Eu2BaO4 crystallizes in the monoclinic Pm space group. There are four inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 8-coordinate geometry to one O(10), one O(9), two equivalent O(16), two equivalent O(4), and two equivalent O(8) atoms. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to one O(10), one O(9), two equivalent O(15), two equivalent O(3), and two equivalent O(7) atoms. In the third Ba site, Ba(3) is bonded in a 8-coordinate geometry to one O(11), one O(12), two equivalent O(14), two equivalent O(2), and two equivalent O(6) atoms. In the fourth Ba site, Ba(4) is bonded in a 8-coordinate geometry to one O(11), one O(12), two equivalent O(1), two equivalent O(13), and two equivalent O(5) atoms. There are eight inequivalent Eu sites. In the first Eu site, Eu(1) is bonded to one O(1), one O(6), two equivalent O(12), and two equivalent O(8) atoms to form a mixture of corner and edge-sharing EuO6 octahedra. The corner-sharing octahedral tilt angles range from 51-62°. In the second Eu site, Eu(2) is bonded to one O(2), one O(5), two equivalent O(11), and two equivalent O(7) atoms to form a mixture of corner and edge-sharing EuO6 octahedra. The corner-sharing octahedral tilt angles range from 51-63°. In the third Eu site, Eu(3) is bonded to one O(3), one O(8), two equivalent O(10), and two equivalent O(6) atoms to form a mixture of corner and edge-sharing EuO6 octahedra. The corner-sharing octahedral tilt angles range from 51-62°. In the fourth Eu site, Eu(4) is bonded to one O(4), one O(7), two equivalent O(5), and two equivalent O(9) atoms to form a mixture of corner and edge-sharing EuO6 octahedra. The corner-sharing octahedral tilt angles range from 51-62°. In the fifth Eu site, Eu(5) is bonded to one O(14), one O(9), two equivalent O(16), and two equivalent O(3) atoms to form a mixture of corner and edge-sharing EuO6 octahedra. The corner-sharing octahedral tilt angles range from 51-62°. In the sixth Eu site, Eu(6) is bonded to one O(10), one O(13), two equivalent O(15), and two equivalent O(4) atoms to form a mixture of corner and edge-sharing EuO6 octahedra. The corner-sharing octahedral tilt angles range from 51-62°. In the seventh Eu site, Eu(7) is bonded to one O(11), one O(16), two equivalent O(1), and two equivalent O(14) atoms to form a mixture of corner and edge-sharing EuO6 octahedra. The corner-sharing octahedral tilt angles range from 51-62°. In the eighth Eu site, Eu(8) is bonded to one O(12), one O(15), two equivalent O(13), and two equivalent O(2) atoms to form a mixture of corner and edge-sharing EuO6 octahedra. The corner-sharing octahedral tilt angles range from 51-63°. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to two equivalent Ba(4), one Eu(1), and two equivalent Eu(7) atoms. In the second O site, O(2) is bonded in a 5-coordinate geometry to two equivalent Ba(3), one Eu(2), and two equivalent Eu(8) atoms. In the third O site, O(3) is bonded in a 5-coordinate geometry to two equivalent Ba(2), one Eu(3), and two equivalent Eu(5) atoms. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to two equivalent Ba(1), one Eu(4), and two equivalent Eu(6) atoms. In the fifth O site, O(5) is bonded to two equivalent Ba(4), one Eu(2), and two equivalent Eu(4) atoms to form a mixture of corner and edge-sharing OBa2Eu3 square pyramids. In the sixth O site, O(6) is bonded to two equivalent Ba(3), one Eu(1), and two equivalent Eu(3) atoms to form a mixture of corner and edge-sharing OBa2Eu3 square pyramids. In the seventh O site, O(7) is bonded to two equivalent Ba(2), one Eu(4), and two equivalent Eu(2) atoms to form a mixture of corner and edge-sharing OBa2Eu3 square pyramids. In the eighth O site, O(8) is bonded to two equivalent Ba(1), one Eu(3), and two equivalent Eu(1) atoms to form a mixture of corner and edge-sharing OBa2Eu3 square pyramids. In the ninth O site, O(9) is bonded to one Ba(1), one Ba(2), one Eu(5), and two equivalent Eu(4) atoms to form a mixture of distorted corner and edge-sharing OBa2Eu3 trigonal bipyramids. In the tenth O site, O(10) is bonded to one Ba(1), one Ba(2), one Eu(6), and two equivalent Eu(3) atoms to form a mixture of distorted corner and edge-sharing OBa2Eu3 trigonal bipyramids. In the eleventh O site, O(11) is bonded to one Ba(3), one Ba(4), one Eu(7), and two equivalent Eu(2) atoms to form a mixture of distorted corner and edge-sharing OBa2Eu3 trigonal bipyramids. In the twelfth O site, O(12) is bonded to one Ba(3), one Ba(4), one Eu(8), and two equivalent Eu(1) atoms to form a mixture of distorted corner and edge-sharing OBa2Eu3 trigonal bipyramids. In the thirteenth O site, O(13) is bonded to two equivalent Ba(4), one Eu(6), and two equivalent Eu(8) atoms to form a mixture of distorted corner and edge-sharing OBa2Eu3 trigonal bipyramids. In the fourteenth O site, O(14) is bonded to two equivalent Ba(3), one Eu(5), and two equivalent Eu(7) atoms to form a mixture of distorted corner and edge-sharing OBa2Eu3 trigonal bipyramids. In the fifteenth O site, O(15) is bonded to two equivalent Ba(2), one Eu(8), and two equivalent Eu(6) atoms to form a mixture of distorted corner and edge-sharing OBa2Eu3 trigonal bipyramids. In the sixteenth O site, O(16) is bonded to two equivalent Ba(1), one Eu(7), and two equivalent Eu(5) atoms to form a mixture of distorted corner and edge-sharing OBa2Eu3 trigonal bipyramids.
Eu2BaO4 crystallizes in the monoclinic Pm space group. There are four inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 8-coordinate geometry to one O(10), one O(9), two equivalent O(16), two equivalent O(4), and two equivalent O(8) atoms. The Ba(1)-O(10) bond length is 2.90 Å. The Ba(1)-O(9) bond length is 2.99 Å. Both Ba(1)-O(16) bond lengths are 2.78 Å. Both Ba(1)-O(4) bond lengths are 2.88 Å. Both Ba(1)-O(8) bond lengths are 2.77 Å. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to one O(10), one O(9), two equivalent O(15), two equivalent O(3), and two equivalent O(7) atoms. The Ba(2)-O(10) bond length is 2.99 Å. The Ba(2)-O(9) bond length is 2.92 Å. Both Ba(2)-O(15) bond lengths are 2.77 Å. Both Ba(2)-O(3) bond lengths are 2.90 Å. Both Ba(2)-O(7) bond lengths are 2.77 Å. In the third Ba site, Ba(3) is bonded in a 8-coordinate geometry to one O(11), one O(12), two equivalent O(14), two equivalent O(2), and two equivalent O(6) atoms. The Ba(3)-O(11) bond length is 2.97 Å. The Ba(3)-O(12) bond length is 2.93 Å. Both Ba(3)-O(14) bond lengths are 2.77 Å. Both Ba(3)-O(2) bond lengths are 2.89 Å. Both Ba(3)-O(6) bond lengths are 2.78 Å. In the fourth Ba site, Ba(4) is bonded in a 8-coordinate geometry to one O(11), one O(12), two equivalent O(1), two equivalent O(13), and two equivalent O(5) atoms. The Ba(4)-O(11) bond length is 2.93 Å. The Ba(4)-O(12) bond length is 2.97 Å. Both Ba(4)-O(1) bond lengths are 2.89 Å. Both Ba(4)-O(13) bond lengths are 2.77 Å. Both Ba(4)-O(5) bond lengths are 2.78 Å. There are eight inequivalent Eu sites. In the first Eu site, Eu(1) is bonded to one O(1), one O(6), two equivalent O(12), and two equivalent O(8) atoms to form a mixture of corner and edge-sharing EuO6 octahedra. The corner-sharing octahedral tilt angles range from 51-62°. The Eu(1)-O(1) bond length is 2.37 Å. The Eu(1)-O(6) bond length is 2.40 Å. Both Eu(1)-O(12) bond lengths are 2.29 Å. Both Eu(1)-O(8) bond lengths are 2.40 Å. In the second Eu site, Eu(2) is bonded to one O(2), one O(5), two equivalent O(11), and two equivalent O(7) atoms to form a mixture of corner and edge-sharing EuO6 octahedra. The corner-sharing octahedral tilt angles range from 51-63°. The Eu(2)-O(2) bond length is 2.37 Å. The Eu(2)-O(5) bond length is 2.40 Å. Both Eu(2)-O(11) bond lengths are 2.30 Å. Both Eu(2)-O(7) bond lengths are 2.39 Å. In the third Eu site, Eu(3) is bonded to one O(3), one O(8), two equivalent O(10), and two equivalent O(6) atoms to form a mixture of corner and edge-sharing EuO6 octahedra. The corner-sharing octahedral tilt angles range from 51-62°. The Eu(3)-O(3) bond length is 2.34 Å. The Eu(3)-O(8) bond length is 2.36 Å. Both Eu(3)-O(10) bond lengths are 2.29 Å. Both Eu(3)-O(6) bond lengths are 2.39 Å. In the fourth Eu site, Eu(4) is bonded to one O(4), one O(7), two equivalent O(5), and two equivalent O(9) atoms to form a mixture of corner and edge-sharing EuO6 octahedra. The corner-sharing octahedral tilt angles range from 51-62°. The Eu(4)-O(4) bond length is 2.37 Å. The Eu(4)-O(7) bond length is 2.40 Å. Both Eu(4)-O(5) bond lengths are 2.39 Å. Both Eu(4)-O(9) bond lengths are 2.30 Å. In the fifth Eu site, Eu(5) is bonded to one O(14), one O(9), two equivalent O(16), and two equivalent O(3) atoms to form a mixture of corner and edge-sharing EuO6 octahedra. The corner-sharing octahedral tilt angles range from 51-62°. The Eu(5)-O(14) bond length is 2.31 Å. The Eu(5)-O(9) bond length is 2.34 Å. Both Eu(5)-O(16) bond lengths are 2.39 Å. Both Eu(5)-O(3) bond lengths are 2.38 Å. In the sixth Eu site, Eu(6) is bonded to one O(10), one O(13), two equivalent O(15), and two equivalent O(4) atoms to form a mixture of corner and edge-sharing EuO6 octahedra. The corner-sharing octahedral tilt angles range from 51-62°. The Eu(6)-O(10) bond length is 2.35 Å. The Eu(6)-O(13) bond length is 2.32 Å. Both Eu(6)-O(15) bond lengths are 2.39 Å. Both Eu(6)-O(4) bond lengths are 2.37 Å. In the seventh Eu site, Eu(7) is bonded to one O(11), one O(16), two equivalent O(1), and two equivalent O(14) atoms to form a mixture of corner and edge-sharing EuO6 octahedra. The corner-sharing octahedral tilt angles range from 51-62°. The Eu(7)-O(11) bond length is 2.34 Å. The Eu(7)-O(16) bond length is 2.32 Å. Both Eu(7)-O(1) bond lengths are 2.37 Å. Both Eu(7)-O(14) bond lengths are 2.39 Å. In the eighth Eu site, Eu(8) is bonded to one O(12), one O(15), two equivalent O(13), and two equivalent O(2) atoms to form a mixture of corner and edge-sharing EuO6 octahedra. The corner-sharing octahedral tilt angles range from 51-63°. The Eu(8)-O(12) bond length is 2.35 Å. The Eu(8)-O(15) bond length is 2.32 Å. Both Eu(8)-O(13) bond lengths are 2.39 Å. Both Eu(8)-O(2) bond lengths are 2.37 Å. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to two equivalent Ba(4), one Eu(1), and two equivalent Eu(7) atoms. In the second O site, O(2) is bonded in a 5-coordinate geometry to two equivalent Ba(3), one Eu(2), and two equivalent Eu(8) atoms. In the third O site, O(3) is bonded in a 5-coordinate geometry to two equivalent Ba(2), one Eu(3), and two equivalent Eu(5) atoms. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to two equivalent Ba(1), one Eu(4), and two equivalent Eu(6) atoms. In the fifth O site, O(5) is bonded to two equivalent Ba(4), one Eu(2), and two equivalent Eu(4) atoms to form a mixture of corner and edge-sharing OBa2Eu3 square pyramids. In the sixth O site, O(6) is bonded to two equivalent Ba(3), one Eu(1), and two equivalent Eu(3) atoms to form a mixture of corner and edge-sharing OBa2Eu3 square pyramids. In the seventh O site, O(7) is bonded to two equivalent Ba(2), one Eu(4), and two equivalent Eu(2) atoms to form a mixture of corner and edge-sharing OBa2Eu3 square pyramids. In the eighth O site, O(8) is bonded to two equivalent Ba(1), one Eu(3), and two equivalent Eu(1) atoms to form a mixture of corner and edge-sharing OBa2Eu3 square pyramids. In the ninth O site, O(9) is bonded to one Ba(1), one Ba(2), one Eu(5), and two equivalent Eu(4) atoms to form a mixture of distorted corner and edge-sharing OBa2Eu3 trigonal bipyramids. In the tenth O site, O(10) is bonded to one Ba(1), one Ba(2), one Eu(6), and two equivalent Eu(3) atoms to form a mixture of distorted corner and edge-sharing OBa2Eu3 trigonal bipyramids. In the eleventh O site, O(11) is bonded to one Ba(3), one Ba(4), one Eu(7), and two equivalent Eu(2) atoms to form a mixture of distorted corner and edge-sharing OBa2Eu3 trigonal bipyramids. In the twelfth O site, O(12) is bonded to one Ba(3), one Ba(4), one Eu(8), and two equivalent Eu(1) atoms to form a mixture of distorted corner and edge-sharing OBa2Eu3 trigonal bipyramids. In the thirteenth O site, O(13) is bonded to two equivalent Ba(4), one Eu(6), and two equivalent Eu(8) atoms to form a mixture of distorted corner and edge-sharing OBa2Eu3 trigonal bipyramids. In the fourteenth O site, O(14) is bonded to two equivalent Ba(3), one Eu(5), and two equivalent Eu(7) atoms to form a mixture of distorted corner and edge-sharing OBa2Eu3 trigonal bipyramids. In the fifteenth O site, O(15) is bonded to two equivalent Ba(2), one Eu(8), and two equivalent Eu(6) atoms to form a mixture of distorted corner and edge-sharing OBa2Eu3 trigonal bipyramids. In the sixteenth O site, O(16) is bonded to two equivalent Ba(1), one Eu(7), and two equivalent Eu(5) atoms to form a mixture of distorted corner and edge-sharing OBa2Eu3 trigonal bipyramids.