品中具有干净的玻璃相。发现玻璃中的玻璃化转变温度T-g类似于609-625K。红外光谱结果表明存在三角[BO3 / 2],四面体[BO4 / 2](-),八面体[OMoO5 // 2](2-)和三角[BOn + 1(3-n)/ 2] (n-)(n = 1,2,3)个单元中的自由氧在玻璃杯中。眼镜在300 K处表现出磁滞回线,其回环面积和矫顽力值相当低,这表明该眼镜具有软铁磁特性。从获得的Weiss常数在300 K下得出的Mo5 +(4d(1))小极化子交换积分的计算值在眼镜中为-0.052 eV。一般在7105和300 K处观察到的电子顺磁共振(EPR)线形是各向同性的。观察到的&so-so值类似于1.90 +/- 0.001-1.93 +/- 0.001,表明顺磁性钼烯基MoO3 +(4d(1))离子呈八面体配位,并具有四方畸变。类似于238-311 nm的光吸收宽带归因于电荷转移现象,玻璃G4中的宽和弱带-750 nm归因于B-2(2g)(I d(xy)> B-2( 1g)(Id(x)(2)-y(2)>)以扭曲的八面体配位形式在Mo5 +(4d(1))离子中跃迁。(C)2015 Elsevier BV保留所有权利。

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