Nowak B, Hayashi S
W. Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wrocław.
Solid State Nucl Magn Reson. 2000;18(1-4):59-69. doi: 10.1006/snmr.2000.0011.
We have studied the microscopic properties of the hexagonal ZrNiAl, a model compound for a wide family of intermetallic compounds crystallizing in this type of structure, by using 27Al NMR spectroscopy. We have investigated the lineshape of static and MAS NMR spectra as a function of magnetic field strength (4.7-9.4 T) and temperature (5-300 K). Our data indicate that the 27Al NMR spectra result from a combined effect of quadrupole and anisotropic shift interactions. The 27Al nuclei are in an environment characterized by the quadrupole coupling constant e2qQ/h of 3.3 MHz, asymmetry parameter etaQ of 0.42, isotropic shift delta(iso) of 393 ppm, shift anisotropy delta(anis) = delta(zz) - (delta(xx) + delta(yy))/2 of 150 ppm, and asymmetry factor etaS of 0.5. They are found to be temperature independent. The spin-lattice relaxation rate measured at 7.05 T is proportional to the temperature with T1T = 135 s K. The mechanisms responsible for observed values of delta(iso), delta(anis), T1T, and the enhanced Korringa constant are discussed.
我们通过使用²⁷Al核磁共振光谱研究了六角形ZrNiAl的微观性质，ZrNiAl是在这种结构中结晶的一大类金属间化合物的模型化合物。我们研究了静态和魔角旋转核磁共振光谱的线形，其作为磁场强度（4.7 - 9.4 T）和温度（5 - 300 K）的函数。我们的数据表明，²⁷Al核磁共振光谱是由四极相互作用和各向异性位移相互作用的综合效应产生的。²⁷Al核所处环境的特征为：四极耦合常数e²qQ/h为3.3 MHz，不对称参数ηQ为0.42，各向同性位移δ(iso)为393 ppm，位移各向异性δ(anis) = δ(zz) - (δ(xx) + δ(yy))/2为150 ppm，以及不对称因子ηS为0.5。发现它们与温度无关。在7.05 T下测量的自旋 - 晶格弛豫率与温度成正比，T1T = 135 s K。讨论了导致观察到的δ(iso)、δ(anis)、T1T值以及增强的科林加常数的机制。
