^<141>Pr nuclear spin relaxation time in Pr and related compounds.

对Pr化合物及其相关化合物：Rco_&lt；5+x&gt；(R=Pr，Tb)，Pr_2Fe_&lt；14&gt；B，Pr_xGd_&lt；1-x&gt；Ni，Sm_xGd_&lt；1-x&gt；Ni和RFE_&lt；11&gt；Ti(R=稀土)进行了稀土自旋回波核磁共振测量。Pr_xGd_&lt；1-x&gt；Ni的^&lt；141&gt；Pr核磁共振信号出现在较宽的频率范围内。在Pr_2Fe_t；14&gt；B和Sm_xGd_&lt；1-x&gt；Ni中，Pr_2Fe_&lt；0.2&gt；Gd_&lt；0.8&gt；Ni的谱宽约为1000 MHz，频率范围为2800~3800 MHz。由超精细场分析估算的化合物中稀土离子的磁矩分别为PrCo_5和Pr_&lt；0.2&Gt；Gd_&lt；0.8&Gt；Ni的2.4和2.6mU_B。在1.4K-4.2K温度范围内测量了PrCo_5、Pr_2Fe_(14)&gt；B和Pr_xGd_&lt；1-x&gt；Ni的核自旋-自旋弛豫时间T_2。结果表明，自旋-自旋弛豫服从简单的指数函数，并呈现快速衰变。在PrCO_5中，1.4K时T_2为4.2musec，4.2K时为2.1musec；在Pr_xGd_1-x&gt；Ni中，x=0.2和0.35时，1.4K时T_2分别为-5musec和-3musec。这大约是Sm_&lt；0.2&gt；Gd_&lt；0.8&gt；Ni中^&lt；147&>Sm的1/20至1/30。假定观测信号主要出现在与-1/2和互变构体1/2跃迁相对应的谱线上，用T_1/T_2=(i+1/2)^2的关系式估算了自旋-晶格弛豫时间T_1，得到PrCo_5和Pr_xGd_1-x&Gt；Ni的T_1T分别为-110Kmusec和-50Kmusec。对于Pr_2Fe_&lt；14&gt；B，f位和g位的T_1T分别为900Kmusec和300Kmusec。

Rare-earth spin-echo NMR measurements have been carried out on Pr compounds and the related compounds : RCo_<5+x> (R=Pr, Tb), Pr_2Fe_<14>B,Pr_xGd_<1-x>Ni, Sm_xGd_<1-x>Ni and RFe_<11>Ti (R=rare-earth). The ^<141>Pr NMR signal of Pr_xGd_<1-x>Ni appeared in the wide frequency range. In the case of Pr_<0.2>Gd_<0.8>Ni, the width of spectrum was about 1000MHz, in the frequency range from 2800 to 3800MHz, which was different from those of Pr_2Fe_<14>B and Sm_xGd_<1-x>Ni. The magnetic moments of rare-earth ions in the compounds which were estimated from the hyperfine field analysis were 2.4 and 2.6mu_B for PrCo_5 and Pr_<0.2>Gd_<0.8>Ni, respectively. ^<141>Pr nuclear spin-spin relaxation times, T_2, have been measured on PrCo_5, Pr_2Fe_<14>B and Pr_xGd_<1-x>Ni in the temperature range from 1.4K to 4.2K.It was found that the spin-spin relaxation followed a simple exponential function and showed fast decay. In PrCo_5, T_2 were 4.2musec at 1.4K and 2.1musec at 4.2K.In Pr_xGd_<1-x>Ni, T_2 at 1.4K were -5musec and -3musec for x=0.2 and 0.35, respectively. These were roughly 1/20 to 1/30 of ^<147>Sm in Sm_<0.2>Gd_<0.8>Ni. Assuming that the observed signals arised mostly from the line corresponding to the -1/2 <tautomer> 1/2 transition, the spin-lattice relaxation time, T_1, was estimated by using the relation T_1/T_2= (I+1/2)^2. T_1T was obtained to be - 110Kmusec and -50Kmusec for PrCo_5 and Pr_xGd_<1-x>Ni, respectively. For Pr_2Fe_<14>B, T_1T were obtained to be 900Kmusec and 300Kmusec for the f and g sites, respectively.