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

Studies on Fruit Development in Pink and White types of Wax Apple (Syzygium samarangense Merr. & Perry) in Goa, India

Fruit development studies were taken up in white and pink types of wax apple trees aging twelve years old at Goa, India. The study was initiated with the onset of flowering in November during the year 2018. After tagging the flowers on anthesis, samples were drawn periodically to record parameters like fruit weight, fruit volume, fruit length and diameter (upper, middle and lower), quality or biochemical parameters like total acids and sugars. Relative growth rate (RGR) was calculated for all parameters and graphs were generated. In both the types, fruit weight, fruit volume, fruit length and diameter increased in a sigmoidal pattern. The quality characters like TSS, total acids and total sugars also showed a sigmoidal pattern of increase whereas the increase in reducing sugars exhibited a double sigmoidal pattern of increase. It was evident from the curves that there was pronounced peak in growth rate between 21 and 28 days after anthesis for fruit weight, fruit volume, fruit length and diameter, in both pink and white types of wax apple

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

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