Niobium-93, lanthanum-139, and tantalum-181 pure NQR in rare earth orthoniobates and lithium tantalate

Cluster Calculations of Electric-Field-Gradients at the Ta Site for the Ferroelectric LiTaO 3 Crystal

“…This corresponds to experimental data represented in Fig. 2 by closed [4] and open [5] diamonds. In [4] the values of the quadrupole coupling constant for Ta were obtained.…”

“…2 by closed [4] and open [5] diamonds. In [4] the values of the quadrupole coupling constant for Ta were obtained. In order to compare those results with our EFG calculations, they were divided by eQ/ h. A value of 3.3 · 10 −24 cm 2 was used for the quadrupole moment of 181 Ta [22].…”

“…The temperature dependence of the EFG tensor at the tantalum site in LiTaO 3 was studied by NQR [4] and MS [5]. The zz-component of the EFG tensor was found to decrease with increasing temperature.…”

“…Closed diamonds show experimental results obtained in[5]; open diamonds show the experimental e 2 q Q/h values from[4] divided by eQ/ h. Other symbols correspond to V zz calculated using the lattice and positional parameters taken from references 15 (circles) and 6 (triangles).…”

Temperature-Induced Changes of the Electronic Structure of Ferroelectric LiTaO3

“…The open circles represent the results of a previous nuclear-quadrupole resonance study of LiTaO s at room temperature and below. 7 As is obvious from Fig. 2(a), V zz varies from about 3x 10 17 to about -2x i0 17 V/cm 2 when the temperature is raised from 4.2 K to -1000 K, with a sign change occurring around 800 K (indicated by a horizontal arrow).…”