Na4LaTa(SiO4)3 is Pb (Zr_0.50 Ti_0.48) O_3-derived structured and crystallizes in the trigonal R3c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 3-coordinate geometry to one O(1), one O(4), and two equivalent O(3) atoms. In the second Na site, Na(2) is bonded in a distorted hexagonal planar geometry to three equivalent O(3) and three equivalent O(4) atoms. La(1) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form distorted LaO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra. Ta(1) is bonded to three equivalent O(2) and three equivalent O(4) atoms to form TaO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with two equivalent La(1)O6 octahedra and corners with two equivalent Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 17-48°. There are four inequivalent O sites. In the first O site, O(3) is bonded in a 5-coordinate geometry to one Na(2), two equivalent Na(1), one La(1), and one Si(1) atom. In the second O site, O(4) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Ta(1), and one Si(1) atom. In the third O site, O(1) is bonded in a 3-coordinate geometry to one Na(1), one La(1), and one Si(1) atom. In the fourth O site, O(2) is bonded in a distorted linear geometry to one Ta(1) and one Si(1) atom.
Na4LaTa(SiO4)3 is Pb (Zr_0.50 Ti_0.48) O_3-derived structured and crystallizes in the trigonal R3c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 3-coordinate geometry to one O(1), one O(4), and two equivalent O(3) atoms. The Na(1)-O(1) bond length is 2.31 Å. The Na(1)-O(4) bond length is 2.48 Å. There is one shorter (2.34 Å) and one longer (2.84 Å) Na(1)-O(3) bond length. In the second Na site, Na(2) is bonded in a distorted hexagonal planar geometry to three equivalent O(3) and three equivalent O(4) atoms. All Na(2)-O(3) bond lengths are 2.68 Å. All Na(2)-O(4) bond lengths are 2.56 Å. La(1) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form distorted LaO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra. All La(1)-O(1) bond lengths are 2.26 Å. All La(1)-O(3) bond lengths are 2.41 Å. Ta(1) is bonded to three equivalent O(2) and three equivalent O(4) atoms to form TaO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra. All Ta(1)-O(2) bond lengths are 2.01 Å. All Ta(1)-O(4) bond lengths are 2.07 Å. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with two equivalent La(1)O6 octahedra and corners with two equivalent Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 17-48°. The Si(1)-O(1) bond length is 1.60 Å. The Si(1)-O(2) bond length is 1.73 Å. The Si(1)-O(3) bond length is 1.61 Å. The Si(1)-O(4) bond length is 1.68 Å. There are four inequivalent O sites. In the first O site, O(3) is bonded in a 5-coordinate geometry to one Na(2), two equivalent Na(1), one La(1), and one Si(1) atom. In the second O site, O(4) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Ta(1), and one Si(1) atom. In the third O site, O(1) is bonded in a 3-coordinate geometry to one Na(1), one La(1), and one Si(1) atom. In the fourth O site, O(2) is bonded in a distorted linear geometry to one Ta(1) and one Si(1) atom.