Ab initio structure determination via powder X-ray diffraction

Structure determination by powder X-ray diffraction data has gone through a recent surge since it has become important to get to the structural information of materials which do not yield good quality single crystals. Although the method of structure completion when once the starting model is provided is facile through the Rietveld refinement technique, the structure solutionab initio is still not push-button technology. In this article a survey of the recent development in this area is provided with an illustration of the structure determination of α-NaBi3V2O10

Comment on "Structure of NaBi3V2O10NaBi_3V_2O_{10} and Implications for Ionic Conductivity"

The recent publication in this journal by Sleight’s group1 describing the structure and ionic conductivity prompts us to comment on their observations in light of our earlier published work. Our publication clearly brought out the existence of two polymorphic modifications of $NaBi{_3}V{_2}O_{10}$ and we were the first to establish the structure of the R form from the ab initio powder X-ray diffraction technique. It may be pointed out that the work published by Sinclair’s group was ambiguous as the structure reported in ref 4 (\beta-form) was entirely different from the one reported in ref 3 for which the conductivity data were provided

Ab initio structure determination via powder X-ray diffraction

Structure determination by powder X-ray diffraction data has gone through a recent surge since it has become important to get to the structural information of materials which do not yield good quality single crystals. Although the method of structure completion when once the starting model is provided is facile through the Rietveld refinement technique, the structure solution ab initio is still not push-button technology. In this article a survey of the recent development in this area is provided with an illustration of the structure determination of alpha-NaBi3V2O10

Comment on "Structure of NaBi3V2O10NaBi_3V_2O_{10} and Implications for Ionic Conductivity"

The recent publication in this journal by Sleight’s group1 describing the structure and ionic conductivity prompts us to comment on their observations in light of our earlier published work. Our publication clearly brought out the existence of two polymorphic modifications of $NaBi{_3}V{_2}O_{10}$ and we were the first to establish the structure of the R form from the ab initio powder X-ray diffraction technique. It may be pointed out that the work published by Sinclair’s group was ambiguous as the structure reported in ref 4 (\beta-form) was entirely different from the one reported in ref 3 for which the conductivity data were provided

Synthesis and structure of M0.5Bi3P2O10M_{0.5}Bi_3P_2O_{10} (M = Ca, Sr, Ba, Pb) series

A series of $M_{0.5}Bi_3P_2O_{10}$ compounds with M = Ca, Sr, Ba and Pb have been synthesized in $MO-Bi_2O_3-P_2O_5$ ternary systems by the ceramic method and the crystal structures were then solved using single-crystal X-ray diffraction data. These compounds are isostructural with $Bi_{6.67}P_4O_{20}$ (triclinic, space group P\bar{1}, Z = 2). The structures consist of infinite chains of $Bi_2O_2$ units along the c axis formed by linking $BiO_8$ and $BiO_6$ polyhedra. These chains are interconnected by $MO_8$ polyhedra forming two-dimensional layers in the ac plane. The phosphate tetrahedra are sandwiched between these layers

A novel oxide ion conductor in a doped Bi<SUB>2</SUB>O<SUB>3-</SUB>V<SUB>2</SUB>O<SUB>5</SUB> system: ab initio structure of a new polymorph of NaBi<SUB>3</SUB>V<SUB>2</SUB>O<SUB>10</SUB> via powder X-ray diffraction

The crystal structure of NaBi3V2O10 has been determined using the ab initio approach followed by Rietveld refinement via powder X-ray diffraction. The unit cell is triclinic, space group P, with a = 7.1964(4) &#197;, b = 7.0367(3) &#197;, c = 5.5139(2) &#197;, &#945; = 84.440(3)&#176;, &#946; = 113.461(2)&#176;, &#947; =112.319(2)&#176; , and V =236.46(2) &#197;3. The final refinements gave Rp = 9.94%, Rwp = 13.11%, and R(I,hkl) = 8.73% for 30 parameters and 4871 data points. These results indicate that this is a polymorph different from that reported previously and represents a new class of oxide ion conductors in solid solution of the Na2O-Bi2O3-V2O5 ternary system. The (Bi2O2)2+ chains extend along the c axis with VO4 units joining the chains along both a and b directions resulting in a hitherto unknown motif in this class of compounds. The structure hence points to a new mode for the mechanism of oxide ion conduction

Synthesis crystal structure and ionic conductivity of Ca<SUB>0.5</SUB>Bi<SUB>3</SUB>V<SUB>2</SUB>O<SUB>10</SUB> and Sr<SUB>0.5</SUB>Bi<SUB>3</SUB>V<SUB>2</SUB>O<SUB>10</SUB>

Two new compounds Ca0.5Bi3V2O10 and Sr0.5Bi3V2O10 have been synthesized in the ternary system: MO-Bi2O3-V2O5 system (M=M2+). The crystal structure of Sr0.5Bi3V2O10 has been determined from single crystal X-ray diffraction data, space group P1- and Z=2, with cell parameters a=7.1453(3) &#197;, b=7.8921(3) &#197;, c=9.3297(3) &#197;, &#945; =106.444(2)&#176;, &#946; =94.088(2)&#176;, &#947; =112.445(2)&#176;, V=456.72(4) &#197;3. Ca0.5Bi3V2O10 is isostructural with Sr0.5Bi3V2O10, with, a=7.0810(2) &#197;, b=7.8447(2) &#197;, c=9.3607(2) &#197;, &#945; =106.202(1)&#176;, &#946; =94.572(1)&#176;, &#947; =112.659(1)&#176;, V=450.38(2) &#197;3 and its structure has been refined by Rietveld method using powder X-ray data. The crystal structure consists of infinite chains of (Bi2O2) along c-axis formed by linkage of BiO8 and BiO6 polyhedra interconnected by MO8 polyhedra forming 2D layers in ac plane. The vanadate tetrahedra are sandwiched between these layers. Conductivity measurements give a maximum conductivity value of 4.54&#215;10-5 and 3.63&#215;10-5 S cm-1 for Ca0.5Bi3V2O10 and Sr0.5Bi3V2O10, respectively at 725 &#176;C