Structure property relationships in the ATi2O4 (A=Na, Ca) family of reduced titanates

Geselbracht, Margret J.; Erickson, A. S.; Rogge, Matthew P.; Greedan, John E.; Walton, Richard I.; Stoltzfus, Matthew W.; Eng, Hank W.; Woodward, Patrick M.

doi:10.1016/j.jssc.2006.07.024

Cited by 14 publications

(11 citation statements)

References 32 publications

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“…Thus, the Ti vacancy induced cation ordering in alternating Ti double layers seems to be very stable at variable temperature conditions, which is different from the case of superstructures in potassium tungsten bronze nanosheets, where the W vacancies become more uniformly distributed at higher temperature 15 . Moreover, the suggested phase transition at ~377 °C 6 does not happen in the current case. It is possible that the existence of cation ordering hinders the transition around T c , or the observed downward trend of magnetic susceptibility below T c is resulted from other factors rather than phase transition as the case of MgTi 2 O 4 .…”

Section: Resultscontrasting

confidence: 49%

“…The existence of Ti-Ti dimmers in CaTi 2 O 4 was also proposed from indirect experimental proofs 6,16 . In the standard CaTi 2 O 4 atomic model, the Ti-Ti distances within double rutile-type chains are 3.135 Å and 3.140 Å, while the Ti-Ti distance between Ti atoms in neighboring double rutile-type chains within a puckered sheet is 2.784 Å 6 . Figure 4d shows the single crystal model of CaTi 2 O 4 projected along c (top) and b (bottom) axes.…”

Section: Resultsmentioning

confidence: 96%

“…Considering the suggested structural transition of CaTi 2 O 4 at ~650 K (377 °C, T c ) 6 , the same sample with surface normal along [001] is heated from 20 °C (room temperature) to 500 °C. Figure 4a–c shows HRTEM images of specific area at 20 °C, 400 °C and 500 °C, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…As the ternary reduced titanate formed by the most close alkali metal to Mg, CaTi 2 O 4 was first synthesized and structurally characterized in 1956 4 , and single crystals of CaTi 2 O 4 was successfully grown in 1998 5 . It is predicted that CaTi 2 O 4 might experience a structural transition at 650 K ( T c ) based on the similar downward trend of magnetic susceptibility below T c 6 as compared to MgTi 2 O 4 7 .…”

Section: Introductionmentioning

confidence: 99%

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Atomic-scale analysis of cation ordering in reduced calcium titanate

Jiang

et al. 2017

Sci Rep

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The phenomenon of cation ordering is closely related to certain physical properties of complex oxides, which necessitates the search of underlying structure-property relationship at atomic resolution. Here we study the superlattices within reduced calcium titanate single crystal micro-pillars, which are unexpected from the originally proposed atomic model. Bright and dark contrasts at alternating Ti double layers perpendicular to b axis are clearly observed, but show no signs in corresponding image simulations based on the proposed atomic model. The multi-dimensional chemical analyses at atomic resolution reveal periodic lower Ti concentrations at alternating Ti double layers perpendicular to b axis. The following in-situ heating experiment shows no phase transition at the reported T c and temperature independence of the superlattices. The dimerization of the Ti-Ti bonds at neighboring double rutile-type chains within Ti puckered sheets are directly observed, which is found to be not disturbed by the cation ordering at alternating Ti double layers. The characterization of cation ordering of complex oxides from chemical and structural point of view at atomic resolution, and its reaction to temperature variations are important for further understanding their basic physical properties and exploiting potential applications.

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Section: Resultscontrasting

confidence: 49%

Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Atomic-scale analysis of cation ordering in reduced calcium titanate

Jiang

et al. 2017

Sci Rep

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“…Reduced titanates have a range of interesting electronic and magnetic properties (Cogle et al, 1991;Schmidt et al, 2004;Zhou & Goodenough, 2005;Geselbracht et al, 2006;Yang et al, 2008), as exemplified by the discovery of high-temperature superconductivity in SrTiO 3 and Li 1+x Ti 2Àx O 4 (Johnston et al, 1973;Jourdan et al, 2003). In 1956, Bertaut & Blum (1956 prepared reduced titanate CaTi 2 O 4 and determined its structure.…”

Section: Introductionmentioning

confidence: 99%

Growth mechanism of titanium monoxide TiO_xon a reduced calcium titanate CaTi₂O₄surface

Cong

Sheng

et al. 2015

J Appl Cryst

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This paper presents an electron microscopy study of reduced calcium titanate crystals (CaTi2O4) and the growth mechanism of titanium monoxide TiOx on a CaTi2O4 surface. Large high‐quality CaTi2O4 crystals were prepared using the molten salt flux method. The crystallographic directions and the growth direction of the CaTi2O4 crystalline needles were confirmed by electron backscatter diffraction and Kikuchi pattern analysis. The low‐angle grain boundaries in CaTi2O4 and the crystallographic orientation relationship between CaTi2O4 and TiOx were investigated using high‐resolution transmission electron microscopy. It is found that both the low‐angle boundaries and the amorphous area may play a key role during the growth process of titanium monoxide TiOx. The results presented here contribute to a better understanding of the detailed growth mechanism of TiOx on a CaTi2O4 surface.

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Structure Property Relationships in the ATi₂O₄ (A: Na, Ca) Family of Reduced Titanates.

et al. 2006

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A: Na is confirmed. Both compounds classify as small band-gap semiconductors. The Ca-containing compound possibly exhibits an insulator-metal transition near 700 K. While Ti-Ti bonding is of minimal importance in NaTi 2 O 4 , the Ti atoms in CaTi2O4 are weakly dimerized at room temperature. -(GESELBRACHT*, M. J.; ERICKSON, A. S.; ROGGE, M. P.; GREEDAN, J. E.; WALTON, R. I.; STOLTZFUS, M. W.; ENG, H. W.; WOODWARD, P. M.; J. Solid State Chem. 179 (2006) 11, 3489-3499; Dep. Chem., Reed Coll., Portland, OR 97202, USA; Eng.) -W. Pewestorf 01-013

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Structure property relationships in the ATi2O4 (A=Na, Ca) family of reduced titanates

Cited by 14 publications

References 32 publications

Atomic-scale analysis of cation ordering in reduced calcium titanate

Atomic-scale analysis of cation ordering in reduced calcium titanate

Growth mechanism of titanium monoxide TiO_xon a reduced calcium titanate CaTi₂O₄surface

Structure Property Relationships in the ATi₂O₄ (A: Na, Ca) Family of Reduced Titanates.

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Structure property relationships in the ATi2O4 (A=Na, Ca) family of reduced titanates

Cited by 14 publications

References 32 publications

Atomic-scale analysis of cation ordering in reduced calcium titanate

Atomic-scale analysis of cation ordering in reduced calcium titanate

Growth mechanism of titanium monoxide TiOxon a reduced calcium titanate CaTi2O4surface