High-pressure structural evolution of a perovskite solid solution (La1−x,Ndx)GaO3

Structure of praseodymium and neodymium gallate glasses

“…2. By comparison with the crystal structures of RGaO 3 (R =Pr or Nd) [23][24][25][26], R 4 Ga 2 O 9 [28,29] (R =Pr or Nd), Nd 3 GaO 6 [45,46] and Nd 3 Ga 5 O 12 [47], the first peak in Pr G(r) at 1.85(2) Å or in Nd G(r) at 1.86(2) Å is attributed to Ga-O correlations and its integration over the range 1.66 ≤ r(Å) ≤ 2.09 gives a coordination number n O Ga = 4.2(1). The second peak in Pr G(r) at 2.44(2) Å or in Nd G(r) at 2.42(2) Å will have a strong contribution from R-O correlations and, in keeping with the larger coherent neutron scattering length of Nd, this peak is more intense for the neodymium gallate glass.…”

“…0.6975) [20]. They also share a similar structural chemistry [21,22], e.g., the rare-earth gallates PrGaO 3 and NdGaO 3 have a perovskite structure [23][24][25][26][27] while Pr 4 Ga 2 O 9 and Nd 4 Ga 2 O 9 also share a common crystal structure [28,29]. By treating Pr 3 + and Nd 3 + as isomorphic pairs and by measuring the diffraction patterns of the glasses it is possible to probe separately the coordination environments of both the rare-earth and gallium atoms.…”

Solid-state NMR calculations for metal oxides and gallates: Shielding and quadrupolar parameters for perovskites and related phases

“…The r ref -values, gradients (m) and root mean square errors obtained from the fits are also shown, along with the standard errors in the former two quantities. (expt) indicates that the fixed experimental structure was used in the calculation [34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53] permitted by symmetry, and is qualitatively reproduced by the calculations: the value obtained from the fixed experimental structure being in marginally better agreement with experiment. As expected, the g Q -values at this site are zero, with the major axis of the EFG tensor oriented along the c-axis of the hexagonal cell, and the two minor axes confined to the ab-plane.…”

“…(expt.) indicates that the fixed experimental structure was used in the calculation [48,[59][60][61][62][63][64][65][66][67][68]. materials studied here.…”

“…Moreover, there remain important questions as to the improvements obtainable from treatments of electron exchange and correlation beyond the pure DFT functional applied here, though it is noted that the deployment of such methods within the GIPAW approach is not yet routine. Table 4 Comparison of the experimental and computed properties related to the anisotropy of, asymmetry in and relative orientation of the chemical shift and electric field gradient tensors at 71 Ga sites [48,[59][60][61][62][63][64][65][66][67][68][69]. …”